| this paper is based on Hainan multi-target ecological geochemical survey data,and focus on the 8713 surface and 2197 deep soils heavy metals As,Cd,Co,Cr,Cu,Hg,Pb,Zn,Ni and Sc.Content characteristics,spatial distribution,variation and influencing factors in soil trace heavy metal elements were discussed on five different parent materials.Compared with the deep soil heavy metals content,in addition to the Cd and Hg,the content of other elements were lower than that of the deep soil,shows that the overall excellent environment quality of the topsoil.In the study,CV of the top and deep soil elements As?Ni?Hg?Cd?Co?Cr?Cu were higher than 100%,indicating that the change of contents of these elements in different parent materials soil.In general,basalt parent material forming soil metals background or baseline values were higher,and the quaternary parent material soil background values were low.Among them,the basalt parent materials topsoil heavy metals Cd?Co?Cr?Cu?Hg?Zn?and Sc background values werel.27?2.03,7.30?28.64,6.70?17.19,4.22?14.69,1.55?1.89,2.30?5.62,10.98?34.68 and 2.90?8.77 times to other four kinds of parent material topsoil.The deep soils baseline value change rule is basically identical with this.Except for Cd and Hg,background values of heavy metals in various parent materials formed were below the baseline value,it may be due to the topsoil by strong weathering and leaching effect,resulting in a huge loss of topsoil elements.Pearson correlation showed that,a significantly positive correlation(0.42**?0.77**)at the P<0.01 significance level were found for As?Co?Cr?Cu?Pb?Zn?Ni?Sc with corresponding metals between the surface and deep soils in the different parent materials.In addition to Cd and Hg.Suggesting these elements were the main source of inherited deep soil parent materials,and Cd,Hg in the topsoil were influence by both geological background and human activities.Spatial distribution of topsoil and deep soil trace metals showed that As?Co?Cr?Cu?Pb?Zn?Ni?and Sc distribution patterns were controlled by the geological background,including Co?Cr?Cu?Zn?Ni?Sc high background value area affected mainly by basaltic parent material.As high value area was dominated mainly by metamorphic rocks,and the high background area of Pb were mainly controlled by the spatial distribution of granite parent material.Spatial distribution of Cd and Hg elements in the surface soil is mainly influenced by traffic emissions or other mining sources.Granite area surface soil heavy metal elements in semivariogram analysis once again showed that at the regional scale,endogenous dominant elements As?Co?Cr?Cu?Pb?Zn?Ni?Sc space variability characteristics,and exogenous were main factors influencing surface soil Cd and Hg spatial variability.Environmental quality evaluation indicated that Hainan single element soil environmental quality generally better.Among them,As?Cd?Hg?Zn soil primary level is higher than the proportion of 90%,the ratio of primary soil Cu,Cr,Pb,Ni more than 80%,and was in the natural background value level.Cr?Cu and Ni elements three and super three soil level proportion is higher,where Cr and Ni were higher than 10%,but the high content areas were the main source of basaltic parent material in the northern Hainan island,rather than anthropogenic input.Comprehensive evaluation shows that about 76.8%of the study area heavy metals in the soil belong to a class of environmental quality standards,only 0.91%of the area of over three standards soil,which Cr?Cu?Ni?Co?Zn and Sc apparently affected by the volcanic basalt geological background.Pb secondary soil levels distribution were connected with granite,whereas Cd and Hg were by the combined effect of geological background human mining and industry.Overall,the content of heavy metals in soils of Hainan province is generally low.According to the soil environment quality evaluation results,there are four main areas need to focus on the prevention:Qiong North basalt area,Changjiang,Daguangba reservoir and the city of Haikou volcano area. |
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