Hydrochemical and statistical analysis of Nitrate pollution of groundwater in Meydavod-Sarleh plain

In the present study, nitrate pollution of groundwater in the Meydavod-Sarleh plain in the north east of Khuzestan province is considered. The rural population of the plain get their drinking water supply from an unconfined aquifer. Two main objectives of this study are: (۱) groundwater nitrate pollution assessment and (۲) its correlation with other ions and water table depth. Identification of probable sources of nitrate pollution, also, has been considered in this article. For assessing the extent of nitrate pollution, all water resources were sampled in wet and dry seasons. The water samples were analysed for major ions, including nitrate by Ion chromatography method. The results showed that the average nitrate concentration in wet season was higher than the average nitrate concentration in dry season. Also, the nitrate concentration in all samples was more than the permissible level (۱۰mg/l). The causes of groundwater pollution were surveyed by statistical methods. The results showed that the distribution of data was normal; the Pearson correlation between nitrate concentration and other parameters (major ions and EC) was negative and different. The difference between the average nitrate concentration in wet season and dry season was significant. The correlation between well depth and water table depth with nitrate concentration also was negative. The zonation analysis of nitrate concentration showed that the difference between the average nitrate concentration of the northern zone of the aquifer and central zone was small, but that the difference between the average nitrate concentration of these two zones and the southern zone was significant.