Department of Plant and Soil Sciences, Delaware Environmental Institute, University of Delaware , Newark, Delaware 19711, United States.
Photon Sciences Division, Brookhaven National Laboratory , Building 743, Upton, New York 11973, United States.
Environ Sci Technol. 2017 Jun 6;51(11):5913-5922. doi: 10.1021/acs.est.6b06152. Epub 2017 May 16.
Climate change-induced perturbations in the hydrologic regime are expected to impact biogeochemical processes, including contaminant mobility and cycling. Elevated levels of geogenic and anthropogenic arsenic are found along many coasts around the world, most notably in south and southeast Asia but also in the United States, particularly along the Mid-Atlantic coast. The mechanism by and the extent to which arsenic may be released in contaminated coastal soils due to sea level rise are unknown. Here we show a series of data from a coastal arsenic-contaminated soil exposed to sea and river waters in biogeochemical microcosm reactors across field-validated redox conditions. We find that reducing conditions lead to arsenic release from historically contaminated coastal soils through reductive dissolution of arsenic-bearing mineral oxides in both sea and river water inundations, with less arsenic release from seawater scenarios than river water due to inhibition of oxide dissolution. For the first time, we systematically display gradation of solid phase soil-arsenic speciation across defined redox windows from reducing to oxidizing conditions in natural waters by combining biogeochemical microcosm experiments and X-ray absorption spectroscopy. Our results demonstrate the threat of sea level rise stands to impact arsenic release from contaminated coastal soils by changing redox conditions.
气候变化引起的水文变化预计将影响生物地球化学过程，包括污染物的迁移和循环。在世界许多沿海地区都发现了高水平的地质成因和人为成因的砷，尤其是在南亚和东南亚，但在美国，特别是在大西洋中部海岸也有发现。由于海平面上升，砷可能会从受污染的沿海土壤中释放出来的机制和程度尚不清楚。在这里，我们展示了一系列数据，这些数据来自于沿海受砷污染的土壤，这些土壤在生物地球化学微宇宙反应器中暴露于海水和河水，跨越了现场验证的氧化还原条件。我们发现，在还原条件下，砷会通过还原溶解含砷矿物氧化物从历史上受污染的沿海土壤中释放出来，而在海水情景下，由于氧化物溶解受到抑制，砷的释放量比河水情景少。这是第一次，我们通过结合生物地球化学微宇宙实验和 X 射线吸收光谱，系统地展示了在自然水中从还原到氧化条件下，定义的氧化还原窗口中固相土壤砷形态的分级。我们的结果表明，由于氧化还原条件的变化，海平面上升有可能对受污染的沿海土壤中砷的释放产生影响。
