Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
Iron “ore” nothing: benthic iron fluxes from the oxygen-deficient Santa Barbara Basin enhance phytoplankton productivity in surface waters
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DOI：
10.5194/bg-21-773-2024
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发表时间：
2024-02
期刊：
影响因子：
4.9
通讯作者：
D. Robinson;A. Pham;D. J. Yousavich;Felix Janssen;F. Wenzhöfer;E. Arrington;Kelsey M. Gosselin;Marco Sandoval-Belmar;Matthew Mar;David L. Valentine;Daniele Bianchi;T. Treude
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文献类型：
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作者：
D. Robinson;A. Pham;D. J. Yousavich;Felix Janssen;F. Wenzhöfer;E. Arrington;Kelsey M. Gosselin;Marco Sandoval-Belmar;Matthew Mar;David L. Valentine;Daniele Bianchi;T. Treude
抽象的。微量金属铁（Fe）是控制浮游植物生产力的必需微量营养素，其随后通过对大量营养素循环的反馈影响有机物质循环。沿着美国西海岸的大陆边缘，高底栖铁释放已被记录，特别是从深缺氧盆地在南加州边界。然而，这种Fe释放对表面初级生产的影响仍然知之甚少。在本研究中，从圣巴巴拉盆地，原位底栖铁通量确定沿着一个横断面从浅到深的网站在盆地。通量介于0.23和4.9 mmol m−2 d−1之间，是迄今报告的最高海底铁通量。为了研究缺氧深盆底栖铁释放对表层浮游植物生产的影响，我们将底栖通量测量与区域海洋模拟系统耦合的生物地球化学元素循环（ROMS-BEC）模型的数值模拟相结合。为此，我们更新了模型铁通量参数化，包括新的底栖通量测量从圣巴巴拉盆地。我们的模拟表明，底栖铁通量提高表面初级生产力，支持底栖铁释放的正反馈减少氧气在底部沃茨。然而，减少浮游植物铁限制增强的海底通量附近的海岸可能会部分补偿进一步离岸增加氮限制，限制这种正反馈的功效。
Abstract. The trace metal iron (Fe) is an essential micronutrient that controls phytoplankton productivity, which subsequently affects organic matter cycling with feedback on the cycling of macronutrients. Along the continental margin of the US West Coast, high benthic Fe release has been documented, in particular from deep anoxic basins in the Southern California Borderland. However, the influence of this Fe release on surface primary production remains poorly understood. In the present study from the Santa Barbara Basin, in situ benthic Fe fluxes were determined along a transect from shallow to deep sites in the basin. Fluxes ranged between 0.23 and 4.9 mmol m−2 d−1, representing some of the highest benthic Fe fluxes reported to date. To investigate the influence of benthic Fe release from the oxygen-deficient deep basin on surface phytoplankton production, we combined benthic flux measurements with numerical simulations using the Regional Ocean Modeling System coupled to the Biogeochemical Elemental Cycling (ROMS-BEC) model. For this purpose, we updated the model Fe flux parameterization to include the new benthic flux measurements from the Santa Barbara Basin. Our simulations suggest that benthic Fe fluxes enhance surface primary production, supporting a positive feedback on benthic Fe release by decreasing oxygen in bottom waters. However, a reduction in phytoplankton Fe limitation by enhanced benthic fluxes near the coast may be partially compensated for by increased nitrogen limitation further offshore, limiting the efficacy of this positive feedback.