Spatial-temporal Change Characteristics of Nitrate in Groundwater in Typical Agricultural Areas of Liao River Basin

NIU Shi-wei;AN Jing-wen;GONG Liang;CAI Guang-xing;HE Zhi-gang;CHEN Yue;LIU Zi-qi;SUI Shi-jiang;Institute of Plant Nutrition and Environmental Resources ,Liaoning Academy of Agricultural Sciences;

agricultural cultivation areas;;groundwater;;nitrate;;well depth

By sampling groundwater samples from 2 839 wells in typical agricultural areas of Liao river basin from 2005 to2012, the nitrate concentration was analyzed to understand and evaluate nitrate status in groundwater of agricultural cultivation areas. The results showed that the average nitric nitrogen concentration of groundwater in typical agricultural areas of Liao river basin was 22.75 mg / L. The groundwater nitrate concentration from wells less than 30 meters depth reached the quality criterion of national groundwater in few years, from the wells in 30~100 meters depth, which met the quality criterion except for 2011, and from wells more than 100 meters depth, all attained Class II water standard, there was a significant correlation between nitrate concentration and over standard rate in different monitoring periods. Nitrate concentration of groundwater was significantly affected by different well depth, in the order of less than 30 m >30 ~100 m > more than 100 m. With the increase of well depth, nitrate concentration of groundwater decreased gradually. From temporal dynamics, nitrate concentration increased year by year, resulting in the further increase of over standard possibility.