Interconnection of nitrogen fixers and iron in the Pacific Ocean: Theory and numerical simulations
Interconnection of nitrogen fixers and iron in the Pacific Ocean: Theory and numerical simulations
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DOI：
10.1029/2011gb004039
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发表时间：
2012-01-26
影响因子：
5.2
通讯作者：
Follows, M. J.
中科院分区：
文献类型：
--
作者：
Dutkiewicz, S.;Ward, B. A.;Follows, M. J.
我们研究了铁供应、铁浓度和太平洋浮游植物群落之间的相互作用。我们提出了一个理论框架，该框架考虑了浮游植物之间对铁和氮资源的竞争，以解释固氮自养生物（重氮营养体，需要更高的铁配额，并且最大生长速度较慢）可以与其他浮游植物共存。该框架还表明，铁和固定氮浓度可以受到当地浮游植物群落的强烈控制。结合三维数值模型的结果，我们描绘了三个不同的生物地球化学省：1)铁供应非常低的重氮营养型被排除在外，铁限制的非重氮营养型浮游植物控制铁浓度；2)过渡区，非重氮营养型浮游植物受氮限制并控制氮浓度，但相对于硝酸盐，铁供应仍然过低，无法支持重氮营养型；3)相对于氮源，铁供应进一步增加，重氮营养体和其他浮游植物共存；氮浓度由非重氮营养体控制，铁浓度由重氮营养体控制。这三个省的边界是由铁的供应量相对于固定氮的供应量来确定的。数值模型和理论为理解铁供应和浮游植物群落结构变化的状态、联系和响应提供了有用的工具。
We examine the interplay between iron supply, iron concentrations and phytoplankton communities in the Pacific Ocean. We present a theoretical framework which considers the competition for iron and nitrogen resources between phytoplankton to explain where nitrogen fixing autotrophs (diazotrophs, which require higher iron quotas, and have slower maximum growth) can co-exist with other phytoplankton. The framework also indicates that iron and fixed nitrogen concentrations can be strongly controlled by the local phytoplankton community. Together with results from a three-dimensional numerical model, we characterize three distinct biogeochemical provinces: 1) where iron supply is very low diazotrophs are excluded, and iron-limited nondiazotrophic phytoplankton control the iron concentrations; 2) a transition region where nondiazotrophic phytoplankton are nitrogen limited and control the nitrogen concentrations, but the iron supply is still too low relative to nitrate to support diazotrophy; 3) where iron supplies increase further relative to the nitrogen source, diazotrophs and other phytoplankton coexist; nitrogen concentrations are controlled by nondiazotrophs and iron concentrations are controlled by diazotrophs. The boundaries of these three provinces are defined by the rate of supply of iron relative to the supply of fixed nitrogen. The numerical model and theory provide a useful tool to understand the state of, links between, and response to changes in iron supply and phytoplankton community structure that have been suggested by observations.