[Ecological Risk Assessment and Source Analysis of Soil Heavy Metals in Different Land Use Patterns in Ningxia]

Taking the soil with different land use patterns in Ningxia as the research object， based on the analysis and determination of the content characteristics of As， Hg， Cr， Ni， Cu， Zn， Cd， and Pb in the samples， the geoaccumulation index and the potential ecological risk index were used to evaluate the risk of metal pollution， and the traceability analysis of the sources of heavy metal pollution was carried out by combining correlation analysis， principal component analysis， and the absolute principal component score-multiple linear regression （APCS-MLR） model. The average contents of Zn and Cd， as well as the average contents of Hg， Cu， Zn， Cd， and Pb in irrigated and paddy field soils exceeded the soil background values in Ningxia. The eight heavy metals in the soil under different land use patterns were lower than the risk screening and control values. The land accumulation index and potential risk index showed that Hg and Cd were the most polluted compared to other elements in these three types of land and were the main soil pollution factors of the three different land use methods. The analysis of the APCS-MLR model showed that the pollution sources of dryland included agriculture， nature， industry， and their mixtures， accounting for 36.6%， 20.1%， 14.1%， and 29.2%， respectively. The pollution sources of irrigated land were nature， transportation-agriculture mixed sources， agricultural sources， industrial sources， and nature-transportation-agriculture-industry mixed sources， accounting for 50.08%， 31.32%， 6.65%， and 11.94%， respectively. The pollution sources of paddy fields included natural-agricultural composite sources， agricultural sources， industrial sources， and natural-agricultural-industrial mixed sources， accounting for 46.81%， 21.24%， 12.65%， and 19.30%， respectively. Through in-depth analysis of pollution sources and influencing factors， this study provides an important basis for formulating targeted pollution prevention and control measures and promotes the process of sustainable agricultural development and ecological environmental protection.