Determination of groundwater quality and pollution potential of the Ceylanpinar Plain

Ceylanpinar Plain has the largest agricultural and animal breeding area of Turkiye. The plain has a surface area of approximately 2.000 km2, about 1.750 km2 of which belong to the Ceylanpinar Directorate of Agriculture in General Directorate of Agriculture (TİGEM). In this study, seasonal average groundwater distribution maps were prepared for sensitive and risky areas in order to monitor the groundwater quality and to determine the potential risk of contamination. The groundwater sampling was carried out for the terms of April 2012, July 2012, November 2012, and January 2013 as representative of one year period. The groundwater samples were analyzed for parameters such as electrical conductivity (EC), temperature, and pH on-site, some metals Mn, Al, Cd, Co, Cr, Fe, Ni, Pb, Si, Ba, and Zn as well as anions and cations such as Ca, Mg, Na, K, chloride (Cl-), fluorine (F-), sulfate (SO4), bicarbonate alkalinity (HCO3), nitrite (NO3), nitrate (NO2) and total phosphate (PO4) measured in the laboratory. Total hardness, Sodium Adsorption Ratio (SAR), % Na and Permanent Sodium Carbonate- Residual Sodium Carbonate (RSC) values, on the other hand, were determined by calculation. The results obtained were assessed using a number of national and international standards and classification. The groundwater was then classified using groundwater hydrochemical facies types (Piper and Schoeller) and irrigation water quality (Wilcox and the U.S. salinity diagram).As a result of the evaluation of many parameters in the groundwater of Ceylanpinar Plain, higher values were observed in the areas particularly of Gumussu and Gokcayir in the discharge basin. EC and nitrate levels were observed to be very high in the same areas exceeding the standard values while there was found to be no risk in terms of heavy metals. Hydrochemical facies classification (Piper Classification) of waters indicates two types of groundwater; type 5 with Ca-HCO3 and type 9 with mixed-water (Ca-Mg-Cl-SO4). The quality of groundwater in terms of irrigation water was assessed using Wilcox diagram and 1 sampling point was found to be