Natali Susan M, Sañudo-Wilhelmy Sergio A, Norby Richard J, Zhang Hong, Finzi Adrien C, Lerdau Manuel T
Botany Department, University of Florida, Gainesville, FL 32611, USA.
Oecologia. 2008 Nov;158(2):343-54. doi: 10.1007/s00442-008-1135-6. Epub 2008 Sep 4.
Fossil fuel combustion is the primary anthropogenic source of both CO2 and Hg to the atmosphere. On a global scale, most Hg that enters ecosystems is derived from atmospheric Hg that deposits onto the land surface. Increasing concentrations of atmospheric CO2 may affect Hg deposition to terrestrial systems and storage in soils through CO(2)-mediated changes in plant and soil properties. We show, using free-air CO2 enrichment (FACE) experiments, that soil Hg concentrations are almost 30% greater under elevated atmospheric CO2 in two temperate forests. There were no direct CO2 effects, however, on litterfall, throughfall or stemflow Hg inputs. Soil Hg was positively correlated with percent soil organic matter (SOM), suggesting that CO(2)-mediated changes in SOM have influenced soil Hg concentrations. Through its impacts on SOM, elevated atmospheric CO2 may increase the Hg storage capacity of soils and modulate the movement of Hg through the biosphere. Such effects of rising CO2, ones that transcend the typically studied effects on C and nutrient cycling, are an important next phase for research on global environmental change.
化石燃料燃烧是大气中二氧化碳和汞的主要人为来源。在全球范围内，进入生态系统的大部分汞来自沉积在陆地表面的大气汞。大气中二氧化碳浓度的增加可能会通过二氧化碳介导的植物和土壤性质变化，影响汞向陆地系统的沉积以及在土壤中的储存。我们通过自由空气二氧化碳富集（FACE）实验表明，在两个温带森林中，大气二氧化碳浓度升高时，土壤汞浓度几乎高出近30%。然而，二氧化碳对凋落物、穿透水或树干流汞输入没有直接影响。土壤汞与土壤有机质（SOM）百分比呈正相关，这表明二氧化碳介导的SOM变化影响了土壤汞浓度。通过对SOM的影响，大气二氧化碳浓度升高可能会增加土壤的汞储存能力，并调节汞在生物圈中的移动。二氧化碳上升的这种影响超越了通常研究的对碳和养分循环的影响，是全球环境变化研究的一个重要的下一阶段。
