Assessment of the Contribution of N-Fertilizers to Nitrate Pollution of Groundwater in Western Iran (Case Study: Ghorveh-Dehgelan Aquifer)

Nitrate pollution of groundwater resources has increasingly become a global concern. Groundwater from the Ghorveh-Dehgelan aquifer serves as the main source of water supply for drinking and irrigation within the province of Kurdistan (western Iran). This study investigated (1) groundwater nitrate status as well as the pollution sources and (2) the spatial extent of groundwater nitrate pollution in the region. A total of 72 and 93 samples of groundwater were taken for measurement of nitrate concentration during 2008 and 2013, respectively. Our results showed that 12 wells (12.9 %) exceeded the World Health Organization's acceptable threshold (50 mg L-1 in 2013. The detailed analysis of spatial distribution of the polluted wells revealed that all are located within areas of irrigated agriculture. In addition, our further investigation of annual fertilizer application and the spatial distribution of polluted wells revealed that input of artificial nitrogen fertilizers to irrigated lands was strongly correlated to nitrate concentration within groundwater in these areas. Moreover, the transportation of nitrate through the aquifer has been mainly controlled by geology and pattern of groundwater flow, and therefore, groundwater flow should be taken into account for future quality management of the aquifer. The results of this study will provide useful guidelines for utilizing of nitrate fertilizers in regards to groundwater quality to avoid repeating the problem of groundwater nitrate pollution.