Spatial distribution, occurrence form, availability and ecological risk assessment of arsenic in soils of riparian zones on the Tibetan Plateau

Abstract

To understand the speciation characteristics, sources, and ecological environmental risks of arsenic in the soil of the Lhasa River riparian zone, the continuous extraction method was used to analyze the total amount and speciation and occurrence characteristics of arsenic in the soil samples of the riparian zone, and the method of risk assessment index was used to conduct a preliminary assessment of its environmental risks in order to understand the speciation and occurrence characteristics of arsenic in the soil of the Lhasa River riparian zone and its ecological environmental risks. The total arsenic concentration in the soil of the Lhasa River riparian zone ranged from 5.23 to 68.7 mg·kg−1, with an average of 21.6 mg·kg−1, which was slightly higher than the background value of Lhasa soil (20 mg·kg−1). The majority of arsenic in soil is in the residual state, and the average proportion of bioavailable arsenic in total arsenic is 1.06 %. The soil arsenic in the Lhasa River riparian zone poses little ecological harm. The distribution of arsenic in the riparian zone is highly influenced by soil physical and chemical parameters (pH, CEC, clay minerals), as well as traffic conditions and altitude. Arsenic originates from a variety of sources, including geothermal development, agricultural operations, and transportation, according to a review of its sources. This finding will serve as a scientific foundation for landscape design, as well as human health and safety protection measures in the Lhasa River riparian zone, as well as a reference for future studies on heavy metal transport, transformation, and source apportionment in worldwide riparian soils.