Title: Spatial Pattern and Ecological Risk of Heavy Metals in Sediments from Maowei Sea,Southern China
Abstract: In Guangxi Province,the Maowei Sea plays an important role in the local aquaculture and oyster nursery through supporting the high productivity. However,the heavy metal pollution in the estuary has deteriorated over the past decades. There are few studies on the spatial pattern and potential ecological risk of heavy metals in the sediments from this estuary. In the present study,sediment samples( 0-30 cm) were collected in seven sites of Maowei Sea in January,2010. The physio-chemical characteristics( e. g.,pH,particle size) as well as the concentrations of heavy metals( i. e.,As,Cd,Cu,Fe,Hg,Mn,Ni,Pb,and Zn),organic matter,total nitrogen( TN) and total phosphorus( TP) were determined in the laboratory. Meanwhile,the potential ecological risk of heavy metals was estimated by using the Hakanson index. The results showed the significant differences in the spatial distribution of heavy metals and the higher concentrations of heavy metals in the inner estuary than the outer part. The pollution of Cd( 1. 1 mgkg in average) and Hg( 0. 3 mgkg in average) were the most serious among these heavy metals. Moreover,there was an increasing trend for Cd and Hg pollution over years. The pollution of Cd and Hg might be associated with the intensive use of phosphate fertilizers,the mining of phosphate ore and the combustion of fossil fuels nearby the estuary. The concentrations of heavy metals except for As,were significantly correlated with the concentrations of organic matter,Fe and total nitrogen,while Cd was highly correlated with TP. It suggested that both biological and chemical processes had significant effects on the geochemical cycling of these heavy metals. On the other hand,significantlypositive relationships were observed among Cu,Hg,Ni,Pb and Zn( P 0. 01),suggesting that they were homologous. Interestingly, significantly negative relationships between Cd and Zn,Pb,Ni,Cu were documented( P 0. 05),indicating that pollution sources and biogeochemistry of Cd were differed from the other metals. Finally,the potential ecological risks of metals in sediments of Maowei Sea decreased as the order: Cd Hg Pb Zn Cu As,and the potential ecological risks caused by Cd and Hg had reached up to the middle level. Moreover,the integrated ecological risks for the sites nearby the outlet of the Maoling River were relatively high,reaching up to the middle level,while those for other sites approached the middle level as well. Therefore,reducing pollution of Cd and Hg would have priority in local environmental management and improvement program.
Publication Year: 2014
Publication Date: 2014-01-01
Language: en
Type: article
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Cited By Count: 9
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