Mercury distribution and transfer in sediment-mangrove system in urban mangroves of fast-developing coastal region, Southern China. (5th August 2020)

• Record Type: Journal Article
• Authors: Chai, Minwei; Li, Ruili; Qiu, Zhigang; Niu, Zhiyuan; Shen, Xiaoxue
• Is Part Of: Estuarine, coastal and shelf science. Volume 240(2020)
• Publication Date: 2020-08-05
• Subjects: Urban mangrove -- Mercury pollution -- Chemical speciation -- Iron plaque -- Translocation; Estuarine oceanography -- Periodicals; Coasts -- Periodicals; Estuarine biology -- Periodicals; Seashore biology -- Periodicals; Coasts; Estuarine biology; Estuarine oceanography; Seashore biology; Periodicals; 551.461805
• DOI: 10.1016/j.ecss.2020.106770
• Languages: English
• ISSNs: 0272-7714

Abstract

Abstract: In urban mangroves affected by surrounding urbanization and anthropogenic activities, the fate of mercury (Hg) in sediment-mangrove system remains unclear. In this study, four urban mangroves with different urban functional zonings in fast-developing Shenzhen of China were selected: Shajing mangrove (SJM) and Xixiang mangrove (XXM) featured with industry district, Futian mangrove (FTM) and Baguang mangrove (BGM) featured with central business district and ecological preserve, respectively. The distributions of Hg in sediment, iron plaque (IP), and Kandelia obovata were determined. The mean concentrations of total Hg in mangrove sediments were SJM > XXM, FTM > BGM. Higher ecological risk was also detected in SJM based on geo-accumulation index, potential ecological risk factor, and contamination factor. The speciation analysis of Hg in non-rhizosphere sediments showed that residual, oxidizable, and volatile Hg acted as dominant fractions in urban mangroves, with volatile Hg to be important for Hg bioaccumulation in K. obovata . IP acted as a natural barrier to limit transfer of Hg from sediment to K. obovate due to lower Hg concentrations in IP compared to that in sediment. In terms of the total and bioavailable Hg, translocation factors (TF) of Hg in mangroves featured with different urban functions were: TFtotal : BGM (0.23) ≈ FTM (0.23) > SJM (0.15) ≈ XXM (0.14); TFavail : BGM (0.81) ≈ FTM (0.74) > SJM (0.40) ≈ XXM (0.37). The reduced TFs of Hg were important for protecting K. obovata from heavy Hg pollution in urban mangroves featured with industry district. Graphical abstract: Image 1 Highlights: Hg pollution in mangrove sediment was highest in Shajing featured with industry district. Volatile Hg in mangrove sediment was related to its bioaccumulation in mangrove plant. Iron plaque acted as a natural barrier for K. obovata 's Hg absorption from sediment. Transfers of Hg in Shajing and Xixiang mangroves were lower than that of Futian and Baguang.