| When the content of heavy metals accumulated in the soil exceeds the environmental carrying capacity of the soil,the function,fertility and composition of the soil will be changed,which will lead to soil pollution.At the same time,the content of heavy metals in the soil can also cause harm to human health and the growth activities of other plants and animals through the material circulation of the ecosystem.It has a serious impact on environmental restoration.Therefore,it is very important to judge whether there is soil pollution in the region and to monitor the soil pollution.In this paper,the soil in the closed pasture area of yanchi county was selected as the research object to analyze the indexes such as the magnetization rate,grain size and heavy metal content of the soil in the research area,and to analyze the correlation between the characteristics of the magnetization rate and the heavy metal pollution status of the soil in the research area,so as to provide theoretical basis for the soil environmental monitoring in the research area.System of 24 sample collected in the 143 soil samples,measured the soil magnetic susceptibility,particle size and heavy metal(Mn,As,Cu,Pb),through the analysis of soil magnetic susceptibility and the change of the section of the particle size and heavy metal element content characteristic and its correlation,in order to investigate the influence of soil magnetic susceptibility factors,analyzes the research area of soil magnetic susceptibility indicating significance of heavy metal pollution.The main research results are as follows:(1)Research the soil in the Xlf the variation range of 13-51×10-8m3/Kg,with a mean of 37.06×10-8m3/Kg,deepens,along with the depth of soil layer soil Xlf showed a decrease trend as a whole.Soil Xfd range is 1.96-13.51%,with the depth of soil layer technology,soil Xfd wave oscillation type change,as a whole have a tendency to increase.The study area soil Xlf?Xhf in Xfd rate present negative correlation,so few SP's contribution to the magnetic particles in the soil.(2)The composition of clay,silt and sand in the wasteland soil of yanchi county varied 0?7.15%?1.57?70.38%?24.20?98.43%,with an average content of 1.98%,23.57%and 74.45%,respectively.The median particle size was 259.41?m at maximum,15.13?m at minimum,and 113.9?m at average.With the deepening of soil depth,the proportion of clay and powder content increased,while the proportion of sand content and median particle size were opposite.Soil susceptibility can be used to indicate changes in soil quality.The change of soil quality is related to factors such as soil parent material,dust process and human activities.According to the analysis above,it can be concluded that the soil quality in the study area is relatively complex and the human disturbance is relatively serious,especially the surface soil,which is seriously polluted by automobile exhaust.(3)The average contents of Mn,As,Cu and Pb in the soil samples in the study area were 308.01mg/kg,8.15 mg/kg,11.76 mg/kg and 15.10 mg/kg,respectively.The heavy metal content of most of the 143 samples exceeded the background value of aeolian soil.The variation coefficients of the four heavy metals ranged from 20 to 100%,all of which were of moderate variation intensity.Among them,the content of Mn,As and Pb is the highest in the soil surface layer,which shows a decreasing trend with the deepening of soil depth,indicating that the source of heavy metal elements may be from human disturbance.(4)The correlation analysis of heavy metal elements in soil samples showed that Mn,As,Pb and Cu were moderately variable from the coefficient of variation,and the contents of all elements presented significant positive correlation,indicating that the four heavy metals had the same source.Through field investigation and relevant map software observation,it is shown that few people in the study area are disturbed,so it can be judged that the four heavy metal elements come from traffic pollution,indicating that the soil in the study area has received traffic pollution.(5)The correlation between the soil magnetization rate and heavy metal content in the study area is As follows:in section S1-S18,the low-frequency soil magnetization rate(replaced by soil Xlf below)is significantly positively correlated with Mn,As and Pb,and the correlation coefficients are 0.589,0.338 and 0.521,respectively(P<0.01).In S19-S24 profile,soil Xlf is significantly negatively correlated with Mn,As and Pb,and the correlation coefficients are-0.353,-0.623 and-0.486,respectively(P<0.01).For Cu element content,in section S1-S14,soil Xlf is positively correlated with Cu element content,and the correlation coefficient R=0.749,P<0.01.In section S15-S24,soil Xlf is significantly negatively correlated with Cu content,and the correlation coefficient R=-0.513,P<0.01.The correlation between soil Xlf and heavy metal elements indicates that the larger the soil Xlf is,the higher the content of heavy metal elements will be.At the same time,it is clarified that there is a similar activity process between heavy metals and magnetic particles.In the study area,soil Xlf can be used to indicate the accumulation degree of heavy metals in the(6)By analyzing the correlation between the magnetization rate and the particle size and the content of heavy metal elements,it can be concluded that the magnetization rate can be used to monitor the pollution degree of heavy metal in soil.At the same time,the convenience and rapidity of soil magnetism can be utilized,and the soil samples are not damaged.It is suitable to use the magnetic susceptibility to evaluate the heavy metal pollution in the soil,which has important practical significance for the soil environmental pollution monitoring in the study area. |
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