Distribution And Sources Apportionment Of PAHs From Liaohe Estuarine Wetland Soils

16 polycyclic aromatic hydrocarbons (PAHs) were measured by GC-FID for 31surface soil samples collected from Liaohe estuary wetland in October 2008, May and August 2009. The distribution of PAHs in soil in the degraded and non-degraded from Liaohe estuarine wetland were investigated in this article. The positive matrix factorization (PMF) and Factor analysis-multiple linear regression analysis (FA–MLR) were used to quantitatively apportion sources of PAHs in surface soils on the basis of diagnostic ratio analysis conclusion. This work would play an important role in understanding the pollution levels and distribution of PAHs in soil and tracking the main PAHs sources in Liaohe estuarine wetland.The results showed that the total concentrations of PAHs in surface soil ranged from 293.4 to 1936.9 ngï¹'g^-1 with a mean of 851.5 ngï¹'g^-1, which is at above the average level of PAHs pollutions compared with relevant areas worldwide. The concentrations of NaP, Phe, Acy, Pyr, Fla, Ace and Fle in different stations were at higher levels, which accounted for more than 65% of the total PAHs contents, while the proportion of the high molecular weight was relatively low, accounting for 20.8%. In the un-degraded areas, the sequence of PAHs concentrations in different seasons was October 2008>May 2009>August 2009. The proportion of low molecular weight is higher than median and high molecular weight in three seasons. The contents of PAHs in the reed field were higher than beach, while the constitute of PAHs rings in two types were similar. There were no correlations between PAHs concentrations and pH, salinity and oil contents, whereas significant correlations were found between PAHs contents and organic matter and clay.In the degraded areas, the order of PAHs concentrations in different seasons is October 2008>May 2009>August 2009. The proportion of low molecular weight is higher than median and high molecular weight in three seasons. The contents of PAHs in the oil well reed field were higher than Suaeda heteroptera degraded area and reed degraded area. The proportions of PAHs were dominated by low molecular weight in three degraded areas, and the oil well reed field showed the feature of oil spill pollution. There were no correlations between PAHs concentrations and pH and salinity, whereas significant correlations were found between PAHs contents and organic matter, clay and oil contents.Diagnostic ratio analysis illustrated that pyrolysis was the main source of PAHs in October 2008, including oil combustion (gasoline combustion and diesel combustion), biomass burning and coal combustion; while the mixed pollution of pyrolysis and oil spill was the dominant PAHs source in May and August 2009, including oil pollution, oil combustion as well as biomass and coal combustion.Based on Spss 13.0 software, FA / MLR model was applied to identify the PAHs sources. The results showed that the major source in October 2008 was coal/vehicular emission, oil/traffic emission and coal combustion, with contributions of and 44.4%, 37.1% and 18.5%. While the mixture of vehicular exhaust and oil spill was the major source in May and August 2009 (accounted for 74.8% and 41.4% respectively).PMF model was also used to quantitatively analyze the main PAHs sources in Liaohe estuary wetlands. The result indicated that the main sources of PAHs were coal combustion, oil spill, traffic emission and coke oven in October 2008, with contributions of 47.6%, 17.9% and 20.0% and 14.5%, respectively. Oil/traffic emission, coal combustion, oil spill and coke oven, with contributions of 32.2%, 28.8%, 24.6% and 14.4%, respectively, were the main PAH sources in May 2009. In August 2009, oil spill with a contribution of 37.6% was dominant, followed by traffic emission, coke oven and coal combustion, with contributions of 32.7%, 13.8%, and 15.9%, respectively. There were some differences between the two models results, and PMF model's result was more suitable for the actual pollutions in Liaohe estuary wetlands. There were some differences between the two models results, and the PMF model's result was more suitable for the actual pollutions in Liaohe estuary wetlands.Comparing the two results from different models, we know that coal combustion, traffic emission, oil spill and coke oven were the sources of PAHs in soils from Liaohe estuarine wetland. The coal combustion and traffic emission dominated in October 2008, while the oil spill and traffic emission were the major PAHs sources in May and August 2009.