Investigation Of Heavy Metal In The Paddy Soil And Rice At An Area Of Anhui

With the rapid development of industrialization, urbanization and agriculturalmodernization, the emission of heavy metals into water, soil and atmosphere is alsogrowing year by year through metal smelting, pesticide and fertilizer applying,domestic wastes incinerating, sludge and sewage using, automobile exhaust emissionsand such channels. It has made a serious threat to the ecological environment. Thenature of heavy metals is relatively stable and it can not be easily metabolized byliving creatures in ecosystem. But it can be easily adsorbed by soil or enriched byorgansim and it has biomagnification. Once the heavy mentals are greatlyaccumulated in plants’ roots, stems, leaves and seeds, it will not only seriously affectthe growth of plants, and will enter the food chain, as a result harm human health.This article is on the basis of soil science, environmental geochemistry, ecologyand other subjects, through detailed field investigations and experimental analysis,studying the content of heavy metals in paddy soil at some parts of Guichi (mainly inthe Qiupu coast), analyzing the enrichment of heavy metals systematically andevaluating the pollution. Based on the evaluating result, a number of proposals areraised to provide the basis for the governance of local paddy soil pollution. The mainresults are as follows:1．The heavy metals in most of soil samples in the research area are higher thanthe background values compared with the national soil background value. Zn is thehighest concentrations and Hg is the lowest in the measured elements. The descendingorder of the content is: Zn>Pb>Cu>As>Cd>Hg.2．During the analysis of relationship among six kinds of heavy metal elementsin paddy soil in study area, except elements Hg and Pb, Hg and Cd, there aresignificant or very significant relationship among all kinds of heavy metal elements,especially element Cu and Zn. High correlation between the heavy metal elements inthe soil indicates that pollutant are coming from same source in this region.3．Considering from the pollution index, Cd’s pollution index is the highest, itsaverage value is1.41, beyond the warning line. Seventy percent of the examplesexceed the warning line. Considering from the integrated pollution index,10samplesare within the guard region. It means that43%of the examples are not polluted. Theremaining samples have been slightly exceeded and in light pollution level.Moderately polluted and heavily polluted samples are not found. 4．Through the heavy mental content statistics and pollution analysis in thestudy area, we found that element Zn is in the highest content in rice. Its averagevalue is22.4mg/kg. The sequence of the remaining elements is: Cu>Cd>As>Pb>Hg.In the evaluation of heavy metal pollutions in rice, there are varying degrees of As, Cdand Cu pollution, especially for As pollution. It has65%of rice samples are gettingcontaminated. Consider from the integrated pollution index，30%of samples testedare not contaminated, other samples are in light pollution.5．In the analysis of heavy metal enrichment in rice, element Cd’s enrichmentfactor is the biggest. It means that Cd is easy to migrate in soil. At the same time, thebioconcentration factors and heavy metal pollution with the grain are not entirelypositive linear correlated. This shows the complexity of migration of heavy metals insoils and crops.Through specific experiments and analysis of experimental data, the followingrecommendations are given for rice cultivation to the research area: Rice-growingareas should be far away from the pollution source; reduce the heavy metals involvedinto the process of rice cultivation; take reasonable control measures in polluted areas.