Evaluation and origin studies of heavy metals in soils around traditional mining regions in the northwest Guizhou district

Abstract

To figure out the situation of toxic metal contamination and its origins in the ground surrounding a former lead-zinc mining region in northwest Guizhou Province, 56 surface soil samples were gathered from the area surrounding the lead-zinc mine dumpsite, and two profile soils were chosen and examined for the presence of the heavy metals Cd, Pb, Cr, Cu, Ni, and Zn. The soil contamination surrounding the lead-zinc mine dumpsite was assessed using the geocumulative index and the technique of comparing the value of the secondary phase with that of the primary phase. The Principal Component Analysis (PCA) and Positive Definition Matrix Factor Decomposition (PMF) simulations were used to identify the sources of pollution in the area, as well as the contribution of the ground metals. The findings indicate that (1) the maximum values of the substances Cd and Pb were near the soil baseline value, and all five elements except Pb had an elevated amount of deviation and are more susceptible to external influences. The heavy metals at every site analyzed within the study area were lower than the soil background value. Analysis of geographical characteristics indicated which high-value regions for Cd, Cu, Pb, and Zn elements exhibited similarities, and the placement of the mining relics in the research zone demonstrated significant consistency; (2) RSP results show that 5% and 4% of the points of Pb and Zn elements have a mild degree of pollution, 4% of the points of Cd elements have a mild degree of pollution, and 2% of the points have a moderate degree of pollution as well as a heavy degree of pollution; (3) Source analysis results show that: Cr from agricultural activity sources contributes to a greater extent, 63.7%; atmospheric deposition sources contribute to Cd, 72.3%; wastewater emission sources contribute to Zn, 72.3%; and the source of Zn, 72.3%; and the source of Zn and Zn from wastewater discharge sources contribute to Zn, 72.3%. ; wastewater discharge sources contributed more to Zn and Ni, 59.1% and 41.9%; transportation sources contributed more to Cu, Ni and Cr, 52.9%, 45.4% and 36.2%; and mining discharge sources contributed more to Pb, 79.9%.