Trace-element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in central China
Journal
Quaternary Research (United States)
Journal Volume
81
Journal Issue
2
Pages
181-188
Date Issued
2014
Author(s)
Abstract
We analyzed variations in the Sr/Ca, Ba/Ca, REE/Ca (REE: rare earth element), Zn/Ca, and Pb/Ca ratios preserved in an annually layered stalagmite, XL21, from central China. The stalagmite record spans the 95year period AD 1914-2008. The Sr/Ca and Ba/Ca ratios have a significant positive correlation with the stalagmite's growth rate, suggesting that they were primarily controlled by growth-rate variations. Variations in REE/Ca ratios are consistent with local temperature changes, suggesting temperature influenced REE concentrations in the stalagmite over decadal to annual timescales. Higher temperature in this humid area can increase vegetation cover, microbial activity, and organic decomposition in the soil, resulting in enhanced pCO2, organic matter concentration and reduced pH, and consequently increased REE mobilization from the overlying soil layer and host rock. Higher temperatures may also increase the natural Zn mobilization from the overlying soil mediated by organic matter and consequently may have led to increased Zn retention in XL21. An increasing trend is seen in the Pb/Ca ratios from XL21 since 1985, which is consistent with increased lead production in this area, and indicates an increase in mine-derived lead pollution in the local environment over the past 30years. © 2013 University of Washington.
Other Subjects
Biogeochemistry; Biological materials; Organic compounds; Pollution; Soils; Trace elements; Zinc; Annually layered stalagmite; Anthropogenic pollution; Central chinas; Environmental pollutions; Microbial activities; Organic decomposition; Positive correlations; REE geochemistry; Climate change; anthropogenic source; climate variation; geochemistry; geological record; paleoclimate; paleotemperature; pollution; rare earth element; stalagmite; timescale; trace element; trend analysis; China
Type
journal article