Distribution and speciation of mercury affected by humic acid in mariculture sites at the Pearl River estuary. (September 2018)

• Record Type: Journal Article
• Authors: Ding, Lingyun; Zhao, Kaiyun; Zhang, Lijuan; Liang, Peng; Wu, Shengchun; Wong, Ming Hung; Tao, Huchun
• Is Part Of: Environmental pollution. Volume 240(2018)
• Page Start: 623
• Page End: 629
• Publication Date: 2018-09
• Subjects: Humic acid -- Mercury -- Methylation -- Adsorption -- Mariculture; Pollution -- Periodicals; Pollution -- Environmental aspects -- Periodicals; Environmental Pollution -- Periodicals; Pollution -- Périodiques; Pollution -- Aspect de l'environnement -- Périodiques; Pollution -- Effets physiologiques -- Périodiques; Pollution; Pollution -- Environmental aspects; Periodicals; Electronic journals; 363.73
• DOI: 10.1016/j.envpol.2018.04.142
• Languages: English
• ISSNs: 0269-7491

Abstract

Abstract: At the Pearl River Estuary of southern China, mercury and its environmental problems have long been a great concern. This study investigated the distribution and speciation of mercury compounds that are significantly influenced by the increasing content of humic acid (HA, a model natural organic matter) in this region. The inorganic mercury and methyl mercury, being adsorbed and converted at different HA levels, were studied in sediments and surface water at both mariculture and their reference sites. In mariculture sediments with higher HA content (up to 4.5%), more mercury were adsorbed at different compound levels, promoting the methylation and accumulation of mercury (P < 0.05) at the sediment-water interface. Seasonal shift in environmental temperature might control the HA content, subsequently favouring mercury methylation (maximum 1.75 ± 0.08 mg L −1 d −1 ) under warm weather conditions. In reference sites received less HA wastes, lower adsorption capacity and methylation rate were observed for mercury in sediments and surface water. Our work points to the significant roles of HA on mercury distribution and speciation both spatially and seasonally, thus addressing the impacts of mariculture activities on estuary eco-system. Graphical abstract: Image 1 Highlights: Higher content of humic acid (HA) was noted in top layers of mariculture sediments. Specific effects of HA on adsorption and methylation of mercury (Hg) were studied. Active Hg methylation occurred at sediment-water interfaces of mariculture estuary. Hg methylation was responded to season shift with temperature and HA changes. Mariculture activities exerted influences on the estuary eco-system of Pearl River. Abstract : Humic acid, an organic matter from mariculture activities, significantly influenced the distribution and speciation of mercury compounds in the eco-system of Pearl River estuary.