Search

Polycyclic aromatic hydrocarbons (PAHs) are typical toxic organic pollutants that can accumulate in sediments and may be toxic to aquatic organisms. In the present study, the contamination level, composition pattern, and sources of sixteen PAHs listed by the United States Environmental Protection Agency were investigated in surface sediments and a sediment core from Daihai Lake, which is located in a typical semiarid area of Inner Mongolia, China, and the ecological risk of these PAHs was assessed. The results show that the total concentration of PAHs in the surface sediments ranged from 204.6 to 344.5 ng/g with an average value of 287.2 ng/g and that compared with other aquatic systems, the level of PAHs in the sediments from Daihai Lake was low. However, a general upward trend was observed for the concentrations of PAHs in the sediment core, which might be related to the increase in human activities in the area. Moreover, the PAH concentrations were significantly positively correlated with the total organic carbon (TOC) content in the sediments, and it is thus inferred that TOC regulates the distribution of PAHs in Daihai Lake. Three-ring and four-ring PAHs were found to be predominant in all the sediment samples, and phenanthrene (Phe) was the most abundant compound. According to the composition of PAHs and the anthracene (Ant)/(Ant+Phe) or fluoranthene (Flt)/(Flt+pyrene (Pyr)) ratios, the PAHs in Daihai Lake mainly originated from the combustion of domestic coal, grass, and wood, and petroleum cannot be ignored as a source considering the growth of industry. Risk assessment based on a comparison of PAH concentrations and the effect range low (ERL) and effect range median (ERM) values demonstrated that acenaphthene (Ace) at 11 sites and fluorene (Flu) at 7 sites had occasional adverse biological effects. [ABSTRACT FROM AUTHOR]

The concentrations of PAHs in the surface waters from seven river basins in China were summarized from literature published from 2000-2010. Subsequently, the risks from individual PAHs and ΣPAHs in the surface waters of China were quantified by comparing the overlap between the probability distributions of exposure concentrations with the probability distributions of toxicity data. The results show that the concentrations of 15 PAHs in the surface waters ranged from 3.09 to 38139.00 ng L, with a geometric mean of 474.93 ng L. The significantly higher concentrations of the 15 PAHs occurred in the surface waters from northern China when compared with those from southern China. The concentrations of the 15 PAHs in Chinese surface waters were higher than those in other waters worldwide. The MOS (margin of safety) values were calculated at 90th percentile values of exposure concentrations and 10th percentile values of toxicity data, with 5.75, 0.17, 2.33, 0.30, 0.57, 1.74, 1.05, and 0.11 for Ace, Ant, Flu, BaP, Flua, Nap, Phe, and Pyr, respectively. The probabilities of the individual PAH concentrations exceeding the 10th percentile value of the toxicity data were 6.06%, 2.07%, 9.51%, and 2.07% for Nap, Ace, Phe, and Flu, respectively, suggesting minimal risk to aquatic organisms; however, the probabilities of BaP, Ant, Flua, and Pyr exceeding this value were 19.49%, 25.46%, 15.15%, and 30.50%, respectively, indicating potential risks. Among the individual PAHs, the ecological risk from Pyr was the highest, followed by, in descending order of risk, Ant, Bap, Flua, Phe, Nap, Flu, and Ace. Additionally, the combined ecological risk of ΣPAH8 in Chinese surface waters was significantly higher than any that of individual PAHs alone. The MOS values in the river basins were < 1, except for the Haihe River Basin, suggesting a potential combined risk from ΣPAH8 in the other six river basins. The probabilities calculation indicate that low to high ecological risk from ΣPAH8 for all aquatic species was reported in the Liaohe River Basin (65.58%), Huaihe River Basin (57.15%), Songhua River Basin (46.49%), Pearl River Basin (38.41%), Yangtze River Basin (25.98%), Yellow River Basin (15.92%), and Haihe River Basin (5.22%). [ABSTRACT FROM AUTHOR]