Atmospheric Mercury Deposition History Recorded Over The Past 1200 Years From Lake Sediments Huguangyan Maar Lake Of Zhanjiang Region

Mercury can transmit through the atmosphere and other media for a long time,resulting in global environmental pollution.Maar lake,as a special crater lake,is not disturbed by the external water system because there is no input and output River,and the mercury in the sedimentary record is mainly derived from atmospheric sedimentation.Therefore,the study of mercury content in the sediments of Maar lake can well reveal the historical records of atmospheric mercury deposition.The history of atmospheric mercury deposition recorded in sediments of Huguangyan Maar lake in Zhanjiang area is studied in this paper.The effects of natural processes and human activities on atmospheric mercury content were discussed.Combined with AMS ¹⁴C and ¹³⁷Cs dating data,a time scale for core is established.On this basis,the mercury content recorded in core samples of Huguangyan Maar lake was determined and the atmospheric mercury deposition flux was calculated.The history of atmospheric mercury deposition in Zhanjiang area in the past 1200 was reconstructed.Comparison of mercury deposition records in other regions of the world,the mechanism of the change of mercury content and sedimentation flux at different stages was discussed,and the following conclusions were obtained:?1?Based on previous AMS¹⁴C and ¹³⁷Cs dating results,the time scale of core is established,and the core age is 766²005 AD.?2?Using water bath digestion-cold atomic fluorescence?AFS?for the 94cm core of lake sediments and lake sediments,the mercury content of 188 samples was tested and the atmospheric mercury deposition flux was calculated.The research results show that the mercury content in Huguangyan Lake Sediments ranges from 0.019 to0.15?g/g,with an average value of 0.049?g/g.The atmospheric mercury deposition flux ranges from 45.771 to 548.13?g.m^-2.yr^-1,with an average value of 135?g.m^-2.yr^-1.?3?The mercury deposition history in the study area was analyzed by using the variation of atmospheric mercury deposition flux and the dating scale in lake sediments.The atmospheric mercury deposition flux did not fluctuate substantially during the period of 800¹760AD,atmospheric mercury is mainly influenced by natural processes during this period.The atmospheric mercury deposition flux began to increase after 1760AD.The increase of atmospheric mercury deposition flux in this period may be due to the development of industrial revolution.It began to increase significantly at about 1970AD and reached the maximum at 1982AD,and then began to decline.The rapid increase of atmospheric mercury flux and the emergence of the maximum in 1982AD may be related to the rapid development of China's economy during this period.The decline of atmospheric mercury flux may be related to the environmental protection policies.?4?The variation curves of mercury deposition flux in Lake rock are compared globally,and the mechanism of mercury deposition flux variation is discussed.The ratio of atmospheric mercury deposition flux to modern mercury flux in the early stage of industrial revolution recorded in lake sediments M/P is calculated.It is consistent with the average level of Lake records in other parts of the world.It is further proved that Mercury is a global pollutant.