State Key Laboratory of Environmental Aquatic Chemistry, Research Centre for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China.
State Key Laboratory of Environmental Aquatic Chemistry, Research Centre for Eco-Environmental Science, Chinese Academy of Sciences, Beijing 100085, China.
Sci Total Environ. 2015 Nov 1;532:617-24. doi: 10.1016/j.scitotenv.2015.06.075. Epub 2015 Jun 25.
Bioturbation can remobilize heavy metal in the sediments and may pose a risk for aquatic biota. The effects of bioturbation/bioirrigation by three different riverine organism types (Tubificid, Chironomid larvae, and Loach) on thallium release from contaminated sediment (10.0 ± 1.1 mg Tl/kg sediment, dry wt.) were evaluated in this study. The bioturbation by the epibenthos clearly caused an increased turbidity in the overlying water, and the effect was in the order of Loach > Chironomid larvae > Tubificid. A significant release of Tl into the water column via the resuspended sediment particles was observed, especially for Loach. During the first few days, the leaching of dissolved Tl from sediment into water was fast, and the dissolved Tl under bioturbation/bioirrigation was much higher than the control group. However, after 14 days, the bioturbation/bioirrigation process seemed to suppress the release of Tl from the sediment particles to water, especially for sediment with Loach. This may partly be due to the sorption or coprecipitation of Tl simultaneous with the formation of iron and manganese hydrous oxides with increased pH values as a consequence of phytoplankton growth. Linear regression analysis confirmed that both the total and particulate Tl concentrations had good correlations with particulate Fe and Mn concentrations as well as turbidity in the overlying water. Additionally, planktonic bacteria may oxidize the Tl(I) to Tl(III), resulting in a reduced solubility of Tl by which Tl(OH)3 becomes the predominant form of Tl.
生物扰动可以使沉积物中的重金属重新移动，从而对水生生物构成风险。本研究评估了三种不同河流生物类型（颤蚓、摇蚊幼虫和泥鳅）的生物扰动/生物灌溉对受污染沉积物（10.0 ± 1.1 mg Tl/kg 沉积物，干重）中铊释放的影响。底栖生物的生物扰动明显导致上覆水中浊度增加，其影响顺序为泥鳅>摇蚊幼虫>颤蚓。通过再悬浮沉积物颗粒，明显观察到铊向水柱中的大量释放，尤其是泥鳅。在最初的几天里，溶解态铊从沉积物中快速浸出到水中，生物扰动/生物灌溉下的溶解态铊明显高于对照组。然而，14 天后，生物扰动/生物灌溉过程似乎抑制了铊从沉积物颗粒向水中的释放，尤其是对于有泥鳅的沉积物。这可能部分是由于铁和锰水合氧化物的形成导致 pH 值增加，从而与铊同时发生吸附或共沉淀，同时浮游植物的生长也会导致这种情况。线性回归分析证实，上覆水中总铊和颗粒态铊浓度与颗粒态铁和锰浓度以及浊度均具有良好的相关性。此外，浮游细菌可能将 Tl(I)氧化为 Tl(III)，从而降低 Tl 的溶解度，使 Tl(OH)3 成为 Tl 的主要形式。
