Impact of intensive agricultural practices on drinking water quality in the Evros region (NE Greece) by GIS analysis.

Chemical fertilizers are used extensively in modern agriculture, in order to improve yield and productivity of agricultural products. However, nutrient leaching from agricultural soil into groundwater resources poses a major environmental and public health concern. The Evros region is one of the largest agricultural areas in Northern Greece, extending over 1.5 million acres of cultivated land. Many of its drinking water resources are of groundwater origin and lie within agricultural areas. In order to assess the impact of agricultural fertilizers on drinking water quality in this region, tap-water samples from 64 different locations were collected and analyzed for the presence of nitrates (NO(3)(-)), nitrites (NO(2)(-)), ammonium (NH(4)(+)), sulfate (SO(4)(-2)) and phosphate (PO(4)(-3)). These chemicals were selected based on the information that ammonium nitrate, ammonium sulfate and inorganic phosphate were the primary fertilizers used in local crop production. NO(3)(-), SO(4)(-2) and PO(4)(-3) levels exceeding accepted values were recorded in 6.25, 4.70 and 9.38% of all sampling points, respectively. NO(2)(-) and NH(4)(+) concentrations, on the other hand, were inside the permitted range. The data generated were introduced into a geographic information system (GIS) program for computer analysis and projection maps representing afflicted areas were created. Our results indicate a profound geographic correlation in the surface distribution of primary contaminants in areas of intensified agricultural production. Thus, drinking water pollution in these areas can be attributed to excessive fertilizer use from agricultural sources.