As water flows from the North Pacific Ocean to the Arctic Ocean, it passes through the shallow eastern shelf of the Bering Sea which serves as a major sink of inorganic nitrogen. This study explores the physical and biological factors that influence the spatiotemporal variability of this sink. A regional relationship of dissolved inorganic nitrogen to inorganic phosphorus (DIN:P) was established for waters entering the shelf. Residuals from this relationship (termed N∗∗) are a measure of the nitrogen deficit and were determined for bottom waters on the shelf using nutrient data collected on 52 hydrographic cruises spanning 2003 – 2018. Spatial variability in N∗∗ was related to advection, cross-shelf and vertical mixing, and residence time (using simulated ages of bottom water over the middle shelf). On average, this deficit accounted for approximately one-third of the inorganic nitrogen that enters the shelf, and the highest deficits (>8 ​μM DIN) were observed on the middle shelf between 60°N and St. Lawrence Island (63°N). Temporal variability in N∗∗ was examined over the middle shelf, and higher nitrogen deficits that occurred in colder years were hypothesized to result from weaker flow and increased export of organic matter in the presence of sea ice. On the southern middle shelf, the volume integrated (40 ​m to bottom) seasonal change in N∗∗ was equivalent to a denitrification rate of 0.7 ​± ​0.3 ​mmol ​N m^-2 d^-1. Rates of nitrogen loss were also estimated by combining N∗∗ with the simulated residence time of water on the shelf and found to be 0.20 ​± ​0.02 ​mmol ​N m^-2 d^-1. These rates were comparable to prior measurements of denitrification/anammox reported on the shelf. The nitrogen deficit could not be wholly ascribed to denitrification/anammox as the N:P stoichiometric ratio in particulate matter is known to be lower at higher latitudes, and a lower ratio was observed when dissolved organic matter was measured in a small number of samples. It remains unclear how future reductions in sea ice might impact the extent of nitrogen loss in the Bering Sea.

当水从北太平洋流向北冰洋时，它会穿过作为无机氮主要汇的白令海东部浅陆架。本研究探讨了影响该汇的时空变异性的物理和生物因素。对于进入陆架的水域，建立了溶解无机氮与无机磷 (DIN:P) 的区域关系。这种关系的残差（称为 N∗∗）是氮缺乏的衡量标准，是使用 2003 年至 2018 年间 52 次水文航行收集的营养数据确定的陆架底部水域。 N∗ 的空间变异性与平流有关，跨搁板和垂直混合，以及停留时间（使用中间搁板底部水的模拟年龄）。一般，这种赤字约占进入陆架的无机氮的三分之一，在 60°N 和圣劳伦斯岛 (63°N) 之间的中间陆架上观察到了最高的赤字 (>8μM DIN)。在中陆架上检查了 N∗∗ 的时间变化，并且假设在较冷的年份发生的较高的氮缺乏是由于在海冰存在下流动较弱和有机物出口增加造成的。在南部中层架子上，N ∗∗的积分体积（从底部到底部40 m）的季节性变化相当于反硝化率为0.7±0.3 mmol·N·m 在中陆架上检查了 N∗∗ 的时间变化，并且假设在较冷的年份发生的较高的氮缺乏是由于在海冰存在下流动较弱和有机物出口增加造成的。在南中陆架上，N∗∗ 的综合体积（40 米到底部）季节性变化相当于反硝化率为 0.7 ± 0.3 mmol N·m 在中陆架上检查了 N∗∗ 的时间变化，并且假设在较冷的年份发生的较高的氮缺乏是由于在海冰存在下流动较弱和有机物出口增加造成的。在南中陆架上，N∗∗ 的综合体积（40 米到底部）季节性变化相当于反硝化率为 0.7 ± 0.3 mmol N·m^-2 d ^-1。还通过将 N∗∗ 与模拟的水在架子上的停留时间相结合来估算氮损失率，结果为 0.20 ± 0.02 mmol N m ^-2 d ^-1。这些速率与货架上报告的反硝化/厌氧氨氧化的先前测量值相当。氮缺乏不能完全归因于反硝化/厌氧氨氧化，因为已知颗粒物质中的 N:P 化学计量比在高纬度地区较低，并且在少量样品中测量溶解有机物时观察到较低的比率。目前尚不清楚未来海冰的减少可能如何影响白令海的氮流失程度。