Diurnal characteristics of migration and transformation of mercury and effects of nitrate in Jialing River, Chongqing, China.
CHEMOSPHERE 2015;
119:634-641. [PMID:
25150466 DOI:
10.1016/j.chemosphere.2014.07.032]
[Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2013] [Revised: 04/30/2014] [Accepted: 07/10/2014] [Indexed: 06/03/2023]
Abstract
Laboratory incubation experiments were performed to identify diurnal characteristics of migration and transformation of mercury (Hg) and effects of nitrate (NO3(-), a hydroxyl radical donor by photolysis) in Jialing River, Chongqing, China. It is found that there are strong diurnal signals of [monomethylmercury (MMHg)] and [reactive Hg (RHg)] in sediment, pore water and overlying water, which suggest that solar radiation may be an important variable that involved in aquatic Hg cycling. Photo-degradation (PD) of MMHg plays a key role in Hg cycling in water systems, and the rates are measured to be 38.22% in March, 2012. The presence of NO3(-) has a marked effect on MMHg PD under solar radiation, and affects inorganic species reducting to Hg(0), resulting in more Hg species available for methylation. So NO3(-) is an important factor for Hg cycling in water systems. Diffusive flux of MMHg, RHg and dissolved Hg (DHg) are 1.92-2.34, 3.43-3.64 and 3.04-5.71 ng m(-2) d(-1) at daytime, and 6.04-6.92, 3.22-3.25 and 7.79-8.37 ng m(-2) d(-1) at nighttime, respectively, implying that sediment is a major Hg source for shallow-water area in Jialing River at springtime. These results show great importance for understanding Hg biogeochemical processes in clear, oligotrophic, shallow, sluggish, and agriculturally-impacted waters.
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