Agricultural activities impact on groundwater nitrate pollution

ABSTRACT

Concern over agricultural diffuse pollution sources in integrated water quality management has been growing recently. High nitrogen fertilizers application rates may increase the potential groundwater pollution. These effects were investigated in Andimeshk and Susa plains that cover an area of 1100 km2 between the Dez and Karkhe rivers in north of Khozestan-Iran. This region divided to 4 sub-regions A, B, C, and D. Additionally 168 groundwater samples were collected from 42 water wells during the months April, May, August, and September of 2004. The Hack-spectrophotometer nitrate test was used to measure the NO3- concentration in water samples. Information about further nitrate data was obtained. A questionnaire procedure was used for collection N-fertilizers application rate data in studied area. The results demonstrated that all of the groundwater samples have NO3- concentration below the EPA MCL [44.27 mg/l] and WHO guideline [50 mg/l]. The mean nitrate concentrations are 16.1, 19.5, 13.3, and 7.9 mg/l in sub-regions A, B, C, and D respectively. There are different amount of N-fertilizers applied in sub-regions A, B, C, and D. Correlation between NO3- concentrations and N-fertilizers rate suggests a inverse correlation between N-fertilizers application rate and ground waters nitrate concentrations in studied area [r=-0.69]