Distribution Characteristics And Source Apportionment Of PAHs And DOM In Jialing River Of Chongqing Section

Polycyclic aromatic hydrocarbons (PAHs) are typical persistent organic pollutantswidely exist in environment, which known for their teratogenic, carcinogenetic andmutagenic effects. The distribution and pollution trend of PAHs in the environment havebecome the focus research in recent years. Dissolved organic matter (DOM) can interactwith the pollutants in the water environment such as metal ions, chemical pesticides andPAHs, therefore affecting their distribution, degradation and toxicity to aquaticorganisms. So DOM has significant impact on the ecosystems and biochemicalprocesses of the water body. Jialing River of Chongqing section was taken as researchtarget to study the concentration, spatial and temporal distribution and sources analysisof PAHs and DOM in the water samples. This study can not only understand the waterenvironmental protection in Jialing River of Chongqing section, but also providesupport for the decision making of water environment protection policy in the ThreeGorges Reservoir.For the PAHs in the Jialing River of Chongqing section: samples of13months(from2007-07to2010-07) were collected from13sampling sites, including:169surface water samples,13suspended particles samples and169surface sedimentsamples. Solid phase extraction, column purification and gas chromatography-massspectrometry (GC-MS) were used to the determination the PAHs in surface watersamples; Soxhlet extraction, column purification and gas chromatography-massspectrometry (GC-MS) were used to the determination the PAHs in suspended particlesand sediment samples. Isotope ratio combing with principal componentanalysis-multiple linear regression were applied for source apportionment andecological risk evaluation of the PAHs in the Jialing River in Chongqing section, theresults showed that:①The ΣPAHs concentration in surface water ranged from245.46ng/L to1074.4ng/L; The predominant PAHs were2-4ring PAHs, the5-6ring PAHs had lowproportion of the total PAHs. The ΣPAHs concentration in suspended particles rangedfrom495.14ng/g to1274.38ng/g; the predominant PAHs were4-5ring PAHs, the6ring and2ring PAHs accounted for low proportion of the total PAHs. The ΣPAHsconcentration in sediments ranged from764.8ng/g to2353.5ng/g with the predominant4ring PAHs, other contribution rate were followed by3ring,5ring,2ring and6ring PAHs.②The PAHs concentration in the surface water and sediment showed similar rulein temporal distribution；PAHs concentration in the dry season was higher than thePAHs in the wet period; the spatial distribution of PAHs concentration in the surfacewater, suspended particles and sediment showed the same trend of” up-down-up-down”alone the river.③DOC and ΣPAHs concentration showed significant positive linear correlation (R=0.83) in the surface water in dry season and no linear correlation in wet season; TOCand ΣPAHs concentration showed significant positive linear correlation (R=0.86) inthe suspended particles in dry season; TOC and ΣPAHs concentration also showedsignificant positive linear correlation in the sediments both in dry and wet season, thecorrelation coefficient were Rdry=0.82, Rwet=0.90respectively.④The ecological risk of16PAHs in Jialing River of Chongqing section was atlow level and showed no great risk to biology in water body. From the exposure model,we knew that PAHs pollution may cause human health risk, but the degree of risk waswithin an acceptable range.⑤The ratios of specific PAHs (Ant/Ant+Phe, Flu/Flu+Pyr and BaA/BaA+Chr) and principal component analysis-multiple linear regression marked that gasolineand diesel engine combustion source is the main PAHs pollution sources of the JialingRiver in Chongqing section, other sources such as petroleum, coal and woodcombustion and external sources were also contributed to the PAHs pollution.For the DOM in the Jialing River of Chongqing section:169surface water samplesof13months (from2007-07to2010-07) were collected from13sampling sites.UV-visible absorption spectroscopy, fluorescence emission spectra andthree-dimensional fluorescence spectra combing with the parallel factor analysis wereused to characterize spectrum characteristics of DOM in the surface water sample ofJialing River in Chongqing section, results showed that:①The DOM fluorescence intensity in the surface sample showed the trend of“up-down-up-down-up-down” in spatial distribution, and the distribution fluorescenceintensity showed closely relationship with the industrial distribution along the JialingRiver and the outside organic matter input; The DOM fluorescence intensity in thesurface sample showed the trend of up-down in temporal distribution, and DOMconcentration in dry season was higher than that of the wet period.②The DOM in the Jialing River of Chongqing section showed predominantly terrestrial origin (including a mayor fulic-like component and humic-like component),protein from Endogenous metabolism contributed little to the water DOM.③Five separate fluorescent components in two categories were identified by thePARAFAC model, including three humic material components C1(250,320nm/400nm),C2(260,360nm/450nm) and C4(230nm/340,450nm)； and two protein-likecomponents C3(260nm/380nm) and C5(280nm/330nm).