The Distribution Characteristics And Ecological Risk Accessment Of PAHs And PAEs In Surface Sediment Of The Songhua River

The Songhua River,as the third largest river in China,belongs to the major rivers and its water resources supply as the drinking water for many cities and irrigation source along the river.Polycyclic aromatic hydrocarbons and phthalic acid esters were two types of hydrophobic toxic organics,which were widely existed in the environment and commonly be found in sediments.Therefore,it is of great significance to study the pollution characteristics and ecological risk of PAHs and PAEs in the sediments of the Songhua River for the residents health and ecological environment protection.The whole basin and typical tributariy of the Songhua River as the research area and the 16kinds of PAHs and 6 kinds of PAEs priority pollutants of USEPA as the research objects,the PAHs and PAEs concentration distribution,composition characteristics and ecological risk of 43 sampling sites in surface sediments were extensively studied based on the established simultaneous detecting PAHs and PAEs method,i.e.accelerated solvent extraction-silica gel column and PSA small column series purification-GC-MS determination.In addition,the sources of PAHs in the Songhua River sediments were also analyzed by characteristic ratio method,characteristic ratio method and positive definite matrix factorization model.The PAHs and PAEs content in the sediments of Songhua River was also compared with other water bodies,and the PAHs and PAEs distribution common characteristics in surface sediments of water bodies were discussed and summarized.The research main conclusions were as follows:?1?The content of organic matter in the surface sediments of the Songhua River Basin was between 0.29%and 5.66%.The major particle sizes of the sediments in the Songhua River were concentrated in the fine sand and medium sand,showing a sandy bed,and the ability to adsorb organic pollutants was relatively weak.?2?Most PAHs in surface sediments of the Songhua River?67.44%?were at moderate or light pollution levels.Among them,the content of?₆PAHs in the second Songhua River was the highest.From the aspect of the proportion of PAHs in each ring,compared with the low-loop PAHs,the proportion of high-ring PAHs was higher?76.73%?.?3?The PAHs in the surface sediments of the Songhua Rive mainly originated from mixed sources of biomass combustion and traffic pollution?45.93%?,coal-fired and coking sources?27.98%?,and petroleum sources?26.09%?,which was in accordance with the energy structure and industrial layout of the research area.It was necessary to minimize the burning of biomass such as straw,promote clean production,strictly control the number of motor vehicles,advocate green travel,increase exhaust emission standards and promote clean energy.Reduce the input of PAHs in sediments from the source.?4?DEHP and DBP were the main components of PAEs in sediments in the study area,and which contents were exceed the control standards for soil PAEs in the United States.The total concentration of?₆PAEs was 819.44-24035.39 ng/g,and the?₆PAEs content of tributary exceeds mainstreams.?5?The ecological risk evaluation results of the PAHs in the surface sediments of the Songhua River showed that 9 sampling sites?20.9%?of the total 43 sites were subject to the frequent ecological risks.The ecological risk evaluation results of PAEs in the surface sediments of the Songhua River illustrated that 26%and 86%sampling sites of the DBP and DEHP exceeded the ERL respectively,and 40%and 93%sites of the DBP and DEHP exceeded the quality warning level promulgated by the Washington State of the United States,which might have a certain ecological risk for the Songhua River and should be pay attention.?6?The contents of PAHs and PAEs in the surface sediments of the Songhua River were higher than those of most of China's water bodies,and were generally at a high level.Both of them show similar distribution characteristics.The faster the urbanization and industrialization process and the denser the population,the higher the content of PAHs and PAEs.The significantly higher levels of PAHs and PAEs at individual sites were mainly affected by point source emissions.