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Characterizing surface soil heavy metal contamination and source attribution in the Qinghai Lake Basin
Summary
Researchers analyzed 227 soil samples across China's Qinghai Lake Basin to map heavy metal contamination, finding generally low pollution levels with transportation as a key source; they recommend future research examine the combined threat of heavy metals and microplastics in alpine ecosystems.
The primary soil types in the Qinghai Lake Basin are meadow soil and gray calcareous soil. This study aims to delineate the characteristics, spatial distribution, and origins of surface soil heavy metals in this region. We collected 227 surface soil samples across various sedimentary landscapes within the basin. Analyses were conducted on twelve heavy metals: As, Ba, Co, Cr, Cu, Mn, Nb, Ni, Pb, V, Zn, and Zr. We employed methods such as the Enrichment Factor (EF), Geo-Accumulation Index (Igeo), Nemero Index (PN), and Absolute Principal Component Scores-Multiple Linear Regression (APCS-MLR) model to quantitatively assess contamination levels and pinpoint potential sources of these metals. Our findings reveal:1. The heavy metal contents in the Qinghai Lake Basin are generally similar to those of the Earth’s crust (UCC). However, compared to the Hoh Xil Nature Reserve, concentrations of Ba, Cr, Mn, Zn, and Zr are significantly higher, suggesting possible point-source pollution. 2. EF, Igeo, and PN analyses indicate a moderate enrichment of Cr, potentially pointing to localized pollution sources. All Igeo values were below zero, suggesting an absence of widespread heavy metal pollution in the basin. The PN values emphasize the influence of extreme values in environmental assessment. 3. APCS-MLR analysis identified natural factors and transportation as the primary sources of surface soil heavy metal pollution, detailing the specific metals influenced by each source. 4. It is recommended to establish long-term monitoring in key areas and strengthen ecological management to prevent potential contamination. Future research should address heavy metal–microplastic co-pollution in alpine ecosystems. Overall, current soil contamination is low, but continued monitoring is necessary.