| Based on synchronous sampling of soil and crops from 39 counties of Chongqing, 456 soil samples and 936 crop samples (including stem, grain of paddy and corn) were collected. Assessment indexes involved in this study included eight kinds of heavy metal such as mercury, cadmium, lead, arsenic, chrome, copper, zinc, and nickel. Meanwhile, corresponding soil characteristics including pH, OM, CEC, CaCO3, exchangeable acid, exchangeable aluminum, total nitrogen, total phosphorous, total potassium, available nitrogen, available phosphorous, available potassium etc. were analyzed. Using statistic software like DPS, SPSS, Excel, and combining with geographical statistic software ArcGIS, concentration characteristic, territorial distribution, pollution level, accumulation situation, and crops contamination of heavy metals in typical agricultural land of Chongqing were analyzed. Moreover, the correlation of heavy metal pollution between soils and crops was also studied, and by means of pot tests, amount of soluble heavy metals was put forward as an index for bioavailablility of heavy metal, which could be applied in environment assessment of arable soil.1 .Concentration and distribution characteristics of heavy metals in arable soils of ChongqingConcentration of seven kinds of heavy metals in arable soil of Chongqing, including mercury, cadmium, lead, arsenic, copper, zinc, and nickel, appeared to be logarithmic positive distribution, while that of chrome presented as positive distribution. According to the above conclusion, arithmetic mean value and standard deviation were adopted as representative indexes in calculation of chrome concentration in soil, whereas geometrical mean value and standard deviation were adopted in the other seven kinds of heavy metals. The distribution range of heavy metal concentration was concluded as following: 31.871-70.200 mg/ kg of chrome (86.6%) with concentrated value of 53.676 mg/kg, 0.032-0.164 mg/ kg of mercury (84.5%) with concentratedvalue of 0.076 mg/kg. 0.155-0.710 mg/kg of cadmium (86.6%) with concentrated value of 0.364 mg/kg, 3.060-21.487 mg/kg of arsenic (82.7%) with concentrated value of 8.094 mg/kg. 7.225-43.550 mg/kg of copper (86.4%) with concentrated value of 19.648 mg/kg, 63.575-139.800 mg/kg of zinc (87.2%) with concentrated value of 95.131 mg/kg, 13.425-54.025 mg /kg of nickel (81.3%) with concentrated value of 29.061 mg/kg, 34.200-84.250 mg / kg of lead (87.8%) with concentrated value of 52.089 mg/ kg.Compared to the worldwide background content of heavy metals, concentration of mercury, cadmium, arsenic, lead, zinc was higher than the mean value of background content, and evident accumulation trend already appeared consequently. Whereas no obvious change was detected in the content of chrome, copper, and nickel.Variation coefficient of these heavy metals followed the sequence of cadmium > arsenic > copper > mercury > zinc > lead > nickel > chrome. Contents of cadmium and arsenic were greatly influenced by anthropogenic pollution. Significant correlations were detected in the relation between cadmium and arsenic, copper and arsenic, zinc and arsenic, cadmium and copper, cadmium and zinc, copper and zinc, zinc and lead, which indicated their sources, might be quite similar.Investigation confirmed that concentrations of heavy metals in soil of Chongqing were influenced by not only geochemical characteristics like soil-forming rocks, but also some anthropogenic factors. Using geographical statistic software ArcGIS, territorial distribution characteristics of heavy metals in arable soil of Chongqing were obtained. Cadmium, arsenic, and lead had evident nugget effect with the ratio of Co /Co+C higher than 50%, which indicated insignificant self-correlation of these elements, and their distribution were highly affected by some random factors. While the Co /Co+C ratio of copper, nickel, mercury, and zinc was less than 50%, which implied strong self-correlation existed in these elements, therefore, their distributions were greatly influenced by systemat...
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