The western Arctic Shelf has long been considered as an important sink of nitrogen because high primary productivity of the shelf water fuels active denitrification within the sediments, which has been recognized to account for all the nitrogen (N) removal of the Pacific water inflow. However, potentially high denitrifying activity was discovered within the oxygenated Chukchi Shelf water during our summer expedition. Based on 15N-isotope pairing incubations, we estimated denitrification rates ranging from 1.8 ± 0.4 to 75.9 ± 8.7 nmol N2 L-1 h-1. We find that the spatial pattern of denitrifying activity follows well with primary productivity, which supplies plentiful fresh organic matter, and there was a strong correlation between integrated denitrification and integrated primary productivity. Considering the active hydrodynamics over the Chukchi Shelf during summer, resuspension of benthic sediment coupled with particle-associated bacteria induces an active denitrification process in the oxic water column. We further extrapolate to the whole Chukchi Shelf and estimate an N removal flux from this cold Arctic shelf water to be 12.2 Tg-N year-1, which compensates for the difference between sediment cores incubation (~ 3 Tg-N year-1) and geochemical estimation based on N deficit relative to phosphorous (~ 16 Tg-N year-1). We infer that dynamic sediment resuspension combined with high biological productivity stimulates intensive denitrification in the water column, potentially creating a nitrogen sink over the shallow Arctic shelves that have previously been unrecognized.

中文翻译：

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在北极的充氧的楚科奇陆架水域中发现了一个潜在的氮汇。

长期以来，西部北极大陆架一直被认为是重要的氮汇，因为架子水的高初级生产力促进了沉积物中的积极反硝化作用，这已被认为是太平洋水流入中所有氮（N）去除的原因。但是，在我们的夏季探险中，在含氧的楚科奇棚架水中发现了潜在的高反硝化活性。基于15N同位素配对孵育，我们估计反硝化速率为1.8±0.4至75.9±8.7 nmol N2 L-1 h-1。我们发现反硝化活动的空间格局与初级生产力很好地相符，后者提供了大量的新鲜有机物，并且综合反硝化与综合初级生产力之间存在很强的相关性。考虑到夏季楚科奇（Chukchi）架上的活跃流体动力学，底栖沉积物的再悬浮与颗粒相关细菌的结合在含氧水柱中引起了活跃的反硝化过程。我们进一步外推到整个楚科奇大陆架，估计从北极寒冷的陆架水中去除的氮通量为12.2 Tg-N year-1，这补偿了沉积物核心温育（〜3 Tg-N year-1）和地球化学估算基于相对于磷的氮亏缺（〜16 Tg-N year-1）。我们推断，动态沉积物的再悬浮与高生物生产力的结合会刺激水柱中的强烈反硝化作用，从而有可能在以前未被认识的北极浅层架上形成氮汇。底栖沉积物的再悬浮与颗粒相关细菌的结合在含氧水柱中引起了积极的反硝化过程。我们进一步外推到整个楚科奇大陆架，估计从北极寒冷的陆架水中去除的氮通量为12.2 Tg-N year-1，这补偿了沉积物核心温育（〜3 Tg-N year-1）和地球化学估算基于相对于磷的氮亏缺（〜16 Tg-N year-1）。我们推断，动态沉积物的再悬浮与高生物生产力的结合会刺激水柱中的强烈反硝化作用，从而有可能在以前未被认识的北极浅层架上形成氮汇。底栖沉积物的再悬浮与颗粒相关细菌的结合在含氧水柱中引起了积极的反硝化过程。我们进一步外推到整个楚科奇大陆架，估计从北极寒冷的陆架水中去除的氮通量为12.2 Tg-N year-1，这补偿了沉积物核心温育（〜3 Tg-N year-1）和地球化学估算基于相对于磷的氮亏缺（〜16 Tg-N year-1）。我们推断，动态沉积物的再悬浮与高生物生产力的结合会刺激水柱中的强烈反硝化作用，并有可能在以前未被认识的北极浅层架上形成氮汇。我们进一步外推到整个楚科奇大陆架，估计从北极寒冷的陆架水中去除的氮通量为12.2 Tg-N year-1，这补偿了沉积物核心温育（〜3 Tg-N year-1）和地球化学估算基于相对于磷的氮亏缺（〜16 Tg-N year-1）。我们推断，动态沉积物的再悬浮与高生物生产力的结合会刺激水柱中的强烈反硝化作用，从而有可能在以前未被认识的北极浅层架上形成氮汇。我们进一步外推到整个楚科奇大陆架，估计从这种寒冷的北极陆架水中去除的氮通量为12.2 Tg-N year-1，这补偿了沉积物核心温育（〜3 Tg-N year-1）和地球化学估算基于相对于磷的氮亏缺（〜16 Tg-N year-1）。我们推断，动态沉积物的再悬浮与高生物生产力的结合会刺激水柱中的强烈反硝化作用，从而有可能在以前未被认识的北极浅层架上形成氮汇。