title: Diurnal characteristics of migration and transformation of mercury and effects of nitrate in Jialing River, Chongqing, China.
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.
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China; School of Chemistry and Material, Guizhou Normal University, Guiyang 550001, China.
authors.forename: Rongguo
authors.initials: R
authors.lastname: Sun
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China. Electronic address: dywang@swu.edu.cn.
authors.forename: Dingyong
authors.initials: D
authors.lastname: Wang
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China.
authors.forename: Wen
authors.initials: W
authors.lastname: Mao
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Ma
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Chongqing Key Laboratory of Soil Multi-scale Interfacial Process, College of Resource and Environment, Southwest University, Chongqing 400715, China; Chongqing Key Laboratory of Agricultural Resources and Environment, Chongqing 400716, China.
authors.forename: Tao
authors.initials: T
authors.lastname: Jiang
mesh_terms: D002681:China; D004784:Environmental Monitoring / Q000379:methods / Q000706:statistics & numerical data*; D019015:Geologic Sediments / Q000737:chemistry; D008628:Mercury / Q000032:analysis*; D009566:Nitrates / Q000032:analysis*; D010782:Photolysis; D045483:Rivers / Q000737:chemistry*; D013054:Spectrophotometry, Atomic; D013472:Sunlight; D014874:Water Pollutants, Chemical / Q000032:analysis*
chemical_list: D009566:Nitrates; D014874:Water Pollutants, Chemical; D008628:Mercury
keywords: Contribution-rate; Diffusive flux; Mercury cycling; Nitrate; Photo-degradation