Seven millennia of Lead (Pb) and mercury (Hg) accumulation in a peat profile, Hani peat land, Jilin,

• 作 者: Atindra Sapkota Xinbin Feng Hong Bing Zhonggen Li
• 机 构: Institute of Geochemistry, Chinese Academy of Sciences, Guanshui Road 46, Guiyang, 550002 Guizhou, C
• 出 处: 第七届全国环境化学学术大会
• 发表日期: 2013年6期
• 关键词: peat lead mercury titanium

　　A peat core of 10 m length was collected from the Hani peatland,Jilin Province,northeast China (42° 43N,126° 31E) which is close to the Northern Peatlands region.The peat land consisted of scattered humps with a sphagnum composition,which is an indicator that the peat land is continuously evolving from mineratrophic (groundwater fed) to ombrotrophic nature (rain water fed).The average dry bulk density and the ash content were 0.1g/cm3 and 20% with both closely following trends in the profile.The 14C age dating of the top 550 cm showed that the peat accumulation for the last seven millennia with peat accumulation rate of approx.12 cm/yr.Taking Titanium (Ti) as an indicator of mineral input,the average concentration was about 0.2% with two peaks at ca.550 cm and 50 cm.The increment of Ti and density at ca.550 cm indicates the changes in either source area of the minerals or the changes in depositional flux or both.At ca.50 cm,the absence of Ti peak coinciding with the increment of density may reflect the changes in plant composition and thus the humification of the peat.For mercury (Hg) the average concentration was 150 ng/g,and showed few elevated peaks.Similarly,for Pb,the concentration remained fairly stable between 50 and 550 cm.Above 50 cm,the concentration increased by more than six times.Combining with the Ti profile,two things could be interpreted: 1) Pb is predominantly of atmospheric origin,and 2) above 50 cm,anthropogenic input may be responsible for increase in Pb.This is also supported by another lithogenic element such as Zr.However,for the precise timing of increment for the last ca.100 years,age dating other than 14C is required.