Controls on surface distributions of dissolved organic carbon and nitrogen in the southeast Pacific Ocean
Controls on surface distributions of dissolved organic carbon and nitrogen in the southeast Pacific Ocean
复制标题
DOI：
10.1016/j.marchem.2022.104136
复制
发表时间：
2022-06
期刊：
影响因子：
3
通讯作者：
M. B. Bif;A. Bourbonnais;Dennis A. Hansell;J. Granger;Holly C. Westbrook;M. Altabet
中科院分区：
文献类型：
--
作者：
M. B. Bif;A. Bourbonnais;Dennis A. Hansell;J. Granger;Holly C. Westbrook;M. Altabet
在这里，我们使用1994年，2007/2008年和2016/2017年在东南太平洋进行的三次区域调查巡航的数据，调查溶解有机碳和氮（DOC和DON）表面分布的控制。虽然DOC和DON的生产同时发生在真光层的环流边缘，预算，占水平运输，生产和消费并不平衡整个区域。我们的研究结果表明，虽然DOC浓度增加内的环流，DON保持在类似的水平相比，利润率。DOC和DON趋势的年际变化很小，除了赤道附近，解释ENSO阶段和季节性。虽然蒸发（降水）的影响并没有显着的贡献变量DOC和DON浓度，在自然发生的15 N/14 N同位素比的差异，从最近的巡航表明净消耗的外来DON内的环流。在最北端和最南端的监测站，在地表[NO3−]被检测到的地方，15 N-DON在300米以上显示出较低的信号，分别为3.8 ± 1.5‰和2.5 ± 1.6‰。在[NO3−]无法检测到的环流内部，观察到平均值为5.0 ± 0.9‰的较高值。这表明，一小部分DON的周转速度比水平运输的时间尺度更快，同位素变化反映了新产生的有机质中15 N-DON的梯度。因此，外来的DON可能是氮有限环境中微生物群落的重要氮源，在关闭营养预算以估计南太平洋副热带环流的生产力时应考虑在内。
Here we use data from three meridional survey cruises that took place in 1994, 2007/2008 and 2016/2017 in the southeast Pacific Ocean to investigate controls on surface distributions of dissolved organic carbon and nitrogen (DOC and DON, respectively). While DOC and DON production occur simultaneously in the euphotic layer of the gyre margins, budgets that account for horizontal transport, production and consumption are not balanced across the region. Our results show that while DOC concentrations increase inside the gyre, DON remains at similar levels in comparison to margins. There is little interannual variability in DOC and DON trends, except near the equator, explained by ENSO phases and seasonality. While the effect of evaporation (precipitation) did not significantly contribute to variable DOC and DON concentrations, differences in the naturally occurring15N/14N isotope ratios from the most recent cruise suggest net consumption of allochthonous DON inside the gyre. In the northernmost and southernmost stations, where surface [NO3−] was detected,15N-DON showed low signatures in the upper 300 m of 3.8 ± 1.5‰ and 2.5 ± 1.6‰, respectively. Inside the gyre where [NO3−] was undetectable, higher values averaging 5.0 ± 0.9‰ were observed. This suggests that a fraction of DON turns over more rapidly than the time scale of horizontal transport, with the isotopic change reflecting the gradient in15N-DON of newly produced organic matter. Thus, allochthonous DON is likely a significant source of nitrogen to microbial communities inside this nitrogen-limited environment and should be taken into consideration when closing nutrient budgets to estimate productivity in the South Pacific Subtropical Gyre.