| Polycyclic aromatic hydrocarbons (PAHs) are a group of ubiquitous persistent organic pollutants that are widely present in air, water, soil and sediment. Due to their high melting point, high logKow, low water solubility, less volatility, and high persistence, PAHs in water systems tend to accumulate in sediments, which will have a long-term impact on benthic organisms.PAHs can also be bio-accumulated through the food chain, and the exposure of humans to PAHs may enhance the risk of cancer and other adverse health effects.Bohai Sea (BS) and adjacent area (AA) are important parts of Chinese coastal waters, which are surrounded by economically developed areas in China. Bohai Sea (BS) is also one of the important parts of Chinese mariculture zone, with mariculture production of 6.01 million tons (mollusc production of 3.82 million tons) every year. Thus, BS plays a decisive role in the fishery products market of the nation, which directly affects the quality of aquatic products and subsequently health safety of consumers.However, studies on the sources and ecological risk of PAHs in BS and AA are quite limited.In addition, there were no studies have been reported previously about the carcinogenic risk (CR) of exposure to PAHs through mollusc ingestion pathways. Therefore, it is necessary to survey the ecological risk and health risk of PAHs in BS and AA.In this thesis, low molecular weight PAHs/high molecular weight PAHs (LMW/HMW),molecular diagnostic ratio and principal component analysis-multiple linear regression (PCA-MLR) were used to distinguish the sources of PAHs. The ecological risk of individual PAHs was evaluated using sediment quality guidelines(SQGs:effects range low (ERL)/effects range median (ERM) and threshold effect level (TEL)/probable effect level (PEL));and the combined ecological risk of PAHs was evaluated using organic carbon (OC)-normalized analysis and mean effects range-median quotient (M-ERM-Q) analysis. In addition, carcinogenic risk (CR) assessment, toxic and mutagenic equivalent (TEQ and MEQ) analysis were used to evaluate potential carcinogenicity, toxicity and mutagenicity of PAHs in sediments from BS and AA. Major conclusions were as following:Twelve PAHs were detected in all samples, excluding naphthalene (NaP), acenaphthylene (Acpy), acenaphthene (Acp) and benz(a)anthracene (BaP), which were not detected in some samples. The total concentrations of PAHs varied from 101.80 to 1211.81 ng.g-1,with a mean value of 388.85 ng.g-1.The PAHs levels in BS and AA were moderate compared to other areas in published researches. The correlation was poor between the concentrations of PAHs and the total organic carbon (TOC)(R=0.31, n=42, P=0.045), which may indicate a non-equilibrium adsorption of PAHs on TOC in BS and AA.The proportion of 4-6 ring-PAHs was quite high. The results of LMW/HMW analysis indicated that PAHs were mainly from pyrogenic sources.Molecular diagnostic indices showed that PAHs were mainly from petroleum sources, biomass, coal and petroleum combustion. Principal component analysis-multiple linear regression (PCA-MLR) suggested that coal combustion, traffic (petroleum combustion), coke production and petroleum sources could be the primary PAH contributors, accounting for 53.0%,32.6%,10.4% and 4.0% of the total concentrations, respectively.Analysis with SQGs (ERM/ERL and TEL/PEL) indicated that acenaphthylene, fluorene, phenanthrene, fluoranthene, pyrene and dibenzo(a,h)anthracene may occasionally cause adverse biological effects in some stations.The OC-normalized concentrations at all stations, except for station 35,were blow TEC values (threshold effect concentration) in both BS and AA, indicating that low adverse ecological effect waslikely to occur with the exception of station 35 where occasional risk may occur. The mean effects range-median quotient (M-ERM-Q) values at all stations in BS and AA were below 0.1,suggesting a relatively low probability of combined biological effects.In addition, the combined biological toxicity of multiple PAHs is lower than the toxicity of the individual PAHs in surface sediments of BS and AA.The CR values for children,teens and adults were 1.76×10-11-5.40×10-5, 3.83×10-12-1.81×10-5 and 7.77×10-12-1.06×10-4,with mean values of 4.12×10-6, 5.90×10-7 and 4.02×10-6, respectively. The 95th percentile CR values for children (1.13×10-5), teens(1.81×10-6) and adults (1.24×10-5) were at 10-6-10-4 range, suggesting potential cancer risks may occur. The CR values of seven carcinogenic PAHs (CPAHs) were at different levels;and the contribution of each CPAH to the total CR decreased in the following order:benzo(a)pyrene (BaP)> indeno(1,2,3-cd)pyrene (InP)>benzo(b)fluoranthene (BbF)>dibenz(a,h)anthracene (DBahA)>benzo(k)fluoranthene (BkF)>benz(a)anthracene (BaA)>chrysene (Chr). Sensitivity analysis suggested that exposure duration (ED), concentrations of BaPeq of CPAHs in sediment (CS), cancer slope factor (CSF), ingestion rate of mollusc (IR) and body weight (BW) were sensitive parameters and posed high influence on output risks. The TEQ and MEQ concentrations of carcinogenic PAHs were2.01-79.10 ng TEQ g-1 and 2.02-98.55 ng MEQ g-1,with a means of 19.22 ng TEQ g-1 and 23.21 ng MEQ g-1,respectively, and were much lower than that of other world wide sediments (804.94 ng TEQ g-1 and 895.09 ng MEQ g-1),suggesting PAHs have low toxicity and mutagenicity in both BS and AS.In addition, the contribution of each carcinogenic PAH to (and the average values of relative contents of) the total TEQ in BS and AS varied according to the following order:BaP (33.73%),InP (23.78%), BbK (15.23%), BghiP (11.88%), DBahA (7.10%),BkF (4.06%), BaA (3.33%)and Chr (0.88%). Moreover, contribution to the total MEQ of BS and AS of each carcinogenic PAH was as follows, in decreasing order:BaP (35.78%)>InP (23.93%)>BbF(15.07%)> BghiP(12.39%)> DBahA (5.20%)>BkF (3.81%)>BaA (3.14%)>Chr (0.81%).Polycyclic aromatic hydrocarbons(PAHs) are a group of ubiquitous persistent organic pollutants that are widely present in air, water, soil and sediments.Due to their high melting point, high logKow, low water solubility, less volatility, and high persistence, PAHs in water systems tend to accumulate in sediments, which will have a long-term impact on benthic organisms.PAHs can also be bio-accumulated through the food chain, and the exposure of humans to PAHs may enhance the risk of cancer and other adverse health effects.Bohai Sea (BS) and adjacent area(AA)are important parts of Chinese coastal waters, which are surrounded by economically developed areas in China. Bohai Sea (BS) is also one of the important parts of Chinese mariculture zone, with mariculture production of 6.01 million tons (mollusc production of 3.82 million tons) every year. Thus, BS plays a decisive role in the fishery products market of the nation, which directly affects the quality of aquatic products and subsequently health safety of consumers. However, studies on the sources and ecological risk of PAHs in BS and AA are quite limited.In addition, there were no studies have been reported previously about the carcinogenic risk (CR) of exposure to PAHs through mollusc ingestion pathways. Therefore,it is necessary to survey the ecological risk and health risk of PAHs in BS and AA.In this thesis, low molecular weight PAHs/high molecular weight PAHs (LMW/HMW), molecular diagnostic ratio and principal component analysis multiple linear regression(PCA-MLR)were used to distinguish the sources of PAHs. The ecological risk of individual PAHs was evaluated using sediment quality guidelines (SQGs:effects range low(ERL)/effects range median(ERM)and threshold effect level (TEL)/probable effect level(PEL));and the combined ecological risk of PAHs was evaluated using organic carbon (OC)-normalized analysis and mean effects range-median quotient (M-ERM-Q) analysis.In addition, carcinogenic risk (CR) assessment, toxic and mutagenic equivalent (TEQ and MEQ) analysis were used to evaluate potential carcinogenicity, toxicity and mutagenicity of PAHs in sediments from BS and AA. Major conclusions were as following:Twelve PAHs were detected in all samples, excluding naphthalene (NaP), acenaphthylene (Acpy), acenaphthene (Acp) and benz(a)anthracene (BaP), which were not detected in some samples.The total concentrations of PAHs varied from 101.80 to 1211.81 ng.g-1,with a mean value of 388.85 ng.g-1.The PAHs levels in BS and AA were moderate compared to other areas in published researches. The correlation was poor between the concentrations of PAHs and the total organic carbon (TOC)(R=0.31, n=42, P=0.045), which may indicate a non-equilibrium adsorption of PAHs on TOC in BS and AA.The proportion of 4-6 ring-PAHs was quite high. The results of LMW/HMW analysis indicated that PAHs were mainly from pyrogenic sources.Molecular diagnostic indices showed that PAHs were mainly from petroleum sources, biomass, coal and petroleum combustion.Principal component analysis-multiple linear regression (PCA-MLR) suggested that coal combustion, traffic (petroleum combustion), coke production and petroleum sources could be the primary PAH contributors, accounting for 53.0%,32.6%,10.4% and 4.0% of the total concentrations, respectively.Analysis with SQGs (ERM/ERL and TEL/PEL) indicated that acenaphthylene, fluorene, phenanthrene,fluoranthene, pyrene and dibenzo(a,h)anthracene may occasionally cause adverse biological effects in some stations. The OC-normalized concentrations at all stations, except for station 35,were blow TEC values (threshold effect concentration) in both BS and AA, indicating that low adverse ecological effect waslikely to occur with the exception of station 35 where occasional risk may occur. The mean effects range-median quotient (M-ERM-Q) values at all stations in BS and AA were below 0.1,suggesting a relatively low probability of combined biological effects.In addition, the combined biological toxicity of multiple PAHs is lower than the toxicity of the individual PAHs in surface sediments of BS and AA.The CR values for children,teens and adults were 1.76x10-11-5.40x10-5, 3.83x10-12-1.81x10-5 and 7.77x10-12-1.06x10-4 with mean values of 4.12x10-6, 5.90x10-7 and 4.02x10-6, respectively. The 95th percentile CR values for children (1.13x10-5), teens(1.81x10-6) and adults(1.24x10-5) were at 10-6-10-4 range, suggesting potential cancer risks may occur. The CR values of seven carcinogenic PAHs (CPAHs) were at different levels; and the contribution of each CPAH to the total CR decreased in the following order:benzo(a)pyrene (BaP)> indeno(1,2,3-cd)pyrene (InP)>benzo(b)fluoranthene (BbF)>dibenz(a,h)anthracene (DBahA)>benzo(k)fluoranthene (BkF)>benz(a)anthracene (BaA)>chrysene (Chr). Sensitivity analysis suggested that exposure duration (ED), concentrations of BaPeq of CPAHs in sediment (CS), cancer slope factor (CSF), ingestion rate of mollusc (IR) and body weight (BW) were sensitive parameters and posed high influence on output risks.The TEQ and MEQ concentrations of carcinogenic PAHs were2.01-79.10 ng TEQ g-1 and 2.02-98.55 ng MEQ g-1,with a means of 19.22 ng TEQ g-1 and 23.21 ng MEQ g-1,respectively, and were much lower than that of other world wide sediments (804.94 ng TEQ g-1 and 895.09 ng MEQ g-1),suggesting PAHs have low toxicity and mutagenicity in both BS and AA.In addition, the contribution of each carcinogenic PAH to (and the average values of relative contents of) the total TEQ in BS and AA varied according to the following order:BaP (33.73%),InP (23.78%), BbK(15.23%), BghiP(11.88%),DBahA (7.10%), BkF (4.06%), BaA (3.33%)and Chr (0.88%). Moreover, contribution to the total MEQ of BS and AA of each carcinogenic PAH was as follows, in decreasing order:BaP(35.78%)>InP (23.93%)>BbF(15.07%)> BghiP(12.39%)>DBahA (5.20%)>BkF (3.81%)>BaA (3.14%)>Chr(0.81%). |
PDF Full Text Request