Global warming plus natural bacteria could release vast carbon deposits currently stored in Arctic soil
May 06, 2005
Increasing concentrations of carbon dioxide in the atmosphere will make global temperatures rise. By studying soil cores from the Arctic, scientists have discovered that this rise in temperature stimulates the growth of microorganisms that can break down long-term stores of carbon, releasing them into the atmosphere as carbon dioxide. This will lead to further increases in global temperatures.
Carbon is held in soil either in material that is easily degraded by chemical and bacterial action (labile soil carbon), or in material that is less easily degraded by microorganisms (resistant soil carbon). About one third of the world’s soil carbon is located in high latitudes such as the Arctic, and much of this effectively locked away in recalcitrant stores.
If this carbon were ever released into the atmosphere as carbon dioxide, the concentration of this ‘green-house gas’ would increase considerably, leading to a substantial increase in global warming.
The question that researchers in Austria, Russia and Finland asked was whether increasing global temperatures that are already predicted could enable micro organisms to use this carbon. Their results are published in this week’s edition of Rapid Communications in Mass Spectrometry.
The researchers incubated soil cores at 2oC, 12oC and 24oC. They found that resistant soil carbon was preferentially respired by arctic microbes at higher temperatures, presumably due to a shift in microbial populations.
They also found that the change in the relative proportion of different microorganisms in the soil was not driven by a depletion of more readily available carbon, but simply by the change in temperature.
“This temperature driven change in availability of resistant carbon is of crucial importance in the context of climate change,” says co-author Andreas Richter who works at the Institute of Ecology and Conservation Biology at the University of Vienna, Austria. “It may be that the whole idea of ‘resistant carbon compounds’ in arctic soils may only be relevant within a cool world and have no place in a future warmer world.”
Source: John Wiley & Sons
据Physorg网5月6日报道，大气中二氧化碳浓度的升高会引起全球气温的上升。科学家在研究北极土样时发现，气温上升刺激微生物的生长，随后微生物对长期以来的碳储存进行分解，以二氧化碳的形式释放到大气中，进一步引起全球气温升高。
土壤中的碳容易被化学作用和细菌分解，称为不稳定土壤碳；比较不容易被微生物分解的，称为高强度土壤碳。全球约三分之一的土壤碳位于高纬度区域内，如北极，而且大部分已经被牢牢地储存起来。
一旦这些碳以二氧化碳的形式被释放到大气中，那么温室气体的浓度将大量增加，引起全球变暖的加剧。
来自奥地利、俄罗斯、和芬兰的研究人员将这项研究结果发表在2005年5月的《质谱学快讯》（Rapid Communications in Mass Spectrometry）上，他们指出：不断上升的全球气温是否早已预示着将促使微生物开始利用碳储存？
研究人员分别将土样置于20摄氏度，120摄氏度 和240摄氏度条件下，发现北极微生物首先将温度较高时的高强度土壤碳用于土壤呼吸。同时还发现，土壤中微生物比例的变化并非来自碳的数量，而是由于温度的变化。
奥地利维也纳大学生态与保护生物学研究院的安德里亚·里克特指出，也许北极土壤中的“高强度碳化合物”在将来越来越暖的世界里将无法存在。
