evaluation of nitrate pollution in groundwater resources of ardabil aquifer using geographical information system

groundwater is one of the most important resources of water supply for various uses in many regions all over the globe including iran. different contaminants severely affect these resources and might render groundwater unsuitable for consumption. groundwater contamination by nitrate is a well known globally growing problem due to the population growth and increase of demand for food supplies. this study was conducted to evaluate the nitrate concentration in water resources of ardabil aquifer using geographical information system. water samples were collected from 63 wells in ardabil aquifer during the september 2014 and analyzed for nitrate concentration. the average nitrate concentration from the wells was 39.18 mgl-1. based on the variography analysis, nitrate concentration showed a good spatial structure which may lead to the high performance of the ordinary kriging (r2=0.508) in predicting the groundwater nitrate spatial pattern. nitrate concentration was very high at the western parts of the aquifer where the ardabil city and its agricultural lands is located. these results clearly indicates that the anthropogenic sources from human activities and agricultural development are the main reasons of the nitrate pollution in this part of the aquifer.