Comprehensive investigation of pollution levels and potential bioavailable risks of 7 potentially toxic elements in Qinghai-Tibet soils by using diffusive gradients in thin-films (DGT)

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ABSTRACT Seven potentially toxic elements (PTEs) including Cr, Ni, Cd, Zn, Cu, Pb and As of soil samples from Qinghai-Tibet Plateau (QTP) were measured to assess the degree of contaminations. To have a comprehensive understanding of PTEs’ risks in QTP, the single-step nitric acid extraction and diffusive gradients in thin-films (DGT) technique were employed in this study for the determination of PTEs’ total amount as well as bioavailable content, respectively. Haibei state of Qinghai province was the most contaminated sites by PTEs. Behaviors of PTEs should be highly concerned as they can produce continuous bioavailable effects to ecological systems. High DGT concentrations of Zn and Cr showed their remarkable available risks in soils. In the environment with insufficient organic matter and slight pH variations, phosphorus level was the main contributor to affect the mobility of labile PTEs, especially for Pb and Ni. Concentration ratio between DGT measurement and soil solution and correlation analysis confirmed the high bioavailability of Pb, Zn and Cr, leading to short-term mixture effects on ecological systems, while the long-term release dynamics were found for As and Cu. Results from road-side and river-side soils of QTP evidenced the short-term bioavailable risks were possibly attributed to intensive anthropogenic activities including traveling industries and vehicle driving, whereas long-term bioavailable risks was from the natural transportation and deposition.