Aug 3 2009
涉及科学家的新研究南安普敦国家海洋学中心（NOCS）强调了铁同位素在海洋科学中解决重要问题的潜在效用。欧洲杯线上买球这些发现发表在《地质杂志》的八月版中。
William Homoky of NOCS measuring iron isotopes
Large regions of the world's oceans have low primary production despite having plenty of macronutrients such as phosphate, nitrate and silicate. This is due a shortage of the essential micro-nutrient iron, which is needed for the growth of phytoplankton. These tiny, plant-like organisms sit at the base of the marine food chain and collectively draw vast amounts of the greenhouse gas carbon dioxide down from the atmosphere through the process of photosynthesis.
A proportion of the carbon is exported to the deep ocean, making the oceans a major carbon dioxide sink, without which global warming would rapidly accelerate. The natural supply of iron to such 'High Nutrient Low Chlorophyll (HNLC) regions is therefore, albeit indirectly, an important determinant of climate.
The importance of dissolved iron in seawater derived from bottom (benthic) sediments is increasingly recognised as being important. Around the continental margins, in particular, iron is released from the sediments during the decomposition of organic carbon by dissimilatory iron-reducing bacteria - micro-organisms that use elemental iron to obtain energy. This leads to the enrichment of iron in pore fluids and bottom waters. However the ubiquity of sedimentary iron inputs to seawater remains unknown.
不同的生物学和化学过程可以留下特征性的同位素“指纹”。此处特别感兴趣的是，沉积物孔流体中的铁同位素可能是通过异化性还原铁细菌的独特示踪剂呼吸的独特示踪剂。
隔离铁还原被认为是地球上最早的代谢途径之一，因此沉积的铁同位素也可能有助于重建古老的海洋中的铁循环。
到目前为止，孔流体的铁同位素测量已仅限于碳供应通常很高的大陆货架，而相互易易化的铁还原是广泛的，排除了与低碳，深水环境的比较。威廉·霍尼基（William Homoky）是南安普敦大学海洋和地球科学学院的一名研究生，他的同事们及其同事们填补了这一空白，以测量来自北加州利润率的鳗鱼河货架中的毛孔流体中的铁同位素（欧洲杯线上买球120 m的水深）和来自南部高原（3000-4000 m的水深）周围南大洋的深海沉积物，在南非东南约1400英里。
"We are excited by our findings not only because they represent the first measurements of their kind, but because they are telling us something important about iron cycling processes in the deep-sea, which can inform future iron isotope investigations in ancient rocks and the modern oceans," said William Homoky.
他们发现，孔隙流体中铁同位素的组成反映了两个部位之间沉积铁回收的不同程度。具体而言，孔流体的铁同位素组成反映了早期成岩作用过程中铁回收的程度，这是由上覆水柱的有机碳输入驱动的。
The researchers believe that iron isotope processing in carbon-limited environments, such as the deep-sea, is important and that it should help future interpretations of the rock record. "Additionally," they say, "the unique isotopic fingerprint of pore fluid iron in continental shelf settings is confirmed, highlighting the potential for iron isotopes to trace the inputs of continental shelf-derived iron in seawater."
Current thesis research aims to improve our understanding of iron cycling between sediments and seawater and compares the affects of contrasting sediment geochemistry on iron flux generating processes.
"In the future I would like to examine processes of sedimentary iron cycling in the high-latitudes, where sediments are subject to enhanced rates of environmental change due to changing climate in these regions," said Homoky.
这项工作得到了英国自然环境研究委员会（NERC）和美国国家科学基金会（NSF）的支持。欧洲杯线上买球在RV Wecoma和RRS发现上进行了研究巡游。