氧化鐵染紅了Taylor冰川,、McMurdo干谷、南極洲,，形成了通常被稱為血瀑布的特性,。
圖片來(lái)源: Benjamin Urmston
據(jù)4月17日的《科學(xué)》雜志報(bào)道說(shuō)，在南極的Blood Falls,，從Taylor Glacier噴嘴流出的富含鐵礦的紅色河流非常醒目地染紅了白色的冰,。 科學(xué)家們現(xiàn)在報(bào)告說(shuō)，這一作為Blood Falls源頭的冰川下水潭居住著在這里生活了數(shù)百萬(wàn)年之久的微生物,。它為人們提供了一個(gè)微生物系統(tǒng)是如何在沒(méi)有光合作用或來(lái)自外部營(yíng)養(yǎng)源的情況下可以長(zhǎng)時(shí)間存活的一個(gè)令人震驚的例子,。
Jill A. Mikucki及其同僚報(bào)告說(shuō)，這一水潭中含有古老的海水,，這些海水是在大約1.5-4百萬(wàn)年前被行進(jìn)中的冰川給截流在那里的,。 該水中缺乏氧氣、鹽度極高而且充滿了鐵質(zhì),。 它還含有硫酸鹽,，這是微生物的一種常見(jiàn)的能源。但令人感到好奇的是那里的硫化物很少，而如果微生物能夠?qū)⒘蛩猁}還原成硫化物的話,，人們預(yù)計(jì)通常會(huì)在那里找到硫化物,。 根據(jù)在硫酸鹽中的氧同位素以及來(lái)自一種叫做“腺苷酰硫酸還原酶”的遺傳學(xué)證據(jù)，文章的作者得出結(jié)論,，這些微生物確實(shí)會(huì)將硫酸鹽進(jìn)行還原,，但它們是通過(guò)一種偶聯(lián)的鐵-硫代謝來(lái)進(jìn)行的，這種代謝所用的是來(lái)自巖床的鐵,，并使得硫酸鹽被還原成一種不同的化合物：亞硫酸鹽,。
研究人員提出，與此種微生物系統(tǒng)類似的情況可能在所謂的“雪球地球”時(shí)期中就已經(jīng)存在,，當(dāng)時(shí)的地球是被冰所覆蓋的,。（生物谷Bioon.com）
生物谷推薦原始出處：
Science 17 April 2009:DOI: 10.1126/science.1167350
A Contemporary Microbially Maintained Subglacial Ferrous "Ocean"
Jill A. Mikucki,1* Ann Pearson,1 David T. Johnston,2 Alexandra V. Turchyn,3 James Farquhar,4 Daniel P. Schrag,1 Ariel D. Anbar,5 John C. Priscu,6 Peter A. Lee7
An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5'-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic. Coupled biogeochemical processes below the glacier enable subglacial microbes to grow in extended isolation, demonstrating how analogous organic-starved systems, such as Neoproterozoic oceans, accumulated Fe(II) despite the presence of an active sulfur cycle.
1 Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138 USA.
2 Department of Organismic and Evolutionary Biology, Harvard University, Cambridge MA, 02138 USA.
3 Department of Earth Sciences, University of Cambridge, Cambridge CB2 3EQ, UK.
4 Department of Geology, University of Maryland, College Park, MD 20742, USA.
5 School of Earth and Space Exploration and Department of Chemistry and Biochemistry, Arizona State University, Tempe, AZ 85287, USA.
6 Department of Land Resources and Environmental Sciences, Montana State University, Bozeman, MT 59717, USA.
7 Hollings Marine Laboratory, College of Charleston, Charleston, SC 29412, USA.
