ECOTERRA Journal of Environmental Research and Protection A hydrochemical approach to the mineral waters from the Eastern Carpathians Boglárka-Mercedesz Kis, Călin Baciu Faculty of Environmental Science and Engineering, University Babeş-Bolyai Cluj-Napoca, Romania. Corresponding author: B. M. Kis, [email protected] Abstract. The Eastern Carpathians are renowned for their mineral water resources, exploited since long time for their therapeutic value. In the present paper we summarize the chemical findings of a research carried out on 104 mineral water spring in the Eastern Carpathians. Two major types of waters (Ca-Na- HCO3 and Na-Cl) were identified based on the analysis of the major ions. The overlapping chemical features give birth to the mixed type of waters found in the southern part of the Eastern Carpathians. All of the waters are associated to bubbling gases of CO2, CH4 or H2S. The chemistry of mineral waters is highly influenced by the type of rocks they are leaching. Considering this aspect the mineral waters from the Eastern Carpathians are mainly influenced by the Neogene to Quaternary volcanic rocks of the Călimani-Gurghiu-Harghita Mountains, the sedimentary deposits of the Transylvanian Basin and the flysch deposits of the Carpathian arc. Key Words: Eastern Carpathians, mineral waters, major ions, CO2. Introduction. When speaking abount mineral waters, or defining the notion of “mineral water”, three aspects must be taken into consideration: geological, medical and social aspects or recent trends on water consumption. These aspects, together with the actual definition of the „mineral water” has changed several times during history from the past until the present. The mineral water resources of the Eastern Carpathians are renowned since historic times when the first spas, like Sărăţel, Anieş (Chintăuan 1998), Borsec, Vâlcele, Odorheiu Secuiesc and the salty fountains of the Transylvanian Basin (Fischer 1887) were constructed at several places by the Romans. For a proper harness of these resources, they were highly examined from different perspectives: chemical, geological, medical etc., using the opportunities and technology of the era. Results are reported in different synthesizing studies, books, monographs, which discuss the therapeutic value, geology and geochemistry of the mineral waters. Description of the mineral water sampling sites in the Eastern Carpathians. The water samples were collected along a 200 km transect at the boundary between the Eastern Carpathians and the Transylvanian Basin marked by the contemporary presence of volcanic and sedimentary formations, including evaporites. From North to South, following the volcanic chain samples were collected from several locations: Valea Vinului, Şanţ, Rodna, Anieş, Parva, Sângeorz Băi, Lunca Ilvei, Măgura Ilvei, Ilva Mare, Colibiţa, Mureşenii Bârgăului, Josenii Bârgăului, Mintiu, Tăure, Blăjenii de Jos, Dumitra, Viişoara, Jabeniţa, Aluniş, Idelciu de Jos, Corund, Odorheiu Secuiesc, Băile Homorod, Vlăhiţa, Băile Chirui, Lueta, Mereşti, Mărtiniş, Sânpaul, Homorod Braşov, Racoş (Figure 1). Ecoterra - Journal of Environmental 8 www.ecoterra-online.ro Research and Protection, 2013, no. 35. Figure 1. Map of the investigated mineral waters between the Eastern Carpathians and the Transylvanian Basin boundary (http://www.google.com/earth/index.html). In the northernmost part of the study area, at Valea Vinului, renowned in the past for its mineral waters with therapeutic effect, but in the present devastated by the mining activities, the mineral waters come to surface from the metamorphic units of Rodnei Mountains, from chloritic schist, sericitic schist, graphitic schist, quarzite. The springs are of Na–Ca–Mg–HCO3–Cl type with Li, Al, Br and dissolved CO2. Sparkling mineral water are present along the Valley of Someşul Mare river, due to the presence of the Someş fault system, which facilitated the uprising of magmas and establishment of several intrusions along the valley also providing the rising path for deep fluids. The mineral waters are found all along the valley and come to surface as springs, fountains and in boreholes. Generally the mineral waters from Şanţ and Rodna are of Na–Ca–Mg–Fe–HCO3 type having trace elements like Br, I, Al, Li and remarkable radioactivity. At Anieş, the first balneological centre of the area, the springs belong to the Na– Ca–Mg–Cl–HCO3 type and have built large travertine cones which reduced the discharges of the springs. To the west the metamorphic structuctures meet the Eocene and Oligocene deposits of the Transulvanian Basin. At Parva the mineral waters are of Ca–Mg–HCO3–Cl type with dissolved CO2 and H2S. At Sângeorz Băi the V-E oriented Someş fault intersects a N-S oriented fault system, resulting in the abundance of mineral waters presently exploited for their therapeutic value and contributing to the flourishing of the spa. The geological setting of the area Eocene and Oligocene deposits of the Bârgăului Mountains, calcareous marls, sandstones and shale complex slashed by the magmatic intrusions, define the water type as Na–Cl–Mg–Cl–HCO3. The mineral waters have formed a large travertine hill. South to the Someşul Mare River the V-E oriented fault system Grădiniţa separates tectonically the Eocene and Oligocene deposits. Along this fault system the valley of Ilva River and a number of mineral water springs can be found eg. Lunca Ilvei, Poiana Ilvei, Măgura Ilvei and Ilva Mare. These groungwaters belong to the Na–Ca–Fe–HCO3–Cl type with Li, Al and Br. The high mineralization of the spring suggests a deeper circulation of these waters and their uprising through the fault systems. Approaching the Transylvanian Basin and the Badenian (Middle Miocene) salt diapirs, in the proximity of Bistriţa, eg. Tăure, Mintiu, Blăjenii de Jos, Dumitra, along the Bistriţa River at Mureşenii Bârgăului, Josenii Bârgăului etc. the groundwaters are of Na–Cl type with high salinity. With few exceptions of spring located Ecoterra - Journal of Environmental 9 www.ecoterra-online.ro Research and Protection, 2013, no. 35. in the neighbourhood of the volcanoes from Călimani Mountains, where CO2 is associated with the groundwaters of Ca–Mg–HCO3 type (eg. Colibiţa), the mineral waters do not contain dissolved CO2. At Viişoara, the presence of dissolved H2S was detected in the white-coloured precipitate of the water (Chintăuan 1998). Following the continuous alignment of salt diapires from Bistriţa to Pintic- Brâncoveneşti-Ideciul de Jos-Jabeniţa-Gurghiu-Orşova-Sovata-Praid, along the Mureş River both the surface and groundwaters get in contact with the outcropping deposits. A series of salty fountains, springs (eg. Orşova, Gurghiu, Jabeniţa, Brâncoveneşti, Lunca Mureşului) and lakes (Jabeniţa, Ideciul de Jos, Sovata) are related to the dissolution of salt and increased mineralization. Some of the lakes are the remnants of old salt mines, which got abandoned and accumulated with groundwaters. These water resources and also the mud are used for treatment in spas of local interest (Jabeniţa, Ideciul de Jos, Sovata) (Szabó 2006a, 2006b). The presence of I in the waters from Ideciul de Jos led to the hypothesis that some of the springs might be formation waters (Molnár-Amărăscu 1961). Salt exploitation stopped in the Mureş valley but still goes on at Praid, where the largest salt diapire is located. Here the NaCl-rich mineral waters have a specific thermal character, reaching temperatures up to 40ºC. From Praid the salt alignments continue through Corund-Odorheiu Secuiesc and the valleys of Homorodul Mare and Homorodul Mic. At Corund two types of mineral waters were described by Pascu (1929): sparkling mineral waters with low salinity of Ca-HCO3 and sparkling mineral waters of Na-Cl type and high mineralization. The latter are the typical CO2-rich highly mineralized groundwaters specific for the contact area between two geological units, the Eastern Carpathians and the Transylvanian Basin and being largely affected by fault systems which facilitate the uprising of deep circulating waters. On the origin of the mineral waters from Corund several hypotheses appared, Bányai (1934) describing the springs as being related to hydrocarbon deposits with simltaneous enrichment of dissolved constituents due to the proximity of salt diapirs with CO2 of non post-volcanic origin, most probably related to the CH4. Molnár-Amărăscu (1961) mentiones the spring of Corund as formation waters, having high Cl, Br and I content. The mineral waters of Corund, similarly to those from Sângeorz Băi and Anieş have large travertine deposist and aragonite minerals unusual for cold CO2-rich waters was also described (Gheorghiu et al 1962). Several mineral water spas of mainly local or national interest are situated on the western slope of Harghita Mountains. These are: Băile Seiche (Odorheiu Secuiesc), Băile Selters (Lueta), Băile Chirui, Vlăhiţa, Băile Homorod. The mineral waters are also used as drinking water and for curative reasons. In the westernmost limit of the post-volcanic area, an interesting mixture between mineral waters originating from volcanic deposits and deep aquifers is represented by the mineral waters from Odorheiu Secuiesc and its small spas Băile Seiche and Kápolnás. These springs are located at the boundary between volcanic and sedimentary deposits. The free gases such as CO2 (90%), H2S and also CH4 (9.8%) from these springs have both post-volcanic and organic origin (Molnár-Amărăscu 1961). According to some authors (Bányai 1934; Molnár-Amărăscu 1961) the CO2 from these springs are not of post-volcanic origin rather they are related to the hydrocarbon deposits. The mineral water types are of Mg-Na-Ca-HCO3-Cl, Na-Mg-Ca-Cl-HCO3 and NaCl type. Along the upper part of Vârghiş-Valley at Băile Selters (Lueta) there are several water springs and one local spa. Some of the springs from this area used to be bottled in the past (Selters spring). The location is named after the mineral waters from Germany (Selterswasser) after their high dissolved CO2 and NaCl content (Bányai 1934). The traditional Nádasszék Spa is used by the local people for healing (Zepeczaner 2009).