科研之友
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摘要
The distribution and fractionation of heavy metals in the sediment cores from five locations and their impacts on ecological health of Chilika lagoon were investigated. The heavy metals Cu, Zn, Pb, Cd, Co, Ni, Mn and Fe were determined in the cores. In general the average concentration of heavy metals in different cores are found in the following order Fe > Mn > Cu > Pb > Zn > Ni > Co > Cd. The cores (C1, C3 and C5) collected near the major fishing villages and jetties have higher metal concentration when compared with cores collected from relatively pristine regions. Correlations between the trace metals and Organic Carbon (OC), Total Nitrogen (TN), Total Phosphorus (TP) and silty clay fraction, suggests that these elements and grain size play a role in controlling the abundance of heavy metals in the sediments. Metals like Pb, Cu, Zn are positively correlated to OC, TN and TP and grain size. Significant enrichment for Pb (EF = 5-20) and moderately significant enrichments for Cu (EF = 2-5) is observed in almost all the cores. Co and Ni are moderately enriched in cores Cl and C2. Extremely severe enrichment for Cd (EF > 40) is observed in core Cl. Runoff from the agricultural fields, untreated sewage discharge and boat traffic are the major heavy metal sources. Roadway runoff, fuel discharge and atmospheric deposition are the dominant source of elevated Pb levels. The fractionation profiles of metals in different cores found them to be associated mostly with residual phase followed by Fe-Mn oxides and organic bound metals. Risk Assessment Code (RAC) reveals significant pollution by Mn in almost all the cores, whereas Pb, Cu and Zn are also present in bioavailable form to some extent in the sediments. In general, Fe-Mn oxides and organic bound metal fraction phases would contribute metals accumulation into the food-chain (i.e plant and fishery resources) consumed by the population create human health hazards.
- 出版日期2019-2-25
