The Relationship Between Climate Change And Atmospheric Deposit On Flux Of Mercury Recorded By Ombrotrophic Peat In The Tanghongling Of The Xiaoxinganling

The sedimentary records of ombrotrophic peat can provide valuable information on the environmental changes during the process of geological history. It is helpful to rebuild the ancient climate and environment by analyzing the records, whereby global change could be better understood. In this paper, field sampling and laboratory analysis were used to investigate the mercury (Hg) deposition history of Ombrotrophic peat in Tang hongling, northeast China. The Hg contents in peat profile and atmosphere were measured and previous data were collected to determine the response of Hg deposit in atmosphere to climate change in recent 5,600 years in northeast China. Moreover, the records of environmental change in the study area are compared with those of other areas within the same period .The results showed that:1.The total Hg concentrations in ombrotrophic peat from northeast China ranged from 150.24 to 4760.12 ng.g-1, with a mean of 540.12 ng.g-1. The maximum values of Hg concentrations were found at 59-cm depth below the surface and minimum ones at 111-cm depth. The deposit flux of atmospheric Hg ranged from 7.14 to 232.06μg.m-2.yr-1, with a mean of 25.73μg.m-2.yr-1。2. The deposit flux of atmospheric Hg in Ombrotrophic peat profiles was closely correlated with regional climate change. According the relationship, ancient climate change nearly 5,600 years was divided into three phases:Ⅰ.5600-2900 aB. P. , with a characteristic as warmer and wetter climate and higher Hg deposition flux, which is because that the warm climate of Holocene period is advantageous to the deposition of atmospheric Hg;Ⅱ.2850-350aB. P. , with a characteristic as wetter and drier climate fluctuations, and the lower deposit flux of atmospheric Hg, which is because that the climate transition from China Megathermal to the cold-wet condition is vital to the deposition of atmospheric Hg ;Ⅲ. 300 years so far,its climate is realatively drier and colder,which attributed to the metal smelting activity induced by modern industrial revolution in the region.3.Volcanic emission is a major natural source of Hg to the atmosphere. The volcanic activity had a short-term and an explosive impacts on atmospheric Hg. After a volcanic eruption, Hg contents in atmosphere could rapidly increase, but subsequently resulting in a long-term abnormal abrupt in stable climate conditions. The Ombrotrophic peat in northeast China records many large-scale volcanic eruption in geological history. Volcanic activity discharges Hg into the atmosphere for a long time, and the Hg could move thousands of kilometers and then participate in the global cycle. Therefore, the Hg is a cross-border global atmospheric pollutant.4. Before Industrial revolution, the Hg contents in the northeast Ombrotrophic peat averaged 552.09 ng·g-1 and the Hg deposit flux in atmosphere did 25.73μg·m-2·yr-1. After the revolution, Hg contents in the northeast Ombrotrophic peat and its deposit flux in atmosphere averaged 330.73 ng·g-1 and 15.43μg.m-2.yr-1, respectively. The changes showed the remarkable effects of human activities on the Hg contents in the ombrotrophic peat. The Hg deposit flux in the Northeast China became small after the Industrial Revolution, which didn't agree with the concerned overseas research. The inconsistence could mainly attribute to relative cold climate in modern times, few and small-scale geologic activities, and low level of industrialization in northeast China as compared to those in other countries.