Distribution, Sources And Ecological Risks Of PAHs In Sediment Of Minjiang River In Fuzhou

Minjiang River is the largest river in Fujian Province, and occupies an important ecological position in this area. The sediments of Minjiang River in Fuzhou city were studied in this paper. The distribution, sources and ecological risk levels of PAHs in the sediments were analyzed by geospatial interpolation combined with other analysis methods. Moreover, the partitioning behaviors and their influencing factors of PAHs in different particle sizes were analyzed too. The main results are as follows:(1) The concentration of total PAHs and PAH isomers obviously showed a downward trend from upstream to downstream in the sediments of Minjiang River in Fuzhou city. In the North Port reach, the concentrations of total PAHs and PAH isomers were suddenly increased, mainly due to the emission of the pollutant from Fuzhou city. The differences in spatial distributions of the concentrations of SOM and PAHs indicated that the most important influence factors for spatial distribution of PAH concentrations was not the SOM concentration but the distribution of contamination sources and the emission of pollutant. There were significant correlations between SOM concentration and the concentrations of total PAHs and most PAH isomors, which indicated that SOM concentration may influence PAH concentration in sediments to some extent.(2) The analysis results of the diagnostic ratios/geospatial interpolation showed that the PAHs originated from oil combustion had the widest spatial ditribution, and the PAHs originated from the combustion of grass, wood and coal were also distributed in the downstream reach. The results of the factor analysis/multiple linear regression showed that major source contributions of PAHs in sediments can be quantified as 31.7% from coal combustion; 25.2% from gasoline combustion; 28.7% from diesel combustion and 14.5% from petroleum leakage. The widest and largest contribution of PAHs originated from oil combustion to total PAHs indicated that oil combustion was the main source of PAHs in the sediments of Minjiang River in Fuzhou city. The PAH source types in the sediments of different reaches of Minjiang River in Fuzhou city were diverse, and so were the contribution of different source,types to total PAHs.(3) Several standards and methods for ecological risk assessment were used to evaluate the ecological risk level of the the PAHs in the sediments of Minjiang River in Fuzhou city. The results of the ERL/ERM and its average quotient showed that the ERL was exceeded by Flu in some regions of Baisha reach and North Port reach, which means there are certain ecological risks in these areas, while other isomers and total PAHs were lower than the ERL. The result of the TEL/PEL showed that the concentration of Nap, Ace, Flu, Phe, Flua and BaA were more than the TEL, which suggests possible ecological risk in these regions. The average quotient of TEL indicated that the PAH contamination in the sediments of Baisha reach and the North Port reach were more likely to have ecological risks. The result of organic carbon normalization showed that none of the PAH contamination in the sediment samples exceeded the TEC, which means there is no ecological risk when accessed using this method.(4) In the sediments of Minjiang River in Fuzhou city, the concentration of PAHs in sand was dominated by the emission of pollutants, but in other particle size fractions, it was mostly affected by organic matter contents. Organic matter concentration was the main impact factor for the spatial distribution of PAH concentration in sand, but in smaller particle size of coarse silt, fine silt and clay, the type of the organic matter was the main impact factor. The results of correlation analysis showed that the correlation between the distribution ratio of organic matter and that of PAHs in fine silt was significant, and in other particle size fractions, all the correlations were extremely significant. So the conclution is that the spatial distribution and the size distribution of PAHs in the sediments of Minjiang river in Fuzhou city mainly depend on the combined effect of size fraction content and the organic matter concentration.