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 occurring ¹⁵N/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 in ¹⁵N-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.

在这里，我们使用 1994 年、2007/2008 年和 2016/2017 年在东南太平洋发生的三个经向调查巡航的数据来研究对溶解有机碳和氮（分别为 DOC 和 DON）表面分布的控制。虽然 DOC 和 DON 生产同时发生在环流边缘的透光层，但考虑到横向运输、生产和消费的预算在整个地区并不平衡。我们的结果表明，虽然 DOC 浓度在环流内增加，但与边缘相比，DON 保持在相似的水平。除了赤道附近，DOC 和 DON 趋势几乎没有年际变化，这可以通过 ENSO 阶段和季节性来解释。虽然蒸发（降水）的影响对 DOC 和 DON 浓度的变化没有显着影响，^{最近一次巡航的15} N/ ¹⁴ N 同位素比率表明环流内的外源 DON 的净消耗量。_{在检测到地表[NO 3} ^- ]的最北和最南台站中， ¹⁵ N-DON在上300 m处显示出低特征，分别为3.8±1.5‰和2.5±1.6‰。在无法检测到[NO ₃ ^- ]的环流内，观察到平均为5.0±0.9‰的较高值。这表明一部分 DON 比水平迁移的时间尺度变化更快，同位素变化反映了¹⁵新产生的有机物的 N-DON。因此，异地 DON 可能是这种氮限制环境内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到这一点。