Influence of catchment vegetation on mercury accumulation in lake sediments from a long-term perspective.
Influence of catchment vegetation on mercury accumulation in lake sediments from a long-term perspective.
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DOI：
10.1016/j.scitotenv.2015.08.133
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发表时间：
2015-12
期刊：
影响因子：
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通讯作者：
J. Rydberg;M. Rösch;Emanuel Heinz;H. Biester
中科院分区：
文献类型：
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作者：
J. Rydberg;M. Rösch;Emanuel Heinz;H. Biester
有机物(OM)循环对环境中汞(Hg)的循环影响很大。因此，重要的是要彻底了解集水区植被的变化--通过其对OM循环的影响--如何影响汞的行为。为了测试植被的变化是否对汞向湖泊的运输产生影响，我们调查了德国南部海伦威泽的沉积物记录。该湖具有明确的全新世植被历史：约8700年，欧洲栎树(Quercus robur，橡树)取代了欧洲栎树(Quercus Robur)，冷杉(Abies Alba)和山毛榉(Fagus Sylvatica)(山毛榉)取代了约5700年。我们特别感兴趣的是测试针叶植物是否比落叶植物导致更大的汞出口到水生系统。当用橡木代替榛子时，减少了土壤侵蚀，增加了从集水区向DOM结合的汞的运输，导致汞浓度和累积速率都增加了(61 ng/cm−1和5.5g/cm−/2yr.−1到118g/cm−1和8.5g/cm−/2−1)。然而，即使随着冷杉和山毛榉的引入，汞浓度也增加了(173 ng/cm−)，由于较高的Hg：C，由于OM的输入减少，汞的积累速率没有增加(7.6 ng/cm−和2年−1)。在大约2,500年BP，汞累积速率和汞浓度表明，向沉积物中额外输入了汞(316ng.cm1和10.3ng.cm−)，这可能是由于该地区人类活动的增加，例如森林燃烧或采矿。我们的结果与几项配对集水区研究的结果进行了对比，这些研究表明，针叶林比落叶林释放的汞更高，需要从长远的角度进行研究，以增加我们对缓慢和渐进过程对汞循环的影响的理解。
Organic matter (OM) cycling has a large impact on the cycling of mercury (Hg) in the environment. Hence, it is important to have a thorough understanding on how changes in, e.g., catchment vegetation – through its effect on OM cycling – affect the behavior of Hg. To test whether shifts in vegetation had an effect on Hg-transport to lakes we investigated a sediment record from Herrenwieser See (Southern Germany). This lake has a well-defined Holocene vegetation history: at ~ 8700 years BPCorylus avellana(hazel) was replaced byQuercus robur(oak),which was replaced byAbies alba(fir) andFagus sylvatica(beech) ~ 5700 years BP). We were particularly interested in testing if coniferous vegetation leads to a larger export of Hg to aquatic systems than deciduous vegetation. When hazel was replaced by oak, reduced soil erosion and increased transport of DOM-bound mercury from the catchment resulted in increases in both Hg-concentrations and accumulation rates (61 ng g− 1and 5.5 ng cm− 2yr.−1to 118 ng g− 1and 8.5 ng cm− 2yr.−1). However, even if Hg-concentrations increased also in association with the introduction of fir and beech (173 ng g− 1), as a result of higher Hg:C, there was no increase in Hg-accumulation rates (7.6 ng cm− 2yr.−1), because of a decreased input of OM. At around 2500 years BP Hg-accumulation rates and Hg-concentration indicated an additional input of Hg to the sediment (316 ng g− 1and 10.3 ng cm− 2yr.−1), which might be due to increased human activities in the area, e.g., forest burning or mining. Our results contrast those of several paired-catchment studies that suggest a higher release of Hg from coniferous than deciduous forest, and there is a need for studies with a long-term perspective to increase our understanding of the effects of slow and gradual processes on mercury cycling.