Determination and mapping of groundwater pollution sources in Yumurtalık Plain

In this study, Yumurtalık Plain, located in Adana province, was selected as the study area. Water samples were taken from 26 points including 21 deep groundwater wells, 2 ponds, 2 streams and 1 location from the Mediterranean Sea every month during the 2020 water year. The water samples were analyzed in laboratory for pH, chlorine, phosphate, nitrite, nitrate, electrical conductivity (EC), temperature and total dissolved solids (TDS). Laboratory analysis results and the changes in the groundwater depth measurements during fall, winter, spring and summer seasons were mapped using the inverse distance weighted (IDW-Inverse Distance Weighted) method in Geographic Information Systems (GIS) environment. In turn, spatiotemporal changes of the studied characteristics of the groundwater system were analyzed according to the seasons. Groundwater temperature values ranged between 17-30 0C, pH values 7.22-8.27, EC values 0.933-2.433 dS m-1, TDS values 586-2656 mg l-1, Nitrite values 0-0.317 mg l-1, Nitrate values 2-48 mg l-1, Phosphate values 0-2.15 mg l-1 and Chlorine values 49-346 mg l-1. The findings obtained were assessed according to US-EPA, WHO, TS 266 and Water Pollution Control Regulation (WPCR) classification criteria. Furthermore, according to the findings, the potential and quality of the waters for drinking and irrigation water were evaluated. Water sources were classified as 'Class IV' water (should be used with caution) according to WPCR in terms of nitrate values and as 'medium quality water' according to US-EPA. In terms of chlorine values, water resources were classified as 'high chlorine risk water' according to US-EPA. As for groundwater wells, well number 21 was found to be 'doubtful' in terms of TDS and EC. In addition, the laboratory analysis results were also evaluated by US salinity classification and Wilcox classification. According to the US salinity classification, well number 17 was classified as C2-S1 and C3-S1 in the fall, well number 19 as C4-S1 in the winter; wells numbered 1, 13 and 15 as C3-S2 in the spring, while all other groundwater wells were classified as C3-S1 (good to permissible) all year round. According to Wilcox classification, well numbered 18 was classified as 'excellent to good' in fall season, well numbered 21 was classified as 'doubtful to usable' in winter season, well 13 was classified as 'doubtful to usable' and well 21 was classified as 'doubtful to unsuitable' in spring season. All other wells were classified as 'good to permissible' in all seasons.