Study On Evaluation And Spatial Distribution Characteristics Of Heavy Metal Pollution In Arable Layer Soil Of Baiyin District

With the rapid development of industry and agriculture, aggravation of the urbanpollution and increase in category and quantity of agrochemicals, contaminations thatcontain heavy metals enter into soil through different approaches, resulting inextremely serious pollution of heavy metals. Therefore, investigation and evaluationof heavy metals in soil environment pollution and its risk profile, find out the soilquality in the environment, strengthen the comprehensive control of soil pollution,protection of human health, which are of great practical significance. Theconcentrations of six kinds of heavy metals in the arable layer soil around Baiyindistrict were determined and analyzed in present study. The spatial characteristics ofall the six heavy metal elements were studied on the base of geostatistics methods.Specifically, the methods of geostatistics and GIS were used to analyze thecharacteristics of heavy metals for spatial variability, spatial distribution, andpollution status in the investigation of the soil. The main result are as follow:(1) The regular pattern of the spatial variation of the heavy metal elements insoils in Baiyin district was as follows: the ratios of nugget value to sill value wasCr>Ni>Pb>As>Cu>Zn. In which, the ratios of nugget value to sill value was largerthan0.75, Ni, Pb, Cr belong to weak spatial correlation. The ratios of nugget value tosill value of As was between0.25and0.75, belong to moderate spatial correlation.The ratios of nugget value to sill value was Less than0.75, Cu and Zn belong tostrong spatial correlation.(2) Concentration maps of six heavy metals in farmland soils obtained by kriginginterpolation. The results showed that, Pb, Zn, Cu, As4high levels of heavy metals inthe area are mainly distributed in the town and surrounding areas Wangxian; Crcontent is relatively high in the regional distribution of Wuchuan Township; heavy metal content of Ni is generally low, the whole area does not exceed the national soilenvironmental quality standards areas.(3) In this study, weights of heavy metal contamination were computedaccording to impacts of heavy metals on human health with the use of improvedclassical analytical hierarchy process (AHP) in the soil environment qualityassessment. The weight coefficient of Pb, Zn, Cu, As, Cr, Ni in pollution assessmentfactor respectively0.3668,0.0220,0.0391,0.3668,0.1026,0.1026, the test (max=6.3013, CR=0.0486<0.1) the satisfactory results with consistency.(4) Compared with the national environmental quality standard value of soil,6kinds of heavy metals in the average levels of the study area did not exceed itsstandard value, the statistical analysis showed that the5heavy metals content whichincludes Pb, Zn, Cu, As, Ni was significantly correlation.(5) Baiyin District farmland topsoil pollution index average of0.3974, theoverall security level of pollution, but there are different degrees of pollution the localarea. Size distribution of different soil pollution level statistics, contaminatedfarmland area of approximately471.05hm2,3.72%of the total arable land, to dealwith the regional ecological risk assessment and take appropriate pollution controlmeasures.