The Pollution Status And Assessment Of Heavy Metals In The Coaster Water Of Sanya Bay And Its Coral Growing Region

With the rapid economic development of Sanya in recent years,the increase of tourism,port construction,transportation,processing industry and other human activities has brought unprecedented pressure on the ecological environment in the coastal waters of Sanya,where some sea area has been seriously polluted with the appearance of turbid water and blackened beaches.Among the many pollutants that has caused great pressure on the ecological environment of Sanya bay,heavy metals have attracted public attention day by day for their durability,high toxicity and refractory,and being apt to bioaccumulation and damage to the ecological balance.This article determined the heavy metals Zn,Cu,Pb,Cd,Cr)in seawater,sediments and coral skeletons of porites of Sanya bay and its coral growing region,analyzed the distribution of the content of heavy metals,assessed the contamination status of heavy metals,and discussed the enrichment of heavy metals by the coral skeletons of porites.The main conclusions are as follows:(1)The average contents of Zn,Cu,Pb,Cd and Cr in seawater of Sanya bay and its coral growing region were 8.59,0.98,1.75,0.05,0.32 μg/L,of which the contents of Zn,Cu,Cd,Cr met the Class I of Water Quality Standard,however,the contents of Pb were beyond the Class I of Water Quality Standard,and the contents of Zn,Cu and Cd had the roughly spatial distribution tendency of high in east and low in west,while the contents of Pb,Cr trended to increased first and then decrease from east to west.Zn,Cu,Pb,Cd were all significantly negatively correlated with pH,which may be related to the adsorption of these heavy metals by the particles.Zn,Cu,Pb and Cd were significantly negative correlated with salinity,probably because of the dilution caused by the river and sea mixing process,however,Cr showed significantly negative correlation with salinity,suggesting that the increase of salinity may promote the desorption function of particulate matters on Cr.Pb and Cd were significantly negatively correlated with dissolved oxygen,indicating that the increase of the contents of Pb and Cd may be related to the oxidative release of particulate matters.Overall,the comprehensive pollution level of heavy metals in the study area was basically pollution-free.Human activities have increased the contents of heavy metals in seawater of Sanya bay,but the level of the heavy metals in the seawater of the coral growing area had no significant effect on the growth of the corals for the moment.(2)The average contents of Zn,Cu,Pb,Cd and Cr in sediments of Sanya bay and its coral growing region were 55.8,8.7,22.2,0.05,20.2 μg/g,which met the Class I of Marine Sediment Quality Standard,and were at lower levels compared with other sea areas.The contents of Zn,Cu and Pb trended to increased first and then decrease from east to west overall,the contents of Cd showed the roughly spatial distribution tendency of high in east and low in west,while the contents of Cr had no obvious spatial distribution.All of sites in the study were contaminated with Pb.The level of the heavy metals in the sediments of the coral growing area showed no significant effect on the growth of the corals for the moment.(3)The average contents of Zn,Cu,Pb,Cd and Cr in coral skeletons of porites in the coral growing region of Sanya were 8.92,10.07,1.02,0.04,0.41μg/g,compared with other coral growth areas,the contents of Pb and Cd in this study were low.The heavy metals in coral skeletons of porites in all sampling sites of the coral growing region presented similar components distribution,where Zn and Cu made up the highest proportions,and Cd came to the lowest.The Cd element in the sediments of the coral growth area had the greatest bioavailability compared to other metals.In coral growing region,coral skeletons and sediments both had different options for the enrichment of heavy metals.In general,the enrichment capacity of the coral skeletons of porites to Zn,Pb and Cr was weaker than that of sediments,while the enrichment capacity of the coral skeletons of porites to Cu and Cd was stronger than that of sediments.(4)The heavy metal pollution in Sanya bay mainly divided into mariculture activities,marine fishing and excavation of activity,the discharge activities of the waste water,waste gas,oil contamination owed to the emissions of agriculture,living and ships,and coastal and offshore engineering activities.