Overlooked contribution of the biological pump to the Pacific Arctic nitrogen deficit

作     者：Hongliang LI Jianfang CHEN Diana RUIZ-PINO Jingjing ZHANG Haiyan JIN Yanpei ZHUANG Youcheng BAI Jian REN Yangjie LI 

作者机构：Key Laboratory of Marine Ecosystem DynamicsSecond Institute of OceanographyMinistry of Natural ResourcesHangzhou310012China State Key Laboratory of Satellite Ocean Environment DynamicsHangzhou310012China Sorbonne Universités(UPMCUniversitéParis 06)-CNRS-IRD-MNHNLOCEAN Laboratory4 Place JussieuParisF-75005France Southern Marine Science and Engineering Guangdong Laboratory(Zhuhai)Zhuhai519080China Polar and Marine Research InstituteJimei UniversityXiamen361021China 

出 版 物：《Science China Earth Sciences》 (中国科学（地球科学英文版）)

年 卷 期：2022年第65卷第8期

页      面：1477-1489页

核心收录：

学科分类：070902[理学-地球化学] 0709[理学-地质学] 070702[理学-海洋化学] 07[理学] 0707[理学-海洋科学] 0705[理学-地理学] 0703[理学-化学] 

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41003036&41941013) the Chinese National Arctic Research Expedition Project(CHINARE) the Cai Yuanpei Program the ICAR Project(China Scholarship Council)。 

主　　题：Nitrogen deficit Biological pump Nutrient Sinking particles Arctic Ocean 

摘      要：The nutrient-rich Pacific Ocean seawater that flows through the Bering Strait into the Chukchi Sea is generally considered to be the most important source of nutrients to the Arctic euphotic zone.The inflow is characterized by nitrogen deficit and low nitrate/phosphate(N/P)ratios;this is ascribed to sedimentary denitrification on the Chukchi shelf by preoccupant opinions.However,the Chukchi Sea also has high primary production,which raises the question of whether the biological pump may also significantly modulate nutrient properties of the throughflow.Here,we show that nitrate concentrations of the Pacific inflow gradually decrease northward in association with notable biological utilization.The phytoplankton N/P uptake ratio was 8.8±2.27,higher than the N/P ratio of Pacific inflow water(5-6).This uptake ratio,in combination with efficient vertical nitrogen export,serves to preferentially remove nitrogen(relative to phosphorus)from upper waters,thereby further intensifying the Arctic nitrogen deficit.Accordingly,as large as about 111.7×10^(9)mol N yr^(−1)of nitrate was extra consumed,according to the real N/P uptake ratio rather than the ratio of the Pacific inflow,which may be as great as half the nitrogen loss ascribed to sedimentary denitrification.Our findings suggest that besides sedimentary denitrification,biological disproportionate utilization of nutrients in the Chukchi Sea upper water is another important contributor to the nitrogen limitation and excess phosphorus in the upper Arctic Ocean.In the rapid Arctic change era,the predicted reinforced biological carbon pump could further impact the nutrient dynamics and biogeochemical process of the Arctic Ocean.