The Study Of Groundwater Nitrogen Contamination In A Riparian Area Of The Hun River, Shenyang

The riparian groundwater demonstrates a high value for exploitation and is oneof the most important water supply sources in China. However, the contamination ofthe riparian groundwater has aroused lots of attention due to the increase of the rangeand intensity of human activities and the contamination of rivers. The nitrogencontamination of the riparian groundwater is worth for research because of itscharacteristics of universality, uniqueness and complexity. This paper carried out astudy on groundwater nitrogen contamination in the riparian area of Hun river, Liguan pu, Shen yang. The research area was divided into the south and the north twoparts and the research measures included hydrochemistry analysis, multiple statisticalanalysis, environment isotope analysis and numerical modeling. The questionsfocused in the paper included the contamination and hydrochemistry characteristics ofthe riparian groundwater, the nitrogen transformation mechanism in the backgroundenvironment, and nitrogen sources as well as their relevant proportions contributed tothe nitrogen contamination. The main conclusions are listed below.(1) Groundwater of the research area was supplied by rainfall, upstreamgroundwater flow and the Hun river. The northern research area was mainly attributedto resident and industrial lands with a high contamination source intensity. Thesouthern research area was mainly covered by the farmland and the green land with alower contamination source intensity. The hydrogen and oxygen isotope analysisdemonstrated that the Hun river could supply the riparian groundwater and the ratecould be up to60%.(2) The northern and southern groundwater in the study area showed differenthydrochemical characteristics by the help of hydrochemistry and multiple statisticalanalyses. Taking the two groundwater environment for comparison, it was found thatthe northern groundwater demonstrated a slightly oxidizing and acidic characteristicand the southern groundwater demonstrated a slightly reducing and alkalinecharacteristic. Although the whole groundwater belonged to the infiltration water type,but the northern groundwater owned a relevant higher content of sodium and chloride ions compared to the southern groundwater. Nitrate and ammonium were the maincontaminants of the north and the south respectively. The TDS and chloride in thenorth were much higher than those of the south.(3) The nitrogen of the northern and the southern groundwater owned differenttransformation mechanisms by the research of hydrochemistry and environmentisotopes. In both the unsaturated zone and the aquifer of the north, their environmentswere in a oxidation condition and the nitrogen was controlled by nitrification. In thesouth, the nitrogen moved in the unsaturated zone was controlled by nitrification. Inthe aquifer, the nitrogen was controlled by denitrification.(4) The nitrogen of the south and the north came from different sources. Themain nitrogen source could be attributed to the feces and sewage discharged byhuman activities by the investigation of local environment and the nitrate isotoperesearch. The numerical modeling combined both the vertical and parallel orientationsrevealed the contribution rates of different nitrogen sources effectively. The nitrogenin the northern groundwater was mainly from the surface contamination sources andthe upstream groundwater, and the corresponding proportions were43.92%,27.37%.The nitrogen in the southern groundwater mainly came from the Hun river and theupstream groundwater, and the corresponding proportions were61.79%,38.06%. As awhole, the surface sources were the main contributor to the groundwater nitrogencontamination.