Analysis of nitrate occurrence and distribution in groundwater in the Gaza Strip using major ion chemistry

Nitrate in groundwater in the Gaza Strip, Palestine has become a serious problem in the last decade. As a result of extensive use of fertilizers, discharging of wastewater from treatment plants, and leakage of wastewater form cesspools, increased levels of nitrate up to 400 mg/l have been detected in groundwater. Nitrate concentrations more than 50 mg l^-1 are very harmful to infant, foetuses, and people health problems. The most efficient way to prevent nitrate impacts is to identify the sources of nitrate and to reduce them at the source. In this study, samples of groundwater from 63 wells were collected and chemically analyzed. Analysis of these samples revealed they have nitrate concentrations more than the maximum permissible limit recommended by World Health Organization (WHO). The major ion chemistry analysis was used to identify nitrate sources. Based on the relation between land use and nitrate concentration in groundwater, sources of nitrate were identified. These sources are: (1) leakage from wastewater treatment plants, (2) leakage from cesspits, and (3) intensive agricultural activities. It was found that the leakage of wastewater from cesspits and over-loaded treatment plants has greater influence on groundwater nitrate contamination more than agricultural activities. This study shows the important role of the type of infiltrated water into the sub-soil, combined land use, in determining the source of nitrate in groundwater.