The Zoning of Nitrate Concentrations in Meymeh Aquifer by Using GIS

The increase of Nitrite and Nitrate in groundwater resources has caused many concerns in agricultural and industrial areas. Nitrate has always been under focus as one of the indicators of chemical water pollution. The Objective of this study is to determine the amount of nitrate in Meymeh aquifer in Isfahan province.
In order to determine the amount of nitrate, Samples were taken from 10 wells based on sampling standards transferred to Water Laboratory for analysis. Spectrophotometric method was performed to measure the amount of nitrate. Then, the zoning of nitrate changes was drawn by using ArcGIS 10 and Interpolation models.
Findings: Electrical conductivitis from the selected wells were from 823 to 4170µs/cm and the average nitrate concentration was 30.64 ppm with a standard deviation 19.77 from 8.51 to 59.43 ppm. In 68% of analysed samples, the standard deviation was observed to be about 19.77 which indicate a close distribution of obtained data to average concentration of results.
Electrical conductivity of water Samples from high elevations toward the plains feeding areas increases from the Northeast and West toward the Central Plains. The highest concentrations of nitrate is related to the southern aquifer that Most likely is due to high groundwater levels and farming activities in the region. Although the average nitrate concentrations in most of the samples is less than 50 ppm, but it is still vital to protect groundwater resources from pollutants.