The impact on atmospheric CO 2 of iron fertilization induced changes in the ocean's biological pump
The impact on atmospheric CO 2 of iron fertilization induced changes in the ocean's biological pump
复制标题
铁施肥引起海洋生物泵变化对大气CO 2 的影响
DOI：
10.5194/bg-5-385-2008
复制
发表时间：
2008
期刊：
影响因子：
4.9
通讯作者：
J. McWilliams
中科院分区：
文献类型：
--
作者：
Xin Jin;N. Gruber;H. Frenzel;S. Doney;J. McWilliams
抽象的。通过数值模拟，我们通过在东热带太平洋高营养、低叶绿素区域的一小块表面区域添加铁元素来量化海洋生物泵的变化对二氧化碳气海平衡的影响。长达十年的施肥实验是在盆地规模、允许涡流耦合的物理/生物地球化学/生态模型中进行的。与之前的研究相反，我们发现通过增强生物输出从富光区去除的大部分溶解无机碳（DIC）被从大气中吸收的二氧化碳所取代。在我们的斑块尺寸实验中，大气吸收效率（100 m 范围内的海气 CO2 通量扰动与输出通量扰动之比）经过 10 年的积分，为 0.75 至 0.93。大气吸收效率对实验持续时间不敏感。控制大气吸收效率的主要因素是增强的生物生产和出口的垂直分布。地表的铁施肥往往会引起主要在地表附近的生产异常，从而导致高效率。相反，引起深层生产异常（例如改变光可用性）的机制往往具有较低的吸收效率，因为大部分去除的 DIC 被横向和垂直传输和混合所取代。尽管大气吸收效率很高，但海洋生物泵的斑块铁施肥往往在此处考虑的十年时间尺度上从大气中去除很少的二氧化碳。
Abstract. Using numerical simulations, we quantify the impact of changes in the ocean's biological pump on the air-sea balance of CO2 by fertilizing a small surface patch in the high-nutrient, low-chlorophyll region of the eastern tropical Pacific with iron. Decade-long fertilization experiments are conducted in a basin-scale, eddy-permitting coupled physical/biogeochemical/ecological model. In contrast to previous studies, we find that most of the dissolved inorganic carbon (DIC) removed from the euphotic zone by the enhanced biological export is replaced by uptake of CO2 from the atmosphere. Atmospheric uptake efficiencies, the ratio of the perturbation in air-sea CO2 flux to the perturbation in export flux across 100 m, integrated over 10 years, are 0.75 to 0.93 in our patch size-scale experiments. The atmospheric uptake efficiency is insensitive to the duration of the experiment. The primary factor controlling the atmospheric uptake efficiency is the vertical distribution of the enhanced biological production and export. Iron fertilization at the surface tends to induce production anomalies primarily near the surface, leading to high efficiencies. In contrast, mechanisms that induce deep production anomalies (e.g. altered light availability) tend to have a low uptake efficiency, since most of the removed DIC is replaced by lateral and vertical transport and mixing. Despite high atmospheric uptake efficiencies, patch-scale iron fertilization of the ocean's biological pump tends to remove little CO2 from the atmosphere over the decadal timescale considered here.