Impacts of agricultural activities on ground water quality in Weishan irrigation district

In order to investigate the groundwater pollution status caused by agricultural activities in the Weishan irrigation district along the Yellow River, a water quality survey was carried out using the point-area combined method.The nitrogen and phosphorus concentration of the groundwater samples were measured and analyzed,and the water quality was assessed according the Quality Standards for Ground Water using the single-index method.The results showed that nearly 30% of the groundwater quality was worse than the level Ⅲ water standard,and the groundwater showed an obvious trend of deterioration year by year.Because of the plain geomorphology,the soil water mainly moved vertically.The nitrogen concentration in the groundwater was affected by irrigation and fertilization remarkably,and increased in recent years.Nitrogen leaching through irrigation and vertical drainage might be the major reason for the nitrogen accumulation in groundwater.