Formation of dense shelf water (DSW) in coastal polynyas (open water or thin sea-ice cover) in the sea-ice zone around Antarctica supplies Antarctic Bottom Water (AABW) through overflow down the continental slope. In coastal polynyas, atmospheric carbon dioxide (CO₂) is absorbed by the ocean in the early spring because of active primary production, and DSW formation is an important process for transporting this carbon from the sea surface to the deep ocean. However, there have been few quantitative evaluations of carbon consumption by active primary production and transport in coastal polynyas. Here, we examined the carbon dynamics in the Cape Darnley polynya (CDP), East Antarctica during austral summer 2009, by using carbonate system parameters combined with oceanographic mooring data. The partial pressure of CO₂ in the CDP surface water was lower than that of the atmosphere and the mean and standard deviation of sea−air CO₂ flux was estimated as −6.5 ± 6.9 mmol C m⁻² d⁻¹ (a negative value indicates absorption of atmospheric CO₂ by the ocean). Vertical profiles of dissolved inorganic carbon (DIC) concentration showed that concentrations in the bottom layer near the ocean floor were lower (by about 20 μmol kg⁻¹) than those in the ambient water (e.g., modified Circumpolar Deep Water, mCDW). The low-DIC in the shelf water was maintained by the strong biological uptake of carbon imported from high-DIC mCDW within the water column. Therefore, low-DIC DSW overflowed down the continental slope, and low-DIC concentrations were maintained through an export pathway to the continental shelf. The annual production of dissolved organic carbon and particulate organic carbon on the shelf was estimated as 0.7 × 10¹¹–1.5 × 10¹¹ mol C using the data for the DIC of DSW and current velocity data from a mooring in the CDP. Our results provide quantitative estimates for the potential role of carbon consumption by the active primary production and carbon transport by dense water formation in Antarctic coastal polynyas.

在南极洲周围海冰区的沿海多年生动物（开阔水域或薄薄的海冰覆盖层）中形成密集的架子水（DSW），通过溢流到大陆坡向南极底水（AABW）供水。在沿海波利亚尼亚，大气中的二氧化碳（CO ₂）由于初级生产活跃，在早春被海洋吸收，而DSW的形成是将这种碳从海面运输到深海的重要过程。但是，很少有定量评估沿海多生鱼类通过主动初级生产和运输所产生的碳消耗。在这里，我们通过结合碳酸盐岩系统参数和海洋系泊数据，研究了南极东部2009年南极州的南达尼利海角（CDP）的碳动力学。CDP地表水中的CO ₂分压低于大气压力，并且海洋CO ₂通量的平均和标准偏差估计为-6.5±6.9 mmol C m ^-2 d ^-1（负值表示海洋吸收了大气中的CO ₂）。溶解的无机碳的垂直剖面（DIC）浓度显示，浓度洋底靠近底部层较低（约20微摩尔千克^-1比在室温的水（例如，修饰的北极圈深水，mCDW））。通过从水柱内高DIC mCDW导入的大量碳生物吸收，可以保持货架水中的低DIC。因此，低DIC的DSW沿大陆坡溢出，并且低DIC浓度通过通往大陆架的出口途径得以维持。架子上的溶解有机碳和颗粒有机碳的年产量估计为0.7×10 ¹¹ –1.5×10 ¹¹ 使用DSW的DIC数据和来自CDP系泊设备的当前速度数据获得摩尔C。我们的结果提供了定量估计，这些活动对南极沿海多生鱼类活跃的初级生产所产生的碳消耗和密集的水形成所产生的碳运输的潜在作用。