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| Characteristics of heavy metals and ecological risk assessment in agricultural soils of Linzhou County，Tibet |
| Received:November 11, 2024 |
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| KeyWord:Linzhou County;high-altitude agricultural areas;agricultural land;heavy metals;distribution characteristics;risk assessment |
| Author Name | Affiliation | | ZHANG Jie | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China | | YUAN Xin | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China | | FENG Junbo | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China | | LIU Kun | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China | | MAO Jin | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China | | SU Jing | Civil-Military Integration Center of China Geological Survey, Chengdu 610036, China |
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| Abstract: |
| To investigate the heterogeneous mechanisms of heavy metal migration and accumulation in high-altitude agricultural soils under unique eco-environmental conditions, a total of 403 soil samples were collected from agricultural lands in southern Linzhou County. Eight heavy metals—arsenic（As）, cadmium（Cd）, chromium（Cr）, copper （Cu）, lead（Pb）, zinc（Zn）, nickel （Ni）, and mercury（Hg）—were analyzed for their concentrations. Integrated with geostatistical analysis to characterize spatial distribution patterns, the environmental quality was comprehensively assessed using single factor index, Nemerow composite index, geo-accumulation index, and potential ecological risk index methodologies. Furthermore, combined application of correlation analysis and principal component analysis（PCA） was conducted to identify predominant contamination sources. The results revealed that the average concentrations of As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn were 21.1, 0.170, 58.4, 24.5, 0.076, 26.0, 31.1 mg·kg-1 and 79.2 mg·kg-1, respectively. All these values were below the screening values established by the Soil Environmental Quality Risk Control Standard for Soil Contamination of Agricultural Land（GB 15618—2018）. When compared to other high-altitude regions, such as the eastern Tibetan Plateau, Linzhou County exhibited higher levels of Cd and Hg, likely due to agricultural practices and traffic-related pollution. In contrast, Cr and Ni concentrations were primarily controlled by the parent material, and their spatial distribution patterns resembled those observed in other regions of the Tibetan Plateau. Univariate index method evaluations indicated that Cd and Hg exhibited higher pollution indices, with certain sampling points showing potential ecological risks. The average Hakanson potential ecological risk index in the study area was 107.42, suggesting low ecological risk, though some points indicated moderate to high risks. As, Cd, Pb, and Zn are primarily derived from traffic sources. Cr and Ni are primarily controlled by background materials. Hg is primarily influenced by the concentrated combustion of fossil fuels and biofuels, whereas Cu is predominantly derived from transportation sources and is also influenced by the parent material of the soil. |
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