Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean
Foraminiferal Isotope Evidence of Reduced Nitrogen Fixation in the Ice Age Atlantic Ocean
复制标题
DOI：
10.1126/science.1165787
复制
发表时间：
2009-01-09
期刊：
影响因子：
56.9
通讯作者：
Haug, G. H.
中科院分区：
文献类型：
--
作者：
Ren, H.;Sigman, D. M.;Haug, G. H.
固定氮(N)是低纬度海洋中藻类的一种限制性营养物质，在冰河时期，它的海洋库存量可能更高，因此有助于在这些间隔期间降低大气中的CO(2)。在加勒比海沉积物浮游有孔虫壳内的有机物中，我们发现末次冰期的（15）N/(14)N比高于当前间冰期的（15）N/(14)N比，表明加勒比海温跃层具有较高的硝酸盐（15）N/(14)N比。这种变化和其他物种特有的差异最好的解释是，在上一个冰河时期，大西洋的固氮量减少。固定减少很可能是对已知的冰期海洋N损失减少的响应，它可能有助于平衡海洋N收支，并抑制冰期-间冰期间N库存的变化。
Fixed nitrogen ( N) is a limiting nutrient for algae in the low- latitude ocean, and its oceanic inventory may have been higher during ice ages, thus helping to lower atmospheric CO(2) during those intervals. In organic matter within planktonic foraminifera shells in Caribbean Sea sediments, we found that the (15)N/(14)N ratio from the last ice age is higher than that from the current interglacial, indicating a higher nitrate (15)N/(14)N ratio in the Caribbean thermocline. This change and other species- specific differences are best explained by less N fixation in the Atlantic during the last ice age. The fixation decrease was most likely a response to a known ice age reduction in ocean N loss, and it would have worked to balance the ocean N budget and to curb ice age- interglacial change in the N inventory.