Permanently anoxic regions in the ocean are widespread and exhibit unique microbial metabolic activity exerting substantial influence on global elemental cycles and climate. Reconstructing microbial metabolic activity rates in these regions has been challenging, due to the technical difficulty of direct rate measurements. In Cariaco Basin, which is the largest permanently anoxic marine basin and an important model system for geobiology, long‐term monitoring has yielded time series for the concentrations of biologically important compounds; however, the underlying metabolite fluxes remain poorly quantified. Here, we present a computational approach for reconstructing vertical fluxes and in situ net production/consumption rates from chemical concentration data, based on a 1‐dimensional time‐dependent diffusive transport model that includes adaptive penalization of overfitting. We use this approach to estimate spatiotemporally resolved fluxes of oxygen, nitrate, hydrogen sulfide, ammonium, methane, and phosphate within the sub‐euphotic Cariaco Basin water column (depths 150–900 m, years 2001–2014) and to identify hotspots of microbial chemolithotrophic activity. Predictions of the fitted models are in excellent agreement with the data and substantially expand our knowledge of the geobiology in Cariaco Basin. In particular, we find that the diffusivity, and consequently fluxes of major reductants such as hydrogen sulfide, and methane, is about two orders of magnitude greater than previously estimated, thus resolving a long‐standing apparent conundrum between electron donor fluxes and measured dark carbon assimilation rates.

中文翻译：

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海洋缺氧生态系统模型中的微生物代谢物通量。

海洋中的永久缺氧区域分布广泛，并表现出独特的微生物代谢活性，对全球元素周期和气候产生重大影响。由于直接速率测量的技术难度，在这些区域中重建微生物代谢活动速率一直具有挑战性。在最大的永久性缺氧海洋盆地和重要的地质生物学模型系统Cariaco盆地，长期监测得出了重要生物化合物浓度的时间序列。但是，基础代谢通量仍然量化较差。在这里，我们提出了一种从化学浓度数据重建垂直通量和原位净生产/消耗率的计算方法，基于一维时变扩散运输模型，其中包括过度拟合的自适应惩罚。我们使用这种方法来估算亚次共生Cariaco盆地水柱（深度150-900 m，2001-2014年）中氧，硝酸盐，硫化氢，铵，甲烷和磷酸盐的时空解析通量，并确定微生物热点化石营养活性。拟合模型的预测与数据非常吻合，并极大地扩展了我们对Cariaco盆地地球生物学的知识。特别是，我们发现扩散率以及主要还原剂（例如硫化氢和甲烷）的通量比先前估计的大约大两个数量级，