| With the rapid development of the social economy,the transformation and destruction of nature by human activities has become more serious,and environmental pollution problems have also occurred frequently.Heavy metals are closely related to activities of human life and production.The sources of pollution mainly include agriculture,industrial and mining,life and transportation.The pollution caused by heavy metals in the soil is characterized by concealment,persistence and excessive harm,which not only threatens the normal operation of the ecosystem,but also endangers human health.There were many incidents of heavy metal poisoning,such as "Cadmium Rice" and "Poisonous Vegetables".The status of heavy metal pollution has been also widely concerned by the society.The investigation and research of heavy metals in soil has also been an academic topic that many researchers have been discussing.Foreign research tended to investigate smallscale,single-factors influence on systems;Domestic research focused on comprehensive issues of large-scale,multi-element,and complex situations.Through the above work,it will provide some help for the division of local ecological protection zones and the maintenance of natural resource protection zones,and provide certain guiding significance for the government to plan the rational use of land and formulate appropriate protection measures.As an important metal strategic resource reserve area in China,the Altay area is at the junction with many countries,and its environmental quality is related to the strategic requirements of Chinese ecological major country and ecological rights.In this paper,7 heavy metals such as arsenic(As),cadmium(Cd),chromium(Cr),copper(Cu),mercury(Hg),lead(Pd)and zinc(Zn)were selected as the research object from the Altay region of Xinjiang.The methods of Single factor pollution index,weighted method improved Nemerow integrated pollution index,Geological accumulation and Potential ecological risk(PER)index evaluation,were used to describe the numerical characteristics of pollution.The software of Surfer was used to spatially interpolate the heavy metal elements to map the spatial distribution of various heavy metals,which lays a foundation for the comprehensive pollution assessment of heavy metals in the soil.Based on the hydrogeological data of the study area,the terrain fluctuation,annual rainfall,soil type,soil texture,vegetation type,lithology,geological disasters,heavy metal pollution were taken as the influencing factors to evaluate the soil ecological environment sensitivity and sensitive area division in the Altay region,which provides some help for the division of soil ecological environment.The main conclusions of the study are as follows:(1)There is a certain similarity in the spatial distribution of heavy metals in the soil,such as,the overall distribution of mercury(Hg)and chromium(Cr)elements,copper(Cu)and arsenic(As)is mainly concentrated in the vicinity of industrial and mining and smelting operations area.The average values of lead(Pd),copper(Cu),chromium(Cr),and arsenic(As)exceed the regional background value,which showed these heavy metal elements have accumulated in the soil.From the distribution map of potential ecological risk effects of soil heavy metals,it could be found that in the northwestern part of Altay,there was a medium potential ecological risk area in the area close to Habahe,Burqin and Jimuna counties.The high-value areas of composite heavy metals were mainly distributed in the vicinity of the intersection of Bahe,Jimunai and Burqin counties,indicating that the accumulation of heavy metals was inseparable from human activities.(2)By the method of Single factor index evaluation,it was found that the average values of zinc(Zn)and copper(Cu)elements exceed 0.7,which is in the state of “warning” and close to “light pollution”.This shows that these two elements have an adverse effect on the local soil quality.The proportion of pollution index about Arsenic(As),chromium(Cr),copper(Cu)and zinc(Zn)which reach level ? was above 15%.And the proportion of zinc is the highest.According to the result of Nemerow integrated pollution index evaluation,the elements of lead(Pd),arsenic(As),zinc(Zn),and chromium(Cr)have an adverse effect on the environment.Using the Geological accumulation evaluation,some samples of zinc(Zn)were found to be moderately heavy metal element land quality and the proportion of arsenic(As),chromium(Cr),cadmium(Cd),and lead(Pd),which were in light-moderate heavy metal element land quality,has reached nearly 22%.According to Potential ecological risk(PER)index evaluation,chromium(Cr)has a small number of potential samples at intermediate levels of potential ecological risk;most samples of mercury(Hg)are at medium to strong levels of potential ecological risk,while a small number of samples are at a strong,slightly graded potential ecological risk.(3)Under the principle of selecting eco-environmental sensitivity evaluation indicators,including the five principles of purpose,integrity,dominance,dynamics and relevance,through understanding the differences in climate change,topography and vegetation distribution in the Altay region of Xinjiang,Unreasonable mining,overgrazing and other reasons,such as soil erosion,ecological function degradation,geological disasters and other actual conditions,the final choice of terrain relief,annual rainfall,soil type,soil texture,vegetation type,lithology,geological disasters,heavy metal pollution The equal impact factors are included in the evaluation index system,and the ecological sensitivity calculation is carried out in the Altay region,and is divided into 4 levels of ecological environment sensitive areas.In general,all areas of the Altay region have a certain degree of sensitive areas,and the sensitivity is gradually increasing from north to south.In the spatial distribution,the main moderately sensitive areas occupying the majority are distributed in the northern Altay Mountains;the high sensitive areas are spread to the southern desert areas with the WuLun River as the center;the extremely sensitive areas surround the entire Altay area,with the main body in the southern desert area.The evaluation results showed that the proportion of moderately sensitive areas was 59.73%,followed by high sensitive areas(31.00%),extremely sensitive areas(7.48%),and low sensitive areas(1.79%). |
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