GROUNDWATER PRESSURES IN Cr(VI) IMPACTED AQUIFERS OF CENTRAL GREECE Ariadne Argyraki1 ([email protected]), Konstantina Pyrgaki1, Efstratios Kelepertzis1, Ifigeneia Megremi1, Fotini Botsou1, Maria Hatzaki1, Dimitris Dermatas2 1 National and Kapodistrian University of Athens, Panepistimiopolis Zographou, 15784 Athens, Greece 2 National Technical University of Athens, Athens 15780, Greece INTRODUCTION LAND USES & WATER DEMANDS Annual Water Demand of Loutraki- Annual Demand of Oinofyta Groundwater quantity and quality can be directly affected through changes in precipitation, PROPORTION OF LANDUSE TYPE IN THE STUDY AREAS Perachora Municipality (106 m3 ) (Asopos) Municipality (106 m3) (NUMBERS INDICATE AREA IN SQ. KM) evapotranspiration, recharge rates, and indirectly through changes in land use, irrigation and 1% 14% other human activities. Here we focus on the water quality of four groundwater bodies in 14% 45% 54% 5% central Greece. A common feature of the studied aquifers is the presence of geogenic Cr(VI), 350 67% linked to ophiolithic rock occurrences. Our data are interpreted within the frame of the ERANETMED CrITERIA project. 548 62 60 Irrigation Drinking Livestock Irrigation Drinking Livestock Industrial In CrITERIA, groundwater quality is assessed following a gradient from relatively wet to dry 406 Annual Demand of Thiva Average Annual Water Demand of conditions along the Tethyan Suture Zone that structurally defines locations of ophiolite Municipality (106 m3) Dirfys-Messapia Municipality (Evia) 22 1 6 3 occurrences, extending from the eastern Mediterranean to Oman. 13 106 6 (10 m ) 5 4% 49 4 5% 9% THIVA- ASOPOS EVIA LOUTRAKI SCHINOS 8% AIM Urban Industrial/ Mineral Extraction 91% 81% Irrigated agricultural Non-irrigated/ Forest/ Bare rocks Irrigation Drinking Livestock Industrial Irrigation Drinking Livestock Industrial We examine the linkage between the presence of mainly geogenic Cr(VI) in groundwater Estimated water demands in the study areas are driven by the current state of landuse. According to data bodies of Central Greece and environmental pressures in the respective aquifers induced by from CORINE 2012 landuse database, irrigated agricultural land imposes the largest proportion of water the combined effect of anthropogenic activities and climate change, within the water recharge demand on recharge areas of the studied water bodies. Especially in the Thiva-Asopos basin water zones. demand for irrigation reaches 91% of the total. This fact, combined with the hypothesis of positive feedbacks between irrigation water return - application SAMPLING AREAS of agrochemicals and Cr(VI) release in groundwater indicates that agriculture is the most significant anthropogenic pressure on groundwater resources with respect to Cr(VI) concentrations. PRESENT & FUTURE CLIMATE PROJECTIONS Precipitation and temperature data under present conditions. In addition to anthropogenic pressures a high spatial resolution analysis has been performed Evia with observational data and climate model Thiva simulations on several time-scales drought and Schinos extreme precipitation, providing a concise picture Loutraki of drought and flooding events for the present and the future climate for the case study areas Maps showing the location of Cr(VI) impacted groundwater bodies in Central (Hatzaki et al. 2017). Greece (left map) and study areas of the ERANETMED CrITERIA project (map above), extending along the Tethyan Suture Zone ophiolites. A decreasing trend in dissolved oxygen (DO) in groundwater is noted on data Background map source: Kaprara et al., 2015 collected in 2017 in all participating countries going from west to east. RESULTS HYDROGEOCHEMISTRY & ANTHROPOGENIC PRESSURES ON GROUNDWATER RESOURCES Boxplot of pH Boxplot of DO(mg/l) 9,0 10 9 8,5 ) 8 l / 7 8,0 g H 6 m ( p 5 O 7,5 D 4 3 7,0 2 1 C.Evia Loutraki Schinos Thiva C.Evia Loutraki Schinos Thiva Location Location Boxplot of CrVI(μg/L) Boxplot of HCO3/Mg (molar ratio) ) o i 18 400 t a 16 r r ) 14 a L 300 l / 12 o g μ 10 m ( ( I 200 8 V g r 6 M C 100 / 4 3 2 O 0 C 0 Spatial distribution of annual precipitation (in mm) as derived from the E-OBS gridded data (map on the left) and interpolated C.Evia Loutraki Schinos Thiva H C.Evia Loutraki Schinos Thiva Location Location maps (right) displaying dry season precipitation totals (in mm) derived from model data for RCP4.5 for the near and the remote future and for RCP8.5 (bottom left and right), respectively. The majority of groundwater samples (>100 measurements) are of Mg-HCO3, Mg-Ca-HCO3 The most significant decrease is seen in annual precipitation for Asopos for the RCP8.5, which and Ca-Mg-HCO3 type. reaches 11.5 mm/decade. The comparison between wet and dry seasons, indicates that for the The dispersion of samples towards high chloride and sodium concentrations indicate the near future the precipitation will remain unaltered. For the remote future, the decrease during the impact of sea water intrusion on the quality of groundwater in some areas. wet season will be of about 25%, for the two scenarios, while the dry season precipitation will undergo significant changes under RCP8.5 that will exceed 42%. Cr(VI) concentrations range between < 2 μg/L and 130 μg/L - in agreement with reported geogenic concentrations from the international literature (Fantoni et al. 2002; Megremi et al. 2013). Cr in groundwater occurs mainly in its hexavalent state which is the toxic form of Cr. CONCLUSIONS 1. A decreasing gradient is observed in DO concentrations moving from Mediterranean countries Most samples have a molar ratio of HCO3/Mg close to 2, indicating water interaction with seprentinite (Fentoni et al. 2002) which is a potential geogenic source of Cr to Oman, indicating changes in biogeochemical conditions taking place within the aquifers when moving along the aridity gradient. The influence of anthropogenic activities such as intensive agriculture is indicated by high 2. Irrigation of agricultural land seems to be the most significant anthropogenic pressure on nitrate concentrations (>50 mg/L) occurring mainly in the groundwater of agricultural areas. groundwater of the groundwater in the Greek study areas, while there is also evidence of water High sulfate and chloride concentrations are more profound in coastal areas, indicating the salinization in coastal areas. impact of sea water intrusion on the quality of groundwater (maps below). 3. The increased predicted climate variability and the trend in precipitation decrease with probable evapotranspiration increase has profound impacts on water balance. These will primarily affect groundwater recharge and quantity in the study areas, but will also lead to increased anthropogenic pressures on water. 4. The key for the estimation of potential groundwater quality feedbacks under changing climate in the future, including geogenic Cr release and oxidation, lies with being able to better constrain and manage the effects of anthropogenic pressures within water recharge zones. REFERENCES Fantoni D., Brozzo G., Canepa M., Cipolli F., Marini L., Ottonell G., Vetuschi Zuccolini M. (2002). Natural hexavalent chromium in groundwaters interacting with ophiolitic rocks, Environ. Geol., 42, 871-882. Hatzaki, M., Argyraki, A., Gkiouleka, I., Paternoster, M., Hatipoglu Bagci, Z., Shammout, M., Moraetis, D., Christou, A., Zissimos, A. and Dermatas, D. (2017) A future climate assessment on the quality and quantity of Cr(VI) contaminated groundwater in the eastern Mediterranean. AGU Fall Meeting, New Orleans 11-15 December 2017. Kaprara, E., Kazakis, N., Simeonidis, K., Coles, S., Zouboulis, A.I., Samaras, P., Mitrakas, M., (2015). Occurrence of Cr(VI) in drinking water of Greece and relation to the geological background. Journal of Hazardous Materials 281, 2-11. Megremi, I., Vasilatos, Ch., Atsarou, A., et al. (2013) Geochemical evidences for the sources of the Cr(VI) contamination in groundwater in central Euboea and Assopos-Thiva basins, Greece: Natural versus anthropogenic origin. European Water, 41, 23-34. ACKNOLWEDGEMENTS The present work was co-funded by the European Union and Greek national funds through the Operational Program "Competitiveness, Entrepreneurship and Innovation", under the ERANETMED 1st Joint Call on Water Resources (project acronym: CrITERIA/ project code: T3EPA-00004)..