title: Mercury Redox Chemistry in Waters of the Eastern Asian Seas: From Polluted Coast to Clean Open Ocean.
abstract: We performed incubation experiments using seawaters from representative marine environments of the eastern Asian seas to determine the mercury (Hg) available for photoreduction (Hgr(II)), to investigate the Hg redox reaction kinetics, and to explore the effect of environmental factors and water chemistry on the Hg redox chemistry. Results show that Hgr(II) accounted for a considerable fraction of total Hg (THg) (%Hgr(II)/THg: 24.90 ± 10.55%, n = 27) and positively correlated with THg. Filtration decreased the Hgr(II) pool of waters with high suspended particulate matter (SPM). The positive linear relationships were found between pseudo-first order rate constants of gross Hg(II) photoreduction (kr) and gross Hg(0) photo-oxidation (ko) with photosynthetically active radiation (PAR). Under the condition of PAR of 1 m mol m(-2) s(-1), the kr were significantly (p < 0.05) lower than ko (kr/ko: 0.86 ± 0.22). The Hg(0) dark oxidation were significantly higher than the Hg(II) dark reduction. The Hg(II) dark reduction was positively correlated to THg, and the anaerobic condition favored the Hg(II) dark reduction. Filtration significantly influenced the Hg photoredox chemistry of waters with high SPM. UVB radiation was important for both Hg(II) photoreduction and Hg(0) photo-oxidation, and the role of other wavebands in photoinduced transformations of Hg varied with the water chemistry.
authors: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, China.
authors: Zhijia
authors: Z
authors: Ci
authors: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, China.
authors: Xiaoshan
authors: X
authors: Zhang
authors: Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences , Beijing, 100085, China.
authors: Yongguang
authors: Y
authors: Yin
authors: Key Lab of Urban Environment and Health, Institute of Urban Environment, Chinese Academy of Sciences , Xiamen, 361021, China.
authors: Jinsheng
authors: J
authors: Chen
authors: Institute of Oceanology, Chinese Academy of Sciences , Qingdao, 266071, China.
authors: Shiwei
authors: S
authors: Wang
mesh_terms: D000332:Aerobiosis; D000693:Anaerobiosis; D005202:Asia, Eastern; D005374:Filtration; D005843:Geography; D007700:Kinetics; D008628:Mercury / Q000737:chemistry*; D009792:Oceans and Seas; D010084:Oxidation-Reduction; D052638:Particulate Matter / Q000032:analysis; D012623:Seawater / Q000737:chemistry*; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis*
chemical_list: D052638:Particulate Matter; D014874:Water Pollutants, Chemical; D014867:Water; D008628:Mercury