| In recent years, soil pollution is becoming more and more serious; especially that the heavy metal pollution is the most serious problems. If the soil was contaminated by heavy metals, the heavy metals will be enriched to the human body through food chain, which could cause harm to human health, so the selected plant area’s environment whether meet the health vegetable production is the most fundamental condition in vegetable cultivation area. In order to ensure the quality of vegetables and safeguard the health of residents in Beibei District, this paper will determine the content of lead and cadimium, available volumes in soil. What’s more, analyzed the features of total capacity, using different standards of lead, cadmium in vegetable soil environment quality to evaluate, analysis the available content of lead and cadmium on the planning area, and analysis the field soil’s lead and cadmium content under different land use patterns. The results showed that:(1) The content of lead average levels was 43.92 mg/kg in Beibei District vegetable soil, the coefficient of variation was 37.3%; the content of cadmium levels average was 0.212mg/kg, the coefficient of variation was 28.3%. If using the township as a statistical unit in the research area, the content of lead is that the first is SanSheng town, second is slot vegetable base, third is LiuYin town, forth is TianFu town, fifth is FuXing town, sixth is Dong Yang town, seventh is ChengJiang town, and the last is JingGuan town. The content of cadmium is that he first is TianFu town, second is FuXing town, third is SanSheng town, forth is DongYang town and JingGuan town, fifth is ChenJiang town, sixth is LiuYin town,and the last is slot vegetable base. From the point of the new planning of the vegetable and original vegetable plot, the new planning of the vegetable’s content of lead was slightly larger than the original planning of the vegetable vegetable plot, the new planning’s total content of cadmium was greater than the original planning of the vegetable. Soil type and distance to highway distance has significant influence to soil total lead content, no significant effect on the content of cadmium, Through the correlation analysis showed that the study area the total content of lead in vegetable soil has significant relationship to soil organic matter, clay and pH value, and the total content of cadmium only has significant relationship with the content of organic matter.(2) From the study area of lead, cadmium in Vegetable Soils in the overall cumulative situation, lead, cadmium accumulation index were more than 1, the study area of lead, cadmium in vegetable soils had different accumulation from different degree; cumulative index distribution of lead, mainly distributed in severe and mild cumulative cadmium accumulation, mainly distributed in mild and moderate accumulation accumulation. Geo accumulation index shows, the study area vegetable soil had been different level of lead and cadmium pollution, and the lead pollution was larger than the cadmium.The individual pollution index indicates that, the study area and each towns’ vegetable soil fully meet the pollution-free vegetable production in the lead and cadmium level, and basically meet the needs of green food vegetables; comprehensive pollution index method show that, under the lead and cadmium working together the study area vegetable soil and each town’s soil were not polluted by the lead and cadmium, but the pollution index were all at the level of alertness. From the point of potential ecological risk index, the study area and each town’s vegetable soil potential ecological risk is that, the lead was at the low level, cadmium at the middle level. From the point of the total potential ecological risk index, the study area and each town’s vegetanble soil were in the mild ecological hazard under the effect of lead and cadmium.From the view point of the original vegetable plantation and the new planning vegetable plantation, the new planning vegetable plantation and the original vegetable soils’average content of lead and cadmium all meet the pollution-free and green vegetable production. But from the point of the geoaccumulation evaluation index results showed that, the Igeo value is greater than 0, the the original vegetable plantation and the new planning vegetable plantation were both affected by the lead and cadmium pollution overall, the original was more serious than the new. Uner the green vegetable production standards, the new and originals’ PN value were more than 0.7 and lower than 1, at the alertness level. This showed that under the comprehensive effected, two types of soil were affected by the pollution; but under the no social effects of pollution standsards, the PN value was lower than 0.7. This showed that the two types of soil were without lead and cadmium pollution. From the total potential ecological risk index to see, the new planning and the original vegetable soil were under mild ecological hazard of lead and cadmium.(3) The average content of availability lead, cadmium is 3.114,0.051 mg/kg in the study area of vegetable soil, which were significantly lower than the Chongqing soil environmental background values, and its coefficient of variation were 30.4%,38.9%; biological validity coefficients were 7.7%, 25.1%. From the point of biological effectiveness coefficient, the study area vegetable soil cadmium’s potential ecological risk was greater than the lead. The study area’s vegetable soil content of lead and cadmium had significant correlation whith the full amount, lead and cadmium total value was main factor to determine the effective content, and lead and cadmium content’s change trend was not entirely consistent with the available content. The lead and cadmium was larger, but the effective content was not greater. Through correlation analysis found that, the study area soil PH value had a significant effect to cadmium, sand, clay and organic matter had significant effect to lead. The soil type had an impact to lead and cadmium content, the purple soil’s lead content was smaller than the lime soil, and the available cadmium content was that, the purple soil greater than the lime soil. From the human activeties, the traffic had obvious effect to the lead content.(4) Through the SPSS statistics descriptive and analysis of variance indicated that, under different land using manners, the early planning area cadmium, available and biological validity coefficients had different degrees, land using manner had influence to it. From the three kinds of land using manners, the lead content was mixed cropping land at first, second was paddy field, the last was original vegetable.Cadmium was original vegetable plantation at first, second was mixed cropping, and the last was paddy field.Soil available Pb content was mixed cropping land at first, second was paddy field, and the last was original vegetable plantation.Available cadmium content was original vegetable plantation at first, second was mixed cropping land, and the last was paddy field.Soil lead bioavailability coefficient was paddy field at first, second was original vegetable plantation, and the last was mixed cropping land. The cadmium was original at first, second was mixed, and the last was paddy field.From the analysis of the influence factors to lead, cadmium and effecitive content diversity under different land using manners found that, the diversity of vehicle exhaust and the application of fertilizer was possible factors to the different effective content.Soil PH value difference and lead, cadmium content difference were possible factors to the fifferent effective content.Biological effectiveness coefficient was mainly affected by lead, cadmium and available content, but also influenced by other factors. Uner the standard of Chongqing city soil lead and cadmium background values, through calculation of geo accumulation method showed that, the study area was lightly polluted by lead and cadmium. Mixed and paddy soils pollution degree was apparent than the original vegetable, original vegetable soil cadmium pollution degree was more obvious than the paddy field and mixed cropping. |
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