title: A Particular River-Whiting Phenomenon Caused by Discharge of Hypolimnetic Water from a Stratified Reservoir.
abstract: A particular river-whiting phenomenon occurred in the early 2000s in the Xiaoche River and since then it has been reoccurring from June to November each year. Residents were surprised by this phenomenon and worried about it. This study was designed to reveal the forming mechanism of the river-whiting phenomenon. A comparison of T, EC, ORP, DO, TDS and δ34S in the culvert water and discharge pipe water with that in the water column of Aha Reservoir strongly indicated that the culvert water and discharge pipe water derived primarily from the hypolimnetic reservoir water. When the hypolimnetic water enriched in SO42- and H2S, through seepage from the penstock, flows into the Xiaoche River, the water's supersaturation degree with respect to CaSO4 is increased as a result of increased temperature and DO, thus colloid CaSO4 can be formed. This is the essential cause of the river-whiting phenomenon. The sources of high concentrations of SO42- and H2S in hypolimnetic water include not only direct SO42- and H2S input of acid mine drainage as a result of irrational coal mining in the watershed, but also the sulfur-enriched surface sediments which may release H2S through the sulfate reduction processes. The contaminated sediment has acted as an important contamination source for sulfur to the overlying water in Aha Reservoir. There are more than 50,000 large dams in the world until now. With the increase of reservoir age and the persistent accumulation of pollutants within the reservoir system, discharged hypolimnetic water may contain high levels of pollutants and lead to unpredicted disasters. More investigations are needed to illuminate the water quality condition of discharge water from reservoirs and estimate its impacts on the downstream eco-environment.
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
authors.forename: Jingan
authors.initials: J
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
authors.forename: Haiquan
authors.initials: H
authors.lastname: Yang
authors.affiliation: Department of Geography, The University of Hong Kong, Pokfulam Road, Hong Kong, China.
authors.forename: David Dian
authors.initials: DD
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
authors.forename: Dan
authors.initials: D
authors.lastname: Xu
authors.affiliation: College of Resources and Environmental Engineering, Guizhou University, Guiyang 550025, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Luo
authors.affiliation: State Key Laboratory of Environmental Geochemistry, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang 550002, China.
authors.forename: Jingfu
authors.initials: J
authors.lastname: Wang
mesh_terms: D002681:China; D045483:Rivers; D014867:Water; D014874:Water Pollutants, Chemical; D014876:Water Pollution
chemical_list: D014874:Water Pollutants, Chemical; D014867:Water