Spatial Variation Of Soil Environment And Magnetic Response Of Heavy Metals In Urban Patterns

Soil heavy metal pollution is a kind of urban environment pollution serious pollu tion type, the urban surface soil is the main accumulation of heavy metal element libra ry, the discretion of the heavy metal content is to indicate one of the main index in the urban environment pollution. The increasingly frequent human activities, such as hou sehold waste, industrial "three wastes", automobile exhaust, etc., will be a lot of poiso nous and harmful chemicals into the environment, causing the accumulation of heavy metal elements in the earth’s surface. Heavy metals in the soil under the action of win d and water on the one hand, respectively, into the atmosphere and water body of atm ospheric pollution, surface water, groundwater, etc., affect the urban environmental qu ality., on the other hand, in the "wind, traffic flow, stream of people" and so on, under dynamic action to swallow and inhalation and skin absorption into the body, cause a harm to human health directly（Lu Ying, 2004）. Therefore, research on urban soil mag netism and pollution evaluation is of great significance. Choose Shanghai demo tape, t his study consists of three different administrative regions（xuhui district, minhang dis trict, the district）, five different functional areas（park, industrial zone, residential area s, green transportation, farmland） of the soil as the research object, by systematically, multiple parameters of soil magnetic parameters is analyzed, and the study of the relat ionship between them, the following conclusions are drawn:（1） The χlf usually with ferrous is closely relative to the content of magnetic minerals. Xuhui district and minhang district and the district soil χlf the range of 12.13^-262.6×10^-8 m3·kg^-1, 24.57 to 112.75×10^-8m3·kg^-1, 15.00 to 220.21×10^-8m3·kg^-1, 12.13^-262.62×10^-8m3·kg^-1, χlf the variation range of fengxian area> minhang district > xuhui district. Contrast χ lf average, it’s not hard to find xuhui district(66.82 ×10^-8m3·kg^-1)>minhang district(47.76×10^-8m3·kg^-1)>sample belt(45.17×10^-8 m3·kg^-1)>district(36.40×10^-8 m3·kg^-1).χlf central Asia ferromagnetism mineral content reflects the samples, so,in sample belt scales, urban areas（e.g., xuhui district） and traffic, industrial concentration area by the intense human disturbance, ferrous magnetic mineral content present a relatively high value as a whole. Suburbs such as cross traffic is relatively small, relatively few human activities, the ferrous magnetic mineral content is lower than the downtown area as a whole. Overall, from the city center to suburb to outer suburbs, ferrous magnetic mineral content is reduced, in turn reflects the degree of urbanization impact on ferrous magnetic mineral content. IV（2） Shanghai urban belt transect soil S^-100 m T change in the range of 54.23 to 101.34%, the average is 79.35%. S-300 m T change in the range of 55.36 101.34%, average 92.38%. S^-100 m T average more than 70%, S-300 m T change between 90-99.9%. Belt transect soil S^-100 m T data is more than 70%, about 88% of S-300 m T data about 80% between 90^-80%, show that in the range of the sample with the soil samples are mainly ferrous magnetic minerals, but at the same time there is a small amount of incomplete antiferromagnetic minerals. χfd% mainly reflects the super paramagnetic grain（SP） contribution to soil magnetism. Sample with soil χfd% change in the range of 0-31.22%, average 1.96%, about 83% of the data is less than 3%, illustrates basic excluding SP samples with grain. Sample take soil samples of Shanghai city, χARM/χlf mean value is 3.57, about 70% data χARM/χlf<4, χARM/SIRM averages 27.23 ×10-5m A^-1, about 64% data χARM/SIRM < 30×10-5m A^-1, the Shanghai sample single domain vacation with soil ferromagnetism mineral grain in central Asia（PSD）、multiple domain（MD） effect.（3） From the administrative region scale, xuhui district, minhang district, the district of magnetism parameters show that the administrative region within the scope of ferrous magnetic mineral dominated the magnetic properties of soil samples, and at the same time with a small amount of incomplete antiferromagnetic minerals. And the ferrous magnetic mineral grains with false effect（PSD）、multiple domain（MD） grain. Contrast district magnetism parameter values can be found, xuhui district samples containing ferrous magnetic minerals in the most, followed by minhang district, ferrous magnetic mineral content in fengxian area are the lowest.（4）From the point of view of function scale, industrial area, residential area, farmland, park, traffic magnetic parameters show that each function of green space within the scope of ferrous magnetic mineral dominated the magnetic properties of soil samples, and at the same time with a small amount of incomplete antiferromagnetic minerals. Ferrous magnetic mineral grain size in various functional areas of each are not identical. χ contrast each function lf values can be found, park(27.39×10^-8 m3·kg^-1) < pujiang farmland(38.5×10^-8 m3·kg^-1) < residential area(43.35 × 10^-8 m3·kg^-1) < industrial zone(45.17×10^-8 m3·kg^-1) < green transportation(63.46× 10^-8 m3·kg^-1). χ lf central Asia reflects the sample ferromagnetism mineral content, therefore, the ferrous magnetic mineral content :garden<pujiang farmland <residential zone< industrial area < green transportation, less human activity area, ferrous magnetic mineral content is relatively small. Park、industrial zone、the traffic green land ferrous magnetic mineral grains with false effect（PSD） 、multiple domain（MD） grain. Residential, pujiang farmland soil ferrous magnetic mineral grain multiple domain（MD） and a mixture of super paramagnetic grain（SP）.（5） The spatial interpolation of soil magnetic coefficients results show that there is obvious regional distribution of magnetic minerals in soils, in residential areas the entrance, near the road, park entrance, industrial areas and intensive areas of human activity, the soil magnetic mineral content is high, the content of SP particles less. This is related to the magnetic minerals produced by industrial production, transportation and commerce.（6） The spatial structure analysis shows that from large scale to scale to small scale, with the decrease of scale, soil magnetic parameters of nugget coefficient decreases, the spatial correlation of soil magnetic parameters gradually increased. Based on the multi-scale analysis of soil environmental magnetic parameters, the multi-scale spatial structure model is established, and the spatial interpolation. The results show that the large scale spatial structure model and the small scale structure model can improve the spatial prediction accuracy of soil magnetic parameters.（7） Of Shanghai urban scales in different contents of heavy metals in the soil and soil magnetic parameters value of correlation analysis, results showed that, soil Cu, Cr, Pb, Zn, Fe and χlf, χARM and SIRM significant correlation. Rate of soil magnetization concentration factor and Tomlinson pollution index（PLI） positive correlation indicates that the magnetic parameters can be used to indicate the degree of heavy metal pollution in soil. According to PLI and Si standards, the overall urban soil in Shanghai city is in medium pollution. The degree of soil pollution from high to low in each functional area is traffic green space >industrial area >residential area >park >farmland.