The Temporal And Spatial Characteristics Of Coral Skeleton Elements From Weizhou Island And Various Kinds Of Biological Factors Influence On Skeleton Elements Content

Coral reefs of Weizhou Island are located in the north rim of the South China Sea(SCS),and the special geographic location makes local coral reefs be easily influenced by climate change and human activities.Given that trace elements in coral skeleton can be applied to record environmental information and evolution history,we investigated the trace elements in coral skeleton situated in Weizhou Island,to establish the temporal and spatial characteristics of local environmental conditions.Firstly,compared with the concentrations of heavy metals in coral skeletons from other areas around the world,the concentrations of Cu,Pb,Cd,Cr from Weizhou Island were relatively lower and the concentrations of Zn were relatively higher.Cluster analysis results suggested that the concentrations of 5 heavy metals along the western coast of Weizhou Island were higher than those along the eastern coast,and the feasible sources were the local oil drilling platforms,shipping,wastewater discharged from the oil terminal treatment plant on the island.Secondly,the results showed that there were significant differences among coral species for Cu,whereas the rest 4 kinds of heavy metals had no difference among 3 species.According to the bioaccumulation factors of the 5 heavy metals in coral skeletons,heavy metals bioaccumulation effect was significant in corals,and obvious differences existed in the values of heavy metals among different coral species.For the bioaccumulation factors,the highest values of Cu,Zn,Cr,Cd were detected in Favia palauensis and Pb was detected in Pavona decussata,while the lowest values of Cu,Zn,Cr were detected in Pavona decussata and Pb,Cd were detected in Porites lutea.The highest concentrations of Cu,Pb,Zn,Cd,Cr,Mn,V were easily appeared in Faviidae and Agariciidae,and the lowest values were easily appeared in Poritidae,which may be related to the fact that the first two family corals have relatively large surface area and porosity.Thirdly,the coral skeleton V/Ca ratios in our syudy showed drastic fluctuations before each oilfield was put into production in local area,that was attributed to oil pollutants released from large amount of drilling mud and solids.Latterly,oil platforms production waste water and the ground crude oil containing oil pollutants led to smaller fluctuations of coral skeleton V/Ca ratios.Besides,obvious correlation results from pearson analysis and the similar concentration changing pattern of Fe,Mn,Cu,Cd,and Cr in coral skeleton with V during the oilfield development,indicating that the same sources resulted in marine environment pollution.This work concluded that using coral skeleton V/Ca to rebuilt and evaluate the influence of serious oil pollution in the coral reefs health of Weizhou Island was effective.