Hydrochemical and stable isotopes indicators for detecting sources of groundwater contamination close to Bahr El-Baqar drain, eastern Nile Delta, Egypt

ABSTRACT Groundwater pollution through the hydraulic connection with wastewater and agricultural drains is a crisis problem facing the developed countries worldwide. Shallow groundwater in the Quaternary aquifer in the eastern Nile delta close to Bahr El-Baqar drain is considered the main source for irrigation and potable water. Geochemistry and stable isotopes (δ 18O, δ 2H and δ 15N) have been utilized to detect the main sources for groundwater contamination. The groundwater samples were classified into two main groups; fresh and brackish water types. The δ18O and δ2H elucidate that the fresh groundwater source is mainly from the recently infiltrated drainage water, while brackish groundwater experience extensive evaporation processes and leaching from the aquifer matrix. High ammonia concentration (4.3 to 37.5 mg/l) indicates the influence of anthropogenic activities and seepage from the sewage drains. The δ15N isotopic content indicates the main groundwater contaminant sources are; sewage disposal, mineral fertilizer, and open drains