Impacts of basal melting of the Totten Ice Shelf and biological productivity on marine biogeochemical components in Sabrina Coast, East Antarctica
Impacts of basal melting of the Totten Ice Shelf and biological productivity on marine biogeochemical components in Sabrina Coast, East Antarctica
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托滕冰架基底融化和生物生产力对东南极洲萨布丽娜海岸海洋生物地球化学成分的影响
DOI：
10.1029/2022gb007510
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发表时间：
2022
影响因子：
5.2
通讯作者：
Aoki Shigeru
中科院分区：
文献类型：
--
作者：
Tamura Tetsuya P.;Nomura Daiki;Hirano Daisuke;Tamura Takeshi;Kiuchi Masaaki;Hashida Gen;Makabe Ryosuke;Ono Kazuya;Ushio Shuki;Yamazaki Kaihe;Nakayama Yoshihiro;Takahashi Keigo D.;Sasaki Hiroko;Murase Hiroto;Aoki Shigeru
为了阐明南极冰盖底部融化和生物生产力对南极沿海沃茨水域生物地球化学过程的影响，测量了2018年春夏期间从托滕冰架（TIS）近海斜坡到冰锋的溶解无机碳（DIC）、总碱度（TA）、无机营养盐、叶绿素和稳定氧同位素比（δ 18 O）的浓度。2019年和2020年。改良环极深水（mCDW）侵入TIS外的大陆架，并沿着测深槽流入TIS空腔，在那里与冰架底部的冰川融水形成浮力混合物。物理海洋过程主要决定DIC、TA和营养盐浓度的分布。然而，光合作用和稀释从海冰和冰架基地融水减少DIC，TA和营养盐浓度在冰锋附近的地表水。这些原因也使2018年和2020年南半球夏季地表水中CO2分压（pCO2）相对于mCDW降低了100 μatm以上，地表水成为大气的强CO2汇。浮游植物光合作用改变DIC和TA的摩尔比为106：16。因此，二氧化碳分压下降主要是由于光合作用，而稀释冰川和海冰融水有一个小的影响。营养盐消耗率表明，光合作用是由水柱中的铁刺激的，除了海冰融水之外，还通过浮力驱动的上升流和基底冰架融水供应到表层。
To clarify the impacts of basal melting of the Antarctic ice sheet and biological productivity on biogeochemical processes in Antarctic coastal waters, concentrations of dissolved inorganic carbon (DIC), total alkalinity (TA), inorganic nutrients, chlorophylla, and stable oxygen isotopic ratios (δ18O) were measured from the offshore slope to the ice front of the Totten Ice Shelf (TIS) during the spring/summer of 2018, 2019, and 2020. Modified Circumpolar Deep Water (mCDW) intruded onto the continental shelf off the TIS and flowed along bathymetric troughs into the TIS cavity, where it formed a buoyant mixture with glacial meltwater from the ice shelf base. Physical oceanographic processes mostly determined the distributions of DIC, TA, and nutrient concentrations. However, photosynthesis and dilution by meltwater from sea ice and the ice shelf base decreased DIC, TA, and nutrient concentrations in surface water near the ice front. These causes also reduced the partial pressure of CO2(pCO2) in surface water by more than 100 μatm with respect to mCDW in austral summer of 2018 and 2020, and the surface water became a strong CO2sink for the atmosphere. Phytoplankton photosynthesis changed DIC and TA in a molar ratio of 106:16. Thus, pCO2decreased mostly as a result of photosynthesis while dilution by glacial and sea ice meltwater had a small effect. The nutrient consumption ratio suggested that photosynthesis was stimulated by iron in the water column, supplied to the surface layer via buoyancy‐driven upwelling and basal ice shelf meltwater in addition to sea ice meltwater.