Nitrite regeneration in the oligotrophic Atlantic Ocean
Nitrite regeneration in the oligotrophic Atlantic Ocean
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DOI：
10.5194/bg-19-1355-2022
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发表时间：
2022-03
期刊：
影响因子：
4.9
通讯作者：
D. Clark;Andrew P. Rees;C. Ferrera;L. Al-Moosawi;P. Somerfield;C. Harris;G. Quartly;S. Goult;G. Tarran;G. Lessin
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文献类型：
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作者：
D. Clark;Andrew P. Rees;C. Ferrera;L. Al-Moosawi;P. Somerfield;C. Harris;G. Quartly;S. Goult;G. Tarran;G. Lessin
抽象的。阳光明媚的开阔海洋中稀缺的营养资源的循环利用对生态系统的功能至关重要。硝化作用将有机质分解产生的铵(NH4+)导向硝酸盐(NO3-)的再生，硝酸盐是光合作用初级生产者的重要资源。然而，在营养稀少的条件下进行硝化速率测量的技术挑战，加上这些环境的偏远性质，意味着数据的可获得性和提供的理解是有限的。这项研究报告了大西洋光区13000公里断面上亚硝酸盐(NO2-)的再生率(RNO2--NH4+氧化产生的第一种硝化产物)。这些测量在相对较高的分辨率(300千米量级)下，允许检查RNO2与环境条件之间的相互作用，这些条件可能需要在模型描述中明确制定。在所有地点，我们都报告了可测量的RNO2，大西洋各省之间和各省内的RNO2存在显着差异。统计分析表明，RNO2与生态系统变量之间存在显著的相关结构，解释了∼数据变异性的65%。采样深度之间的差异与水平解析的差异相同或大于水平解析的差异，从而确定了深度层之间不同的生物地球化学生态位。RNO2和环境变量之间的最佳总体匹配结合了叶绿素a浓度、光相持续时间和硅酸盐浓度(代表水柱物理不稳定性的短期示踪剂)。在此基础上，我们假设RNO2与溶解有机氮(DON)的短期自养产生和异养分解有关，DON可再生NH4+并支持NH4+氧化。然而，这并不能解释南半球深度真光区的RNO2显著大于北半球的观测结果。我们提出了一个补充假设，即观测反映了从大西洋东部边界上升流生态系统向环流内部的横向输送提供的DON浓度的差异。
Abstract. The recycling of scarce nutrient resources in the sunlit open ocean is crucial to ecosystem function. Nitrification directs ammonium (NH4+) derived from organic matter decomposition towards the regeneration of nitrate (NO3-), an important resource for photosynthetic primary producers. However, the technical challenge of making nitrification rate measurements in oligotrophic conditions combined with the remote nature of these environments means that data availability, and the understanding that provides, is limited. This study reports nitrite (NO2-) regeneration rate (RNO2 – the first product of nitrification derived from NH4+ oxidation) over a 13 000 km transect within the photic zone of the Atlantic Ocean. These measurements, at relatively high resolution (order 300 km), permit the examination of interactions between RNO2 and environmental conditions that may warrant explicit development in model descriptions. At all locations we report measurable RNO2 with significant variability between and within Atlantic provinces. Statistical analysis indicated significant correlative structure between RNO2 and ecosystem variables, explaining ∼65 % of the data variability. Differences between sampling depths were of the same magnitude as or greater than horizontally resolved differences, identifying distinct biogeochemical niches between depth horizons. The best overall match between RNO2 and environmental variables combined chlorophyll-a concentration, light-phase duration, and silicate concentration (representing a short-term tracer of water column physical instability). On this basis we hypothesize that RNO2 is related to the short-term autotrophic production and heterotrophic decomposition of dissolved organic nitrogen (DON), which regenerates NH4+ and supports NH4+ oxidation. However, this did not explain the observation that RNO2 in the deep euphotic zone was significantly greater in the Southern Hemisphere compared to the Northern Hemisphere. We present the complimentary hypothesis that observations reflect the difference in DON concentration supplied by lateral transport into the gyre interior from the Atlantic's eastern boundary upwelling ecosystems.