Factors controlling the accumulation and ecological risk of trace metal(loid)s in river sediments in agricultural field

• Published in: Chemosphere (Oxford) 2020-03, Vol.243, p.125359, Article 125359
• Main Authors: Mao, Lingchen, Liu, Libo, Yan, Nanxia, Li, Feipeng, Tao, Hong, Ye, Hua, Wen, Haifeng
• Format: Article
• Language: English
• Subjects: Agriculture; Chemical Fractionation; China; Eco-risk assessment; Ecology; Environmental Monitoring - methods; Fractionation; Geologic Sediments - chemistry; Metals, Heavy - analysis; Metals, Heavy - toxicity; Mobility; Positive matrix factorization; Risk Assessment; Rivers - chemistry; Source apportionment; Trace Elements - analysis; Trace Elements - toxicity; Water Pollutants, Chemical - analysis; Water Pollutants, Chemical - toxicity
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2019.125359

There is an increasing concern of ecological risk from toxic trace metals in sediments to aquatic environment in agricultural field. However, the knowledge of factors that control the accumulation and risk of trace metals in such environment is limited. In this study, we conducted source apportionment of 9 trace metal(loid)s in river sediments on Chongming Islands, China, where there had been >120 years of agricultural practice. The influence from sediment properties on metal accumulation and mobility were also discussed. The results indicate that anthropogenic metal input generally elevated Cd, Sb, Pb and Zn concentrations as their average values were 3.3, 2.6, 1.6 and 1.6 times of the background respectively. Significantly high As (max = 28.2 mg/kg) and Cu (max = 145.6 mg/kg) were also found in some individual sites. Positive matrix factorization analysis suggests that atmospheric deposition contributed 53.5% and 54.7% of the total Sb and Pb respectively, while most anthropogenic Cd, Cu, As and Zn was agriculture-derived. Amorphous Fe, Mn and Al oxides and organic matter were the most important binding phases which favour trace metal accumulation. Fractionation information from BCR sequential extraction suggests high potential mobility of Cd (>37% in acid extractable fraction). Fe/Mn oxides bound As, Cd, Cu, Pb and Zn (reducible fraction), which comprised 15–26% of the total, increased the ecological risk in anoxic sediments. The potential ecological risk index and risk assessment code identified more than 74% of the sampling sites as high to extremely high ecological risk because of the high toxicity and mobility of Cd. [Display omitted] •PMF identified five potential trace metal sources in sediment in agricultural field.•Aerosol deposition and agricultural activities were the main anthropogenic sources.•Amorphous mineral oxides and organic matter favour metal accumulation.•The reducible fraction of metals increased the eco-risk in anoxic condition.•Cd showed the highest ecological risk because of its high mobility and toxicity.