1. Salinity and redox conditions affect the methyl mercury formation in sediment of Suaeda heteroptera wetlands of Liaoning province, Northeast China.
- Author
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Li, Hang, Zheng, Dongmei, Yang, Jisong, Wu, Chenghao, Zhang, Shiwei, Li, Huiying, and Ma, Huanchi
- Subjects
MERCURY ,METHYLMERCURY ,SALINITY ,WETLANDS ,SEDIMENTS ,SULFATE-reducing bacteria - Abstract
Using a laboratory simulation experiment, we studied the trend of change in methylmercury (MeHg) content of sediments in response to the changing salinity of flooding water (deionized water, 0.5%, 1.0%, 1.5%, and 2.0%) and sulfate-reducing bacteria (SRB) content for both the surface layer (0–10 cm) and the bottom layer (10–20 cm) of Suaeda heteroptera wetland sediments in the Liaohe estuary under anaerobic and aerobic conditions, respectively. The results showed that under AAC (anaerobic conditions), the MeHg content in the surface and bottom sediment layers increased first and then decreased over time and was highest at the 14th day. In contrast, under AC (aerobic conditions), the MeHg content in sediments of both layers increased slowly with increasing test time. The MeHg content in sediments increased first and then decreased with rising salinity and was highest at a salinity of 1.0%. Among the samples collected at different experimental stages, the SRB content in the sediments showed a decreasing trend with rising flooding salinity under AAC and AC. The MeHg and SRB contents were higher under anaerobic conditions than under aerobic conditions. Linear fitting results showed that there was no linear correlation between MeHg contents and SRB quantities in surface and bottom sediments under AAC and AC (R
2 < 0.1). Collectively, these results suggest an important role for flooding salinity and anaerobic-aerobic conditions in the production of MeHg in S. heteroptera wetlands of the Liaohe estuary, and may predict the ecological risk of methylmercury according to the change of salinity. • MeHg in sediments response to the change of salinity (CK, 0.5%, 1.0%, 1.5%, and 2.0%) of water was studied. • The highest MeHg occurred at 1.0% salinity of water and MeHg in all sediment increased substantially. • MeHg in sediment increased in less extent in the aerobic conditions compared to the anaerobic conditions. • Other bacteria apart from SRB might be responsible for the MeHg change in such estuary environment. [ABSTRACT FROM AUTHOR]- Published
- 2019
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