Spatial Analysis And Pollution Evaluation Of Cadmium Copper Zinc Lead In Soil Of Hubei

Soil is one of basic elements of ecosystem, one of the most important natural resources, survival material of human, and the main components of the ecological environment. As the industry’s long-term development, limited cultivated land resources are subject to invasion and pollution, soil environmental conditions not only directly affect national economic development and environmental security of land and resources, but also are related to the safety of agricultural products and human health directly. According to the State Environmental Protection Administration "on the National Survey of soil pollution of the notice"（UNCED [2006] No. 116）, the Environmental Monitoring Central Station of Hubei started a comprehensive investigation on situation of soil pollution of Hubei in 2007.This paper studies on the soils of Hubei province, in the investigation and analysis of the samples, based on the use of geographic information systems and statistical software to study the distribution of heavy metal content of soils of Hubei province, to analyze the spatial structure features of soil heavy metal content with the spatial variability of function model, and make regional estimation. At last make the valuation on the heavy metal contamination of soils in Hubei Province. The research results are shown as follow1. The mean content of cadmium, copper, lead and zinc in soil was 0.110mg/kg 29.53mg/kg, 29.46mg/kg and 72.71mg/kg respectively. The distribution of heavy metals in soils in the districts of Hubei were as follows, the maximum contents of cadmium was 0.135mg/kg in soil of Jingzhou and Qianjiang ,and the minimum was 0.012mg/kg, in the soil of Xiangfan; the maximum contents of copper was 44.36mg/kg in the soil of Shennongjia, and the minimum was 24.07mg/kg, in Yichang; the maximum contents of zinc was 116.19mg/kg in the soil of Huangshi, and the minimum was 55.67mg/kg, in the soil of Jingmen; the maximum contents of lead was 33.29mg/kg in the soil of Huangshi, and the minimum was 24.15mg/kg, in the soil of Huanggang.2. Spatial interpolation of geostatistics could reflect the distribution of cadmium, copper, lead and zinc content in soil of Hubei, in which the semi-variance function of zinc was Spherical model, and the cadmium, copper and lead were exponential model; the ratio of nugget value to still value （C₀/C₀+C） was lead>cadmium>copper>zinc; The ratio between 25%-75%. The results indicated that the four elements belonged to median correlation in the space.3. The change trend of spatial variation regulations of cadmium and zinc content were the same approximately, in soil of Hubei. They were both lower in the central , increased gradually to the surrounding regions; the copper content was lower in the middle and higher on the both sides in the east and west direction, no obvious changes in from the north to the south direction; the lead content was higher in the central and southeast, lower elsewhere.4. Evaluation results showed that: Hubei soil was mainly polluted by copper and lead, the 2/3 points of Hubei was suffered mild copper pollution, mainly concentrated in the southeast and south and the northwest. The 90% points of Hubei were undergoed mild lead pollution, and moderate pollution in certain points. The comprehensive pollution index was 0.59, indicating that on the whole soil in Hubei was clean. Among them, 15.15% of samples were iv in the alert level; 4.71% of samples were in the light pollution level; 0.40% of samples were in the moderate pollution level; and 0.13% of samples were only in the heavy pollution level. There were different degrees of pollution levels in the soil of Hubei province. Huangshi, Xiantao, Jingzhou, Wuhan, Huanggang and Shennongjia belonged to the light level pollution by the four heavy metals; Enshi, Shiyan, Qianjiang and other regions were in the alert level; the soil of Jingmen, Yichang, Xiaogan, Suizhou and Tianmen, Xianning were safe.