Mechanism of N- Nitrate pollution of Kashan plain aquifer

In this research, the hydrogeochemical situation of Kashan aquifer, its pollution to nitrate and nitrite and their mechanism were studied. For this purpose, 42 water samples from the aquifer were prepared and analyzed. The results showed that chloride and sulfate are predominant anions and sodium and calcium are dominant cations. The results about the permitted range of TDS, pH, Na, K, Cl-, SO42-, NO3-, NO2-, Ca2 and Mg2 variables showed that respectively, 97.61%, 40.47%, 100%, 97.61%, 95.23%, 38.09%, 95.24%, 83.34% and 95.23% of region water resources have unauthorized status according to WHO and ISIRI standards. Correlation between NO3- with Na, K, Ca2 , Mg2, Cl-, SO42-, NO2-, TDS and EC was 0.68, 0.50, 0.63, 0.52, 0.64, -0.34, 0.32, 0.64, 0.64, respectively. other results showed that nitrate varied between 1.86 to 1034 and had an average of 118.76 mg/lit. Also, 40.49%, 21.42% and 38.9% of the samples for nitrate were slightly polluted, polluted and highly polluted, respectively. For more precise investigation of aquifer contamination, based on WHO recommendation, the combined results of nitrate and nitrite showed that 95.23% of the samples had a non-allowable concentration. Therefore, only small parts of the aquifer in the south, southwest and west have acceptable situation.