Chemoautotrophy in the redox transition zone of the Cariaco Basin: A significant midwater source of organic carbon production
Chemoautotrophy in the redox transition zone of the Cariaco Basin: A significant midwater source of organic carbon production
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DOI：
10.4319/lo.2001.46.1.0148
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发表时间：
2001-01
影响因子：
4.5
通讯作者：
Gordon T. Taylor;M. Iabichella;T. Ho;M. Scranton;R. Thunell;F. Muller‐Karger;R. Varela
中科院分区：
文献类型：
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作者：
Gordon T. Taylor;M. Iabichella;T. Ho;M. Scranton;R. Thunell;F. Muller‐Karger;R. Varela
在Cariaco时间序列计划期间，Cariaco盆地氧化还原过渡区(RTZ)的微生物现存量、细菌产量和醋酸盐周转率持续上升，RTZ是氧化还原电位最陡峭的深度区间(~240-450m)。在71次观测中，有16次在该区域(455米)以下的沉积物陷阱中捕获了异常高的颗粒碳通量。在这里，我们提出了新的证据，表明细菌化学自养在减少的硫物种的推动下，支持了RTZ活跃的次生微生物食物网，并可能是盆地内部不稳定的、化学上独特的、沉积的生物成因碎片的一个巨大的中水来源。溶解无机碳同化(27~159mmolCm−2d−1)相当于同期初级生产量的10%~333%。然而，电子供体和电子受体向RTZ的垂直扩散速率不足以支持这一生产。因此，为了平衡电子当量，氧水的显著侧向侵入、混合过程或C、S、N、Mn和Fe在RTZ的密集循环是必要的。化学自养生产似乎在时间上与季节性上升流和水华等短期表面过程脱钩，并可能在年际到年代际时间尺度上对表面生产力和深水通风的长期变化更敏感。研究结果表明，水中有机碳的产生可能对盆地的沉积记录做出了独特的贡献，从而改变了对其古气候学的解释。
During the CARIACO time series program, microbial standing stocks, bacterial production, and acetate turnover were consistently elevated in the redox transition zone (RTZ) of the Cariaco Basin, the depth interval (~240–450 m) of steepest gradient in oxidation‐reduction potential. Anomalously high fluxes of particulate carbon were captured in sediment traps below this zone (455 m) in 16 of 71 observations. Here we present new evidence that bacterial chemoautotrophy, fueled by reduced sulfur species, supports an active secondary microbial food web in the RTZ and is potentially a large midwater source of labile, chemically unique, sedimenting biogenic debris to the basin's interior. Dissolved inorganic carbon assimilation (27–159 mmol C m−2 d−1) in this zone was equivalent to 10%–333% of contemporaneous primary production, depending on the season. However, vertical diffusion rates to the RTZ of electron donors and electron acceptors were inadequate to support this production. Therefore, significant lateral intrusions of oxic waters, mixing processes, or intensive cycling of C, S, N, Mn, and Fe across the RTZ are necessary to balance electron equivalents. Chemoautotrophic production appears to be decoupled temporally from short‐term surface processes, such as seasonal upwelling and blooms, and potentially is more responsive to long‐term changes in surface productivity and deep‐water ventilation on interannual to decadal timescales. Findings suggest that midwater production of organic carbon may contribute a unique signature to the basin's sediment record, thereby altering its paleoclimatological interpretation.