Investigation of Hydrochemical Characteristics of Groundwater in the Harzandat Aquifer, Northwest of Iran
Total Page：16
File Type：pdf, Size：1020Kb
Environ Monit Assess DOI 10.1007/s10661-010-1575-4 Investigation of hydrochemical characteristics of groundwater in the Harzandat aquifer, Northwest of Iran Nosrat Aghazadeh · A. A. Mogaddam Received: 30 November 2009 / Accepted: 15 June 2010 © Springer Science+Business Media B.V. 2010 2+) − 2−) Abstract The Harzandat plain is part of the East Mg and weak acids (HCO3 ,CO3 .The Azerbaijan province, which lies between Marand chemical quality of groundwater is related to and Jolfa cities, northwestern of Iran, and its the dissolution of minerals, ion exchange, and groundwater resources are developed for water the residence time of the groundwater in contact supply and irrigation purposes. The main litho- with rock materials. The results of calculation sat- logic units consist chiefly of limestone, dolomite, uration index by computer program PHREEQC shale, conglomerate, marl, and igneous rocks. In shows that nearly all of the water samples were order to evaluate the quality of groundwater in supersaturated with respect to carbonate minerals study area, 36 samples were collected and an- (calcite, dolomite and aragonite) and undersatu- alyzed for various ions. Chemical indexes like rated with respect to sulfate minerals (gypsum and sodium adsorption ratio, percentage of sodium, anhydrite). Assessment of water samples from residual sodium carbonate, and permeability in- various methods indicated that groundwater in dex were calculated. Based on the analytical re- study area is chemically unsuitable for drinking sults, groundwater in the area is generally very and agricultural uses. hard, brackish, high to very high saline and al- kaline in nature. The abundance of the ma- Keywords Groundwater quality · − − 2− · · jor ions is as follows: Cl >HCO3 >SO4 and Harzandat plain Hydrochemical Na+>Ca2+>Mg2+>K+. The dominant hydrochem- Hydrogeochemical processes · Saturation index ical facieses of groundwater is Na−Cl type, and + +) − 2−) alkalis (Na ,K and strong acids (Cl ,SO4 + are slightly dominating over alkali earths (Ca2 , Introduction Understanding of the aquifer hydraulic properties B and hydrochemical characteristics of water is cru- N. Aghazadeh ( ) cial for groundwater planning and management in Department of Geology, Urmia Azad University, Urmia, 57159-44867, Iran the study area. Generally, the motion of ground- e-mail: [email protected], water along its flow paths below the ground sur- [email protected] face increases the concentration of the chemical species (Domenico and Schwartz 1990; Freeze A. A. Mogaddam Department of Geology, Tabriz University, and Cherry 1979; Kortatsi 2007). The quality of Tabriz, Iran groundwater is the resultant of all the processes Environ Monit Assess and reactions that act on the water from the and its average annual rainfall is about 280 mm, moment it condenses in the atmosphere to the which 70% of it falls during the spring and win- time it is discharged by a well (Arumugam and ter seasons. Groundwater is an important water Elangovan 2009). Hence, the groundwater chem- resource for drinking, agriculture, and industrial istry could reveal important information on the uses in the study area. Low precipitation and over- geological history of the aquifers and the suitabil- exploitation of groundwater resources in recent ity of groundwater for domestic, industrial, and years have caused an extensive groundwater level agricultural purposes. decline in this plain prohibiting further develop- Hydrochemical evaluation of groundwater sys- ment of the aquifer. tems are usually based on the availability of a large amount of information concerning ground- water chemistry. Groundwater chemistry, in turn, Geology and hydrogeology depends on a number of factors, such as general geology, degree of chemical weathering of the From a geological point of view, the investi- various rock types, quality of recharge water, and gated area is located in the Alborz–Azerbaijan inputs from sources other than water–rock inter- zone of Iran, and it is covered by Devonian action. Such factors and their interactions result to Quaternary sediments (Nabavi 1976). Triassic in a complex groundwater quality (Ayenew et al. sedimentary rocks consist of dolomite and thin 2008; Domenico and Schwartz 1990; Giridharan limestone. Jurassic and Cretaceous formations et al. 2008; Guler and Thyne 2004). in the study area chiefly comprise green shale The rapid increase in the population of the and flysch-type sediments. Andesitic, dacitic and country has led to large-scale groundwater devel- rhyodacitic igneous rocks of Devonian age are opments in some areas. Intensive cultivating and outcropped in many mountainous areas. As a urban development has caused a high demand on consequence, the Quaternary deposits are mainly groundwater resources in arid and semiarid re- characterized by silty-muddy layers alternating gions of the world and Iran while putting these re- with sandy and sometimes gravel lenses. The ex- sources at greater risk to contamination (Asghari posed lithological units of the Harzandat plain Moghaddam and Najib 2006; Giridharan et al. range in age from Devonian to Quaternary 2008; Khazaei et al. 2006; Jalali 2007; Tayfur et al. and have different hydrogeological characteris- 2008). In this study, physical, hydrogeological, and tics (Fig. 1). The units of similar hydrogeological hydrochemical data from the groundwater system characteristics are summarized in Table 1 and will be integrated and used to determine the main are qualitatively grouped as impermeable, semi- factors and mechanisms controlling the chemistry permeable, and permeable. of groundwater in the area. The chemical quality In the study area, the Devonian Formations of groundwater is related to both the lithology of and intrusive rocks are impermeable, and the Tri- the area and the residence time of the water in assic formations (limestone, calcareous shale, and contact with rock materials. dolomite) and Eocene Formations (Flysch type sediment, tuff, pyroclastics, and sandstone) are semi-permeable. The red and green gypsiferous Description of the study area marl, green shale, alluvium, and red conglomer- ates are permeable (Aghazadeh and Mogaddam The study area is part of the Aras river drainage 2004). basin and lies between latitudes 38◦35 to 38◦45 N The groundwater of the study area occurs un- and 45◦30 to 45◦45 E (Fig. 1). Harzandat plain der unconfined conditions. The result obtained covers an area of 78.6 km2 (Fig. 1). The area form drilled wells indicates that the thickness of has a cold temperate climate and the air temper- the alluvium aquifer in average is 65 m (Azerbaijan ature is highest in August (24.4◦C) and lowest Regional Water Authority 2004). The maximum in January (−2.6◦C) with an annual average of thickness is about 170 m, which lies in the central 13.2◦C. The climate of the study area is semiarid part of the plain. The general groundwater flow Environ Monit Assess 46 Caspian 45,30 Sea PI Js Hadiy Shahr Re1 38,45 Tehran Re2 Zal I.R.Iran Drd 60 Oryantapeh Mc,s Harzand Re3 Study Area Ea OLv Persian Zonuz Gulf Ec 38,30 Qal Eu Marand Town 30 Eu Qtr Dad Village Lake Harzand Galingaieh Main Road Ef 0 4 Km Et,p Shabestar Ef Tabriz Eu Urmia Lake 30 Qal Ec LEGEND Emg N Synclinal axis Et,p Eu Fault 45,30 30 38,35 Strike and dip Alluvium(Qal) Pyroclastics(Eu) 45,45 Quat. Travertine(Qtr) Tuff,pyroclastics(Et,p) Village conglomerate(PI) Andesite(Ea) Shale Plio. Drainage Jura. Shemshak formation(Js) marl(Emg) Red conglomerate(Mc,s) - Pale. Eoce. Dolomite and thin limestone Mioc. Tria. Elika formation(Re1,2,3) Dacit (OLv) Red conglomerate (Ec) Olig. Red sandstone(Es) Andesite dacite(Dad) 0 2 Km Flysch type sediment(Ef) Rhyodacite(Drd) Fig. 1 Geology and hydrogeology units of the study area direction in the aquifer is from SE to NW (Fig. 2), from the aquifer during the water year 2002– and its depth to water table varies from 6 to 2003 is about five million cubic meters. The mean 46 m below the ground level. Abstraction rate seasonal groundwater levels fluctuations of the Table 1 Stratigraphic Age Formation Hydrogeologic relations of the geologic properties units in the study area al) showing hydrogeologic Quaternary Alluvium(Q Permeable tr properties Travertine(Q ) Pliocene Poorly consolidate conglomerate(PI) Semipermeable Miocene Red conglomerate(Mc,s) Permeable Oligocene Dacit flows and domes(OLv) Impermeable Eocene Pyroclastics(Eu) Semipermeable Tuff,pyroclastics(Et,p) Semipermeable Andesite(Ea) Impermeable Red and green gypsiferous marl(Emg) Permeable Cretaceous Flysch type sediment(Ku) Semipermeable Jurassic Green shale(Shemshak formation)(Js) Semipermeable Triassic Dolomite and thin limestone(Elika formation)(Re) Semipermeable Devonian Andesite dacite(Dad) Impermeable Rhyodacite(Drd) Impermeable Environ Monit Assess Fig. 2 Location of N groundwater samples in 38,45 study area 0 5 3 1 0 6 3 1 0 7 3 1 Oryanthapeh 80 13 38,40 Galinghaieh 1410 Harzand 0 142 0 0 4 1 Village 1430 Observation well 1390 Water sample Flow Line 45,30 0 2 Km 45,45 38,35 2−) study area indicates that the maximum and mini- contents. Sulfates (SO4 were estimated using mum water level is in May and September, respec- the colorimetric technique. tively (Aghazadeh 2004). Results and discussion Materials and methods Groundwater chemistry In order to evaluate the quality of groundwater in study area, groundwater samples were collected The overall groundwater pH and EC values of from 36 shallow and deep wells and springs of the study area are ranging from 6.8 to 8.2 and the area during May 2005. The pH and electrical 990 to 6220 μS/cm, respectively. The large vari- conductivity (EC) were measured using digital ation in EC is mainly attributed to geochemical conductivity meters immediately after sampling. processes prevailing in this region. Total dissolved Water sample collected in the field were ana- solids (TDS) in the study area vary from 653 to lyzed in the laboratory for cations (Ca2+,Mg2+, 4,000 mg/l.