To clarify the effect of basal melting of ice tongues/ice shelf on the CO₂ system in the Antarctic continental margin, seawater samples were collected for analysis of dissolved inorganic carbon (DIC), total alkalinity (TA), nutrients, chlorophyll a (chl.a), and oxygen isotopic ratios at the ice front of the Shirase Glacier Tongue (SGT) in Lützow-Holm Bay (LHB), East Antarctica during the summers of 2017 and 2018. At depths greater than ∼20 dbar in LHB, CO₂ system parameters were strongly influenced by the dilution effect of SGT basal melting and the inflow of modified Circumpolar Deep Water (mCDW). The distributions of DIC and TA agreed well with an offshore origin of mCDW that flowed beneath the SGT and mixing of basal meltwater and mCDW beneath the SGT. The fraction of SGT meltwater was highest at the station near the ice front. Dilution by SGT basal meltwater reduced the partial pressure of CO₂ in the mCDW from 431 to 387 μatm. The water then became a sink rather than source of atmospheric CO₂. In the sea surface, DIC and TA were strongly influenced by biological processes. Salinity-normalized DIC decreased with the increase of salinity-normalized TA in accord with 106:16 C:N molar stoichiometry; the chl.a concentration at the sea surface was as high as 31 μg L⁻¹.

中文翻译：

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Shirase冰川舌的基础融化对南极东部Lützow-Holm湾的CO2系统的影响

为了阐明冰舌/冰架的基础融化对南极大陆边缘CO ₂系统的影响，收集了海水样品以分析溶解的无机碳（DIC），总碱度（TA），养分，叶绿素a（chl） .a），以及在2017年和2018年夏季，南极州东吕茨霍姆湾（LHB）的Shirase冰川舌（SGT）的冰锋处的氧同位素比。CO处LHB的深度约20 dbar以上_2个SGT基础融化的稀释作用和改良的圆极深水（mCDW）的流入对系统参数有很大的影响。DIC和TA的分布与mCDW的近海起源非常吻合，后者在SGT下方流动，而基础熔体水和mCDW在SGT下方混合。SGT融水的比例在靠近冰面的站点最高。SGT基础熔体水稀释将mCDW中的CO ₂分压从431μatm降低到387μatm。然后，水变成了汇，而不是大气中的CO _2的来源。。在海面，DIC和TA受生物过程的强烈影响。盐度归一化DIC随盐度归一化TA的增加而降低，符合106：16 C：N摩尔化学计量比；海面的chl.a浓度高达31μgL ^-1。