Key Laboratory of Environmental Nanotechnology and Health Effects, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China.
Key Laboratory of Environmental Nanotechnology and Health Effects, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, PR China.
Water Res. 2019 Mar 1;150:191-199. doi: 10.1016/j.watres.2018.11.046. Epub 2018 Nov 21.
Many arsenic-bearing freshwaters are facing with eutrophication and consequent algae-induced anoxia/hypoxia events. However, arsenic cycling in eutrophic waters and its impact on public health are poorly understood. Laboratory simulation experiments are performed in this study to investigate the effect of algal blooms on the cycling of arsenic in a sediment-water-air system. We found that the anoxia induced by the degradation of algal biomass promoted an acute arsenic (mostly As(III)) release within two days from sediment to both the water and atmosphere, and the release effluxes were proportional to the algae dosage. The reduction and methylation of arsenic were enhanced at the sediment-water interface, owing to the significant increase in arsenate reductase genes (arrA and arsC), and arsenite methyltransferase genes (arsM) caused by increased anoxia. The analysis of synchrotron-based X-ray absorption spectroscopy indicated that the concomitantly released natural organic matter (NOM) and sulfur (S) at the sediment-water interface reduced the As(III) release to a certain extent in the later reducing period of incubation, by forming AsS (43-51%) and As(III)-Fe-NOM (28-35%). Our results highlight the needs for the in-situ assessment of volatile arsenic in eutrophic freshwaters with its risk to human and animal health.
许多含砷的淡水面临富营养化和随之而来的藻类引发的缺氧/低氧事件。然而，富营养化水中的砷循环及其对公共健康的影响还知之甚少。本研究通过实验室模拟实验，研究了藻类水华对沉积物-水-气系统中砷循环的影响。我们发现，藻类生物量降解引起的缺氧在两天内从沉积物向水和大气中急性释放（主要是 As(III)），释放通量与藻类剂量成正比。由于缺氧增加，砷酸盐还原酶基因（arrA 和 arsC）和亚砷酸盐甲基转移酶基因（arsM）显著增加，促进了砷在沉积物-水界面的还原和甲基化。基于同步加速器的 X 射线吸收光谱分析表明，同时在沉积物-水界面释放的天然有机物 (NOM) 和硫 (S) 在培养的后期还原期在一定程度上减少了 As(III)的释放，形成了 AsS（43-51%）和 As(III)-Fe-NOM（28-35%）。我们的结果强调了需要对富营养化淡水中易挥发砷进行现场评估及其对人类和动物健康的风险。
