| Polycyclic aromatic hydrocarbons (PAHs), as one of the typical persistent organicpollutants, are widely distributed in the aquatic environment. Because of carcinogenicand mutagenic effects or (anti)-estrogenic activities, detection and contaminationprocess of PAHs in the ecological environment has become hot issues in the field ofenvironmental science and technology. At present, surface and underground water inmany parts of the world have varying degrees of pollution by PAHs. The behaviors ofPAHs in the environment: easy to migrate to organic phase from the aqueous phase,adsorb onto particulate matters, and final settlement into the sediments by gravity, arehighly depended on their sorption characteristics to suspended solid particles andsurface sediment, due to their n-octanol/water partition coefficient and strong lipidsolubility. The sediments are the important reservoirs of PAHs in the aquaticenvironment. This paper focused on typical surface sediments in Chongqing section ofthe Yangtze River and Jialing River. Sorption and partition properties of model PAH onsurface sediments with different grain sizes, as well as the effect of clay minerals（Kaolinite and Montmorillonite）on its sorption behaviors were conducted on the basisof the physical and chemical characteristics of surface sediments and PAHs backgroundconcentration therein. In the meantime, removal countermeasures on water purificationwere also discussed according to the existing water purification process and occurrenceconditions of PAHs in trace level. The main researches are as follows:①This paper adopted appropriate methods of Gas Chromatography-MassSpectrometry for detection of PAHs in surface sediment samples. The optimumextraction and cleanup procedures were examined using accelerated solvent extraction,automated gel permeation chromatography.②Based on the conclusion of the first stage study work, sorption mechanismswere studied through sorption/desorption experiments of fluoranthene (fluo) on typicalsediments collected from several sections of Chongqing downtown area in YangtzeRiver and Jialing River. In addition, this paper made an analysis of the relationshipbetween clay minerals, sediment grain size, crystal structure and the sorption capacityof surface sediments.③A prophase water environmental health risk assessment model showed that thehealth risk caused by drinking water means was still at an acceptable level, while more and more attention should be paid. Preliminary discussion about removalcountermeasures on water purification were conducted on the basis of traditional waterplants craft: coagulation–sedimentation–filtration–disinfection.The experimental results showed that certain correlation between the sorptionability and grain sizes of sediment were existed. The blend of clay minerals in sedimentsamples significantly enhanced their adsorption properties for fluo, which indicated aconsiderable portion of fluo were adsorbed onto inorganic mineral surfaces whiledistributing in organic phase. The adsorption effects of the inorganic minerals for fluocould not be neglected. To deal with PAHs compounds, the enhanced coagulation,advanced oxidation, physical adsorption, or the combinations, has become a stable andefficient way for water purification.Project supported by the National Natural Science Foundation of China andChongqing Municipal Commission of Construction. The study provide the theory basisfor the fate of PAHs in water/sediment system, as well as for the prevention of organic–inorganic compound pollution.Yangtze River and Jialing River are the main sources ofindustry, agriculture and domestic water in Chongqing area. As the "Water QualityStandard for Drinking Water" implemented, higher demand for PAHs concentrationstandard in the aquatic environment are required. Therefore, this paper has importantpractical significance on guarantee of drinking water and ecological environmentalsafety. |
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