A Study On The Occurrence Of Heavy Metals In Liaohe Estuary Wetland And Rongcheng Bay

Estuary wetlands and bays are two kinds of important and typical home of heavy metal pollutants when they are abandoned in the environment. The heavy metal pollution seriously threatened environment quality, ecosystemhealth and the seafood security. This article has two study geographic areas they are Liaohe estuary wetland and Rongcheng bay. The sampled time of Liaohe wetland were Oct.2008, Mar.2009 and from May 2009 to Sep.2009. The investigation of Rongcheng bay last from Feb. 2009 to Jan.2010. The heavy metal elements consist Cu, Pb, Zn, Cr, Cd, Hg and As.The concentration of various heavy metal elements in these two research area was measured, and the potential ecological risk index (RI) as the quantitative diagnostic tool, was used to evaluate the pollution degree of various heavy metals in the soils and sediments.The content of Cu, Pb, Zn, Cr, Cd and their speciation in the soils and sediments were determined by atomic absorption spectrophotometry (AAS) and graphite furnace atomic absorption spectrophotometry (GFAAS), the content of Hg, As and their speciation in the soils and sediments were determined by atomic fluorescence spectrometry (AFS), the concentration of Cu, Pb, Zn, Cr, Cd, Hg, As in the water samples were determined by inductively coupled plasma mass spectrometry (ICP-MS).The main conclusions can be summed up as follows.The assessment of potential ecological risk revealed that the potential ecological risk of these heavy metals to the Liaohe estuary wetland ecology system is very light or middling, with the order of light potential ecological risk level of all these heavy metals ranging as:Cd>Pb>Cu>Cr>Zn. The pollution of Cd is the most seriously in Liaohe estury wetland, so that the point of the heavy metal contamination countermeasure in urban soil of Liaohe estuary wetland is Cd. The concentrations of various heavy metal elements are first-class of water environment quality standards basically, meet the requirements of the State. There is unconspicuous difference in the spatial distribution of the various heavy metal elements concentrations of water samples which were sampled from Liaohe estuary wetland.,except Hg. But there is biggish difference temporal variations.There are two reasons for temporal variations, one point is because the spring release on the region, irrigation reed field, the other one is due to environmental changes in other factors such as seasonal temperature changes and etc.The assessment of potential ecological risk revealed that the potential ecological risk of these heavy metals to the Rongcheng bay ocean ecology system is very light or middling, with the order of light potential ecological risk level of all these heavy metals ranging as:Zn>Pb>Cu>Cr, the environmental quality of the bases being monitored is in good condition on the whole.