Abstract
The Hun-Taizi River watershed includes the main part of the Liaoning central urban agglomeration, which contains six cities with an 80-year industrial history. A total of 272 samples were collected from different land use areas within the study area to estimate the concentration levels, spatial distributions and potential sources of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), mercury (Hg), nickel (Ni), lead (Pb) and zinc (Zn) with a geographic information system (GIS), principal component analysis (PCA) and canonical correspondence analysis (CCA). Only the concentration of Cd was over the national standard value (GB 15618–2018). However, the heavy metal concentrations at 24.54%, 71.43%, 63.37%, 85.71, 70.33%, 53.11%, and 72.16% of the sampling points were higher than the local soil background values for As, Cd, Cr, Cu, Hg, Ni, Pb and Zn, respectively, which were used as standard values in this study. The maximal values of Cd (16.61 times higher than the background value) and Hg (12.18 times higher than the background value) had high concentrations, while Cd was present in the study area at higher values than in some other basins in China. Cd was the primary pollutant in the study area due to its concentration and potential ecological risk contribution. The results of the potential ecological risk index (RI) calculation showed that the overall heavy metal pollution level of the soil was considerably high. Three groups of heavy metals with similar distributions and sources were identified through PCA. The results of the CCA showed that the distribution of mines was the strongest factor affecting the distributions of Ni, As, Zn, Pb, and Cd. However, Cu was strongly influenced by the distance to the nearest river. These findings can provide scientific support for critical planning and strategies for soil pollution control and removal to support the sustainable development of the study area.
Highlights
The Hun-Taizi River watershed includes the main part of the Liaoning central urban agglomeration, which contains six cities with an 80-year industrial history
This study addressed three goals: (1) to evaluate the overall and individual land use pollution conditions of As, Hg, Cd, Cu, Zn, Cr, Pb, and Ni based on the local natural background values in the Hu-Taizi River watershed, (2) to characterize the spatial distribution of these eight heavy metal elements with geographic information system (GIS), and (3) to assess the ecological risk potential sources with multivariate statistical methods
Two high-value risk index (RI) regions accounted for 4.33% of the study area and were mainly determined by the Cd distribution
Summary
The Hun-Taizi River watershed includes the main part of the Liaoning central urban agglomeration, which contains six cities with an 80-year industrial history. Sustained and intensive human activities, especially agricultural and industrial production, in urban agglomeration areas have brought heavy metal pollution to surface soils in many areas[2,3]. Efforts have been devoted to researching the spatial distribution, ecological risks and human health risks of soil heavy metal pollution in cities[15,23]. Soil heavy metal pollution studies have mostly used contamination to background value ratios[24,25], GIS software for spatial distribution estimation[8,16], driving factors analysis with multivariate statistics[26], meta-analysis[14]. Spatial statistics is a powerful tool for estimating the correlations among spatial factors, and some studies have tried to estimate the sources of heavy metal pollutants with multivariate geostatistical analysis methods[29,30]
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