Persistent Organic Pollutants And Heavy Metals In Surface Sediments And Marine Organisms From Coastal Areas

Zhejiang province is located in the southeast coastal areas of China, with the total coastline about 6,321 km in length. There are four bays, i.e. Hangzhou bay, Xiangshan harbour, Sanmen bay and Yueqing bay, and 3,016 islands in this area. The region also includes Zhoushan fishing ground, which is the largest one in China and an internationally important fishing ground that contains many actual and potential maricultural sites. In recent twenty years, with the rapid economic development of Changjiang Delta area, the coastal environment was increasingly influenced by pollutants from Changjiang River and Qiangtang River runoffs, and non-point land-based pollutants from Jiangsu, Zhejiang and Shanghai in addition to activities of marine aquaculture, fishing and shipping, etc. The status of environmental quality in the area is deteriorating in recent years. In this study, the levels, distribution features, impact factors and ecological risks of the persistent organic pollutants (POPs), i.e. polychlorinated biphenyls, polycyclic aromatic hydrocarbons and organochlorine pesticides, and heavy metals in surface sediments from Changjiang estuary, Hangzhou Bay and Zhoushan marine areas and marine animals from coastal areas of Zhejiang were analyzed and evaluated for the purpose of further understanding the situations of pollution level in this area. The results are listed as follows.An isotope dilution-high resolution gas chromatography/ion trap mass Spectrometry (HRGC/ITMS) method with purification-separation by gel permeation chromatography (GPC) and aluminosilicate column techniques was developed for quantification and identification of 20 organochlorine pesticides (OCPs), 28 PCB congeners and 16 PAH compounds in marine shellfishes. The GPC elution time for target chemicals and elution volumes of two continual eluting solvents from aluminosilicate column were optimized. The results showed that the method detection limits were 0.01～0.14 for PCBs, 0.02～0.17 for OC pesticides and 0.52～0.81 ng/g (wet weight) for PAHs. The recovery percentages and RSDs of two-level spiked samples were in the ranges of 84.1%～120.2% and 5.6～15.9% for PCBs, 62.3%～123.1% and 8.7～20.5% for PAHs, and 77.3%～127.5% and 3.1～18.7% for OC pesticides, respectively. In this method, three groups of organic compounds from shellfishes were simultaneously cleaned up and separated. The method reduced cost and time for sample pretreatment and was applied in analyzing POPs in marine organisms of the study.By using the established HRGC/ITMS method for analyzing multiresidual POPs in marine organisms, the levels of OC pesticides, PCBs and PAHs in shellfishes, fishes and shrimps collected from 12 counties (cities) from coastal areas of Zhejiang were analyzed and the results were summarized as follows.The predominating components of organochlorine (OC) pesticides in marine organisms were p,p'-DDE, p,p'-DDD, p,p'-DDT,γ-chlordan andα-chlordan. The ratios of DDT/(DDE+DDD) indicated that DDTs pesticides or input of new pesticides containing DDTs pesticides possibly existed in six areas such as Shengsi, Putuo, Ninghai, Yueqing, Jiaojiang and Yuhuan.In this study, PCB52,PCB66,PCB153,PCB138,PCB101,PCB180 and PCB118 were the predominating congeners in examined shellfishes, Bombay duck (Harpodon nehereus) and Exopalaemen carinicauda. The hexa-chlorinated PCB congeners in marine organisms were predominant followed by tetra, penta, tri and hepta chlorinated PCB congeners.The PAHs compounds in shellfishes were dominated by highly condensed ring structure while the two and three-ring PAHs in Bombay duck and Exopalaemen carinicauda were the predominating compounds..The levels of POPs in shellfishes were markedly higher than those in Bombay duck and Exopalaemen carinicauda indicating the stronger abilities of shellfishes in accumulating POPs. The distribution features of POPs in marine organisms from the study area showed that the levels of PCBs and PAHs in shellfishes from Yueqing were higher, while OC pesticides and PAHs in shellfishes from Shengsi and Putuo were in higher levels. The levels of OC pesticides and PAHs in Bombay duck from the study area were in similar levels except that PCBs in Bombay duck from Jiaojiang was in higher level. The levels of OC pesticides and PCBs in Exopalaemen carinicauda from Ninghai and Yuhuan were higher, while PAHs in the study area were in similar levels.The levels of DDTs in some samples of shellfishes, Bombay duck and Exopalaemen carinicauda had exceeded the tolerance levels of Europe, USEPA and marine organisms quality standards of China. Among them, the shellfishes had the highest ratios of exceeding tolerance. The results of cancer risks evaluation indicated that the EDI values of organic pollutants in marine organisms were lower than the corresponding values of RfD and CBC. Furthermore, the EDI values of DDTs and HCHs were much lower than the ADI values recommended by FAO/WHO. There are no cancer risks existed for the residents of Zhejiang province in consuming fishery products such as shellfishes, Bombay duck and Exopalaemen carinicauda.The results of organic pollutants in surface sediments from Changjiang estuary, Hangzhou Bay and Zhoushan marine area showed that the area with the higher values of organic pollutants was found in Nanhuizui area near the south branch of Changjiang estuary and north bank of Hangzhou Bay. The levels of organic pollutants in sediments from north branch of Changjiang estuary were significantly lower than those from south branch indicating that the organic pollutants were mainly from land based sources, especially from runoffs of Changjiang River.The predominant distribution patterns of PAHs in the surface sediments, grouped by number of rings, were the same in the study area. PAHs in sediments were dominated by 3- and 4-ring followed by 5-, 2- and 6-ring PAHs. The sources of PAHs were mainly from pyrogenic or combustion of wood and coal, the petroleum pollution was also one of sources of PAHs in sediments. PCBs in sediments were dominated by low chlorinated PCB congeners. The ratios of DDT/(DDE+DDD) indicated that no new input sources of DDTs pesticides existed in the study area.The results showed that organic carbon contents was a dominating factor controlling the levels of PAHs, PCBs and OC pesticides in sediments and the organic pollutants had the same characteristics of source, i.e. runoffs of Changjiang River.The levels of PAHs, PCBs and OC pesticides in most sediment samples were lower than the corresponding ER-L values of NOAA SQG, indicating that overall quality status of sediments was in good conditions. However, fluorene concentrations in some sampling sites near south branch of Changjiang estuary and mouth of Hangzhou Bay exceeded the ER-L value, while DDTs levels in sediments of over half sampling sites exceeded the ER-L value. The overall concentrations of organic pollutants in the study area were in lower or medium level compared with those from other areas. In the study area, the surface sediments analyzed by grain size were mainly composed of clayey silt and silt. The total levels of Cu, Cr, Fe and Ni in surface sediments were lower than the background contents, while Pb, Zn and Mn concentrations were higher than the background values in the middle of Hangzhou Bay and inner Yangtze River estuary. The distribution of total metal concentrations in the study area showed similar patterns, decreasing from the inner toward the mouth of Yangtze River estuary or Hangzhou Bay. However, elevated levels of heavy metals were observed in the middle of Hangzhou Bay. The total concentrations of heavy metals were lower than the Grade II of Marine Sediment Quality of China or ER-M and PEL values. Further correlation analyses confirmed that the levels of heavy metals and organic carbon were highly correlated with the clay component of the surface sediments, indicating that the variations of heavy metals and organic carbon concentrations were controlled by grain size of the terrigenous sediments. The high positive correlations among heavy metals showed that the surface sediments were from a similar terrigenous source or a result of similar mechanisms of transport and accumulation within the sediments. Sequential extraction analyses indicated that the heavy metals (Cr, Fe, Ni, Pb, Zn and Cu) were mainly retained in the residual fraction, suggesting lower pollution risks with respect to those metals, while Cd and Mn had the potential risks of environmental pollution.Cu, Pb, Zn, Cd, Hg and As in fishes, shellfishes, shrimps and cephalopods from coastal areas of Zhejiang were in lower levels compared with those from domestic and foreign countries. The levels of Zn and Cu in marine organisms were relatively higher, while those of Pb,Cd,As and Hg were in lower levels. The shellfishes had strongest abilities in accumulating heavy metals followed by cephalopods, shrimps and fishes. The results of evaluation indicated that the examined marine organisms were not heavily contaminated by heavy metals, while Cu and Cd in shellfishes, As and Zn in fishes and As in shrimps were in minor pollution level. Except that Cd in shellfishes and shrimps, and As in shrimps exceeded the tolerance levels of Australian standard, other heavy metals were inferior to the tolerance levels suggesting that the overall quality status of marine organisms in the study area was in good condition.