Isotopic Investigation on the Evolution of Groundwater Dynamics in the Principal Aquifers in the Southern Dobrudja FINAL REPORT for the PERIOD 1983-12-01 - 1986-11-30

Report IMo. IfiEA R - 3621-F

TITLE Isotopic investigation on the evolution of groundwater dynamics in the principal aquifers in the southern Dobrudja FINAL REPORT FOR THE PERIOD 1983-12-01 - 1986-11-30

AUTHOR(S) Dr. Tenu, ft.

INSTITUTE Institute of Meteorology and Hydrology, Bucharest, Romania

INTERNATIONAL ATOMIC ENERGY AGENCY DATE December 198(í

i INSTITUTE OP METEOROLOGY AND HYDROLOGY Bucharest - Romania

ISOTOPIC INVESTIGATION ON THE EVOLUTION OF GROUNDWATER DYNAMICS IN THE PRINCIPAL AQUIFERS IN THE SOUTHERN DOBRUDJA

Contraot IAEA number J621/RB - Final report -

Bucharest - 1986 INSTITUTE Oí1 METEOROLOGY AND HÏDROLOGÏ Bucharest - Romania

LIST OF SIGNATURES

Head of Institute: Dro I. Draghici VA\^

Chief Scientific Investigator; Dr A. Tenu

Additional Scientific Staff: F.D. Davidescu Ana Slaves cu

Other Staff: M. Cunescu G. Mihordea ÂJp^ CONTENTS: %

I» INTRODUCTION 4

2« P3GI0NAL GEOLOGICAL AND HÏ.DROGEO LOGICAL CONDITIONS 5 2ol. Physiografical framework 5 2c2. Geological background 6 2.2.1. Bed rock ? 2.2o2. Sediment cover 7 2.2„3. Tectonics 20 2,3« Hydrogeological considerations 20 2.3.1° Short history of the research 21 2.3°2o Presentation of the aquifers 22 2.3.3» Elements of hydrochemistry 30

3. EXPERIMENTAL RESULTS AND DISCUSSIONS 37 3.1. Sampling network 37 3.2. Experiments 37 3o3o Validity of results 39 3.4-. Isotopic composition of meteoric waters ...... 40 3«5. Iso topic composition of surface waters ...„. 42 3.6. Isotopic composition of groundwaters 44 3.6.1. Globally-spacial characterization „ 44 3.6.2. The Sarmatian aquifer „. 47 3.6.3. The Barremian-Jurassic aquifer 51 3.7. Certain considerations on the age 14 correction methods of C 62

4O CONCLUSIONS 66

fy?*?'& .'~'*í*f&&^<^y APPENDED TABLES CONCERNING THE EXPERIMENTAL RESULTS ...... 68

TABLE I - Groundwater chemistry in the Sarmatian formation o 69 TABLE II - Groundwater chemistry in the Barremian-Jurassic formation 71 TABLE III - PRECIPITATIONS: Meteorological station Constantza 74 TABLE IV - SURFACE WATER: results of isotope analysis (sampling May 1984) 77 TABLE V - SURFACE WATER: results of isotope analysis (sampling May 1985) « 78 TABLE VI - SURFACE WATER: results of isotope analysis (sampling May 1986) <, 79 TABLE VII - GROUNDWATER: results of isotope analysis (sampling May 1984) e 80 TABLE VIII - GHOUNDWATER: results of isotope analysis (sampling May 1785) « 82 TABLE IX - GROUNDWATER; results of isotope analysis (sampling May 1986) 85 TABLE X - GROUNDWATER: results of § 15C and radio carbon analysis 88 TABLE XI - Table for chemical parameter computation required in radiocarbon correction 90 14. TABLE XII - Table for the computation of initial C activity (A,.) by means the Fontes-Garnier method ...? 93 TABLE XIII i- Comparative table of the ages computed by various methods 97

REFERENCES 100 1. INTRODUCTION

This work has been issued in the Institute of Meteorology and Hydrology, Bucharest - Romania in terms of the research contract 5621/fiB concluded with the International Atomic Energy Agency in Vienna. The extent of the contract was over three years, covering the time span: December, 1, 1983 - November, 30, 1986. The objective of the research was the application of environmental isotope technique to the hydrogeological study of Southern Dobrudja, a region fully justifying an isotopic study at a regional scale both due to the importance of ground aquifers and to the rate of anthropic changes. Among the major objectives considered, the following are worth mentioning: - delimiting the recharge areas of the Sarmatian and the Barremian-Jurassic aquifers; - determining certain hydrodynamics regional parameters of the two aquifers; - assessing the modifications undergone in the general framework of the regional isotopic distribution range with time, consequence to the surface waters influences. The approach of this study was a complex one which provided both a thorough understanding of the natural background (geology, tectonics, hydrogeology, hydrochemistry) and a judicious selection of the network of water points, as well as an efficient testing each year. The total number of determinations performed in situ, or in the laboratory, occasioned by this contract, was about 1,000 mostly devoted to analyses of environmental isotopes *H, D, 0, ^C and C As this paper is the final report of the research contract it covers the analytical results presented in the annual progress reports as well. - 5 -

2. REGIONAL GEOLOGICAL AND HTDROGEOLOGICAL CONDITIONS

2.1. Physiographical framework The area being investigated lies south-eastern Romania, namely the southernmost third of Dobrudja. It is bordered by the Danube in the west, the Bulgarian frontier in the south, the Black Sea in the east and the Capidava-Ovidiu fault in the north. From a morphological stand point, the region looks like a flat plateau domina- ting by its steep walls the Danube course and the Black Sea in the west and in the east, respectively. In point of alti- 20" tude, the region generally covers the O 120 240Km range 50-150 m, gradually higher towards the south-southwest ¡ Fig.l. Map showing the survey area. where the altitude reaches 207 m in the neigj bourhood of the border. As far as the hydrography of the region is concerned, it should be mentioned that the south Dobrudjan plateau shows the poorest network of permanent and half-permanent rivers in the entire Romania, i.e. practically 0 Km/Km . The valleys are generall shaped as canyons with steep symmetrical walls mainly reaching the Black Sea towards the east and the Danube towards the west. In the area adjacent to the littoral, there are some natural lakes of great economic, balneological and touristic importance among which, mention should be made of the Lake Siutghiol, Lake Techirghiol and Lake Mangalia. They occurred consequence to certain genetical mechanisms in old estuaries, lagoons, etc. (ARIADNÁ BREIER, 1976). j Even more important than the natural hydrographical network is the network of canals in the area. Mention should be - 6 -

first made of the great canal linking the Danube and the Black Sea, • open to navigation on its main course following the old track of of the Oarasu valley between Cernavoda and Basarabi (with the northern branch: Poarta Alba - Midia - Navodari still in work). There are also numerous canals making up the irrigation system which covers at present about 3,000 Km (i.e. 70% of south Dobrudja s surface). It is here, in the littoral area and the southern part of the region that the thermal regime recorded the highest values of the mean multiannual temperature in Romania - above 11°C. The multiannual average of the temperatures in January covers the tange from -2°C to +1°C, gradually increasing from the Danube to the Black Sea shore where it reaches the multiannual minima, -25° at Mangalia, while the multiannual average in July was 22-24°C with maxima up to 38,5°C at Constantza. The average multiannual amounts of precipitations recorded were something between 370 mm in the littoral zone (Mangalia, Constantsa) and 470 mm towards the south-west where the relief formations are higher in the neighbourhood of the Bulgarian border« These precipitation amounts are unevenly distributed in time and space and the rainfalls are of torrential type. Evaportion amounts to 850-950 mm which accounts for the half-arid climate in the region. The winds prevailing in the region blow from the north all the year round and at times, from the west; the annual average wind-speed exceeds 4-5 m/s.

2.2. Geological background Southern Dobrudja stands out from the adjacent region as a platform sharing the Carpathian foreland characteristics and defines itself as a self-contained geological-structural unit.. It is separated from Wallachian Platform by the Danube fault in the west, from the central Dobrudjan massif in the north by the Capidava- Ovidiu fault, while toward the east, it is continued with the Black Sea shelf. The basement of this unit consists of a crystalline bedrock covered by a thick unfolded pack of sediments deposits of various ages. The stratigraphical sequences outcrop either in land patches or. in the Danubian cliffs and the steep slopes of the valleys. Fig. 2 - Map of Southern Dobrud^a showing locations of the structural drillings and the geological cross-sections. WLrnavoda 1- The well having provided Í5061 structural data and the \ 5026 indicative; 2- Geolo- /J Medgidia - Castelu ical section line -*s ochirleni T^rS&=*^®*SQS3 Fig. 3).

Basarabi 5052

Techirghioj Lake

5033 Plopeni Lake *\ TaHageac Lake 5057

Mangalia ¡IV 15081 «ti - 8 -

2.2.1, Bed rook As the geological studies revealed, the basement of the south Dobrudjan platform was consolidated during the Karelian orogenesis. This basement does not outcrop; it was identified at varying depths only at the time of drilling in the areas west from the Siutghiol Lake (Palazu Mara - Coco su), at Cernavodä - Tortonfonu - Medgidia - Basarabi (Fig.3, section 2-2' and 3-5') ûn'd west from the Techirgiol Lake (Topraisar-Tuzla). It consists in granite gnais overlopped by mesómetamorphic crystalline schists and green schists. A significant uplift of the basement with mesozonal schists along the axis and green schists along the flank was revealed by the drillings at Palazu Mare (according to G. VASILESCU et al., 1964, the Jurassic/crystalline boundary is at 550 m depth). Another area of basement uplift in the fault ridge was identified et Tuzla - Topraisar by geophysical studies and by drilling.

2,2.2. Sediment cover In Southern Dobrudja the sediment cover lies in Silurian, devonian, triassic, Jurassic, cretaceous, tertiary and quaternary deposits characterized by a system of weak folds and numerous simple and angular unconformities* The Silurian, developed in the southern half of the south Dobrudjan platform was detected at 418 m depth in the area Tuzla and at 1,200 m around Mangalia (Pig.3» section 2-2'). It is represented by a series white quartzite and black clay covered by shales and fractured limestones. The Devonian lies in the south-eastern part of the region and was found by drilling south from Cobadin place (Fig.3» section II-II', IV-IV, 1-1« and 2-2'). On the whole, it i3 represented by clays, quartz sandstones, marls and marly limestone. The litho- f acial characteristic of the devonian deposit lies in the prevailii: pellite faciès for the Lover Devonian, detrital faciès for the Middle Devonian and carbonate faciès for the Upper Devonian. The Triassic, was put forth by drilling in the Adamclisi and the Lake Techirghiol areas (Fig.3, sections II-II1, III-III1 and 1-1•) where, beneath the.Jurassic ox cretaceous deposits, - 9 -

+200' 0-

-500-

-1.000-

-400 10 Km

-800- - 10 -

2-2'

+200

-500-

-1.000-

-1.500-

3-3' 1 +200- 2 î 3 -400 4 -800

-1.2001 10 Km

Fig. 3 - Geological cross-section of the Southern Dobrudja. Pc=precambrian: mesometamorphic crystalline schist; S=silurian: quartzy and argillaceous sandstone; D=devonian; clayey types, quartzy sandstone, marls, limestone-marls; T=triasic: quartzy sandstone; J=Jurassic: carbonate types; K-i ne=neocomian: marly and challcy limestone; K-i br = barremian: carbonate deposits prevailing in reef faciès; Ki al=albian: glauconitic sands, sandstone, conglomerates; K2 cm=cenomanian:micro conglomerates, sandstones, marly limestone and sands; K2 sn=senonian: prevailing chalky deposits; Pgo=eocene; nummulitic limestones; N^ to=tortonian: clays, cñalky sandstones, sands; N^ sm=sariaatian: prevailing limestones; Q=quaternary: loess deposits. 1- normal £eologi- cal limit; 2- geological transgression limit; 3- structural drilling along the cross-section; 4— structural drilling designed along the section. - 11 -

a formation of alternating quartzite and redish violet clay- sandstones was intercepted and considered a lower Triassic tinder germanic faciès by analogy with the lithofacies of the Wallachian platform. The Jurassic is the oldest formation outcropping, even if sporadically, in southern Dobrudja. Outcrops of Jurassic formations may be found south from the Cap idava-Ovidiu fault in spam locations between the Danube bank and the Siutghiol Lake (Ovidiu place); towards the south and south-east the Jurassic deposits lie under cretaceous and tertiary formations revealed by drilling everywhere in the region except the horst at Tuzla-Topraisar (Fig.3). From a pétrographie standpoint the Jurassic layer is made up of carbonate deposits (reef and dolomite limestones) while in stratigraphie terms the middle Jurassic layers (Bathonian and Callovian) and the upper Jurassic ones (Oxfordian and Kimmeridgian) were identified by means of fossil study. The thickness of the Jurassic deposits (Fig.4) generally varies within the range 500-800 m with the lowest values at Adamclisi-Cobadin and the highest at Oltina, Castelu and north from Negru Vodä. A roughly identical distribution of the isopachytes in the Jurassic deposits may be also found in the isobaths of the Jurassic bed (Fig.5). A bolt of the axis south Adamclisi-Cobadin with bilateral deepening towards SE and NW; the fault approximately following the canal between the Danube and the Black Sea induces another structural discontinuity, a deepening of the Jurassic bed north from the fault starting from NW and SE. The Cretaceous is largely developed in the south Dobrudjan platform occurring particularly on the valleys of the right side tributaries of the Danube. The paleonthological studies showed that all subdivisions of the cretaceous system from the Valanginian to the Senonian are present in the sequences of cretaceous deposits even if the chronology is not uninterrupted. The Neocomian outcrops in the western part of the region being investigated, in the Danube cliffs and in the drilling wells at Cernavoda and Pestera (Fig.5, sections 2-2* and 3-3*); it consists in chalk limestones covered by marly limestone. The Barremian ^s weH represented .in the area, covering the entire areal exception being made of a zone situated in the south - east (Fig,6). It outcrops along the right bank of the Danube, I*s, Pig. 4- - Map of the Jurassic depo- I sits isopachytes. 1- Jurassic deposits isopachyte and its value in meters; 2- fault affecting the Jurassic deposits and its relative movement direction; 5- area lacking Jurassic deposits.

Pig. 6 - Isopachytes of the entire pack of barremian-Jurassic deposits. 1- isopachyte and its value in meters; 2- area where the barremian and juras- aic deposits do not form a unitary pack; 3- area where only jurassio deposits are to be found (Jbar- remian eroded); 4- area where both the Jurassic and the barreraian deposits are Çochirleni Medgidia missing (eroded). Lake

B Ü

5 10 Km

1 '¿00— - 15 -

at Cernavodä, over both valley sides of the Carasu river (i.e. the canal linking the Danube and the Black Sea) and its main tributaries as well as on the bank of the Lake Siutghiol at Ovidiu; towards the south, the barremian deposits is open in narrow belts along all valleys reaching the Danube. The barremian deposits are placed transgressively over the ¿Jurassic ones thus making up a unitary pack of great hydrogeological significance in the entire area. It is orly in the area: Cernavodä - Tortomanu - Castelu.that a neocomian layer interferes between these two formations (Pig.6), The Barremian is mainly represented by pseudo-oolitic and reef limestones (facies urgonian) as well as higgly fissured and karsted dolomite limestones sometimes exceeding 400 m in thickness (e.g. F-5o48; Pig.3, section I-I1)• Against the background of Jurassic dolomites and barremian limestone small Agtian patches are encountered in the continental facies represented by sands, gravels and junks of cross stratification as well as many coloured kaolinitic clays. The albian deposits are of limitted expansion occurring particularly in the northern third of the area under consideration; these deposits consist in sands and sandstone with a basic microconglomerate horizon. The Cenomanian may be encountered outcropping over limitted areas along some valley sides in the north of the area being investigated (including the Carasu valley); in the south, the cehomanian deposits were traced by drilling up to the Bulgarian border (Pig.5). It is represented by a detrital facies with a phosphate microconglomerate at its bottom over which chalky free- stones, marly limestones and sands are disposed. The Senonian is transgressive over various older terms and is represented by a microconglomerate as a basement and chalky deposits thereon (white chalk with flint concretions and chalky marls). These formations outcrop along the Carasu valley and the river courses of northern and southern tributaries up to the shore of the Siutghiol Lake (at Ovidiu); deep in the ground the presence of the senonian deposits was signalled over an extensive area reaching south to the Plopeni and the Tatlageac lakes (Pig.9) in layers as thick as 500 m in certain locations. - 16 -

The Paleogene is represented in the region by paleonthological dated Eocene and Oligocène ones supposed in terms of lithological similitude. The Eocene was traced by drillingj it consists in a continuous patch in the sout-eastern extremity of the region (Fig.9) on quartzy sands, sometimes glauconites with rare intercalations of chalky sandstone covered by gritty nummulitic limestones. Some clay dysodile schists, traced by drillings south from Mangalia place were assumed to belong to the Oligocène. The Neogene is represented by Miocene (Tortonian and Sarmatian) and the Pliocene. The tortonian deposits are transgressive and reach a thickness of up to 1 m in general; they consist of a greenish or yellowish clay horizon over which limestones, chalky marls and chalky sandstones are displayed. The Sarmatian is well developed in southern Dobrudja, displayed as an almost continuous plate in the whole area, south- east from an imaginary line which might link Bäneasa place and Lake Siutghiol (the lo m isopachyte). The thickness of this formation is increasing continuously and reaches 100 m in the area Lake Tatlageac and even 150 m south from Mangalia (Pig.7). The map with the bedrock isobath (Fig.8) emphasizes the existence of two high zones (west from Negru Voda and Cobadin) with a lowering towards the south-east down to -200 m near Mangalia place. The sarmatian deposits outcrop over large valley sides along main rivers. Within the sarmatian deposit two layers of different ages were distinguished: the Middle Sarmatian layer (Bessarabian) consisting of greenish base clay and limestones having diatomlte and bentonite intercalations and un Upper Sarmatian layer (Kersonian) in chalky faciès represented by oolitic limestones with thin clay intercalations as well as sands and chalky sandstones. The pliocene deposit only occurs in the Danubian area (Fig.9) as a consequence to a transgression from the Dacian basin, when formation belonging to the Pontian (marl type of deposits) the Dacian (prevalingly sandy) and the Levantine (lake and clay limestone were deposited. During, the Quaternary, South Dobrudja developed as a lift region. Although deposits belonging to the lower Pleistocene and Fig. 7 - Isopachytes of the sarma- +"iian deposits. 1- Isopa- yy chyte and its value in meters; sy 2- discontinous sarmatian area If having thickness of less ^^y =::::: than 10 m. /^ ^ Pig. 8 - Isobaths in the sarraa- tian bed. 1- Isobath, To tomanu and its absolute level; ternavodaA L 2- discontinous sarmatian area having thickness of less than 10 m. l#

M 00 te. i*y

ß U 5 10 Km

1 10. Piß» 9 - Map of the areal extension minor aquifers. 1- Well ving provided structural data its indicative; 2- geological tion line; 3- areal extension the senonian deposits; A— sam of the eocene; 5- same, < the pliocene.

/x\ x-x-x-x-x, ^j it - xV- x- x- x- x-/ / - x-\5058x_ n.J. cnnc x *. » Manga1" .. ene/. ..XSOft?—.

--- /" - 2o -

Ho lo cene are worth mentioning here, account being taken of their regional significance only the loess deposits of eolian origin belonging to the Middle-Upper Pleistocene with a reddish, sandy clay and frequent clay intercalations representing fossil soils.

2.2.3. Tectonics The South-Dobrudjan platform stands out as a lift region on the Danubian fault against the Wallachian Platform. The consolidation of the south Dobrudjan platform took place during the karelian orogenesis; further on the baikalian orogenesis brought about a heavy fracturing of the basement very much like a ruptured tectonics which divided it into blocks (Fig.3). The sediment cover overlopped in several major cycles, i.e.: the Silurian-Devonian, the Triassic-Upper Cretaceous and the Eocene- Sarmatian. These deposits undergone numerous orogenetical stages which led less to their folding than to disjunctive tectonic thus genera- ting an uneven tabular structure of fracture lines. Besides the tectonic lines of major importance such as: the Danube fault and the Capidava-Ovidiu fault there is a network of faults in southern Dobrudja generally directed east-westwards and north-southwards dividing the region into an alternating sequence of horsts and grabens. Of particular hydrogeological significance among these are: - the Palazu uplift, where the barremian-jurassic deposits outcrop on the Siutghiol lake shore; - the Tuzla-Topraisar horst (in the Techirghiol lake area) having the role of hydrodynamic barrier for the waters from the Jurassic aquifer; - the uplift of the Oobadin, and - the lowlands south from the Mangalia Lake, both,to be found as such in the Jurassic and sarmatian deposits (Pig. 5 and Fig.8).

2,3. Hydro geological considerations As is has been shown by this review on the geological structure in southern Dobrud.ja, there are favourable conditions for groundwater deposit formation at varying levels from the crystalline besement to the quaternary loess deposits. Of particular interest from an económico standpoint are only two deposits: - 21 -

the sarmatian and the barremian-Jurassic aquifers as they have a satisfactory potential yield and significant expansion. In order to build up a complete hydrogeological image of the area one could add the so-called minor aquifers, i.e. the pliocene, eocene and senonian ones having limited importance.

2.3.1« Short history of the research . • The earliest attempts in the study of the south Dobrudjan hydrogeo logy were carried on by G. MAOOVEI who drew before the World War I a general hydrogeo logical map defining by hydro isohyps es the expansion of three aquifers having developed within the pliocene and sarmatian deposits. After 194-0 drilling works were initiated to various purposes and the data thus acquired allowed of working out a first hydrogeological synthesis of Dobrudja (R. CIOCIEDEL and EM. PROTOPOPESCU FACHE, 1955). TMs synthesis is supported by a sketeley hydrogeo logical map of the region describing the pliocene, sarmatian and lower cretaceous aquifers. After 197o the hydrogeo logical research in South Dobrudja gathered full swing; numerous drillings were performed, zonal studies were published involving multiple subjects and aspects (A. TENU and G. NEACSU, 1968; T. NIOOLAE et. al. 1983} F.D. DAVIDESCÜ etîal.1983, etc.). Various hypotheses on aquifer recharge are debated (1973) &nâ doctor degree papers are written about certain zones within this area (N. PITU, 1981; R. TODEA, 1982). The isotopic research in Dobrudja began in 1971 by tritium and deuterium analyses (A. TENU, 1973). At that time isotopic iso- gradients (D) were traced for the barremian-Jurassic and sarmatian aquifers, suggesting the location of recharge areas for the aquifers being investigated and the role of hydrogeological barrier played by the Tuzla-Topraisar horst was identified also emphasizing the water migration from the Jurassic to the cenomanian. A more comprehensive study for the range of environmental isotopes (D, 0, ^C and C used in few investigation points was published two years later (A. TENU et. al., 1975). The study was mainly f o cussed on the barremian-jurassic aquifer for the first time supported by concrete elements concerning the recharge aquifers, the main flowing direction and speeds, the modifications of the hydrodynamic pattern in time, etc. The data provided by this study - 22 -

facilitated working out an APPENDIX in which attempts were made turning into account the deuterium excess in the groundwater as an index of palaeotemperatures and finally of water ages. All the isotopic data acquired up* to 1980 lay at the basis of a synthesis (A. TENIS et al., 1983) briefly resuming the conclusions already reached for South Dobrudja both as far as the regional study of the main aquifers and of some local aspects are concerned* Among the problems of local interest mention should be made of the interrelations between lake Siutghiol and the groundwater captations on its western shore having facilitated the application of a tritium based isotopic method for the quantitative assessment of the water mixture (A« TENU, 197o). Due to its practical interest the phenomenon was analysed every year up to 1980 (F.D. DAVIDESCU, 1981). It was also within the isotopic research that the study carried out by L. BLAGA and L.M. BLAGA (1976) should be mentioned for its, concern on deuterium concentration in the surface waters in the area.

2.3.2. Presentation of the aquifers Before embarking on any presentation of the main aquifers some briefing on thejninor_açjuifers will be given. Their expansion over the areal is rendered in Pig.9. - The pliocene aquifer developed discontinuously along the Danube, over a stretch of varying width up to about 15 Km. The main aquifer layer is stored within the prevailingly sandy dacian; above this, two other layers are locally superposed on a clay layer support still less significant from a potential and quality standpoint. The flowing direction of water in this aquifer is southeast-northwest, from piezometric levels of 105 m (south from Ostrov) towards the levels below 80 m (Oltina). This aquifer, being of little economic importance, is not drilled but makes itself manifest by some springs. - The eocene aquifer developed in.the south-eastern part of the region, south from the Techirghiol lake. Its waters are stored within the numulite limestones at the top of the eocene and locally in the sands separated from the sarmatian by a greenish bentonitic clay to be encountered everywhere in the area except for the Tatlageac Costinesti, N. Pitu's studies (1981) based on level measurements and water chemistry showed that there is no continuous hydraulic link between the eocene and sarmatian aquifers and that the permeability - 23 -

in the eocene deposits is 20-50 times lower than of the sarmatian. Mention should be made that the eocene waters contain small amounts of HpS which turn them inadequate for drinking ar household uses» These reasons account for the.little interest shown in understanding the eocene waters so far. - The senonian aquifer developed in the central-eastern part of the area connected with the chalk deposits; the aquifer bed is made of greenish marly clay towards the upper part of the senonian formation. The waters within this aquifer flows from the south northwards (B. CIOCIBDEL and EM. PBOTOFOPESCU-PACHE, 1955) due to the link with barremian-¿Jurassic aquifer and to water migration from the Jurassic deposits of the Mangalia zone towards the cenomanian and senonian layers in the Tuzla-Topraisar horst. She main hydro geo logical parameters of the chalky aquifer (M. EASCU, 1983) are: coefficients of hydraulic conductivity, K = 0,02 - 10 m/day and the coefficients of transmissivity, T s 50 - 1,000 m/day2 ; the well capacity were something betwwen 1 and 30 1/s for lower ings of water table of 0,5 up to 20 m, depending on the intensity of the tectonic fissuration and on the physical alteration. The sarmatian and the barremian-¿Jurassic aquifers are considered among t>ke_ma¿or_ac¡uifers belonging to the area under study. As the geological description showed, the sarmatian deposits of a prevailingly limestone faciès, locally fissured and karstified, may be encounteread almost all over South Dobrudja. Although, due to their lithofacial nature they are capable to store water, being based on an impervious clay horizon, the sarmatian deposits are significant from a hydrogeological viewpoint only in the south- eastern part of the region, where then depth exceeds 10 m (Pig.?) and where, the aquifer continuity, is also provided by the lover degree of morphological fragmentariness and the deeper layer. Of particular importance in this aquifer is its south-eastern part, a border area to Bulgaria, one side parallel to the seashore - line which would, pass through the Negru Vodä up to the canal linking the Danube with Black Sea in the north. This last area is characterized by 50-150 m depths of the sarmatian formation and by an obvious south-eastern lowering (from +60 m at Co badin to -200 m from the Mangalia Lake). It is worth mentioning that the sarmatian deposits snow a dorsal along the line west Negru Vodä - Plopeni - Cobadin which - 24 -

undergoes lowering in the west and especially towards the east- south-east (Fig.8). The hydroisopiestios of the sarmatian aquifers drawn in terms of the information received from different sources (Fig.lo) reveal a quite complicated hydrogeological pattern. The existence of a supply from the pre-Balkan zone (Bulgaria) in the north may be noticed as well as a quite extended "plateau" in the Cobadin zone and divergent radial flow directions better represented in the eastern half of the area. The hydraulic gradients vary from 0.01 in the areas south from Constantza and south from Bäneasa to 0.004 in Negru Vodä reaching even lower values in the area between Lakes îîangalia and Techirghiol. From the standpoint of its levels the sarmatian aquifer makes itself manifest in differentiated ways: - in the western part of the Negru Vodä - Plopeni - Cobadin dorsal, where the entire group of sarmatian formations occurs above the valley level, the aquifer has a free level and makes generally manifest through contact springs} - in the eastern part of the dorsal, the layer gets lower down, is pressurized and consequently will come out only upwards by drilling. It is only in some areas on the cliff of the Black Sea and on the banks of the Techirghiol, Tatlageac, Mangalia lakes, where the sarmatian is partially intercepted by the local morphology that this deposit makes itself manifest through errosion springs. The main hydraulic parameters of this aquifer are: the coefficient of hydraulic conductivity K = 0.02 - 5.0 m/day, the coefficient of transmissivity, T = 50 - 300 m/day and the well capacity (Q) are somewhat between 0.02 and 10 1/s with lowerings of water table of 0.5 - 10 m p It should be also added that about 1,300 Em. of the area under consideration being of hydrogeological major importance and therefore the sarmatian aquifer is turned into account for household supply and various other uses; in this respect eleven water catchments were organized as well as numerous individual drilling points which amount to 120 wells in all. The average yield exceeds 1 nr/s. The hydraulic improvement structures and management carried on since 1970 led to an increased level of the sarmatian groundwater (even by more than 15 m in the Lake Techirghiol area). Fig. 10 - Hydroisopiestics of the sarmatian aquifer (processing of the data supplied by the Geological Institute-1969, H. TODEA-1982 and the authors' observations-1984-). 1- Well having provided level Cernavoda Tortoinanu data; 2- hydroisopiestic and its absolute level; 3- direction of flow. - 26 -

The barremian-jurassic aquifer is linked to the reef and dolomite limestones even turned tectonic and karstic here and there thus forming a unit whole in all Southern Dobrudja (Pig.6). It is only in the northern part of the area (Cernavodä-Tortomanu-Castelu) that the Jurassic and the barremian aquifers are separated by neocomian deposits consisting of little permeable marls and clays. It should be also noticed that in the Tuzla-Topraisar horst, the entire barremian-jurassic complex is missing while in an aria adjacent to this only the barremian is eroded as the Jurassic is present. As far as the depth of the unit pack of carbonate barremian- jurassic rocks is concerned, one can notice a gradual decrease from the west (the Danubian area) eastwards, i.e. from 1,100 m in the neighbourhood of the lakes Oltina and Dunäreni to 400 m at Mangalia and Constantza (Pig.6). The contribution of the Jurassic deposits is over 50% (Fig.4). The hydro iso pies tics of the barremian-¿Jurassic aquifer drawn on account of the data supplied by the drillings in 1970-1983 (Fig.11) show a recharge from the pre-Balkan Platform with SW - HE flowing direction in the neighbourhood of the border; this flow then becomes radially divergent, towards the east in the south - eastern part of the region and towards the north-east and north in the central and northen parts of the region. A particular case is encountered immediately south from Tuzla-Topraisar in the Lake Techirghiol area. The flow is directed NE-SW finally reaching to Mangalia. The hydraulic gradients are generally small ranging from 0.0002 in the central part of the region under consideration (Cobadin - Pestera - Medgidia) to 0.0005 in the area Baneasa - Lake Tatalgeac and even 0.0016 south-east from Constantza. The piezometric level of water in this complex is ascending almost everywhere in the region excepting an area situated south from the horst Tuzla-Topraisar where it makes manifest artesian under pressure head of up to 15 m. This is in fact the only area in the region where the level of barremian-Jurassic is superior to the sarmatian. These two elements corroborated with the changed flowing sense seem to indicate the existence of a very deep water inflow from the ante-Jurassic formations, very probably devonian, ascending through the south Fig. 11 - Hydroisopiestics of the barremian-àurassic aquifer (the map is based on the data obtained in situ, in the period 197O-tl983). 1- Well having provided level data; 2- hydroisopiestic and its absolute level; 3- direction of flow.

ß u 1. o

2.^-15 5 10Km 3. - 28 -

boundary horst fracture under the impulse of a higher reservoir pressure than the immediately higher aguifers. This link between aquifers and tectonics is confirmed by the fact that consequence to the tremor do us earthquake of March, I977 a well in the horst drilled for catchments in the cenomanian hydrulically linked with the ;jurassio began to behave strongly artesian. Somewhat slighter, the behaviour was the same with F-IMH situated on the shore of Lake Siutghiol. To make the hydrogeological image of this aquifer more complete, one should add that the Juras- sic on the western shore of Lake Siutghiol was artesian since old times (at Caragea-Dermen, north from Constantza there were catchment spring as early as in ancient Roman times) up to 1950-1955 when the several wells drilled in the area, out of which one is situated in the very Lake Siutghiol, 500- m from the shore, revealed piezometric levels of +5 ... +6 m. The aquifer layer from the barremian-jurassic in the neighbourhood of Lake Siutghiol is bordered in the north by the displacement line of Capidava-Ovidiu reaching the lake; along this fault the Jurassic aquifer discharges naturally, the lake being permanently supplied with about 1.3 m/s by means of some springs situated under the lake bottom. The main hydrogeological parameters of the barremian-Jurassic aquifers are: coefficients of hydraulic conductivity K = 1.0 - 20.0 m/day, transmissivity T = 250 - 6500 m2/day and the discharges (Q) obtained are generally ranging from 3 1/s to 150 1/s frecu^ntly taking average values of 10-20 1/s for drawdowns of several meters. Fig.12 shows the areal distribution of the coefficients of hydraulic conductivity, in good relation with the zonal distribution of transmissivities. Mention is made that then is an obvious areal variability of the relative productivity of the two formations making up this aquifer: as the barremian and the Jurassic have almost equal discharges in the south-western half, in the north-eastern part the Jurassic becomes much more productive. The barremian-jurassic having an extensive spread all over southern Dobrudja, it stands out as the major source of water supply for Constantza, the northern part of the fiomanian littoral and many other social-economic objects. This supply is achieved by means of

_ ÍLO Fig. 12 - Coefficients of hydraulic conductivity (m/day) of the barremian-jurassic aquifer (the map Tasaul Lake is based on the data obtained in the period 1970-1983). 1- Well having provided hydraulic conductivity data; 2- isoline of hydraulic conductivity and its value in m/day.

( 0 J/? •) Techirghio ^ Ostrov £~Bugeac Lake

e u

0 5 10Km

1 • 2 ->* - 30 -

several catchments the most significant of which are situated along the western shore of Lake Siutghiol: Caragea-Dermen, Cismea I and Cismea II, besides numerous single wells. The total number of operation wells is estimated at about 150 extracting a discharge of over 5. m/s from the area. This discharge comes rouggly from the three catchments mentioned above (3 m/s).

2.3.5» Elements of hydro chemistry The sarmatian and barremian-áurassic aquifers will be mainly referred to as far as the hydrochemical elements are concerned. As for the_sarmatian_a<3uifer Table I presents 21 complete chemical analyses with the major ions given both in mg/1 and in me/1; the ionic formulae were also established and two characteristic ratios were computed. The chemical analyses do not come entirely from the hydrogeological wells in use and they do not correspond to the isotope sampling network. The location of waterpoints having the order numbers as in Table I is shown in Fig.13» As shown by the distribution of the values taken by the fix residual shomwn in the paranthesis there are only two points having values of over 1,000 mg/1, the largest amount of values being something in the »ange 550-750 mg/1. One cannot establish a firm sense of development for this parameter within the area being analysed. Interesting information is supplied by the ratio rSO^/rCl. The highest value is encountered in P-3 Credinlpa (point 6) situated in the neighbourhood of fresh water accumulations on the Urluia valley. The low values are grouped in the neighbourhood of some faults and they increase with the departure from the faults; this becomes ever more obvious in the case of points: 11 - Amzacea and 15 - Gostinesti situated very near the fault bordering in the south the horst Tuzla-Topraisar as well as point 2o - Mangalia on the fault Lake Mangalia (cf. Fig.4). However, the hypothesis holds true that all points situated in the neighbourhood of some faults low values taken by this parameter. As the area situated south from the horst Tuzla-Topraisar is the only one having the reservoir pressure in the barremian-¿Juras- sic aquifer higher than in the sarmatian and the points quoted for a Fig. 13 - Hydro Chemical map of the Sarmatian aquifer waters. 1- Water point supplying hydrochemical information with the index of the order number (cf. TABLE I) and the TDS (mg/1); 2-4- Cationic formulae.

Medgidia Castelu

Techirghi Lau 1(590) I ,-V W654) / I

Tatlageac Lake )*^ W600) i •M(760)

2. ICa>Mg>Na+K Negru Voda 0 3. IlMg>Ca>Na+K 4. IIlNa+K>Mg>Ca 100

Pig.14. Piper diagrame for Sarmatiaa aquifer waters %:Saibev0 assiSned correspond to those in*

*S04/rCl ratio dependence on tectonics snow an ascending transfer of NaCl-rich water. The diagram presented in Pig.14 renders the global ionic and anionic characteristic of the sarmatian waters. Thus, from an anionic viewpoint the waters are quite homogenous, almost equally bicarbo- nated, chloride and sulphur. In cationic terms thés are prevailingly of sodxum, calcium and niagnezium type in almost equal ratios. - 33 -

As far as ï;ke_barremian-3urassiç_aa,uifer is concerned Table II of similar content with TábllT, shorts 33 complete chemica: analyses derived from the hydrogeological drillings carried out in 1970-1983 account being taken of the structural data as well. The Piper diagram in Pig.15 is first and foremost showing the fact that the water belonging to this complex are very similar -to the sarmatian water but several water points (numbers 25, 26, 28, 29, 3o, 31, 32) show higher Na(K;)Cl contents.

100 0 0 20 M> 60 80 100 Ca

Pig.15. Piper diagram for Barremian-Jurassic aquifer waters. The numbers assigned correspond to those in TABEE II. Pig. 16 - Distribution of the TDS (mg/1) for the Barremian-Jurassic aquifer waters. The map was drawn in terms of the information obtained on drilling in 1970-1985 (TABLE II).,. rtfavoda Tortomanu 1- Water point having supplied hydrochemical data; 2- Isoline and its value (mg/1); 3- Area lacking Barremian- Jurassic deposits.

Ostrov C^Bugeac Lake

8 U

S 10 Km Fig. 17 - Areal zoning of the Bar- reihian-Jurassic complex according to the water ionic formulae. 1- Water point having sup- Cernavoda Tortomanu plied hydro chemical information; 2- area lacking Barremian- Jurassic deposits; 3_8- ionic formulae. 0

Mg>Ca>Na+K

Na+K>Mg>Ca

>Mg>Ca - 36 -

This "be comes obvious in the an ion triangle where these points are individualized as a separate field. The study of the territorial distribution of these points showed that they cover exclusively the areal situated south from the horst Tuzla-Topraisar, up to the border. In fact, superposing the two Piper diagrams one can conclude that the water chemistry of the two aquifers in the area under study is roughly identical but the waters in the barremian- jurassic are richer in alkaline and chloride sails still poorer in sulphates. This conclusion is obvious when the series of rSO^/rCI values for the two aquifers (Tables I and II)„ Prom the total mineralization standpoint both the data in the table and the isolines in Pig.16 show that in most part of the region the values are within the range 400-600 mg/l; only in the south of the horst Tuzla-Topraisar and accidentally in the north, where the total mineralization exceeds 1400 mg/1 (Mangalia). The shape of the isolines shows a progressive development from the southwest (minimum values) along two separate dirctions, aport from the horst: to the east and to the northeast, the latter being strongly disturbed in the area of maximum development of the senonian chalks. Figure 17 showed a zoning of the hydro chemical type of water in the barremian-Jurassic complex according to some ionic formulae given in the legend of the image and following a sequence that mirrors in general the stages of hydro chemical metamorphosis. It should be first noticed that the sequence of zones I-II-III-IV-V-VI coresponds to the increase of total mineralization shown in Fig.16. The occurence of a small area of type I (Castelu-Basarabi) is generated by a recharge through a typical surface waters having penetrated through the permeable senonian chalks. - 37 -

3. EXPERIMENTAL RESULTS AND DISCUSSIONS

Jol. Sampling network. The study of aquifers in Southern Dobrudja was mainly based on the determination of environmental isotopes (-'H, D, 0, C and ^C) but alongside with therm other physico-chemical parameters were determined both in situ and in the laboratory, i.e. specific electrical conductivity, liardness, alkalinity, pH, etc., which stand as useful parameters either in certain interpretations Tit \-z and in correcting radiocarbon ages. Excepting the " C and ^C analyses which were carried out at a single stage, all determinations were resumed annually using samples taken in May from a network of waters points maintained unchanged. The selection of sampling points to make up the network took place at the first stage of the study according to an original and consistent outlook upon the natural framework and to the thorough analysis of the present state of each well in view of observing three major objectives: - a mostly uniform cover of the territory; - the choice of representative sampling points; - the certainty that, with groundwater aquifers, the selected wells capture the aquifer being investigated, exclusively. In order to provide a mostly comprehensive image of the spacial isotopic distribution in the region and in view of studying the inter-relationships between various types of waters, a smaller set of sampling points from minor aquifers (Pliocene and Senonian) as well as from the surface waters (the Danube, the Black Sea, the littoral lakes, the irrigation network) were also considered besides the main aquifers (Barremian-Jurassic and Sarmatian). Likewise, the systematic sampling and analysis of atmospheric precipitations in the area was organized at the meteorological station Constantza over an almost three year interval. The network thus devised is shown in Figure 18. 3.2. Experiments. As far as its concerns the way the isotopic analyses are carried out, the following specifications call themselves to the fore: - tritium was determined through spectrometry in liquid Fig. 18 - Sampling points for water from Southern Dobrudja. 1- Rainfall; 2- surface water; 5- groundwater from the pliocene aquifer; 4— same, sarmatian; 5- same, senonian; 5- same, barremian-Jurassic; A- the canal Danube-Black Sea; B~ major irrigation canal. The numbers are those in TABLES IV-X.

• Ostrov/'-'Bugeac Lake

—0"t 5 —20- B PlópeniLake ' \ ° u 19m * VaHageac Lake y j °7i 10 Km Negru Vodâj 21*® 1# 2vfl 7 , - 39 -

scintillation after a mono s tage electrolitical enri clament. The measurements were performed using a liquid scintillation spectrometer TRI-CARB Packard model 3320, the significance threshold being usually 5 TU; - radiocarbon was also determined by spectrometry in liquid scintillation using the benzol which was synthetized from a BaCO* precipitated in the field from the water sample. The measurements were performed, as.in the case of tritium, by means of the same device, the significance limit being usually 2 p.m.c; - the stable isotopes D, 0 and '0 were determined using a mass-spectrometer, type Varian System MAT 250 after a preparation according to the classical methodologies. The accuracy of the isotopic analysis was Í0.1%o for oxygen and carbon and íl%o for hydrogen.

3o3- Validity of results. The total number of determinations occasioned by this study exceeded 1,000 out of wich 600 were isotope analyses. The results of these analyses are given in the tables attached at the end of this paper. Table III covers the results on precipitations, Tables IV to VI refer to surface waters while Tables VII to X refer to groundwaters« The final three tables in the annex (Tables XI to XIII) cover the computation data for the radiocarbon ages corrected through various methods. In spite of the particular care shown in selecting the "secure" sampling water points to assess the age of the aquifer formation and also despite the careful sampling process two cases still occur red when the water samples being investigated were derived from other formation than the one initially supposed. These special cases were found, on account of the experimental data, no sooner than the final stage of interpretation. However, we chose not to modify the initial order established in Tables III-X in oreder to avoid confusions and inadvertencies as to the data previously comunicated in. the progress reports. The former of the above mentioned cases is the Oltina - spring (item I„2 in Tables VII-IX) having been considered to drain undoubtedly the Pliocene aquifer; however, the experimental data finally proved that its waters derive from the Barremian-Jurassic aquifer. - 4o -

The latter of these cases was the G and ^C analyses assumed to have been performed on the water captured in F- Plopeni (item IV,18 in Table X) and belonging to the Barremian- Jurassic aquifer. By the time the carbonates were being sampled the F~5o74- well was inoperative because of some checking-up opera- tions and therefore the samples were taken in another well in the area, supposed to capture water from the same aquifer. The isotopic results proved that the well having been used was in fact draining in the Sarmatian. This aspect was further on confirmed by the lithological checking-up o Considering the unreliability of these data they were not considered in any of the interpretation for either of the formations o It should also be mentioned that some degree of uncertainty concerning the origin of waters in the Dobromir Deal and Báneasa springs; they were considered to drain the sarmatian aquifer in terms of geological grounds. This uncertainty was suggested by the age determined through radiocarbon while the other isotopic analyses failed to sort things out. These points were finally taken into consideration for the Sarmatian aquifers, under certain reserve» Last but not least, it should be mentioned that, according to the latest interpretations some pairs of isotopic values seemed doubtful, probably consequence to some analytical errors and were, therefore discarded in interpretation; it is the case of the precipitations fallen in April 1983 (Table III) and of twelfth point - Sarmatian - in 1986 (Table IX).

3.4. Isotopic composition of meteoric waters. As it has already been mentioned, all the experimental data concerning precipitation water are given in Table III«, The data on stable isotopes helped drawing the correlation diagram shown in Fig. 19«. It emphasizes the fact that the local monthly precipitation points (L-iJWL) are approximately around a general correlation line of the precipitations (the mean world line -MWL), but the analytical computation of the regression line led to a slightly different equation, i.e.

5D = 7.2o18O + 3,2 (1) -20

|5D = 8.17 8180*10.56 -40

• \,

\ •60- Q §D=7.2 S18O*3.2J I/O n=30; r=0.96;

•80

•

-100 /

-13 -11 •9 -7 -5 -3 §180 %o

Fig. 19. The oD -5 0 diagramme of the local precipitation water (L-MWL) at the station in Constantza. These points represent determinations performed in the time interval 1983-1986,, The empty square renders the isotope composition of the input function computed as a weighted mean over the period November - March inclusively*

The intersection point of this line with the iäWL has the coordinates 5D = -58.0%o and 5 0 = -8,5%o- In comparison with the equation found by A. TEÎÎU and FoD. DAVIDE3CU (1984) for the precipitations in western Romania, o*D = 6,7 5 0-3,1, this equation draws nearer the classical MWL formula but it keeps still quite remote from A. KIR's line (1967) whose deuterium excesses relative to a mean ocean water was +22%o. This proves the fact that at least in the sampling interval the meteoric waters in Southern Dobrudja did not show the classical characteristics of the East-Mediterranean region from an isotopic standpoint as we expected in terms of the previous studies (A. TENU et al., 1976). - 42 -

Another element that should be "brought to the fore is the fact that the shape of the computed correlation line for meteoric waters suggest the existence of some evaportion phenomena during the rainfall, probably consequence to low relative humidities, with high temperature ranges. The computation of the local input function was in terms of the weighted mean which considered the low temperature interval (November - March, inclusively, n=10) according to the formula below:

w where, P refers to the amount of precipitations and § to the isotopic composition. The values thus computed are:

18 S ow = -li.o %o these values are shown in Fig.19 as well. The input function for ^H was computed in a similar way, n=13, wich resulted in: A\ = 27.6 TU

3»5- Isoto pic composition of surface waters. The isotopic composition of surface waters is given in Tbles IV-VI, corresponding to the years 1984, 1985 and 1986, respectively. The review of the sampling water points and of the experimental results shows the existence of very different surface waters in the area, from the isotopic standpoint. Thus, the Black Sea and the littoral lakes are characterized by heavy isotopes in large concentrations, while the Danube and the canals have low such concentrations. This genetical separation is clearly illustrated by ]Pigo2o. Of particular interest for the relationship between surface and groundwater is the group Danube-canaIs, wich might stand as the recharge source of shallow aquifers in certain zones. The spring multiannual mean of isotopic composition for this group of waters was computed as an arithmetic average, resulting in the following values: 5D = -75,7 %o ; 5180 = -10.1 foo - 43 -

-20-

-40

Danube and /, chañéis group ^\NN»V /C , o -60- / Black Sea and i/o lakes group

•60 • ; f 2 • 3 100-

-S

1Pig.2O. Correlation §D - 51 0 for the surface water in Southern Dobrudja; 1.-determinations carried out in 1984; 2.- in 1985; 3.- in 1986; 4.- the average isotope composition of the surface water in spring (multiannual average).

These values are figured on the § D - § 0 diagram for the surface waters (Pig.20). It is also this diagram that shows the disposition of the values (found over the three research years for the surface waters) within a belt along and below the L-MWL which could be interpreted as a consequence of some more or less significant evaporation phenomena, depending on the water body. Taking into account only the values corresponding to the year 1986 a regression line for the surface waters of the form below was found: SD = 4.9 S180 - 14 (3) for n=8, with r = o„98 - 44 -

3.6. Iso to pic composition of grouttdwaters.

3o60lo Globally-spaoial characterization. The iso topic concentrations determined in the grotindwaters having been investigated along the three years of study are shown extensively in Tables VII-X. For a more convenient global characterization mean values were computed, moreover for the year 1986» according to types of waters or aquifers. These values are further on presented in three synthetic tables.

Stable isotope mean concentration according to water types in Southern Dobrudja Table 1.

i r Type of water - n - n z: SD %O ö0

Meteoric waters 30 -58.9*15,6 -8.6*2«1 Surface waters 8 -42.9*19.6 -6,0*3.0 Pliocene aquifer 1 -60.8 -8,9 Sarmatian aquifer 11 -66,1*4.7 -10,0*0 ,6 Senonian aquifer 2 -76,2*2.0 -10.8*0.2 Barremian-Jurassic aquifer 22 -78.0*8,0 -11.1*1.0

The values supplied by the sampling of May, 1986 were taken into consideration, except for the meteoric waters wich an average of the years I983-I986 was used.

A close analysis of Table 1 would emphasize the fact that for each type of water in the area a self contained average isotopic composition is characteristic. Account being taken of groundwaters only, it is obvious that the deeper the aquifer is situated the poorer its heavy isotope concentration. This orderly progressive stratification of the isotopic composition within the ground might be accounted for by the fact that the main aquifer waters belong to geological eras characterized by different climates or that the recharge areas are situated at higher altitu- des the deeper the aquifer location« - 45 -

She synthetio tritium data in Table 2 come to confirm the stratification revealed by the stable isotopes and to provide extremely additional elements. Thus, as far as the waters in the Sarmatian deposit are concerned the average 14 TU content contradict the possibility of water being stored at geological times and therefore in very different climatic conditions relative to the present climate; mention is made that the major role with this aquifer is played by the isotopic composition of the recharge water in its turn dependent on altitude and on the dynamics of the evaporation-condensation processes.

Mean tritium concentrations (TU) of the different water types in Southern Dobrudja* Table 2.

Range of values Type of water -n- ¿2~ in i Minimum Maximum value value

Meteoric waters 13 ¿—•O1™* d 14 45 Surface waters 8 3OÍ5 24 41 Pliocene aquifer 1 16 - - Sarmatian aquifer 12 14Í12 <5 41 Senonian aquifer 2 12±2 10 13 Barr.-Jurass. aquifer 22 <5 <5 11

The values supplied by the sampling of May 1986 viere considered, excepting the meteoric water values made up from the average over 1985 and 1986.

In the case of the Barreaiian-Jurassic aquifer, exception being made of the two points where the influence of surface water is definitely proved, the ^H concentrations are below the threshold traceable by spectrometry in liquid scintillation (<5TU) wich gives way to both hypotheses. For a complete global image of the isoto pic composition of both major aquifers, Table 3 provides a synthesis of their average 1*^5G and 14G concentrations. As it may be noticed the two aquifers are clearly distinguishable from the view point of carbon isotopes as well. The Barremian-Jurassic aquifer waters are not only much poorer in mean radiocarbon contents than the Sarmatian _ 46 -

ones but they are richer in S ^C concentration as well, wich points out an advanced isotopic exchange with the matrix carbonate implicitely assuming longer residence times«

Average ^C and C contents in the major aquifers of Southern Dobrudja. Table 3

515O l4C (pmc) Aquifer -n- ' 1 ^ , n ñ5 RangR e x± "" 2•1 Rangfc

Sanaa tian 10 -10 .0 -11 .0 . . -8.2 42 .5 15 -7 v . 85.7

n T Barr.-Jurass. 19 9? -9 ,4. • *" -L o 4 12 .8 2 -9 . . 79.0

This way, the age difference between the two aquifers is once more proved, at a global scale.

The evolution of groundwater conductivity ' «••7 P ^ (uS.crcT ) in Southern Dobrudgaf^ r ' Table 4.

19 8 4 '19 8 5 19 8 6 Aquii'er • • • -n- 5¿ n

Plio cene 1 1,100 _ 897 _ 900 _ Sarmatian 11 1,226 335 1,415 317 1,271 374 Senonian 2 823 113 1,142 12 945 135 Barr emian-Jurass i c? ' 20 725 112 983 129 739 137

''The conductivity determinations were carried out in May each year. 'The statistical computations took into account strictly the same wells for a given aquifer in all years. ^The F-5082 Mangalia, well having a conductivity value above 3»000 ^.S.cm" , was disregarde as it was considered to reflect a strictly local situation. - 47 -

Prom the standpoint of electric conductivity the waters in the area, the major ones particularly, are significant by different (Table 4), the Barremian-Jurassic ones having characteristic conductivities much below 1,000 >*S.cm~ on the average while the Sarmatian constantly exceeds this value.

3.6.2. The Sarmatian aquifer. The quite uneven territorial distribution of the sampling water points as wel as the chaotic variability of some isotopic con4 tents made it impossible to draw isoline maps for the Sarmatian. Consequently, the discussion of this aquifer will be based on the table data and on some correlation diagrams. As far as the tritium is concerned one should notice the existence of a quite large variability field of the values. Por example, the values vary in 1986 (Table IX) from <5 TU to 41 TU which points to the fact that this aquifer is not screened properly in its upper part which makes it subject to the influence of surface waters in several zones. Coroborating the tritium data for the three observation years with the hydrogeological and tectonic situation, the values around 10 TU were taken for characteristic data of the aquifer provided the natural recharge only. The higher values are due to recentmost inlet3 from the surface either occasioned by structural uplifts and the consequent reduction of the half-impervious cover or by the existence of irrigation canals in the region. A special case seems to be that of P-6 Costinesti which supplied a value of <5 TU all over the interval of investigation (three years). The interpretation of this particular case is feasi- ble only by corroborating this values with the regional tectonic and hydrogeological elements relative to the Barremian-Jurassic. The explanation of this tritium poor water lies in the ascent of a deep water along the tectonic line bordering to the south the Tuzla-Topraisar horst. The stable isotope values in 1986 extended over 165 -ranges for D and 2.4(5 - ranges for 0 were correlated to the diagram in Pig.21„ Por the Sarmatian aquifer a regression equation of the following form was computed: §D = 6.9 S180 + 2.9 00 which is almost identical to the L-MWL equation but indicating somewhat more significant evaporation processes. - 4-8 -

•20

-40

£•60

=0.98 -80-

-100-

-73 •11 -9 -7 -5 I 18Q %o

Fig.21,, Correlation diagram §D - h 0 for the two main groundwater aquifers in southern Dobrudja. The points represent the values determined in 1986j triangle - water from the Sarmatian aquifers; full points - water from the Barremian-Jurassic aquifers; a,b,c - isotopic mean values corresponding to 1986 for the Black Sea, the littoral lakes and the hydrographyc network and channels.

In fact, a close study of the diagram in Fig.21 revelas the fact that almost all points (excepting P-6 Costinesti) are grouped around "c" which represents the average isoto pic composition of the hydrographie and canal network. This observation sup- ports the previously forewarded assumtion concerning the zonal adventive recharge. The P-6 Costinesti point, with its low values of heavy isotopes suggests either a type of water originating from ligghtly differing meteo-climatic conditions or, rather, from a mixture which comes to support the hypotesis of a deep component. The ages computed through radiocarbon and corrected througr the Fontes-Garnier method as well as the 0 ^0 values were noted down as points on the map in Fig.22. It is worth mentioning that the highest S C values are to be found in the two points situatei - 49 -

in the west of the region which,could hint at some water contribution from the subjacent aquifer. In the east, the values are all under -9 %o.

Fig.22. Sampling network for C and ' ^C analyses in the case of the Sarmatian aquifer; 1- point of data-supplying and its indicative in terms of Table XEII. The numerator shows the corrected value of age according to the Fontes-Garnier's method in thousands of years and the denominator the value of 5!3c one; 2 - areal with discontinuous Sarmatian and thickness of less than 10 m.

The corrected ages all show a ageing from the area of points 4- - Credin-fca and 3 - Amzacea, an area with heavy surface water losses, towards the Black Sea littoral. As this aging direction corresponds to the flowing direction determined by hydrochemical means (Fig.10) an attempt was made to construct a correlation diagram between age and distance (Fig.23) for the littoral area in terms of some isochrones previously drawn. The actual flowing velocity thus determined is 0.8 m/year. For the same region, assuming i =0.003.determined accor-

ding to the hydrogeological map and K = 0ol m/day, the resulting Darcy's velocity is O0l m/year. On account of these data an average effective porosity, me = 0.12 can be computed, wich is a plausible value for the type of rocks in the area. : , The conductivity values determined for the Sarmntian waters emphasize the lowest Tatlageac 15- values (generally below 1,000 uS. cm" ) in the points Dobro- mir Deal and Bäneasa, the very en 10 objectives in the western part •o 10-

Fig. 23t, ¿The variation of the and that the chalky formations i^G age with the distance within the Sarmatian aquifer of the Barremian and of the of the littoral zone. The num- Sarmatian in an altered state bers correspond to the ordinal numbers of the Table XIII. oan be indistinct, it is not imposible that they should drain the Barremian-Jurassic aquifer only. This assumption does not contradict the §D and § 0 contents either. As far as the evolution of the isotopic contents in time is concerned one should not fail the notice that the present ran¿e of recorded values as against the first deuterium analyses published ( A. TENU, 1973) is the same ( § D = -61/co ... -77foo) but their distribution no longer allows of a firm progressive development. This may be interpreted as a consequence of the local non-uniform influences from the surface. As the oxygen-18 or heavy carbon isotope analyses were not done in advance, no comments on their development in time can be forewarded. Against the background of what has been shown so far, the hydrodynamic characteristics of the waters stored in the Sarmatian formations (ci". A. TENU et al. 198$) are pertinent and, accompli- shed by some recentmost observations may be sketchily presented as follows: - 51 -

- the natural recharge area located south from Negru Vodä on Bulgarian territory; - the existence of an area, south from the Techirghiol Lake with deep waters that make themselves manifest by ascending through a major fracture; - absence of any drainage self-contained areas in the region; - radial-divergent type of flow with lower gradients along the Negru Vodä - Adamclisi direction due to the natural discharges through springs and relatively high gradients along the Negru Vodä- Mangalia direction, consequence to the aquifer getting pressurized.

3.6„3. The Barremian-Jurassic aquifer. This aquifer is more extensive than the Sarmatian, having rather uniformly distributed observation points and, as the study shows, less subject to the outer influences is most adequate for areal interpretations. As for the tritium, only two points indicated.constantly low tritium contents over the three years of study, i.e. F-CAP Esechioi, located in the neighbourhood of a recharge area and P-7 Caragea-Dermen, a well located at very low distance from the Lake Siutghiol bank. All other determinations were practically below the detection threshold, excepting F-5O74- Plopeni in 1984- (Table VII) but this determination was performed on an improperly 14- collected sample, which was also the case of C. Consequently, practically the entire Barremian-Jurassic aquifer in the area being investigated is lacking in tritium thus demonstrating a quite safe screening from the outer influences. 1 ñ As for the stables isotopes D and 0, the values of 1986, for instance, are distributed in the area into ranges of about 57 § and 4-§ respectively, somewhat larger than in the case of the Sarmatian. The areal distribution of the §D values (Pig.24-) shows a progressive tendency towards negative values from the 3-W (Ostrov, Bäneasa, Dobromir Deal) where values above -65%o are encountered towards the east and north-east. The minimum values of the area are recorded in the Cobadin zone along the prolongation of the Tuzla-Topraisar horst. A low value ( §D = -87,7%o) was also found in the well at Costinesti (F-5068), the nearest southern point from the horst. Sinoe Lake J Fig. 24 - The map with isoconoentra- tions in §D for the Bar- remian-Jurassic aquifer. I- Water point having supplied to TABLE IX} 2-.isoconcentration line §D and its value in %o; 3- area with ernavoda Tortoman lacking Barremian-Jurassic h deposits. In drawing the map the data obtained in 1986 werw used.

Mangada _ r2 Manga lia Lake The areal distribution of the § 0 (Fig.25) shows an identical aspect of the curves, with maximum values ($18O=-9%o) in the south-western extremity of the area and the minimum ones in the Co "badin area.

6 U 0 5 10Km ,. i Negru voaaj ~ t JL \ 21 \Mang 1 .10

Fig.25. The isoconcentration map in § 0 for the Barremian-Jurassic aquifer. 1.Water point having supplied data and its indicative according to Table IX; 2. Isoconcentration line § 1°O and its value in %o; 3. The Barremian-Jurassic deposits are missing in this area. In drawing this map the data obtained in 1986 were used. c 18 S D - ô 0 diagram.(Jig.21) spotlights a very good correlation of the values (r=0.98) with the regression line of the form below: §D = 7.A-S180 + 4.4 (5) remarkably close to the L-MWL. The distribution field of the points is situated at more megative values than with Sarmatian and also below the isotopic composition of the surface waters. It is certainly the case of an aquifer recharged from meteoric waters - 54- -

only, having infiltrated rapidly in the.ground. Considering the field of maximum point-density (of« Pig.21) superposing the input function rendered in Fig«, 19» one can state beyond doubt that the recharge waters come from the November-March season. Direct lincks between the Barre,mia-Jurassic aquifer and the surface waters of the "c" type in JFig.21 do not exist.

100 / 90 /Young" waters 80 70 / ° 60 / / 50 / / UO / / 30 / / o/ 20 / 7 / O / / / o 10 / °fl / ,'o\ 9 / / 8 / o P 7- / o 6 y 5 / ° /,' ' Central-southern / . / zone „Old" waters / 3

2 -" • 1—•^ , , 1 , . , • 1 r—»- •7.0 •8.0 -9.0 -10.0

Fig.26. The correlation p.m.c. - â C for the Barremian-Jurassic aquifer.

This statement is in fact supported by the â ^C and radiocarbon contents to be found in good agreement (Pig.26). Besides this conclusion, the diagram also proves that, excepting the central-southern area, the flow in the entire region is facilitated through a homogeneous matrix, quite uniformly from the - 55 -

hydraulic standpoint and in relatively long times. Along the three points located in an arch like way in the central-southern part (21 - Negru Vodä, 17 - Independen-fca and 15 - Cobadin) the flow is unfavoured by hydrodynamic conditions differing from the rest of the regipn, consequence to certain structural or lithofacial changes. In this area one encounters the lowest transimis- sivities in the region,, C fio As the presentation of à D and ó O areal distribution revealed, in the area Cobadin and Costinesti only low values are found. This distribution is valid not only for 1986 but also for all the years being investigated. In the Costinesti area, where both the Barremian-Jurassic and the Sarmatian are drilled and piezometric data are available for the former aquifer, can provide a clearer explanation of the phenomenon. The deep water ascends under a higher pressure than Barremian-Jurassic and an isotopic composition poor in heavy isotopes; the ascension takes place through the fracture in the south of the Tuzla-Topraisar horst,, This water influences the Barremian- Jurassic to a great extent but to a lesser extent is it present in the Sarmatian, moreover under isotopic aspect. As no other explanation seems plausible for the Cobadin area, we consider that this phenomenon is identical with the ascending leakage along the fracture prolongation in the north of the horst. The radiocarbon analyses carried out on the carbonates sampled in the Barremian-Jurassic aquifer varied from 2.9 pmc in P-5082 Mangalia and 79.0 pmc at F-CAP Esechioi..The areal distribution of the radiometric ages is rendered in Fig.27. As it can be noticed the younger waters are encountered in the south-west of the region, the ages growing rapidly toward the north (Oltina), lower toward the north-east (Pestera - Cobadin) and very low toward the east (Mangalia). In the Poarta Alba - Basarabi zone the 17.5 x lCr closing isochrone emphasizes the existence of some adventive recharge area interrupting the progressive evolution of the ages towards the area of major discharge in the north of Constantza. The presence of this recharge zone is due to the Senonian chalky formation having a maximum thichness here and to the Danube - Black Sea canal routing large amounts of water,. The hydrodynamic image offered by radiocarbon can be therefore restricted to the following model: the recharge area Pig. 27 - The map of ^0 isochrones based on the radiometric ages computed for the Barremian-. Jurassic aquifer. 1- Water point having supplied data and its indicative according to TABEE Xj Cernavoda Tortomanu 2- isochrone and its value in thousands of years; 5- area lacking Barremian- Jurassic deposits. Cochirleni Med ¡dia s Lake a - 57 -

located in the south-west of the region, the mainly flow direction to the north-east towards the Lake Siutghiol, the natural discharge zone. A secondary flowing direction is directed west-eastward, even a little towards east-southeast from the recharge area towards the Lake Mangalia«

Distance, Km

14- Figo28. Variation of the C age with the distance within the Barremian-Jurassic aquifer» The numbers correspond to the ordinal numbers of Table XIII.

The correlation of the corrected age by means of the Fontes-Garnier method (Pig.28) with the distance results an actual velocity of 2O6 m/year along the Esechioi - Bäneasa section and 5o4- m/year along the Bäneasa - Tortomanu stretch. These values are almost identical to the ones determined by A. TENU et al., in 1975 for the same area, and also very close to the values computed by J.GH. FONTES and J.M.GARNIER in 1979 for an aquifer composed of karstified limestones and fractured sandstones of Paleozoic age in Belgium and northen Prance. Por the stretch between Plopeni and Mangalia the real velocity computed through radiocarbon is around 11 m/year. These values together with the ones derived from the hydrogeological map (Pig«11) allow of computing the effective porosity. The range of values determined for this parameter is from 0.05 in the region 1 east Cobadin to 0.24 in west Adamclisi. As for the evolution in time of the isotopic compositions determined for the Barremian-Jurassic aquifer, the comparison of the 1974 values (Pig.29) with the values occasioned by this study (Figs.24, 25 and 27) reveals no significant differences in the range of values and the variation sense. The Constanfa modifications in the shope Cobadin ^Osfrov^ 2 3-

The radiometric 0 ages of two Barremian-Jurassic water samples within a 12-year interval« Table 5.

Sampring point Radiometrie age, years 1974 1986

F-IMH, Mamaia 16,8?6 19,100 F-5082, Mangalia 24,353 29,250

An analysis of the overall hydrogeological situation would lead us take this phenomenon for real and assign it to involving some deep old waters from the lower parts of the aquifer, towards their upper part exploited. In the case of the Senonian aquifer in the Basarabi zone, the same aging phenomenon of the apparent age from about 3,000 years in 1974 to 6,600 years in 1986 was relevant. Account being taken of the tritium outcomes the phenomenon was considered apparent only and due to the activization of the surface infiltration 14 directly into the chalk which decreased the initial C activity (A ) significantly. In fact, the corrections performed according to the Fontes-Garnier model decreased the age for 1986 down to 1,700 years. A parameter having changed to a great extent between the two time thresholds is the deuterium excess A o D computed as USD = §D - 8 S 0. The average excess computed as the arithmetic mean for the entire Barremian-Jurassic aquifer at the 1986 stage (in 22 sampling points) is +11.2%o while at the stage 1974 (in 7

such points) A § D = 21o8%o. This excess of increased value in 1974 lay at the basis of a methodology using this excess as a possible index for the paleotemperature variations and implicitely for the determination approximately of groundwater ages (A« TEMJ et al., 1975). Unfortunately, the reducing deuterium excess determined during this study made it impossible to check up the suggested methodology. It should be also emphasized that there is still no solid explanation for this phenomenon which remains a further subject for our studies» The model of grounwater flow through the Barremian-Juras- sic aquifer can be syntheticaly presented in the map of Fig,30, Pig« 30 - Tne schetchy representation of the groundwater flow model in the Bar- remian-Jurassio aquifer. 1- The front of the main recharge area; 2.a- water flowing direction through the aquifer confirmed by isotopic grounds, b- preferrential flowing direction*, 3.a- natural drainage area of the aquí-* Tortomanu VoVo fer, b- major drainage area; 4- adventive recharge area; $- area of low transmissivities (about 100 m2/day); 6- the Tuzla-Topraisar horst. an area with lacking (eroded) Barremian-Jurassic deposits.

o a • 0 a i Vi * • 4 5 - 61 -

wich, was drawn by integrating within a unit sketch of all elements available: hydrogeological, hydrochemical and isotopic. In this scheme only the major elements, having been confirmed by all working methods were retained. Therefore, although the hyrogeolo- gical map (Figo 11,) suggested the existence of a recharge area in the Negru Vodä region, the fact that it was not confirmed in the aquifer economy by corresponding transmissivity values or by isotopic contents (D, O and 0 in particular) prevented the area from being figured in the scheme. The major model characteristics are the following: - the existence of a unique recharge area located south from Ostrov - Tufani; the front line of this area on entering the Romanian territory was figured in the scheme. The waters penetra- ting through this front are drawn from the pre-Balkan Platform consequence to the infiltration of precipitations or of some rivers that dry up completely in this region; - the flowing directions lead these water courses prefe- rably towards the north-east with a reaching point in the great drainage area adjacent to the Lake Siutghiol, where there are both natural emergences under the form of under-lake springs (Q «" 1»3 r/s) and artificial ones (catchments having Q «s 3 m/s). A part of this major flow is directed towards the east-southeast reaching finally the drainage zone around the Lake Mangalia; - the real flowing velocity vary from 2.6 m/year (in the Esechioi - Bäneasa zone) to 5»4- m/year (in the Pestera -r Tortomanu region) reaching 11 m/year (in the Plopeni - Mangalia zone) after the waters crossed the low transmissivity threshold: Negru Yoda - Cobadin. This general scheme correspond to a large extent to the" outlook forewarded by A. TENU et al. in 1975. The latest studies contributed the following elements to the previous scheme: - the existence of a secondary flowing direction towards the Tortomanu drainage area, expanding over the Capidava-Ovidiu fault and continuing the major area of the Siutghiol; - the existence of an unexpected curvilinear flowing direction from the southern part of the Tuzla-Topraisar horst towards Mangalia. It is worth mentioning that there is a good agreement in this case between the piezometry elements and the isotopy one wich led to acceptance of an apparently impossible situation; - 62 -

- the existence of some areas (Costinesti and Cobadin) with active ascending drainage along the fractures delimiting the Tuzla-Topraisar horst; this phenomenon was spotligkted especially in isotopic terms; - altough» the aquifer enjoys good screening in its upper part, an adventive recharge was identified in the area Poarta Albä- Basarabi, the branching zone of the Danube - Black Sea canal, at the same time representing an area of maximum Senonian development which serves as an "antechamber" for the Barremian-Jurassic recharge; - the lack of any flow from the major recharge area of the aquifer to the Danube was put forth by means of some very old age gradients found along the Esechioi - Oltina line; - the old ages (over 15,000 years of corrected ages) of the Barremian-Jurassic groundwaters in the south-east of the region, south from the Tuzla-Topraisar horst, could be explained by tracing the belt closing up the hydraulic continuity of Fegru Vodä - Cobadin (T =r 100 m2/day as against the rest of the region T s 1,000-5,000 m2/day).

3o?» Certain considerations on the age correction 1 ¿L methods of 0. Beyond the actual conclusions yielded by the radiocarbon analyses having been included in the previous chapters, it might be useful to assess the correction degree of some routine methods, employed for carbonated aquifers developed at a regional scale. In this respect all the analyses carried on concerning the two major aquifers have been processed by computing the radiometric a¿es on the one hand and on the other hand some corrected ages using the Vogel, Pearson and Fontes-Garnier methods, selected for being representative. In determining these corrected ages chemical, isotopic and computational parameters were used according to some already established methodologies (FONTES and GARNIER, 1979). These parameters were either determined in situ or in the laboratory computed by some more or less classical formulae or else estimated or appreciated by comparison. In fact by analysing the data of Tables XI-XIII and their footnotes are clearly shown by the working procedures and parameters. - 63 -

As expected, a map of isochrones drawn for an aquifer on account of the corrected ages (in terms of the Fontes-Garnier method - Pig,31, in fact the most tiresome method) do not differ substantially from the map of isochrones of radiometric ages shown in Fig,27. Only the individual values are modified and this modification differs depending on age to the extent to wich it does not shade the initial pattern,-

Fig#31. The map with corrected G isochrones according to the Fontes-Garnier method, for the Barremian-Jurassic aguifer, 1.- data supplying water point and the value of its age in thousands of years; 2.- isochrone and its value in thousands of years; 3»- area with missing Barremian-Jurassic deposits.

All the corrected ages resulting from computations were averaged for the two main aquifers and for each model as shown in Table 6. ' To put it briefly, the conclusions of this numerical analysis and of the data in Fig,32 based on individual computed values are the following: - 64 - Average C ages (thousands of years) for the Sarmatian and Barremian-Jurassic aquifers depending on the computation model. Table 6.

Age Sarmatian aquifer Barremian-Jurassic aouifer S % of the computation n of the n radiometric n 21 *t-1 radiometric me tho d age age Radiometric 10 8,5 100 20 19.0 100 Vogel 10 8.1 95 20 17.8 94 Pearson 10 5.3 62 20 12.8 67 Fontes-Garnier 10 5.5 65 19 11.6 61

= 0.85 b=-2,900 01 r= 0.99 «3

10 15 20 25 30 Radiometrie*ages - 103years

Pig.32. Correlation between the radiometric ages of C and the corrected ages by three methods for the Éarremian-Jurassic aquifer. In computing the regression equations Y = aX + b (a,b and r coefficient being supplied in the special cases squares for each method) a set of 18 couples of values were used for wich both ages were computed. - 65 -

- The reduction of the radiometric ages through correction is, with comparable ages, greater with waters stored in a carbonated aquifer than with porous aquifer system. As shown in Table 6, with both aquifers in Southern Dobrudja the corrected average ages reach almost 60% of the radiometric ages in the case of Pearson and Fontes-Garnier methods«, On

another hand, according to A. TENU and FCD. DAVIDE30U, 1984, the reduction was not more than 25% for a non-thermal porous aquifer having an average corrected age of about 22 x lo^ years using the same computation methods. - It cannot be assessed that for carbonated aquifers there should be a certain correction method which could lead to maximum reductions of the radiometric ages. A close look at Table 6 would show that in the particular case of Southern Dobrudja the Pearson and Fontes-Garnier methods lead in turn to the greatest corrections of 14C ages for the two aquifers. - The correlation between radiometric ages and corrected ages is mainly dependent on the strength of the pmc - § C correlation within the aquifer being considered» Thus, the age correlation is very good in the case of the Barremian-Jurassic aquifer (Fig.32) consequence to the good correlation shown in Fig.26. With the Sarmatian aquifer the age correlation is only satisfactory if Pearson's method is applied and it becomes quite inoperative with Fontes-Garnier1s method where the chemical correction interferes« ~ 66 -

4. CONCLUSIONS

The study carried on being of a regional nydrogeological - isotopic character led to outlining a set of very important conclusions that might be of help in defining the groundflow of the two main aquifers being investigated. Some of these conclusions, already touched upon in sections 3.6„2. and 3*6,3. of this report, are however of local practical applicability restricted to the very area under consideration and need not being resumed. This final section will briefly present some elements of more general concern detached from the isotopic study performed. 1. First of all it should be emphasized that in the study of karst-chalky aquifers in the area, more than with other types of aquifers the isotopic methods proved very useful in specifying certain essential aspects of the hydrodynamic situation and even of quantitative assessement of some hydrogeological parameters otherwise impossible to obtain by classical methods of study. The validity of the data provided by environmental isotopes is proved by their recurrence in the Barremian-Jurassic aquifer, at intervals of over 10 years, both in terms of essential model features and of the computed parameter values. 2. A quite unique aspect clearly brought to the fore by this piece of research is the utmost importance of tectonics in determining the regional hydrodynamic pattern of the Barremian - Jurassic aquifer« It is worth noticing that the drainage areas, both the one in the north-east of the region and the one in the south-east are conditioned by the existence of two regional fractures: the Capidava-Ovidiu and the Mangalia faults, respectively; the zones with ascending leakage at the Barremian-Jurassic and at the Sarmatian levels are also influenced by tectonics, namely, by the faults delimitting the Tuzla-Topraisar horst. Against this background, certain seemingly paradoxical piezometric situations could be admitted of an accounted for«, 3. As far as the main south-Dobrudjan aquifers are concerned two essential aspects are worth emphasizing in establishing the clear-cut distinction between them revealed on account of environmental isotopes; 3.1. The Saraatian waters proved to be recharged mainly from surface waters circulated in the region while the Barremian - - 67 -

Jurassic ones are recharged from meteoric waters exclusively and having fallen durixig the cold season in higher regions situated south from Romania's territory; ¡5.2o It was also proved that the extensive hydraulic and land reclamation works in the area were echoed at the level of the Sarmatian aquifer but failed to influence the Barremian - Jurassic which is better screened. 4. The radiocarbon analyses proved very useful in defining the groundwater flow model, particularly in the case of the Barremian-Jurassic. The processing of these analyses in view of performing corrections with various methods hinted at the fact that, in the case of carbonated aquifers, the methods employed reduce the radiometric age by down to 40%, substantially more than with some porous aquifers of comparable ages. - 68 -

APPENDED TABLES CONCERNING

THE EXPERIMENTAL RESULTS Groundwater chemistry in tiie Sarmatian formation.

TABLE I

Fixed 2+ 2+ + + 2 Sample ; Na +K SO ." 01" HCO7. Ionic Location residue rSO N° pH formula rCa

1. 2. 3. 6. 7. 8. 10. 11. 12. 13. 40,8 193,7 36,0 Na+K > Mg ^ Oa 1. Abrud, spring 7,2 740 1,17 2,10 8,51 2,13 1,01 ""972Ö CO3 > SO4 > 01 144.0 8 210,6 218,0 542. 2. Adamolisi, spring 7,0 1285 1,37 0,71 CO3 > Gl > SO4 ; 3. Sipotele, spring 7,1 725 58 8,5 9?,3 98,3 62^0 480, Na-t-K > Mg gs Ca 1,08 1,17 -» .7x7 4732 2705 T7V 4,9 64,6 68,7 58,0 414,88 Ca > Mfi = Na+K 4. MoVila Verde, spring 7,0 555 003* ülP-öü/j. 0,64 f789 "2781 T745 67? 6,80 o Ca $:Jflg >Na+K 5. Plopeni, JM- 7,5 972 126,0 74,0 31,7 192,0 135.0 0,96 1,05 , 6,50 57w 1738 4,00 3,8l 6. Crédita, P-3 7,5 654 84,0 38,8 40,0 224,0 176,9 Ca>Mg>Na-j-K 0,75 3,00 T774" 4,éb 27W 45,5 31,9 79,0 64^0 457^5 Oa>Mg>Na+K 0,73 7. Negresti, CAP 7,0 590 GO3 > Gl » ÖO4. 0,91 69.2 134.0 71.0 Ca >Ha+K>Mg 0,47 8. Oonacu, CAP 7,5 654 CO3 > SO4. > ÖI 1,39 9. Chirnogeni, CAP 8,1 550 40 86 37.8 54.0 00,0 Na+K > Mfe - Oá 0,98 0,51 0,79 1,52 872Ö 003>01>S0zt. 1. 2. 5. 4. 8, 9. 10. 11. 12, 15. Ca > Ha j-K 10. Oerohezu, 7,5 870 mm 0,55 0 ,91 86 420,0 Na+K > Ca > Mg 11. Amaacea, P-2 7,2 1975 9,7 160.7 57,j88 195.195,00 0,52 0 ,21 £ w 6,88 CO3 > 01 > ÖO4 727^799 172• » -0 375y». 0 12. lièrent, CAP 7,0 760 40,3 144.4 91,5 84.0 Ha+K > Ca > Mfi 0,75 0 ,80 5752 b,28 iTw 2757 CO3 > 01 5s SO4 44 >Ka+K 13 « Teohirghiol, P-ll 7.4 700 55,3 38.9 97,9 154.0 0,75 0 ,55 45,2 473^ TTtg 270t 377H 488,0 Ma+K>Mg>0a 14. Biruin-fca, JP-8 7,0 780 37.9 204,5 117,7 150,0 •S',00 1,44 0 ,67 "57Í2 ~"878§ "•"274ÏÏ ~3767 8,2 811 40,6 124,2 488,0 Na-t-K > MK ^ Ca ,24 « 15. Costine§ti, P-6 5,00 CO3 > 01 1,05 0 45,7 151,0 55,9 176.0 Na-fK > Mg > Ca 16. Duloeçti, CAP 7.5 750 1,65 0,22 * .tc~ ¥ï% 5,70 Î7Î2 4,96 CO3 > 01 > SO4 1 49.5 51,1 164,8 69,1 108.0 470.0 1,04 0 17o Tatlageao, P-5 7,5 600 CO3 > ül > 8U4. 8,0 627 72.0 58,0 65,5 124,0 56. 1,52 0 ,95 18. Cotu Väii, F-5 CO3 > 01 67.2 55.5 68,8 143,6 86,0 Mg >Ca>Na+K 19. AH?e§ti, P-5 6,8y 580 1,31 1 ,25 3755 %m 27W 2,9$ 2743 CO3 > SO4 > 01 Mg >Ca 20. Mangalia, P-4 ,0 228,0 1,20 0 ,05 7,9 74-5 CO3 > 01 > SOz|. 21. Vania Veobe, MCE 25.2 20 1,9 124.0 Na+K > Ca > Mg 0,80 0 ,30 7,5 690 7Ü 3755 »£0 CO3 > 01 > ä Groundwater chemistry in the Barremian-Jurassio formations

TABLE II

Fixed „ 2+ 2+ + + 2 iample residue Na +K SO " 01 HCO5 Ionic Location PH ii ... N2 Cmg.l'Vme.l""1) formula rCa

1. 2. 3. 4. 5. 6. 7. 80 9. 10. 11. 12. 13. 1. 5061, Cernavodä 7,0 500,0 1,03 0,74 •» 83.8 2. 5044, OJoïtomanu 6,4 524,0 85.1 K 1>08 73 27599 $TSQÍ>ÓÓ °» 102,6 46,2 65,6 168, Ca>Mg>NotK 0f?4 lj31 . 3. 5053, Oastelu 6,5 667,1 5TI20" 7 4. 5091, Medgidia 7,0 523,0 67.2 0,95 0,70 ^ .89.7 49.1 72,4 0,90 1,47 5. 5036, Poarta Alba 6,8 784,0 4,476 4,040 60,1 J0.8 88,0 81,6 6. 5034, Oarasu 6,4 522,0 Ï7S32" 1,39 0,80 rTît m 62, 80,6 1,23 0,90 7. 5038, Cooosu 6,5 526,0 46, 27275 60,1 49.2 61,0 439.2 Mg>Qa>Na+K 1>35 1>21 8. 5047, Alimanu 6,5 562,0 77Í9S 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 15.

5046, 59,3 44 7 71,7 81.8 578.3 ;>Na+K»Ca , o/. 9. Pe§tera 6, 5 554, 0 lf24 0,95 p,oyí 1, A/3 0,200 TUT 10. 5052, Siminoc 436, ,75,7 63.8 250.6 Ca>Mg>Na-t-K 6, 5 0 37678 27B39 T^oT 1,5Í5 1,800 0,77 0,84 _55.9 49.6 268.4 Mg>Ca>Wa+K 11. 5035, Murfatlar 6, 3 418,,0 0,83 1,64-4 1,164 T7399" 47395 1,25 ¡>Na+K>0a 12. 5042, Poarta Alba 6,,5 752,,0 75.4 58.8 li AQA 127.7 33g.6 2 CCZ 1^ 1,32 0,94 p,obp 4, opy 4,üöy 3,39° p,bO2 5»>00 OÍ T 40,2 131.4 120,6 547 7 13. 5037, Poarta Alba 6,,3 964,,0 37 JL ti. 377Î5 3; 6^7 0,73 1,08 4,546 3^oB 3,402 5,698 14. 5040, Palas 61,8 36.6 121,4 99.3 353.9 6,»8 590,,0 3,084 37ÖT2 4^ 27525 2,801 0,98 0,90 68,1 57œa I 15. Valu lui Traian »0 630,,0 114,8 329.4 5039, 7, 3,398 37Ís| 2,798 57395 1,09 0,85 ^ 76.8 572.2 Ca>Mg>Na+K n 16. 5063, Adamelisi 6,• 7 522,,o _79,3 0,88 37957 3,481 T79èB T7599" lÜ99 1,00 ( 17. 5060, Bäräganu 6, 684, 65.9 110.8 105.6 ,7 »o 37149 2,572 4,ö20 2,199 ^95 0,91 0,79 18. 5062, Báneasa 450 49.8 457.6 7»0 ,0 0^9" Ô,60l 775OÜ 1,29 1,13 19. 5067, Cobadin 692 71.3 53.0 ¿i¿L Q 7,0 ,0 37358 4736T 1,953 I7M •2;oóo 1,23 0,93 20. 5054, CiobániCa 6 ,9 518 •o 70.1 82.6 78.0 1,02 37Í9B 37M 2,449 T772ÇT 272OÔ m 0,78 OöiL C* 21. 5064, Independería 6 340 60.1 „33,3 46.1 84.5 49.6 Oa>Mg>Na»K 0,91 ,9 ,0 2,740 I775V 1,35$ 1,31 Il II II • CO oo 00 11 II KN g o II II i-l g o o o II II O II II cT II II II II • LN. VD vO CM H r-i ON IA II II CM O VO LA o O 00 II II H •k o II II O 1-1 II II II II II II M CÖ 1 II II o + O II s II II CO cö 1° a CO A A\ ta II A Ö A Ut A II II -l A a IIo Ä II II 1-1 o A, II o ta â il II H A O o A A II * A A\ + si KN 11 II O + O O II II cö o o II II S o II II II II II CO 11 II II II II II II II II II 11 II II II II II II II 11 II B * II H H a II H II M II M* • 11 II CO II II I! II Il II II II II II II II 11 II- • VO •» II II IN- II II II II II II II II II- • il II vO U II II II II II II II II II II II • II II IA ir\ II II II il II II II II II II vo o II II •k I! • 4 (M CM LA II II 4- o o 00 CM it LA CM II II LTV LA fA LA 11 II o» II II II II ÍÍ LA II il II • KO VO KO VO CN CO II 8 ** il o n 8 u u n n » 05 W cd a) n a> 4S n o to> » • Cfa as II CM ta o 60 -P II o ©

• O o • • o • • ru fA LA VO 00 O CM tA (M (M CM CM CM CM CM rA ^A PRECIPITATION i' Meteorological station Constanta Lat. 44°13» N; Long. 28°38' E; Alt. 13 mal;

Mean Ann. Preco=s379 mm; Mean Ann0 Temp.=11,2°C,

TABLE III

•sel Xear Month Preo. Type 7.P. Temp. Conduct. 5H, TU ¿D (mm) () () 1. 2. . 3. 4. 5. 6. 8. 10.

1983 04 13.3 R 10.5 11.0 - - -46.2 -4.4' 1983 05 22.2 R 15.9 20,5 - - - - 1983 06 40.7 • R 16,4 19.7 260 33+2 -42,7 -6.0 1983 07 33.5 R 19.7 22.4 320 , 54+3 -54.8 -7.1 1983 08 27.0 R 28.0 20.9 350 64+4 -50.9 -6.9 1983 09/ 4.8 R 16,9 19.0 «. - - - 1983 10 14.8 R 11*4 12.5 — - -63.5 -7.8 1983 11 25.6 R+Sn 7.5 4.7 280 38+2 -91 « 2 -12,4 1983 12 20.8 R+Sn 6.9. 2.8 270. 30+2 -73.2 -10,0 1984 01 65.3 R+Sn 7.1 3.4 390 27+2 -70.7 -10.9 1984 02 .37.7 R+Sn 1.0 6.4 330 23+1 -71,8 -10.Q 1984 03 77.6 R 7.2 3.6 250 31+2 -57.8 -7.9 1984 04 35.8 R 9.7 8,5 270 37+2 -71.1 -10.6 1984 05 29.4 R 14.7 15.4 200 26+2 -21.0 -3.7 1984 06 25.9 R 17.1 19.0 350 32+2 -42.6 -5.9 aassss:SSBSSSSSSS II II KN CN CN IA vD vO it i-l CN IA CM H UN rH KN II • - • • » • • • e e H Il H vO co I I 00 00 00 r-l 1 CN VO CO I I VO 00 II II I I 1 1 1 1 1 1 1 1 3 II

II 1 -11 . -11 . -12 . -10 . II II II II II II 11 II SI II • 00 ON O i-l CM O CM ON VO ON CN IA CM II II ON » • II CO CM 00 II ON r-l CO it I I it KN 00 UN IN t-1 CN II S LA VO CN KN IA KN UN VO CN CN 00 VO II II KN VO I I i I II II I I I 1 I I I I I I I II II II II II II II II II It CM. CM, CM. CM «H, rH r-l CM, r-l II + +1 +1 +1 +1 *l +1 +1II u co I I PU X) * KN I I •Í *T IA CM' H

n KN CM 28 + CM r-l r-l CM CM II u CM CM M KN KN 11 u II u II u II u II il U II ¡Í II u • O UN UN UN IA UN O O UN II II CN IA KN it CM CO tN _ I I KN UN r-l VO II II KN KN CM CN C^M 8r-l SCM KN KN KN KN II H II II II II II II II II II II II II II II II II ONUN00 CMCOINOVO CMUNONVO ONCMCNitCOvQKNCM II II « tl II VO O ON CN r-l CM UN r-l O VO CM CN KN CM KN II II CM H II r-l i-l CM rH II II II II II II II II II 11 II r-l LA CN UN UN KN KNKNONtNCMONOCNCOvOCO ONKN II II 00 CN CN it ON VO VOOOUNONOCMVOHONCNvOlAtN II H r-l H r-l H r-l CM CM rW rH II II II II II II 11 II II II II II Pî 04 II il II II II II II II 11 II II ON H O VO CM ON UN CN i-l KN O VO CN H CM rH II KN r-IKNCMKNOCMitUN CM VO i-l ON CN O rH VO CO rH II KN KN CN H CM CM KN KN IN CM rH CN CM CM II II H II II II II II • IN.COONOr-ICMrHCMKN

II t/ 9 H LA UN H !! A «** UV *v W «V **W *a«^ *«V »*** »•** W &W **V 1W H n ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON *J> II n rH rH rHHrHHHHi-HHHHrHrHr-IrHr-IrHrH.H II 10,

Computed for T = 25°C.

Oï SURFACE WATER: results of isotope analysis (sampling May 1984)

TABLE IV

Conduct. Isotope composition Lab. Sampling point No. %, TU fo £188l0

1. 2609 The Danube (Cernavoda) 420 32+2 -90o3 -11 »7

2. 2608 Canal the Danube - the Black 1,010 19+1 -?8O9 -11 o 2 Sea (Medgidia) 5- 2634 Siutghiol Lake (Caragea-Dermen) 1,780 28+2 -47.5 -5.8 4. 2591 Maáor irrigation canal (Topraisar) 1,583 36+2 -88.1 -11,2 5. 2755 Plopeni Lake (Credin^a) 810 36+2 -48.0 -5<>5 6. 2638 — The Black Sea (Mamaia) 22,560 16+1 -50.4 -6.0 7. 2616 The Black Sea (Eforie Nord) 24,280 39+2 -48.1 -5.2 8. 2605 Techirghiol Lake (Wharf) 71,380 37+2 -43.3 -4.4 SURFACE WATERj results of isotope analysis (sampling May 1985)

TABLE V

• • Lab. Hardness Conduct. Isotope composition Sampling point 1 No. .-« (j.S.cm- ) 5H, TU ft

1. 2835 The Danube (Cernavoda) 10 553 33+2 -77.3 -9.6 2. 2832 Canal the Danube - the Black 17 937 29+2 -68.3 -8.9 Sea (Medgidia) 2841 3. Siutghiol Lake (Caragea-Dermen) 30 2,125 27+2 -40.2 -3.4 00 4. 2819 Major irrigation canal (Topraisar) 16 943 32+2 -76.9 -9.4 5. 2830- Plopeni Lake (Credin-fca) 11 867 33+2 -36.9 -3.4 6. 2839 The Black Sea (Mamaia) - 22,043 25+2 -29.2 -2.8 7. 2859 The Black Sea (Eforie Nord). - 14,300 40+2 -38.1 -5o5 8. 2858 Techirghiol Lake (Wharf) - 50,600 39+2 -31.2 -2.3 SURFACE WATER: results of isotope analysis (sampling May 1986)

TABLE VI

Lab. Hardness Conduct. Isotope composition Sampling point 8 No. (jU/S.cm""1) 5H, TU P 0

1. 3012 The Danube (Cernavoda) 11 335 41+3 -68.8 -10.1 2. 3015 Canal the Danube - the Black 13 570 35+6 -68,0 -10.1 i Sea (Medgidia) 3. 3017 Siutghiol Lake (Caragea-Dermen) 26 1,850 28+^ -37.8 -4.3 4. 3037 Major irrigation oanal (Topraisar) 25 1,070 24+4 -64.8 -9.0 1 5. 3034 Plopeni Lake (Credin^) 13 800 30+6 -34.0 -3.7 6. 3020 The Black Sea (Mámala) - 23,915 28+4 -26.1 -4.1 7. 3025 The Black Sea (ECorie Nord) - 23,335 27+4 -20 oO -3.1 8. 3052 Techirghiol Lake (Wharf) - 77,125 24+4 -23 » 6 -5.2 - 80 -

GROUKDV/ATER: results of isotope analysis (sampling May 1984)

TABLE VII

Lab. Sampling point Conduct. 3H> TU ¿D 0 No. (JtS. cm—" ; 1. 2. •3. 4. 5. 6. 7o

I o Groundwater in the Pliocene formation

1. 2617 Ostrov, spring 1,100 24+2 -86O4 -10 .8 2. 2618 Oltina, spring 960 <5 -91o2 -11 o4

II . Groundwater in the sarmatian „matrix" 1. 2600 P-ll, Techirghiol 2,030 12+1 -77o9 -9 »7 2. 2614 Moviliza, well 1,190 33+2 -80o3 -9 ,9 3, 2596 P-2, Amzacea 1,380 11+1 -80.0 -10 .1 4, 2606 P-3, Credint/a 1,230 54+3. -75.5 -9 -5 5. 2611 I Costinesti 1,160 <5 -97.0 -13<.1 6„ 2615 P-v Dulcesti 1,380 54+3 -80.2 -10,.2 7. 2620 P-3, . lageac 1,230 <5 -92.2 -11,.9 8o 2592 P-CAP, U. 'TOOgeni 1,400 18+1 -77.5 -10,.4 9. 2602 Movlla Vera,- well 1,660 20+1 -81.5 -11,.5 10., 2621 Dobromir Deal, spring 780 8+1 -85.3 -11,.5 11. 2628 Bäneasa, spring 940 7+1 -86ol -11,."6 12. 2624 P-5, Albesti 1,260 16+1 -88o3 -11,• 3 13. 2342 P-4 IBP, Mangalia 1,720 <5 -99.3 -11, •4

III. , Groundwater in the Senonian formation 1. 2598 P-l, Basarabi 940 i 21+1 -88.4 -11,.9 2. 2642 P-CAP, Valu lui Traian 710 33+2 -90.9 -10, 3 , Groundwater in the Barremian-Jurassic jformations 1. 2604 P-5044, Tortomanu 710 <5 -92.8 -11. 9 2o 2599 P-5O91f Medgidia 710 -107.2 -12. 7 # - 81 -

1. 2. 3. 4, 5. 6O 7.

3. 2603 £-5053, Castélu 1,,000 6+1 -84,5 -10.4 4„ 2636 F-5036, Poarta Alba 720 <5 -94c 1 -12.4 5. 2632 P-7t Caragea Dermen 820 5£i -92.7 -11.8 6. 2631 F-10, Cismea II 730 -98.2 -12.7 7. 2640 P-l, Ciçmea I-A 700 <5 -94.1 -12.6 8o 2633 F-IMH, Mamaia 780 <5 -95 oO -12.8 9. 2643 F-2 bis, Constanza 710 <5 -95o5 -12o9 10. 2613 F-5048, Oltina 600 <5 -1O3»5 -12.4 lio 2590 F-5047, Alimanu 680 <5 -90 » 3 -11.4 12. 2594 F-5046, Pestera 680 <5 -105.2 -13,1 13, 2593 F-5067, Cobadin 640 <5 -113o3 -14«, 5 14. 2595 P-5063, Adamclisi 740 <5 -93.6 -Ilo5 15 o 2627 F-CAP, E§ecMoi 1,470 17+1 -84.3 -10.5 16. 2612 F-5062, Baneasa 690 <5 -88.8 -10,8 17. 2607 F-5064, Independen^a 790 <5 -95.0 -11.7 18, 2597 P-5074, Plopeni 650 10+1 -96 o 6 -12.3 19. 2601 P-5066, Gen. Scärisor0 660 <5 -105.2 -11.9 20. 2610 P-5068, Costineçti 1,020 <5 -108.3 -13.3 ¿1. 2619 P-5065, Negru Voda 540 <5 -102.1 -12.8 22. 2625 P-5082, Mangalia 3,060 <5 -107«0 -13.5 GROUNDWATER: results of isotope analysis (sampling May 1985)

TABLE VIII

Lab. Hardness Conduct. 18 • lío. Sampling point <°G) (ytcSoCm ) H, TU ¿>D 6 o

1. 2. 3. 4. 5. 6. 7. 8O

I. Groundwater in the Pliooene formation 1. 2846 Ostrov, spring 23 897 20+2 -76.7 -9.5 2, 2847 Oltina, spring 27 1,211 <5 -81.2 -10.1 i

II. Groundwater in the sarmatian ^matrix" CO ro 1. 2856 P-ll, Techirghiol 35 2,516 10+2 -72.9 -9.3 2, 2818 Moviliza, well 21 1,258 40+3 -66.5 -9,3 5. 2829 P-2, Amzacea 17 1,597 7+1 -7192 -9.2 4. 2823 P-3, CredinÇa 22 1,246 41+3 -68 0 6 -8.7 5. 2857 P-6, Gostinesti 18 1,500 <5 -72.7 -10.7 6. 2855 P-CAP, Imlcesti 13 1,491 10+2 -71.7 -9.5 7. 2853 P-3, Tatlageao 16 1,585 7+1 -75.1 -10.1 8, 2822 P-CAP, Chirnogeni 51 1,681 12+2 -73.0 -9.7 9. 2821 MoVila Verde, well 107 4,555 20+2 -69.1 -9.0 10. 2814 Dotiromir Deal, spring 18 990 8+1 -71.6 -9.8 1. 2. 4. 5. 6. 7. 8. 11. 2845 Bäneasa, spring 16 1,036 9+2 -72.8 -9.5 12. 2815 P-5, Albesti 15 1,385 20+2 -65.7 -9.6 13. — F-4 IBP, Mangalia1)

III. Groundwater in the Senonian formation 1. 2824 P-l, Basarabi 21 1,130 15+3 -7b. 3 •11.5 2. 2820 F-CAP, Valu lui Traian 23 1,153 12+2 -76.4 -10.4 IV. Groundwater in the Barremian-Jurassio formations 1. F-5044, Tortomanu OD 2. 2833 F-5O91, Medgidia 18 955 -79 o 1 -10.7 VN 3. 2837 F-5053, Castelu 23 1,141 ¿5 -79 o 7 -11. ¿ 4. 2Q38 F-5036, Poarta Alba 20 1,036 -79.3 -11.2 5. 2840 P-7, Caragea Dermen 22 1,158 10+2 -82.7 -10.7 6. 2843 P-10, Ciçmea II 19 1,042 -82.3 -10.9 7. 2842 P-l, Cismea I-A 21 1,112 -80.9 -11,2 8. 2852 F-IMH, Mauiaia 20 1,060 <5 -87.2 -11.4 9. 2851 P-2 Ms, Constanta 19 1,002 <5 -84.5 -11.5 10. 2848 F-5048, Oltina 16 838 <5 -79.5 -10,8 11. 2850 J?-5047, Alimanu 19 897 <5 -74.4 -10.0 12. 2836 F-5046, Pestera 19 926 -86.5 -11.6 1. 2. 3o 4. 5. 6» . 7. 80

15. 2831 F-5067, Cobadin 18 850 <5 -97 06 -12,4 1*. 2844 F-5063, Adamclisi 20 1,036 <5 -80.6 -10.6 15. 2849 F-CAP, Eçechioi * 19 996 9+2 -67,4 -9.5 16. 2828 F-5062, Bäneasa 20 955 <5 -71.5 -9,6 17, 2827 F-5064, Independerá 19 996 <5 -76.3 -10.2 18, 2825 P-5074, Plopeni 17 902 <5 -79.7 -10,7 19, 2826 F-5066, Gen0 Soariçoreanu 18 885 <5 -840 8 -10 06 20. 2854 F-5068, Costineçti 9 1,246 <5 -93.* -12.4 21. 2P17 F-5065, Negru Vodä 14 651 <5 -87.7 -12,1 22. * 2816 F-5082, Mangalia 8 3,902 45 -90.1 -11.5 I

' Sampled could not taken.

^ Replaced this year by F-CAP GxrliÇa situated about 3 km N-NE. GBOTMDWATERs results of isotope analysis (sampling May 1986)

TABLE IX

Hardness Conduct. • Sampling point 5 No. H, TU h 1. 2. 3. 4. 5. 6. 7. 8.

I. Groundwater in the Pliocene formation 1. 3007 Ostrov, spring 30 900 16+5 -60.8 -8.9 2. 3031 Oltina, spring 23 835 <5 -76.2 -10.8 II. Groundwater in the sarmatian ^matrix" 1. 3051 P-ll, Teohirghiol 35 2,190 8+2 -65*8 -10.2 2. 3050 Moviliza, well 17 1,120 41+5 -60,6 -9.9 3. 3044 P-2, Amzaoea 16 1,^30 <5 -69,5 -10,2 4. 3042 P-3, Credin-fca 23 1,060 53+3 -60,9 -9.5 5. 3033 P-6, Costinesti 16 1,310 ¿5 -76.6 -11.2 6. 3035 F-CAP, Dulcesti 12 1,410 8+2 -61.1 -8,8 7, 3036 P-3, Tatlageac 14 1,230 7+2 -71.5 -10,1 8. 3041 F-CAP, Chimo geni 27 1,490 10+2 -65.9 -9,6 9, 3009 Movila Verde, well 11 670 I9+4 -65.4 -9.9 10. 5008 Dobromir Deal, spring 16 715 7+4 -66.6 -10.5 1. 2. 3. 4. 5. 6. 7. 8.

11. 3022 Bäneasa, spring 17 800 9+4 -67.2 -10.1 12. 3039 P-5, Albeçti 14 1,230 25+5 -44.4 -6.5 13.. - F-4 IBP, Mangalia^ — - - — -

Ill . Groundwater in the Senonian formation 1. 3021 P-l, Basarabi 19 810 13+3 -78,1 -11.0 2. 3026 F-CAP, Valu lui Traian 21 1,080 10+1 -74.2 -10.6

IV • Groundwater in the Barremian-Jui?assio formal3 ions 1. 3013 F-5044, Tortomanu 18 680 <5 -82.6 -11.7 I 2. 3014 F-5091, Medgidia 15 710 <5 -79.7 -11.3 oo 3. 3010 F-5053, Gastelu 21 825 <5 -78.3 -11.1 4. 3030 F-5036, Poarta Alba 17 745 <5 -77.4 -10.9 5. 3018 P-7, Oaragea Dermen 22 1,050 11+2 -71.6 -10.5 6. 3024 P-10, Ciçmea II 18 745 <5 -74.2 -10.7 7. 3023 P-l, Cismea I-A 18 810 <5 -75.3 -11.0 8. 3019 F-IMH, Mamaia 18 780 <5 -77.0 -11,2 9. 3011 F-2 bis, Constanta 17 735 <5 -76.5 -11.0 10, 3032 F-5048, Oltina 16 625 <5 -75.8 -11,0 11. 3028 F-5047, Alimanu 18 650 <5 -65.7 -10.2 12. 3016 F-5046, Peçtera 17 650 -80.5 -11.5 1. , 2. 3. 4. 5. 6. 7. 8.

13. 3045 F-5067, Cobadin 15 645 <5 -97.0 •13.0 14. 3027 F-5063, Adamclisi 19 735 <5 -81.7 -11.2 15. 3029 F-CAP, E§ecliioi2) 17 735 11+4 -63.3 -8.8 16. 3049 F-5062, Báneasa 18 660 <5 -61.3 -9.0 17. ;K)47 F-5064, Independerá 20 770 <5 -75.8 -10.8 18, 3048 F-5074, Píopeni 17 655 <5 -78.3 -11.4 19. 3043 F-5066, Gen. Scärisoreanu 17 635 <5 -85.9 -11.8 20. 3046 $• 5068, Costinesti 18 1,120 c5 -87.7 -12o7 21. 3038 F-5065» ITegru Vodä 14 555 <5 -84.1 -12.3 22. . 3040 F-5082, Mangalia 8 3,170 <5 -86.4 -12.1

1) Sampled could not be taken. 2) Replaced this year by F-CAP Girlitz situated about 3 km N-NE. - 88 -

GROUITDWATER: results of S15C and radio carbon analysis ^

TABIE X

radio carbon Sampling point Pi pmc rad. age ' 1. 2, 3o 4, 5.

1. Ostrov, spring -11o7 107.0+1o2 R 2. Oltina, spring - - —

II. Groundwater in the sarmatian ^matrix"

1. P-ll, Techirghiol -9.3 15.7+0.9 15,300+ 500 2. Moviliza, well -10 .9 81.6+1,2 1,680+ 120 3. P-2, Amzacea -9»2 52,4+1.5 5,340+ 240 4O P-3, Credin-fca -9.7 85.7+0.6 1,280+ 50 5. P-6, Costinesti -10 ,6 19,0+0.6 13,73o7 250 6. F-CAP, Dulceçti -10, .4 30,6+1.1 9,790+ 300 7. P-3, Tatlageac -11, .0 17.3+0.9 14,500+ 400 8. P-CAP, Ghirnogeni - - - 9. Movila Verde, well — — - 10. Dobromir Deal, spring -8, .2 35.9+0.9 8,470+ 200 11. Bäneasa, spring -8«,8 55o7+2.0 4,840+ 300 12, P-5, Albesti -10. 6 30.6+0,8 9,790+ 200 13. F-4 IBP, MangaXia - - —

III. Groundwater in the Senonian formation 1. P-l, Basarabi -8. 5 44,8+0.4 6,640+ 75

IV. Groundwater i5_the_Barremian-Jurassio_formations 1, P-5044, Tortomanu -7.4 5.7+1.0 23,700+1,500 2. P-509I, Medgidia -7.7 7.8+0.6 21,100+ 700 - 89 -

1. 2. 3. 4. 5.

3. F-5053, Castelu -7.2 6.5+0.7 22,600+ 900 4. F-5036, Poarta Alba -7.7 13.8+0.5 16,400+ 300 5. P-7» Carasea Derraen - - - 6. P-10, Siçmea II - - - 7. P-l, Ciçmea I-A -8.1 9.9+0.6 19,100+ 500 8, F-IMH, Mamaia -8.0 9.9+0.4 19,100+ 300 9. F-2 bis, Constanta -8.1 9,7+0,9 19,300+ 750 10. F-5048 , Oltina -7.0 3.8+0.5 27,000+1» 200 "1, 000 11. P-5047 , Alimanu -7.4 11,1+0.4 18,200+ 300 12, F-5046 , Peçtera -8,1 IO.6+O06 18,550+ 45O 15, F-5067 , Cobadlû -8.7 9.5+0.6 19,500+ 500 14. F-5063 , Adamclisi -8.9 22.9+0.4 12,200^ 150 15. F-OAP, E§ech.ioi -9.4 79,0+0,9 1,950+ 100 16, F-5062, Báneasa -8.0 17.5-0,6 14,400+ 300 17. F-5064, Independent a -8.8 7,l+po4 21,900+ 500 18. F-5074, Plopeni -10.2 82o7+0.6 1,570+ 60 19, F-5066, Gen. Scäri§oreanu -8,1 7.9+0.3 20,900+ 500 20. F-5068, Cosfeineçti -1.4 4.0+0.5 26,600+1, 100 21. F-5065, Negru Vodä -7.9 4.1+0,5 26,400+1, 100 200 22. F-5082, Mangalia - 2.9+0.4 29,250+^ 100

' In order to maintain the same identification numbers as in the appended figure, the table includes all the groundwater points selected for the study; the unfilled blanks denote the unsampled sources for radiocarbon and & C analysis.

2^ Calculated using a ha3i-time of 5,730 years; H is recent. Table for chemical parameter computation required in radiocarbon correction TABLE XI ———— — —— —-—— Dissolved carbo- _, p) 3) 1PH nate species ' °T GM Sample HGO," H2C03(aq) > lab. field .0 mmoli.!*"1 me v.l mev.l"1 mmoli.l

1. 2. 3P 4«, 5. 6. 7o 8.

I, Groundwater in the IPliocene formation 1. : Ostrov spring 7.8 7.0 11.395 2.848 14.243 5-697

II. Groundwater in the sarmatian ^matrix" • 1« P-ll, leohirghiol 7.7 7.1 8,498 1.618 10.116 4.249 2, Moviliza, well 7.2 7.1 9.899 1.885 11.784 4,949 3* P-2, Amzacea 7.7 7.0 10.497 2,624 13.121 5.248 4, P-3, Credin^a 7.3 7.2 6.900 1.123 8.023 3.450 5. P-6, Costinesti 7.4 7.2 7,798 1.269 9.067 3.899 6, F-CAP, Dulcesti 8.0 7.1 9.899 1.885 11.784 4.949 ?• P-3, Tatlageao 7.9 7.2 7.555 1.229 8.784 3.777 8. Dobromir D., spring 7.6 7.0 5.998 1.499 7.497 2.999 Sam IV 2. 3o Hro 5. 6. 7o 8. * Bäneasa,, spring 2 1, 624 4.998 9. 8,3 7. 9.997 ,627 11. 10. P-5, Albesti 8,1 7. 1 7.798 1..485 9. 283 3.899 III. Groundwater in the Senonian formation 1. P-l, Basarabi 7,6 7,,1 4.398 0 .776 5. 174 2.199 IV. Groundwater in the Barremian-Jurassio formations 1, F-5044,, Tortomanu 7,7 7..2 4.800 0 .200 5,,000 2.400 2, F-5091,, Medgidia 7.8 7,.3 4.800 0 ,148 4.,948 2.400 3. F-5053,, Castelu 7.6 7..2 4.599 0 ,242 4..841 2,299 4. F-5036,,.Poarta Alba 7.1 7,.1 4.799 1 .199 5..998 2.399 5.' P-l, Cismea I-A 7,2 6,.9 4.999 0 .682 5..681 2,499 6, F-^IMH, Mamaia 7.3 7..0 4.499 0 .499 4,.998 2.249 7. F-*2 bis, Constanza 7.3 7.1 5.099 0 .566 5-,665 2.549 8/ "ni C^\ È% O, 01tina 8.2 7,4 5.199 0 .052 5..251 2.599 9. F-5047:, Alimanu 7.4 7.1 5.898 0 .512 6,.410 2.949 lo« F-5046, Pestera 7.4 7.0 4,499 0 ,391 4,.890 2,249 11, F^5067, Cobadin 7.9 7,3 3.797 0 .077 3.874 1,898 12,' F-5063, Adamolisi 8.0 7,3 5.199 0 .106 5.305 2,599 13f' F-OAP, Eseohioi 7,6 7,2 6.498 0 .342 6 .840 3.249 14. F-5062, Bäneasa 7.8 7.2 6.198 0 .191 6 .389 3.099 •1.' 2. 3o 4. 5. 6. 7. 8.

15, F-5064, Independerá 7.8 7.1 4.882 0.151 5.053 2.441 16, F~507VPlopeni 7.8 7.3 5.199 0.160 5,559 2.599 17, ÏV-5066, Gen. Scärisoreanu 7.7 7.2 5.199 0,216 5.415 2.599 18, P-5068, Costinesti 7.6 7.1 5.201 0.168 5.569 1.601 19. F-5065, Negru Vodä 7,2 6.9 5.799 0,518 4.317 1.899 20.' Ï-5D82, Mangalia 8.4 7.6 9.197 - 9.197 4.598

' Due to the pH field values, CO, is absent in all samples.

' Cm - total dissolved carbonate, molal concentration.

* - mineral origin carbonate, molal concentration. Table for the computation of initial C activity < by means of the Pontes - Gamier method (1979)

TABLE XII

V 6' No. Sample TU m.moli/1 m.moli/1 % °mod

1. 2. 3. 4. 5o 6. 7. 8O 9. 10.

I. Groundwater in the Pliocene formation i 1. Ostrov, spring 107.0 24 -11.7 14,243 0.0 5.697 125 104.0 vO

II. Groundwater in the sarmatian „matrix" 1 1. P-ll, Techirghiol 15.7 12 -9.3 10,116 +1,0 4,249 110 61,7 2, Moviliza, well 81,6 33 -10,9 11,784 +1,0 4,949 120 93,5 3, P-!-2, Amzaoea 5294 11 -9,2 13,121 +1,0 5,248 110 56,9 4, P-3, CredinÇa 85o7 54 -9.7 8,023 +1,0 3.450 130 82.1 5. P-6, Costineçti 19.0 <5 -10,6 9,067 +1.0 3.899 100 75.0 6. F-CAP, Dulcesti 50,6 54 -10,4 11,784 +1,0 4,949 120 85,4 7, P*»3i Tatlageao 17,3 <5 -11,0 8,784 +1,0 3,777 100 80,4 8, Dobromir Deal, spring 35,9 8 -8,2 7,497 +1,0 2,999 110 42,0 9* Bäneasa, spring 7 -8.8 11.624 +1.0 4.998 110 55.8 1. 2. 4. 5. 7. 8. 9. 10. 10. P-5, Albesti 30.6 16 -10»6 9.283 +1.0 3.899 110 81.1

III» Groundwater in the Senonian formation 1. P-l, Basarabi 44.8 21 -8,5 5.174 +1.0 2,199 120 55.1

IV. Groundwater in the Barremian-Jurassic formations 1. F-5044, Tortomanu <5 -7.4 5,000 +0,6 2,400 100 35.4 2. ÎV5091, Me^gidia 7,8 <5 -7,7 4,948 +0,6 2,400 100 40,5 3. P-5053, Castelu 6.5 6 -7,2 4,841 +0,6 2,299 100 31,7 4. ïV5036,.Poarta Alba 13o8 <5 -7,7 5,998 +0,6 2,399 100 27,5 5. P-l, Cismea I-A 9.9 <5 -8,1 5,681 +0,6 2,499 100 39.4 6. FT-IMH , - Marnai a 9,9 <5 -8,0 . 4,998 +0,6 2,249 100 39.5 7. F-2 bis., Constanta 9.7 <5 -8.1 5,665 +0,6 2,549 100 40,8 8, F~5048, Oltina - 3.8 <5 -7,0 5,251 +0,6 2,599 100 31.9 9. F~5047, Alimanu 11,1 <5 -7,4 6,410 +0,6 2,949 100 32,4 10. F-5046, Pe§tera 10,6 <5 -8,1 4,890 +0,6 2,249 100 42,3 11, F-5067, Cobadin 9.5 <5 -8,7 3,874 +0,6 1,898 100 55.6 12. F-5063, Adamclisi 22,9 <5 -8,9 5,305 +0,6 2,599 100 58.4 13. F-CAP,.Eseohioi 79.0 17 -9,4 6,840 +0,6 3.249 120 76,0 14. F-5062, Bäneasa 17,5 <5 -8,0 6,389 +0,6 3.099 100 44,7 15. F-5064, Independerá 7.1 <5 -8.8 5.033 +0.6 2.441 100 56.1 1. ' ' 2. 3. 4. 5. 6. 7. 8. 9. 10.

16, ÎV5074, Plopeni 82,7 10 -10,2 5»359 +0,6 2,599 HO 83,8

17» F-5066, Gen. Scärisoreanu 799 <5 -8,1 59415 +0,6 2,599 100 45,6 18, P-5068,-Costineçti 4,0 <5 -1.4 3,369 +0,6 1,601 100 -51,6 19» P^5065, Negru Vodä 4,1 <5 -7*9 4,317 +0,6 1,899 100 36,4 2) 20, F-5082, Mangalia 2.9 <5 -7.3 9»197 +0o6 4.598 100 36.8

1 - A ). T ^ " T ^ g J Ao * - M

wher«, besides CT and Cjj defined at the foot of (TABLE XI, the following are added: A„ s 1/J"0 activity of gaseous CO- in the soil at the moment of water infiltration into O 111

the, ground. With those samples that have A^ < 85 % Cmo¿ and ^ 5 TU, Ag was considered as G A was 100 pmc; with those samples having tritium contents or activities Am > 85 % mod» g estimated on account of NYDAL and IÖVSEa?H'S diagram (1970); AJJ = 0 activity of the solid carbonate participating in the componence of the

rocks; for all aquifers AM = 0; £= isotopic enriohment factor (per mil) at equilibrium between gaseous C02 and solid carbonate ß15C ?So s -10.5 (computed according to DEINES et al. (1974) formula, for n Í4 an average aquifer temperature of 17 0), As.far as the isotope enrichment factor of 0 is concerned it is assumed that £14C %0L 0.2 £130 #o (CRAIG, 1954); s "^Q contents (per mil) of the total dissolved carbonate«, S*, a *C contents (per mil) of the solid carbonate participating in the componence M of the rock through wich water circulates! in the case of the Barremian-Juraasic aquifer the Ow a +0.6 %o value wa3 reached while for the remaining aquifers it was approximated«, = ^*G contents of gaseous CO^ in the soil at the moment of water infiltration, into the underground; was appreciated (T"*C a -17 %o vs PDB on account of the geographical position, climate and the prevailing type of photosynthesis (type Calvin, three - carbon - atom pathway)«

Value according TENU et al. (1975).

0% Comparative table of the ages computed by various methods1^

TABLE XIII

Radiometrie Fontes-Garnier•s J 3) model ' 13 ages2) Vogel's model Pearson's model Q ño o S a m p 1 e y* O «° o *»; t , ag e t , ag e ñ -P a t , ag e H

1. 2. 3. 4. 5o 6. 7. 8O 9. 10 11. 12o 13o 14.

I • Groundwater in the Plio cene formation 1. Ostrov, spring 107.0 -0.068 R 106.3 -0,006 R 86.0 -0.218 R 104.0 -0.028 R

> 1. p-11, Techirghiol 15.7 1.852 15.3 . 93.5 1.784 14,8 62,9 1,388 11 .5 61,7 1,368 11,3 2, Moviliza, well 81,6 0,203 1.7 102,0 0,223 1,8 79.3 -0,028 R 93.5 0,136 1.1 3. P-2, Amzacea 52,4 0,646 5,3 93,5 0,579 4,8 62,3 0,173 1 .4 56,9 0.082 0.7 4. P-3, Credin-Ça 85.7 0.154 1.3 110,5 0,254 2,1 77,3 -0,103 R 82.1 -0.042 R 5, P-6, Costinesti 19.0 1,661 13,7 85 »O 1,498 12,4 64,4 1,221 10 .1 75.0 1.373 11,4 6, F-CAP, Dulcesti 30,6 1,184 9.8 102,0 1,204 10,0 76,0 0,909 7,5 85,4 1,026 8,5 7. P-3, Tatlageac 17.3 1.754 14.5 85.0 1.592 13o2 66.7 1.349 11 .2 80.4 1.536 12.7 Lo 2. 3. 4. 5. 6o 7. 8 9o 10 o 11 12 13. 14 * * 8, Dobromir D., spring 35,9 1, 024 8, 5 93, 5 o, 957 7, 9 56, 2 o, 448 3,7 42, 0 0, 157 1. 3 9, Bäneasa, spring 55,7 0, 585 4, 8 93, 5 0, 518 4, 3 59, 9 0, 072 0, 6 55*8 0, 002 R LO. P-5, Albesti 30.6 1. 184 9. 8 93. 5 lo 117 9. 2 70o 9 Oo 840 6. 9 81, 1 0. 974 80 1

III . Groundwater in the Senonian formatiorL

lo P-l, Basarabi 44.8 0, 803 6c 6 102, 0 0, 822 6, 8 63. 3 0. 345 2. 9 55*1 0. 207 1. 7

". Groundwater in the Barremian-Jurassic formations s 1. F-5044, Tortomanu 5.7' 2.865 23.7 85,,0 2,,702 22,3 45,5 2,,077 17, 2 35, 4 J-< 826 15. 1 2, P-5091, Medgidia 7,8 2,,551 21,,1 85 ,0 2 ,388 19,,7 47,,2 1,,800 14,9 40, 5 1,,647 13, 6 3, F-5053, Castelu 6,5 2,733 22,,6 85 •o 2,571 21,,3 44,,3 1 ,919 15,9 31.7 1,584 13, 1 1 4, P-5036,: Poarta Alba 13,8 1 »981 16 ,4 85 ,0 1 ,818 15 >o 47 ,2 1 ,299 10,,2 27,,5 0 ,689 5, 7 vO ,4 1 4 5, P-l, Cismea IjA 9,9 2 ,313 19 .1 85 ,0 2 .150 17 »8 49 »4 1,607 13,,3 39 »381 11, • 6, P-IMH, Mamaia 9,9 2 ,313 19 ,1 85 ,0 2 ,150 17 ,8 48 »9 1 ,597 13 >2 39,5 1 ,383 11, 4 7, P-2 bis, Constanza 9,7 2 ,333 19 P3 85 ,0 2 ,171 17 ,9 49 ,4 1 ,627 13 ,5 40 ,8 1 ,436 11, 9 8. P-5048, Oltina 3,8 3.270 27 ,0 .85 ,0 3,107 25 ,7 43 ,2 2,430 20 »1 31 »9 2 ,127 17, 6 9, P-5047, Alimanu * 11,1 2 ,198 18 ,2 85,0 2,035 16 ,8 45 ,5 1 9410 11 32 ,4 1 ,071 8, 9 10, P-5046, Pestera 10,6 2 ,244 18 ,6 85 ,0 2 ,081 17 ,2 49 ,4 1,539 12 ,7 42 ,3 1,384 11, 4 11, F-5067, Cobadin 9,5 2 ,354 19 ,5 85,0 2 ,191 18 ,1 52 ,8 1 ,715 14 ,2 55 ,6 1 ,767 14,,6 12, P-5063, Adamclisi .22,9 1,474 12 ,2 85 ,0 1,311 10 ,8 54 ,0 0 ,857 7.1 58 ,4 0 ,936 7«,7 13, P-CAP,-Eseonioi 79,0 0 ,236 2 ,0 102 »o 0 ,255 2 ,1 68 ,2 -0 ,147 ]B 76 ,0 -0 ,038 R 14. P-5062, Bäneasa 17c5 1 .743 14 .4 85 .0 1 .580 13.1 48 .9 1 o027 8.5 44 o7 0 o937 7 ,8 1. " . .2. 3. 4„ 5. 6o 7. 8. 90 10. 11. 12. 13. 14.

15. F-5064, Independen^ 7»! 2,654 21,9 85,0 2,482 20.5 53,4 2,017 16.7 56,1 2,067 17,1

16, P-5074, Plopeni 82,7 0,190 1,6 93,5 0,123 191 67,5 -0,203 ß. 83,8 0,013 0,1 17* F-5066, Gen. Scäris. 7,9 2,538 21,0 85,0 2,375 19,6 48,9 1,822 15,1 45.6 1O753 14.5 18, P-5068, Costinesti 4,0 3t219 26,6 85,0 3,056 25«3 11.4 1,047 8,7 -51,6 .- - 19, F-5065rHegru Vodá 4,1 3,194 26,4 85,0 3,031 25,1 48,3 2,466 20,4 36,4 2,183 18,1

20, F-5082, Mangalia 2.9 3.540 29,3 85.0 3c378 27o9 44.9 2.739 22„6 36O8 2.541 21.0

Ages romided to the nearest oentury and expressed in thousand of years; R is recent (after 1953).

Ao =100

Ao = 0.85.Ag

A - ^ M A - 100 -

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