Evaluation And Early Warning Analysis Of Heavy Metal Pollution Of Soil In Ebinur Lake Basin

With the development of material civilization,the impact of human activities on the natural environment has become increasingly obvious.A series of problems caused by heavy metal pollution are destroying the balance of nature itself.Heavy metals can pollute water,air,and soil,and have a profound impact on soil quality,structure,and classification management.Therefore,in land classification management,agricultural safety planting,soil pollution prevention and control,and ecological civilization construction,the study of soil heavy metal pollution has important guiding significance for the above work.Taking the soil of the Ebinur Lake basin as the research object,using SPSS20.0software to carry out descriptive analysis and frequency analysis of the soil heavy metal content data in the Ebinur Lake basin,using traditional evaluation methods(multi-factor comprehensive evaluation,Nemeiro pollution index evaluation and Principal component analysis)conducted soil pollution risk assessment on 8 heavy metals in soil samples from the Ebinur Lake Basin.In view of the problem that the traditional evaluation method has the risk level or the threshold setting of the pollution degree affected by human factors,this research cooperates with the analysis method based on BP neural network to carry out pollution evaluation and analysis,and adopts the decision tree algorithm to conduct early warning analysis of the Aibi Lake Basin.The main conclusions are as follows:(1)From the distribution characteristics of heavy metals in the soil,we can see that the contents of cadmium,mercury,lead,chromium,and nickel in the soil at all monitoring points in the Ebinur Lake Basin are lower than the selected value,and there is no risk or the risk is negligible.There are "abnormal data points" in the content of copper and zinc in the soil,and the content of copper and zinc in very few soil samples is higher than the risk screening value.The arsenic content in the soil samples at some monitoring points is higher than the risk screening value,which indicates that there may be a risk of heavy metal arsenic contamination in the soil of Lake Ebinur.(2)According to traditional evaluation methods,the largest single factor pollution index is arsenic pollutants.The heavy metals copper-lead and chromium-nickel have a strong correlation.The enrichment of arsenic element is more complicated,and it is obviously mutually exclusive with other heavy metal elements.This reflects the existence of soil heavy metal pollutants on the one hand.Certain homology,difference and combination.The distribution of the total scores of all soil samples is relatively concentrated and the scores are low,indicating that the content of heavy metal pollutants in this area is less,and the soil environmental quality is good.The analysis of its source may be mainly due to the role of natural geological background.(3)Compared with the traditional methods,the comprehensive evaluation method based on the BP neural network model can prospectively grasp the pollution of all metal elements,so as to predict the possible metal element pollution.At the same time,the biggest shortcoming of the traditional evaluation method is that the threshold setting of the risk level or pollution degree is affected by human factors,which will eventually affect the true degree of soil metal pollution.However,the model overcomes this shortcoming of the traditional evaluation method,making the evaluation of the soil metal pollution degree more accurately determined by the data itself,and can predict the soil metal pollution degree prospectively.Thereby establishing a link between the pollution level of heavy metals and pollution evaluation,which is more conducive to risk assessment and hazard treatment.(4)Through the analysis of the decision tree algorithm,it can be obtained that arsenic is more likely to affect the degree of environmental pollution.This may be because some of the sampling points in the study area are surrounded by transportation land,and the heavy metals emitted by transportation have high bioavailability.On the other hand,considering that As has other sources,it is likely to be related to its natural geological background.