Inversion Of Heavy Metal Pollution In Soil And Evaluation Of Soil Ecological Environment In Loess Covered Area

The environmental conditions in the loess-covered area in Shaanxi Province are poor,and the man-made activities such as industry and agriculture are frequent,resulting in increasing soil heavy metal pollution.Geochemical methods have discrete,transient and local defects in the study of soil heavy metal pollution.It is difficult to comprehensively and dynamically reflect the real environmental conditions.The characteristics of quantitative remote sensing can make up for these shortcomings well.Its timeliness and spatial characteristics can monitor heavy metal pollution and environmental conditions more intuitively and timely,and adapt to the development needs of the information age.In this study,Fengxiang County,Linyou County and Qianyang County in the northern part of Baoji City,Shaanxi Province were used as research areas.Firstly,soil sample collection and field chemical analysis of soil samples were carried out by field spectrometer in the field,and soil samples were analyzed in detail.The relationship between heavy metal content and soil spectrum and transform spectrum was used to find the characteristic band of spectral response,and three methods of single-band regression analysis,multiple stepwise regression analysis and partial least squares regression analysis were used to construct the inversion of soil heavy metal content.The model was validated using the soil samples from the validation group.Then through fuzzy comprehensive evaluation method,the fuzzy metal content of all points is calculated by fuzzy mathematics.Through the obtained fuzzy matrix,the pollution level of each sampling point is calculated,and the local pollution situation is analyzed,and the two fuzzy comprehensive evaluations are compared.The method analyzes the applicability of the two methods and selects a method more suitable for loess coverage to evaluate the environment.Then through cluster analysis and correlation analysis between heavy metal elements,the source law of heavy metal pollution elements is explored,which has certain reference value for soil heavy metal inversion and ecological environment evaluation research,and does not provide basis for environmental management in loess area in the future.The research in this paper shows that:1.The soil heavy metals in some sampling points in the study area exceeded the standard,and the Cd element exceeded the standard.2.Perform band transformation on the original spectrum.Through correlation calculation,it is found that the best response of soil spectrum is between 900 nm and 980 nm.3.Several methods have been used to model heavy metal contaminated elements.The results show that the multiplication model has the highest fitness and the minimum.4.Through the method of fuzzy comprehensive evaluation and fuzzy cluster analysis,the pollution sources are analyzed.The pollution sources are mainly located near the road with dense traffic flow and near the lead-zinc plant.