title: Ecological risk and pollution history of heavy metals in Nansha mangrove, South China.
abstract: Owing to the Industrial Revolution in the late 1970s, heavy metal pollution has been regarded as a serious threat to mangrove ecosystems in the region of the Pearl River Estuary, potentially affecting human health. The present study attempted to characterize the ecological risk of heavy metals (Cd, Cr, Cu, Mn, Ni, Pb and Zn) in Nansha mangrove, South China, by estimating their concentrations in the surface sediment. In addition, the pollution history of heavy metals was examined by determining the concentrations of heavy metals along the depth gradient. The phytoremediation potential of heavy metals by the dominant plants in Nansha mangrove, namely Sonneratia apetala and Cyperus malaccensis, was also studied. Results found that the surface sediment was severely contaminated with heavy metals, probably due to the discharge of industrial sewage into the Pearl River Estuary. Spatial variation of heavy metals was generally unobvious. The ecological risk of heavy metals was very high, largely due to Cd contamination. All heavy metals, except Mn, decreased with depth, indicating that heavy metal pollution has been deteriorating since 1979. Worse still, the dominant plants in Nansha mangrove had limited capability to remove the heavy metals from sediment. Therefore, we propose that immediate actions, such as regulation of discharge standards of industrial sewage, should be taken by the authorities concerned to mitigate the ecological risk posed by heavy metals.
authors.affiliation: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China; Key Laboratory of Water Quality Safety and Protection in Pearl River Delta, Ministry of Education, Guangzhou University, Guangzhou 510006, China; Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China. Electronic address: wuqihang@gzhu.edu.cn.
authors.forename: Qihang
authors.initials: Q
authors.lastname: Wu
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Nora F Y
authors.initials: NF
authors.lastname: Tam
authors.affiliation: Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, China.
authors.forename: Jonathan Y S
authors.initials: JY
authors.lastname: Leung
authors.affiliation: School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China.
authors.forename: Xizhen
authors.initials: X
authors.lastname: Zhou
authors.affiliation: Department of Civil Engineering, Auburn University, Auburn, AL 36849, United States.
authors.forename: Jie
authors.initials: J
authors.lastname: Fu
authors.affiliation: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
authors.forename: Bo
authors.initials: B
authors.lastname: Yao
authors.affiliation: School of Environmental Science and Engineering, Guangzhou University, Guangzhou 510006, China.
authors.forename: Xuexia
authors.initials: X
authors.lastname: Huang
authors.affiliation: School of Geographical Sciences, Guangzhou University, Guangzhou 510006, China.
authors.forename: Lihua
authors.initials: L
authors.lastname: Xia
mesh_terms: D001673:Biodegradation, Environmental; D002681:China; D029786:Cyperus / Q000378:metabolism; D004463:Ecology; D004784:Environmental Monitoring; D019015:Geologic Sediments / Q000737:chemistry*; D029561:Lythraceae / Q000378:metabolism; D019216:Metals, Heavy / Q000032:analysis*; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000032:analysis*; D053833:Wetlands
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical
keywords: Ecological risk assessment; Heavy metal; Mangrove; Phytoremediation; Pollution; Sediment