Heavy Metal Pollution and Source Contributions in Agricultural Soils Developed from Karst Landform in the Southwestern Region of China

Abstract

Heavy metal pollution of soil in agricultural areas is the most prominent environmental pollution problem in China, seriously affecting human health and food security. It has become one of the environmental problems to which all sectors of society attach great importance. Soil heavy metals in the weathering area of hazardous geological bodies in southwest China have naturally high background attributes. Therefore, ecological risk assessment and analysis of potential sources of soil heavy metals in southwest China is of great significance for soil health management, soil heavy metal pollution control and territorial spatial planning. In this study, we collected 787 soil samples (0–20 cm) in Xuanwei County in China and analyzed the concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in soils. Igeo, RI, HI and CR were used to calculate the pollution levels, ecological risks and human health risks. Additionally, the PMF model and one-way ANOVA were used to identify the potential sources and discuss the factors affecting the enrichment of heavy metals. The results showed that the mean contents of the surface soils were 1.190 (Cd), 139.4 (Cr), 96.74 (Cu), 0.081 (Hg), 56.97 (Ni), 46.66 (Pb) and 130.1 (Zn) mg/kg. All heavy metals exceeded the background values of the A layer soil in Yunnan Province. The Igeo showed that Cd was the most hazardous element in the study area, followed by Cu, Cr, As, Ni and Pb. The RI showed that low ecological risks, moderate ecological risks, considerable ecological risks and strong ecological risks accounted for 3.81%, 55.27%, 37.74% and 3.18%, respectively, of the total samples, and Cd was the main dominant element. The HI values of the As element in children were greater than 1, indicating a non-carcinogenic risk, and other elements’ risks were acceptable. The CR values of Cr and Ni were higher than their limits (1 × 10−4), and both had carcinogenic risks in children and adults, as did As in children. According to the PMF model, four heavy metals sources were identified: geological sources (32%), sources from mining activities (19.38%), atmospheric deposition sources (17.57%) and agricultural sources (31.05%). Thereinto, As and Pb were mainly derived from agricultural sources, Cd and Cr were mainly associated with geological sources, Cu was largely from mining activity sources, Hg was mainly from atmospheric deposition sources and Ni and Zn were mainly from geological sources, mining activities and agricultural activities. The parent material has a significant influence on the enrichment of heavy metals in the soil, and the heavy metals are significantly enriched in the carbonate parent material and quaternary parent material. Topography also plays a role in heavy metal accumulation; Cd, Cr, Cu, Ni and Zn gradually decreased with the increase in altitude, and As and Pb increased with the increase in altitude. Mn-oxide played a crucial part in the enrichment of Cu and Zn, while SOC, K2O and pH had little influence on the accumulation of heavy metals.

Ecological risk and spatial distribution, sources of heavy metals in typical purple soils, southwest China

“…The altitude (X 4 ) of research area has a significant impact on 8 HMs spatial distribution, especially on Cu and Ni. Many previous studies have also shown similar conclusions 49 , 50 . Interestingly, comparing the Pearson correlation analysis, it was found that there was consistency and difference in the results between Pearson correlation analysis with geographic detection analysis.…”

Source identification and driving factor apportionment for soil potentially toxic elements via combining APCS-MLR, UNMIX, PMF and GDM

“…After years of urbanization and industrialization, soil potentially toxic elements (PTEPTEs) pollution caused by high-intensity and intensive human activities has become a global environmental problem 1 – 6 . It changes the chemical and physical properties of soil, reduces the quality of soil and crops, and further endangers human health through the food chain 1 , 7 – 9 . In China, the pollution of PTEs in soil is more prominent in some areas.…”

Influence of inherent minerals on metalworking fluids sludge pyrolysis: Products characterization and heavy metals behavior

“…Currently, the primary methods for disposing of MFS include landfills and incineration. Nevertheless, landfills can pose a significant risk of groundwater contamination due to leachate-containing contaminants from MFS, and land resources are also growing progressively limited [ 4 ]. On the other hand, incineration is a well-established technology for the safe disposal of MFS, but it does face challenges related to pollutant emissions and high operational costs [ 5 ].…”