Occurrence Chalacteristics Of Polycyclic Aromatic Hydrocarbons In Typical Volcanic Lake Sediments

In this study,by analyzing the content and component chalacteristics of PAHs in the columnar Sedimentary column coreary cores of typical volcanic lakes such as Lake Tianchi of,Alshan Wusulangzi,Luming and Chala lakes,the sources and relative contribution rates of PAHs were qualitatively and quantitatively studied by using correlation analysis,ring ratio,chalacteristic ratio and positive definite matrix factorization model（PMF）.At the same time,the potential ecological risks of PAHs pollution in the Sedimentary column coreary cores of Lake Tianchi,Lake Wusulangzi,Lake Luming and Lake Chala were evaluated for ecological environment and human health.Combined with atmospheric backward trajectory model of climate model,PAHs input trajectory and potential pollution source area of typical volcanic lakes and lakes under the influence of different air masses were analyzed.The main research conclusions are as follows:（1）The comparative analysis of PAHs content in the Sedimentary column cores of typical volcanic lakes showed that the content of Pa Hs in Lake Chala（99.26-2006.33 ng.g-1,with an average value of 290.72 ng.g-1）was higher than that in Lake Tianchi of Arshan（36.86～313.86 ng.g-1,The mean value was 157.84 ng.g-1）>Wusu Langzi Lake（28.82～324.19 ng.g-1）>Lake Luming（41.33～215.32 ng.g-1）>the mean value was 77.41 ng.g-1.The content of PAHs in the Sedimentary column cores of typical volcanic lakes such as Lake Tianchi of Arshan,Wusu Langzi and Lake Lumings is significantly lower than that of Taihu Lake and Chaohu Lake in the economically developed areas of eastern China.Among the PAHs components,the low cyclic compounds were the dominant components in the Sedimentary column cores of the four lakes,which showed that the Lake Chala was significantly higher than the Lake Tianchi of Arshan,Lake Luming and Lake Wusulangzi.The high cyclic compounds in Lake Chala and Lake Usulangzi are higher than those in the other two lakes.The ecological risk assessment showed that Lake Luming had the highest RQ_sumvalue compared with the other three lakes,followed by Lake Chala,Lake Tianchi of Arshan and Lake Wusulangzi.Therefore,Lake Luming had the highest risk of medium PAHs to the ecosystem,which was mainly related to the high content of high-cyclic compounds.The exposure of local residents of the four lakes to nine PAHs contaminants in lake Sedimentary column cores（Nap,Acy,Ace,Flu,Phe,Ant,Fla,Pyr and Ba P）through skin contact does not present a significant non-carcinogenic risk.All eight PAHs（Ba A,Chr,Bk F,ba P,Dah A,Bghi P,In P）pose certain health risks.（2）The total organic matter content is ranked as Lake Wusulangzi>Lake Tianchi of Arshan>Lake Luming>Lake Chala.The total organic matter content is mainly related to aquaculture activities and decomposition rate of organic matter.For example,Lake Wusulangzi is one of the famous cold-water fish producing areas in Arshan City,and a large amount of bait is also one of the reasons for its high organic matter content.However,the decomposition rate of organic matter formed by deep water plant residues in Lake Tianchi of Arshan and Lake Luming was slow,resulting in high TOC content in the lakes.There is no obvious positive correlation between PAHs and TOC and their components in the Sedimentary column coreary cores of typical volcanic lakes such as Lake Tianchi of Arshan Chala and Lake Luming,while there is relatively obvious positive correlation between total PAHs and TOC,NHC and BC in Lake Wusulangzi.（3）Quantitative analysis of PAHs in typical volcanic lake Sedimentary column cores by PMF showed that coal burning source accounted for 55.8%,oil leakage/biomass burning source accounted for 31.5%,and traffic emission source of fossil fuel mixed combustion accounted for 12.7%.The fossil fuel mix in Lake Chala’s Sedimentary column cores accounts for the majority,with oil spills/biomass sources accounting for 44.4%and coal burning only 9%;Both Lake Wusulangzi and Lake Luming take oil leakage/biomass burning as the main source,and the proportion of coal burning source in Lake Wusulangzi（28.4%）is larger than that in Lake Luming（10.1%）.（4）Lake Tianchi of Arshan,Wusu Langzi Lake and Lake Luming are distributed in high latitude and high altitude areas,which is consistent with the condition of condensation settlement after PAHs transmission in the atmosphere.Therefore,combined with the backward track-cluster analysis results,the chalacteristics of typical volcanic Lake Tianchi of Arshan and the Sedimentary column cores of Lake Luming and Usu Langzi Lake are on the input track of PAHs.A local air mass with a long transmission distance appeared,and its input direction was in the eastern region.The specific input track was as follows:it started from the Greater Khingan Mountains to the west,passed Hulunbuir City on the Inner Mongolia Plateau and arrived at the Lake District of Arshan City.