Analysis of nitrate contamination of Gaza coastal aquifer, Palestine

The ongoing degradation of the water quality of the Gaza Coastal Aquifer (GCA) is of a great concern for the different authorities and agencies involved in the water sector in the Gaza Strip, Palestine. The GCA is almost the only source of fresh water to over 1.5 million residents where it is utilized extensively to satisfy agricultural, domestic, and industrial water demands. The aquifer is currently being overpumped where pumping largely exceeds total recharge. In addition, mammade sources of pollution endanger the water resources supplies in the major municipalities of the Gaza Strip. Many water quality parameters in the GCA presently exceed the maximum contaminant level (MCL) of the US Environmental Protection Agency drinking water standards, especially for nitrate and chloride. This case study analyzes nitrate concentration distribution for the GCA at different levels such as land use classes and sampling depth. Nitrate concentration data from 1990 and from 2000 to 2004 were compiled and assembled into a single composite database. A geographic information system was used to assess the spatial and temporal variability of nitrate occurrences in the aquifer. Results show that the first quartile of nitrate concentration for the years 1990 and 2000-2004 exceeds the MCL. In addition, the analyses demonstrated a generally increasing trend in groundwater nitrate concentration. The areas with the most elevated nitrate concentrations are areas characterized by heavy agricultural activities and urban areas. Elevated nitrate concentrations in the GCA indicate anthropogenic contamination sources.