Recent atmospheric lead deposition recorded in an ombrotrophic peat bog of Great Hinggan Mountains, Northeast China, from ~(210)Pb and ~(137)Cs dating

摘要

Radioactive markers are useful in dating lead deposition patterns from industrialization in peat archive. Peat cores were collected in an ombrotrophic peat bog in the Great Hinggan Mountains in Northeast China in September 2008 and dated using ~(210)Pb and ~(137)Cs radiometric techniques. The mosses in both cores were examined systematically for dry bulk density, water and ash content. Lead also was measured using atomic emission spectroscopy with inductively coupled plasma (ICP-AES). Both patterned peat profiles were preserved well without evident anthropogenic disturbance. Unsupported ~(210)Pb and ~(137)Cs decreased with the depth in both of the two sample cores. The ~(210)Pb chronologies were established using the constant rate of supply model (CRS) and are in good agreement with the ~(137)Cs time marker. Recent atmospheric ~(210)Pb flux in Great Hinggan Mountains peat bog was estimated to be 337 Bq m~(-2) y~(-1) which is consistent with published data for the region. Lead deposition rate in this region was also derived from these two peat cores and ranged from 24.6 to 55.8 mgm~(-2)y~(-1) with a range of Pb concentration of 14-262 μg g~(-1). The Pb deposition patterns were consistent with increasing industrialization over the last 135-170 y, with a peak of production and coal burning in the last 50 y in Northeast China. This work presents a first estimation of atmospheric Pb deposition rate in peatlands in China and suggests an increasing trend of environmental pollution due to anthropogenic contaminants in the atmosphere. More attention should be paid to current local pollution problems, and society should take actions to seek a balance between economic development and environmental protection.