Heavy Metal Variation History Since 1600 Years Recorded In Sediments Of Sihailongwan Maar Lake

Human activities have great impacts on the ecological environment,causing regional and even global environmental pollution and ecological destruction.Among the pollutants caused by human activities,heavy metals have received widespread attention due to its strong toxicity and enrichment.After the Industrial Revolution,the atmospheric heavy metal content rapidly increased due to human activities,and then deposited in lakes,leading to heavy metal pollution of lake environments.Therefore,reconstructing high-resolution record of heavy metal pollution and exploring the causes of its changes can provide a reference for future atmospheric heavy metal pollution control.However,the imprecise dating and low resolution of heavy metal pollution records reconstructed by lake sediments generally affects the exploration of the causes of atmospheric heavy metal pollution.In this study,sediment cores from Sihailongwan Lake,a maar lake,were studied.210Pb-137Cs,AMS14C and varve counting methods were used to reconstruct an accurate chronological framework.After determining the provenance of clastic materials in sediments using element concentrations,high-resolution atmospheric heavy metal records over the past 1600 years were constructed,and the heavy metal pollution in the lake was evaluated.Then we compared the changes in Hg and Pb pollution in different regions,respectively,to study the differences of the pollutants in different regions and analyzed the related forcing mechanisms.The main conclusions of this study are as follows:(1)Comparison of principal elements and rare earth elements in the sediment of Sihailongwan Lake and other potential sources show that the debris materials in sediments of Sihailongwan Lake in the past 1600 years are mainly eolian deposition.Therefore,the heavy metals in the sediment are also from atmospheric deposition,and can be used to reconstruct the history of atmospheric heavy metal pollution.(2)As shown by the high-resolution Hg fluxes in the sediments of Sihailongwan Lake,the increase in atmospheric Hg content after 1850 AD was mainly influenced by the global increase in atmospheric Hg concentration due to the Industrial Revolution;the rapid increase in atmospheric Hg content from 1950 to 1961 AD was influenced by both northeastern China and global atmospheric Hg emissions;and the rapid increase in Hg content from 1980 to 1994 AD was mainly influenced by Asian regional Hg emissions.Element Hg started to cause contamination in Sihailongwan Lake since 1800 AD,and the contamination rapidly increased after 1980 AD and reached a higher level in 1986 AD.(3)There are differences in the history of other heavy metal elements changes in the sediments of Sihailongwan Lake.The enrichment factor and ground accumulation index show that Sihailongwan was polluted by Pb after 1928 AD,by Cd after 1952 AD,by Zn after 1992 AD,but unpolluted by Cr and Cu.The above differences may be related to the different types of industrial development in the region.In general,the heavy metal pollution in the sediments of Sihailongwan Lake is not serious.(4)Comparison of the historical changes of atmospheric Hg and Pb records show that both the initial rising time of atmospheric Hg and Pb and the history of changes in different records are mainly caused by the different processes of Hg and Pb emissions in different regions.The impact of regional events and the area influenced by the events should be well considered when study historical changes in atmospheric Hg and Pb contents in different regions.