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Quaternary Res:谭亮成等石笋微量元素研究中获进展

  1. 石笋
  2. 微量元素
  3. 进展

来源:地球环境研究所 2014-03-31 22:24

洞穴石笋以其沉积连续、分辨率高、测年精确等优点,在第四纪气候-环境研究中受到广泛关注。然而,以往研究大多集中于石笋的碳、氧同位素上,对微量元素,尤其是稀土元素(REE)和重金属元素的关注不够。

洞穴石笋以其沉积连续、分辨率高、测年精确等优点,在第四纪气候-环境研究中受到广泛关注。然而,以往研究大多集中于石笋的碳、氧同位素上,对微量元素,尤其是稀土元素(REE)和重金属元素的关注不够。

中国科学院地球环境研究所副研究员谭亮成及其合作者对采自秦岭南坡的一支年纹层石笋近百年的Sr/Ca、Ba/Ca、REE/Ca,Zn/Ca和Pb/Ca的变化进行了详细分析和讨论。结果显示最近95年(1914-2008)石笋Sr/Ca、Ba/Ca和生长速率显著相关,主要受控于温度控制下的生长速率变化。石笋的稀土元素(REE)在年到年代际尺度上的变化也主要受控于外界温度。高温能增加洞穴上覆植被盖度、土壤中微生物的活动以及有机质的分解,导致更高的土壤CO2分压以及有机酸浓度等,因此增加土壤和基岩中REE的活动性,造成石笋中REE的增加。另外,高温还能提高土壤中与有机质相关的Zn的活动性,造成石笋中Zn含量的增加。相比其他微量元素,石笋中的Pb含量从1985年以来有非常异常的显著增加趋势,和当地铅矿的开采历史吻合,指示过去30年采矿活动对当地环境的污染。这揭示有精确测年优势的洞穴石笋在示踪历史时期环境污染中的潜力。

该项研究成果发表于地学期刊Quaternary Research上,并获选为当期封面文章(Tan L., et al. Trace element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in Central China. Quaternary Research, 2014, 81: 181-188)。  (生物谷Bioon.com)

生物谷推荐的英文摘要:

Quaternary Research   doi:10.1016/j.yqres.2013.12.001

Trace-element variations in an annually layered stalagmite as recorders of climatic changes and anthropogenic pollution in Central China

Liangcheng Tana, , , , Chuan-Chou Shenb, Yanjun Caia, Li Lob, Hai Chengc, Zhisheng Ana

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 95 year 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 30 years.

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