Environmental and Ecological Risk Assessment of Trace Metal Contamination in Mangrove Ecosystems: A Case from Zhangjiangkou Mangrove National Nature Reserve, China.

Jun Wang,Huihong Du,Kai Chen,Wenqing Wang,Mengyang Liu,Hengxiang Deng,Minggang Cai,Junhua Liang,Sha-Yen Cheng,Ye Xu,Tong He,Hongwei Ke

doi:10.1155/2016/2167053

Abstract

Zhangjiangkou Mangrove National Nature Reserve is a subtropical wetland ecosystem in southeast coast of China, which is of dense population and rapid development. The concentrations, sources, and pollution assessment of trace metals (Cu, Cd, Pb, Cr, Zn, As, and Hg) in surface sediment from 29 sites and the biota specimen were investigated for better ecological risk assessment and environmental management. The ranges of trace metals in mg/kg sediment were as follows: Cu (10.79–26.66), Cd (0.03–0.19), Pb (36.71–59.86), Cr (9.67–134.51), Zn (119.69–157.84), As (15.65–31.60), and Hg (0.00–0.08). The sequences of the bioaccumulation of studied metals are Zn > Cu > As > Cr > Pb > Cd > Hg with few exceptions. Cluster analysis and principal component analysis revealed that the trace metals in the studied area mainly derived from anthropogenic activities, such as industrial effluents, agricultural waste, and domestic sewage. Pollution load index and geoaccumulation index were calculated for trace metals in surface sediments, which indicated unpolluted status in general except Pb, Cr, and As.

Highlights

Differing from the land ecosystem and marine ecosystem in the structure and function, the mangrove wetland, periodically suffering seawater immersion, locates in the dynamic ocean and land interface of tropics and subtropics and plays an extremely important role in the global ecological balance [1, 2]
Since many mangrove ecosystems are close to urban development which is tied to industrialization and human activities, the important intertidal zone is subjected to contamination from a variety of human activities [3,4,5], because it is always located near the coast where the wind is weak and the water movement is slow and the pollutants can directly settle in the sediments [6]
Higher concentrations of trace metals are generally found in the fine-grained sediments in the western coastal region of Zhangjiang River Estuary

Summary

Introduction

Differing from the land ecosystem and marine ecosystem in the structure and function, the mangrove wetland, periodically suffering seawater immersion, locates in the dynamic ocean and land interface of tropics and subtropics and plays an extremely important role in the global ecological balance [1, 2]. Since many mangrove ecosystems are close to urban development which is tied to industrialization and human activities, the important intertidal zone is subjected to contamination from a variety of human activities [3,4,5], because it is always located near the coast where the wind is weak and the water movement is slow and the pollutants can directly settle in the sediments [6]. Inherent physical and chemical properties of mangrove sediments confer an extraordinary capacity to accumulate materials or pollutants discharged to the nearshore marine environment [7, 8]. Trace metals with low solubility in water are adsorbed and accumulated in sediments [10].

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Conclusion