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
據(jù)Physorg網(wǎng)5月6日報(bào)道，大氣中二氧化碳濃度的升高會(huì)引起全球氣溫的上升,?？茖W(xué)家在研究北極土樣時(shí)發(fā)現(xiàn)，氣溫上升刺激微生物的生長,，隨后微生物對長期以來的碳儲(chǔ)存進(jìn)行分解,，以二氧化碳的形式釋放到大氣中，進(jìn)一步引起全球氣溫升高,。
土壤中的碳容易被化學(xué)作用和細(xì)菌分解,，稱為不穩(wěn)定土壤碳；比較不容易被微生物分解的,，稱為高強(qiáng)度土壤碳,。全球約三分之一的土壤碳位于高緯度區(qū)域內(nèi),，如北極，而且大部分已經(jīng)被牢牢地儲(chǔ)存起來,。
一旦這些碳以二氧化碳的形式被釋放到大氣中,，那么溫室氣體的濃度將大量增加，引起全球變暖的加劇,。
來自奧地利,、俄羅斯、和芬蘭的研究人員將這項(xiàng)研究結(jié)果發(fā)表在2005年5月的《質(zhì)譜學(xué)快訊》（Rapid Communications in Mass Spectrometry）上,，他們指出：不斷上升的全球氣溫是否早已預(yù)示著將促使微生物開始利用碳儲(chǔ)存,？
研究人員分別將土樣置于20攝氏度，120攝氏度 和240攝氏度條件下,，發(fā)現(xiàn)北極微生物首先將溫度較高時(shí)的高強(qiáng)度土壤碳用于土壤呼吸,。同時(shí)還發(fā)現(xiàn)，土壤中微生物比例的變化并非來自碳的數(shù)量,，而是由于溫度的變化,。
奧地利維也納大學(xué)生態(tài)與保護(hù)生物學(xué)研究院的安德里亞·里克特指出，也許北極土壤中的“高強(qiáng)度碳化合物”在將來越來越暖的世界里將無法存在,。
