Source Apportionment Of Organic Contaminants Of Shoal-lake System From Songnen Plain And Comparative Research

In recent years,the exploitation of Daqing Oilfield,sewage discharge and aquaculture,have polluted partial lakes and shoals on Songnen Plain by organic pollutants. Finding out the sources of pollutants in shoal-lake system from Songnen Plain is essential to the accurate evaluation of environment quality and effective control of environment pollution.In that case,n-alkanes,isoprenoids,unresolved complex mixture(UCM),terpenoids and long-chain alkylbenzenes were determined and analysed in 15 samples by GC-MS, sampled from 13 lake shoals on Songnen Plain.Using analytical method of above mentioned composition and distribution characteristics,the sources and contamination levels of these compounds can be revealed.Furthermore,via comparing the characteristics of organic matters accumulated in lakes to shoals and discussing the trend of environmental change,following statements were made:1.The characteristics of n-alkanes,including C_max,odd-even carbon predominance and maturity,show that the primary source for n-alkanes was oil and its derivatives in shoals of Sanyong,Unnamed(HLJA-3) and Xiangyang,while,that was the degraded derivatives of algae in Unnamed(HLJA-10) shoal and the degraded products of plants in other shoals.Meanwhile,the characteristics of Paq,indicate that the primary source for the high molecular weight n-alkanes was mainly derived from reed in shoals of Bali, Sanyong,Longhu,Yamendage,Halahong and Keqin,and from submerged/floatin macrophytes in other shoals.2.Except Shiyu shoal,UCM bulge is obvious in other shoals.Features of UCM attribute to algae's and microbial biodegradation in shoals of Sanyong and Unnamed (HLJA-10),to weight oil such as lubricating oil in Bali shoal,and to crude oil in shoals of Yamendage,Halahongpao and Keqin.3.Including Ts/(Ts+Tm)values 0.45～0.51,gamma-n-wax/C₃₀ hopane averages 0.26 and C₃₁22S/(22S+22R) is 0.52～0.55 in shoals of Bali,Xiangyang,Halahong and Keqin,as well as,C₂₉ββ/(aa+ββ) values 0.46～0.50 and aaaC₂₉ 20S/(20R+20S) is 0.41～0.50 in shoals of Bali,Xiangyang,Halahong,Xi and Keqin,the composition and distribution characteristics of terpanes and steranes are similar with those of Daqing crude oil,which reflects the pollutants were derived from oil or its derivatives.4.Containing Cholestan-3-one in Bali shoal and Cholesta-4,6-dien-3-one in Unnamed(HLJA-3) shoal,may be contaminated by sewage.While,Stigmast-8(14)-en-3-ol found out in Keqin shoal was derived from herbivore's faeces.5.Founding out C₁₆,C₁₇,C₁₈ long-straight-chain alkylbenzene and C₁₇,C₁₈,C₁₉,C₂₀ long-isomerous-chain alkylbenzene with equal abundance in Keqin shoal,inflected those were derived from the detergent of sewage and oil or its derivatives.Overall,All shoals were polluted by oil or its derivatives except shoals of Longhu, Lianhuan,Unnamed(HLJA-10) and Shiyu.Among them,the oil pollution in Sanyong shoal and Unnamed(HLJA-3) shoal,which lie in the City of Daqing,is more obvious associated with the distribution of oil wells all around.Moreover,the shoals of Bali, Unnamed(HLJA-3),Xi,Unnamed(HLJA-12) and Keqin were polluted by sewage,and shoals of Xiangyang,Halahong,Unnamed(HLJA-12) and Keqin were contaminated because of aquaculture.In addition,the Pr/Ph values of all shoals less than 1,denoting phytane in a dominant position,meanwhile low-carbon alkane with even carbon predominance in the shoals of Sanyong,Lianhuan,Unnamed(HLJA-10),show a super-salt environment,which is in accordance to the salinization of Songnen Plain.Farthermore,the characteristics of organic matter in shoals and lakes are different. Source from terrestrial plants in shoals is greater than that in lake sediments,and phytane predominance in shoals is more clear than that in lake sediments,showing salinity of shoals is more serious than that of lake sediments.The Salinizating evolution of shoal-lake system will become the major environmental problems on Songnen Plain.