Soil-water Geological Environment Characteristics And Quality Analysis Of Su-Xi-Chang Region

Su-Xi-Chang Region is one of the most densely regions of developed cities with developed traffic and superior geographical location in the southern part of the Jiangsu Province of the Yangtze River Delta region. With the rapid development of local economic development, sharp increasing population, largely exploitation of water resources, mineral resources and other resources, Su-Xi-Chang Region had a great many problems such as sustaining decline of groundwater, land subsidence, soil-water geological environment pollution and other geo-environmental problems. When the soil-water geological environment were polluted, especially the shallow groundwater and soil which are in most relation to human beings were polluted, the pollutants would have effect on water and crops. Therefore, to investigate and evaluate the quality and pollution situation of the soil-water geological environment has important practical significance to protect people's health.On the basis of the summary of the research present status of the soil-water geological environment survey and monitoring at home and abroad, Su-Xi-Chang Region is regarded as the research object in the paper. A few monitoring wells'data about water levels and water quality since 1983, precipitation data since 1999, and multi-purpose regional geochemical survey data have been selected. 90 phreatic water samples and 400 surface soil samples were collected and examined in 2010. Then to use the statistical software SPSS to analyze the value of Ca2+, Cl-, CO₃^2-, Fe, HCO₃^-, NH₄⁺, NO₂^-, NO₃^-, pH, SO₄^2- (total 31 indexes) in phreatic water and the value of Al, As, C, Ca, Cd, Cr, Cu, Fe, Hg, N, Ni, P, Pb, pH, Se, Si, Zn, TOC(total 52 indexes) in the soil. And then using the selected soil-water geological environment data and monitoring data in 2010, to draw the mass distribution maps of water level and quality of phreatic water, soil quality and integrated quality evaluation of phreatic water and soil with the application of Nemero Index by MapGIS software. Lastly, through the study on distribution and evolution features of water level and quality, hydrochemical charactars, the characters and evolutionary trends of regional soil geochemistry, to make the evaluation of soil environment quality and analyze the spatial correlation between water and soil.It can be found that shallow buried depth of ground water table of Su-Xi-Chang Region is 1³m basically. Water is mainly polluted by Fe, Mn and the "three-nitrogen" and soil is mainly polluted by heavy metals. Soils in serious contamination are mainly distributed in cities and suburbs especially in transitional zone of Suzhou and Wuxi with the largest distribution area. Finally, there are similar spatial distribution characteristics between severe water pollution areas and heavy metal soil pollution areas. There are overlaps between the two areas to a considerable degree which means that an area both with poor phreatic water quality and serious heavy metal pollution exists. the reasons maybe from a common pollution source which both causes soil pollution and shallow groundwater. It needs more investigation and analysis to find the specific pollution source.