Pollution History And Source Analysis Of Polycyclic Aromatic Hydrocarbons In Sediments Of Hulun Lake And Chagan Lake

Polycyclic aromatic hydrocarbons(PAHs),as a class of toxic and carcinogenic persistent organic pollutants,can be released by human combustion sources and transported to remote areas by the atmosphere over long distances.Lake sediments are high resolution records of pollutants in the environment and play a unique role in the inversion of past human activities and climate change.Compared with other regions,there are few historical studies on PAHs pollution in northern lakes,but its pollution status cannot be ignored.PAHs has a "global fractionation effect" and is prone to sedimentation and enrichment in high latitudes through evaporation-condensation.Under the influence of increasingly intensified human activities,it is particularly important to clarify the PAHs pollution history,pollution sources and human activities in the surface environment of northern China.Hulun Lake and Chagan Lake are typical lakes in northeast China and important aquaculture areas.After reform and opening up,economy in the two lakes developed quickly,then some environmental issues,to more deeply understand the evolution law of environmental pollution,two area to explore the human impact on the environment of energy utilization,and pollution mechanism of two regions,Hulun Lake and Chagan Lake sedimentary cores as the research object,analyzing 16 US EPA optimal control of lake sediment core content of PAHs,supplemented by the establishment of the 210 Pb dating,sediment grain size,heavy metal content,analysis of two of PAHs pollution in lake sediments columnar core history,pollution sources,and risk assessment.The main research results are as follows:(1)Dating and deposition rate results of the two lakes show that the core deposition years of Hulun Lake and Chagan Lake are 1865~2016 and 1877~2017,respectively,and the deposition history is 151 years and 140 years,respectively.The deposition rate of Hulun Lake is lower than that of Chagan Lake.Hulun Lake experienced a process from slow to fast,while Chagan Lake experienced a process from slow to fast to slow.(2)16 PAHs were detected in the sediment cores of the two lakes.The total PAHs content in Hulun Lake was 282.9~1056.9 ng/g,with an average of 596.5 ng/g.The total PAHs content in Chagan Lake was 305.9~1214.4 ng/g,with an average of 586.5 ng/g.The content of PAHs in 8 carcinogenic and teratogenic substances was 14.73~180.29 ng/g,with an average of 71.25 ng/g,9.83~268.10 ng/g,with an average of 110.29 ng/g.In terms of the overall content of PAHs in sediments,there was no significant difference in the total amount of PAHs between Hulun Lake and Chagan Lake,but the PAHs of each ring showed a significant difference between the two lakes(P<0.05).Three ring compounds were dominant PAHs components in the two lakes,and the distribution trend of other ring compounds was 4 ring > 2 ring > 5 ring > 6 ring.(3)The results of vertical distribution of PAHs content in Hulun Lake and Chagan Lake show obvious periodical characteristics.Before the 1970 s in Hulun Lake and the 1960 s in Chagan Lake,PAHs content remained at a low value and showed an insignificant increase trend.PAHs content in Hulun Lake increased significantly from the 1970 s and Chagan Lake from the 1960 s to the early 21 st century.After 2000,PAHs content in the two lakes decreased,and the degree of PAHs pollution was alleviated.(4)The main sources of PAHs were identified by isomer ratio method,and the results showed that the main sources of PAHs in Hulun Lake and Chagan Lake area were the combustion of vegetation coal,oil leakage and the combustion of petroleum products.In the sedimentary stage I and II of the two lakes,the combustion of vegetation and lignin occupied the main source,but the proportion decreased with the increase of age,and the proportion of petroleum product combustion source increased.In sedimentary stage III,the combustion source of vegetation coal in Hulun Lake was still dominant,while the combustion source of petroleum products in Chagan Lake was dominant.(5)Heavy metals and PAHs correlation analysis results show that Hulun Lake BbF,BkF,DahA,IcdP,BghiP and heavy metal Cr,Mn,Co,Cu and zinc,As,Cd,Pb has significant positive correlation(P < 0.05),while the Chagan Lake BbF,BkF,BaP,DahA,IcdP,BghiP with heavy metals As,Cd,Pb has a significant positive correlation(P < 0.01),to explain the source of the PAHs in the sediments with car exhaust.(6)The grain size of Hulun Lake is fine as a whole,and the grain size of Chagan Lake is coarse as a whole.PAHs components related to the particle size analysis results show that Hulun Lake three ring and six ring PAHs and instructs the atmospheric transmission source C3 sensitive components(34.67~56.74 μm)grade is significantly related to the Chagan Lake 2~6 ring PAHs component and indicates the C3 sensitive atmospheric transmission source component(15.14~34.67 μm)grade is significantly related to the speculation lake.According to lake PAHs from atmospheric source of longdistance migration,while the Chagan Lake PAHs mainly comes from the local atmospheric input source.(7)The ecological risk and health risk were evaluated by using the low value of effect interval(ERL)/median value of effect interval(ERM)and the toxic equivalent of 8 carcinogenic teratogenic PAHs.The results showed that both Chagan Lake and Hulun Lake were at potential ecological risk.Health risk assessment showed that the carcinogenic teratogenic effect of Hulun Lake was lower than that of Chagan Lake.