Zunyi County, Analysis Of The Relationship Of The Cadmium Content In Agricultural Soils And Vegetables

In the paper,the samples is be collected with the GPS,involving 15 town in Zunyi County,the total soil samples is 889.at the stone time,with collecting vegetable samples.These Samples are analyzed by graphite furnace atomic absorption spectrophotometry,the uncertainty of Cd for soil and vegetables with this method are 0.032 and 0.001mg/kg.Mathematical Statistics analysis use Excel,Spss software. The results are as follows:The content of Cd is 0.357mg/kg in Zunyi County agricultural soil,exceeding rate is 67.3%,the coefficient of variation is 79.35%,The content of Cd is beyond the standard,the distribution of it is non-uniform.The single Cd pollution index is 3.43,exceeding 3.0,for heavy pollution.From the partial,the Cd pollution index of Sancha,Longkeng,Yaxi,Fengxiang,Shiban town is from 1.0 to 2.0,for light pollution; the Cd pollution index of Sanhe,Gongjiang,Wujiang,Leshan,Panshui,Mati,Xinmin town is from 2.0 to 3.0,for the middle pollution,the Cd pollution index of Nanbai, Maoli,Shangji town exceed 3.0,for heavy pollution.Although the levels of Cd is dangerously high in the most of Zunyi County agricultural soil,the vegetable content of Cd is not in excess of the national standard (0.05mg/kg),the enriclunent of Cd changes 0.009～0.109,enrichment capability is significant difference.It can be divided into two categories,the first category of red pepper,tomato,cabbage,spinach,Cd concentration enrichment is higher,the second category of cucumber,eggplant,beans,beans,Cd enrichment is lower,the Cd enrichment capability of its edible part is relatively weak.Clearly,the Cd content of leafy vegetables and rhizomes are significantly higher than that of fruits and legumes. The Cd enrichment capacity of vegetables which the edible far from the soil is relatively low,and cadmium migration path longer relevant.Although the edible part of red pepper,tomato also far from the soil,the enrichment capacity of Cd is higher,it reflects the different vegetables on the different absorption of.Cd characteristics.The Cd content relations between the red pepper,tomato,cabbage and the soil are quadratic polynomial,a significantly positive Cd content correlation between the spinach and the soil is linear equations.The high Cd content of vegetable reflect also high Cd content in the soil.And from the correlation coefficient,it can be viewed that the Cd in soil is not all absorbed by plants and different vegetables on the different absorption capacity of Cd in the oil. Through Health Risk Analysis,the residents in Zunyi County intake cadmium in the amount of 13.2μg/d from vegetable,the number is Lower than the Cd content adults under the maximum allowable intake(ADI value) 60μg/d(adult,to 60 kg) which is ruled by the World Health Organization(WHO) and the United States Environmental Protection Agency(USEPA).Although the vegetables Cd content well below "limits for cadmium in food hygiene standards"(GB15201-94),for some people,the health risks of cadmium still cause for concern.In the water solution test of pepper,with the increase of concentration of Cd, Pepper biomass,plant height with a downward trend,the Cd content of plants growing on the whole.The second dealt level with a slight increase in height,it notes that the low concentration of Cd will promote the growth of pepper.In the pepper plant,Cd content root＞stem＞leaf,and the Cd content in root is far greater than stems and leaves.It notes that in the Cd pollution solution test,pepper absorbs the main Cd from root and transmits extremely low Cd to stem and leaf is.The Cd content relations between the pepper plant root,stem,leaf and in the test solution are polynomial model,and it is positive conelation.The high Cd content of pepper plant reflects also high Cd content in the test solution.Comparing the Cd content relation curve between vegetables and soil(in the ChapterⅣ),this Cd relationship between the pepper plant and the test solution is good and as a very significant positive correlation.This may be the reasons of fertilization,pesticides and other factors in large field.So,here is some corresponding Cd pollution control and protection technology. First,the chemical measures,phytoremediation,scientific fertilization methods can be taken to reduce soil Cd content.Secondly,local conditions can be operated according to the different crops with the characteristics of the different absorption Cd,it can take different and selective cultivation.For example,If in the serious Cd pollution region, it can plant beans,beans,such as Cd accumulation ability weak melons,beans vegetabls.If in the lower Cd content region,it can plant pepper,tomato,etc.Cd enrichment ability of vegetables...