Nedrich Sara M, Burton G Allen
Department of Earth and Environmental Sciences, University of Michigan, Ann Arbor, Michigan, USA.
School of Natural Resources and Environment, University of Michigan, Ann Arbor, Michigan, USA.
Environ Toxicol Chem. 2017 Sep;36(9):2456-2464. doi: 10.1002/etc.3783. Epub 2017 Mar 31.
Increased variability in lake and river water levels associated with changing climate could impact the fate and effects of metals in redox-sensitive sediments through the alteration of microbial communities and of acid-base and redox chemistry. The objective of the present study was to determine the influence of water level fluctuation on metal speciation in porewater and predict environmental risk to high-carbonate systems. Using experimental microcosms with sediments collected from 4 metal-contaminated coastal freshwater wetlands in Michigan, USA, we conducted water level fluctuation experiments. Porewater and sediment metals (Ca, Cu, Fe, Mg, Mn, Ni, Zn) and important metal binding phases (iron-oxide speciation, acid-volatile sulfide) were quantified. In a short-term drying (seiche) experiment, there were decreases in all porewater metals after inundation of saturated sediments. During a drought experiment, re-inundation of oxidized sediments increased porewater Cu, Zn, Mg, Ca for most sites. Porewater Zn increased after inundation to levels exceeding the US Environmental Protection Agency threshold for chronic toxicity. These data show that the dissolution of metal carbonates and metal sulfates contributes to metal release after re-flooding and indicate that we might expect increased ecological risk to organisms present in drought-sensitive regions where altered hydroperiods are likely to increase metal bioavailability. Environ Toxicol Chem 2017;36:2456-2464. © 2017 SETAC.
与气候变化相关的湖泊和河流水位变率增加，可能通过改变微生物群落以及酸碱和氧化还原化学，影响氧化还原敏感沉积物中金属的归宿和效应。本研究的目的是确定水位波动对孔隙水中金属形态的影响，并预测高碳酸盐系统的环境风险。我们使用从美国密歇根州4个受金属污染的沿海淡水湿地采集的沉积物进行实验微观模拟，开展了水位波动实验。对孔隙水和沉积物中的金属（钙、铜、铁、镁、锰、镍、锌）以及重要的金属结合相（铁氧化物形态、酸挥发性硫化物）进行了量化。在短期干燥（假潮）实验中，饱和沉积物被淹没后，所有孔隙水中的金属含量均下降。在干旱实验中，对于大多数地点，氧化沉积物重新被淹没后，孔隙水中的铜、锌、镁、钙含量增加。淹没后孔隙水中的锌含量增加，超过了美国环境保护局的慢性毒性阈值。这些数据表明，金属碳酸盐和金属硫酸盐的溶解导致了重新注水后金属的释放，并表明在干旱敏感地区，水文周期的改变可能会增加金属的生物有效性，我们可能预计对这些地区生物的生态风险会增加。《环境毒理学与化学》2017年；36:2456 - 2464。© 2017 SETAC。
