Long-term (16000yr) controls on mercury accumulation reconstructed using a peat record from Dajiuhu mire, central China
LI Yuan-ping1,2, MA Chun-mei2, ZHU Cheng2, HUNG Run1, ZHENG Chao-gui3
1. School of Environment and Tourism, West Anhui University, Lu'an 237012, China;
2. School of Geographic and Oceanographic Sciences, Nanjing University, Nanjing 210046, China;
3. School of Geography Information and Tourism, Chuzhou University, Chuzhou 239000, China
In the present study, a peat core sampled in Dajiuhu montane mire, Hubei province, extending back to 16,000yr BP was analyzed for Hg accumulation and main environmental processes involved in the control of Hg concentrations. Based on Ti, Al, Sc, Rb, Sr, Pb and Zn contents as well as humification and δ13C of the core, principal component analysis (PCA) and stepwise regression analysis revealed that main processes controlling Hg concentrations included the mineral input by precipitation and runoff (PC1), dust deposition (PC2), wet deposition (PC3) and peat decomposition (PC4). On the basis of the relative importance of each factor on Hg concentrations, the 16,000yr record of the Dajiuhu peat core could be divided into six main phases. During phaseⅠ(16.0~15.6cal kyr BP), reduced regional dustfall and peat decomposition resulted in decreased Hg concentrations. In PhaseⅡ(15.6~14.2cal kyr BP) ,significantly increased atmospheric wet deposition and fluxes of particulate and dissolved terrestrial organic matter from soils under enhanced terrestrial productivity after the last glacial period were probably responsible for higher Hg concentrations. In phase Ⅲ(14.2~11.3cal kyr BP), Hg concentrations were enhanced later during the Younger Dryas(12.3~11.3cal kyr BP) by increased regional dustfall and peat decomposition. During phase Ⅳ(11.3~4.3cal kyr BP), although significant volatility of the four factors, Hg concentrations were higher as a whole. Lower Hg concentration in phase Ⅴ(4.3~3.1cal kyr BP) were mainly resulted from apparent decrease in atmospheric wet and dry deposition. In phase Ⅵ(3.1cal kyr BP to present), the Hg concentration increased with decreasing depth, albeit with evident volatility. This phase was characterized by reduced input of mineral matter into the mire and gradual increase in regional dustfall, indicating precipitation reduction and progressively increasing influence of anthropogenic activities on Hg accumulation in the peat.
李远平, 马春梅, 朱诚, 黄润, 郑朝贵. 大九湖泥炭地距今16000年以来Hg沉积记录及影响因子[J]. 中国环境科学, 2017, 37(3): 1103-1110.
LI Yuan-ping, MA Chun-mei, ZHU Cheng, HUNG Run, ZHENG Chao-gui. Long-term (16000yr) controls on mercury accumulation reconstructed using a peat record from Dajiuhu mire, central China. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(3): 1103-1110.
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