Environmental Characteristics Of Persistent Pollutants In Aquatic Environment Of Songhua River (Jilin Province)

Songhua River (Jilin Province) is the main water source of agricultural andindustrial production and the main artery of the economic development of JilinProvince, China. Emissions of pollutants along Songhua River were significantlyreduced and the water quality had some improvement afer the policy of recuperateand build up strength from China’s environmental protection department in2006. ButIndustrial structure was not reasonable and the extensive mode of economic growthwas backward along Songhua River.With the rise of the modern industrial, more andmore types and emissions of pollutants were discharged into Songhua River directlyor indirectly, which produced more and more serious water environmental problems.Persistent pollutants (including heavy metals, persistent organic pollutants, etc.) areresistant to degradation and have the characteristics of biomagnification andbiomagnification, which led to its pollution problems caused for concern. Theunderstanding of the content and spatial distribution of persistent pollutants and thepollution status quo evaluation, exploring the formation process and mechanism of thepollution of the main characteristics of pollutants and evaluation of the waterpersistent organic pollutants to the effects on aquatic organisms in Songhua Rive haveimportant significance to the pollution control and the formulation of the developmentplan of Songhua River.The whole studied area of Songhua River (Jilin Province) was dvided into threerepresentative regions: the source of the river, the upper reaches of the river, themiddle and lower reaches of the river, which were set50water samples and39surface sediment sampling sites and4core sediment sampling sites. Research ofpersistent pollutants in the water samples, surface sediments and core sediments of these areas was carried out from August2011to June2012. Heavy metals,hexachloro-cyclohexane (HCHs) and dichloro-diphenyl-trichloroethane (DDTs) aswell as16kinds of polycyclic aromatic hydrocarbons (PAHs) were analysed in thewater samples. Heavy metals, HCHs, DDTs and16PAHs were analysed in the surfacesediment samples. Analysis of heavy metals, HCHs and DDTs was in the coresediment samples. The contents of heavy metal and persistent organic pollutants weremeasured by atomic absorption spectrophotometry and gas chromatogramphy-massspectrometry respectively.The object of this study was the preindustrial sediment samples and thesediments and water samples of source water area that were less affected by human.The background values of heavy metals in the water samples and sediments wereinvestigated. The results showed that the mean background values of heavy metalsand in the aqueous phase were: Zn7.70μg/L, Pb1.60μg/L, Cu5.25μg/L, Fe1.03mg/L.The values were similar to the background of the major rivers and lakes ofthe Heilongjiang River. Compared with chemical properties of the source of SonghuaRiver, the research data was basically similar. The average background values ofheavy metals in the pre-industrial sediments: Cd1.72μg/g, Cu15.83μg/g, Pb23.26μg/g, Ni62.16μg/g, Zn63.25μg/g, Mn329.07μg/g, Fe0.63%. The contents ofCd, Ni were significantly higher compared with background values of heavy metals inthe sediments of other tributaries of Songhua River Basin.The analysis result of heavy metals showed that: the water quality of samplesfrom source of the river remained in a state of the natural background, basicallyunpolluted. The pollution of Pb, Cu, Cr were more serious in the upper reaches of theriver, and and only reached Grade Ⅴ standard.Pb pollution was the most serious inthe middle and lower reaches of the sub-region. The content anlysis of PAHs andOCPs showed that: the contents of PAHs were maintained at the state of naturalbackground in the the source of the river and the upper reaches of the river. Thepollution of OCPs in the region was more serious. The monitoring results of themiddle and lower reaches of the river were much higher than the source and upperreaches of the river. Detection rate of organochlorine pesticides in the region was very low, and β-HCH was the major isomer. The contents of DDTs were not detected. Themore serious point was Xinxing Forest Town from the spatial distribution of waterpollution in the region of the source of the river. The pollution of Piao River, MuqiRiver, Lishugou and Huifa River were more serious in the upper reaches of the river.The pollution of Xiushui River was the most serious in the middle and lower reachesof the river.The analysis of content of heavy metals in the surface sediments showed that thecontent of heavy metals in the surface sediments of the source of the river remained inthe state of the natural background. The contents of Cd and Pb were significantlymore than the natural background and the content of Ni was also higher. The contentsof heavy metals in the middle and lower reaches of the river were similar to the theupper reaches of the river. The pollution of Cd and Pb was also serious and theaverage contents increased. The analysis of content of PAHs in the surface sedimetsshowed that the rings of PAHs were mainly lower than4rings and the proportion of5～6rings increased in the middle and lower reaches of the river. The total content ofPAHs in the surface sediments of the the upper reaches of the river was similar to themiddle and lower reaches of the river but they were all higher than the averagecontent of PAHs of the source of the river. The sources of heavy metals and PAHs inthe sediments were evaluated quantitatively with application of factor analysis model.The results showed that the sources of heavy metals were the wastewater of lead-acidbatteries, metal smelting, automobile exhaust and coal-fired which was Pb as themajor pollutant and the industrial wastewater of electroplate, iron and steel, electricalmachinery and equipment manufacturing which was Cd as the major pollutant. Thesources of PAHs were mainly from traffic, coal combustion and life and industrialsewage discharge. Most of the sampling sites were influenced by two and two or moresources. Analysis of the content of OCPs showed that the HCHs average content inthe surface sediments of the upper and lower reaches of the river was lower than thecontent of the source of the river and the isomers of HCHs were mainly β-HCH. Thesouce of HCHs was mainly from historical emissions and there was no DDTspollution in recent years in the region. Analysis of vertical distribution of the persistent pollutants showed that distribution characteristics of Cu, Zn, Pb wereaffected by human factors mostly and the contents had a clear upward trend in thesurface sediments. The contents of organochlorine pesticides in the sediments werevery low with the peak values between12～18cm. It illustrated that a large number oforganochlorine pesticides were used in agricultural production in history. Theevaluation results of the content of heavy metals in the surface sediments showed thatthe contents of heavy metals were almost lower than the natural background valuesexcept Cd if making an assessment of soil quality standards. The evaluation resultswhich applied Index of Geoaccumulation and Multivariate Pollution Index showedthat most of the sampling points located in the minor contamination. There werefewer sampling points which were moderately polluted and severely polluted and theywere all concentrated in the middle and lower reaches of the river.The influencing factors of release, release kinetics as well as the different releaseof different texture sediments of persistant pollutants were studied in the sediments.The release law of heavy metals showed that the release rate of heavy metals from thesediments was accelerated with the increasing of stirring speed, humus concentrationand aeration. The release of heavy metals was inhibited with the rise of pH. Kineticstudies indicated that the release of heavy metals from sediments was basicallycompleted in about eight hours. The release quantities of heavy metals from differentsediments were affected by properties of sediments and heavy metal speciation. Therelease law of PAHs showed that the release rate of PAHs from the sediments wasaccelerated with the increasing of stirring speed and temperatures while other factorshad little effect. Kinetic studies indicated that PAHs in the sediments had been in arapid-release and the release time was0.5h. Kinetic studies showed the adsorption/desorption rate of fluoranthene and pyrene was much greater than the Philippines,acenaphthylene and fluoranthene, which illustrated that multi-ring PAHs whichentered the water were more easily into the sediment and difficult to release. Therelease rate of the five kinds of PAHs was fluorene> phenanthrene> acenaphthylene>pyrene> fluoranthene. The release rates of PAHs from different sediments were ininversely proportional to the amount of the sediment organic matters. The indicative characteristics of heavy metal pollution on the quality of theaquatic ecosystems were evaluated by SEM and the AVI relationship research. Theresults showed that ΣSEM/AVS of sampling sites were less than2and SEM-AVSwere less than0.5which indicated heavy metals in the sediments of Sencond SonghuaRiver basically did not produce toxic on benthic animals. The ecological risk indexmethod was applicated to evaluate the risk of heavy metals in the sediments to benthicanimals. The results showed that the ecological risk of heavy metals of most locationshad a minor level. Cd was overwhelmingly dominant from the contrast of potentialecological risk which was almost decisive basis in the evaluation of potentialecological risk in the current heavy metal pollution in the sediments. The exposure riskevaluation of PAHs in the sediments showed that the risk of exposure of PAHs werelower than10%except fluorene and acenaphthylene. The total contents of PAHs werelower than ERL, which suggested not obvious risk of exposure of PAHs in thesediments.Quantitative analysis of the risk to aquatic organisms of PAHs in the watershowed that PAHs in the water were no prominent influence on aquatic organismexcept sand fleas. Therefore, the risk of PAHs in the water to aquatic organisms wasvery low and the pollution was also slightly polluted on the whole.