Macronutrient biogeochemistry in Antarctic land-fast sea ice: Insights from a circumpolar data compilation
Macronutrient biogeochemistry in Antarctic land-fast sea ice: Insights from a circumpolar data compilation
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DOI：
10.1016/j.marchem.2023.104324
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发表时间：
2023-11-01
期刊：
影响因子：
3
通讯作者：
Delilleo，Bruno
中科院分区：
文献类型：
--
作者：
Henley，Sian F.;Cozzi，Stefano;Delilleo，Bruno
南极海冰在南大洋海洋地球化学和地球气候系统中起着重要的调节作用。然而，我们对海冰地球化学循环的理解受到足够的时间和空间尺度上的相关数据的限制。在这里，我们提出了一个新的公开汇编的宏量营养素浓度数据从南极洲陆地固定海冰，涵盖了整个季节周期，使用来自南极洲周围的数据集，以及一个较小的数据集的宏量营养素浓度在邻近的海水。我们显示了一个强大的季节性循环，营养浓度高，在秋季和冬季，由于供应从下垫面沃茨，然后利用在春季和夏季的混合冰藻群落组成的硅藻和非硅质物种。我们的数据表明，冰藻初级生产的营养限制，硅限制可能是最普遍的，虽然周围的海冰藻类的每种营养素的亲和力仍然存在不确定性。有机物的再矿化和营养物质的再循环促使无机氮、磷酸盐和在较小程度上的草酸在一些冰芯中大量积累，其浓度远远超过表面沃茨中的浓度。营养盐供应到快冰是由盐水对流，血小板冰积累和纳入冰基质，冰下潮流，而营养盐吸附到海冰表面，生物膜的形成，非生物矿物沉淀和溶解也可以影响快冰营养循环。硝酸盐，铵和草酸的浓度普遍较高，在固定冰比南极浮冰报告，这可能支持通常观察到的较高的藻类生物量在固定冰环境。
Antarctic sea ice plays an important role in Southern Ocean biogeochemistry and mediating Earth's climate system. Yet our understanding of biogeochemical cycling in sea ice is limited by the availability of relevant data over sufficient temporal and spatial scales. Here we present a new publicly available compilation of macronutrient concentration data from Antarctic land-fast sea ice, covering the full seasonal cycle using datasets from around Antarctica, as well as a smaller dataset of macronutrient concentrations in adjacent seawater. We show a strong seasonal cycle whereby nutrient concentrations are high during autumn and winter, due to supply from underlying surface waters, and then are utilised in spring and summer by mixed ice algal communities consisting of diatoms and non-siliceous species. Our data indicate some degree of nutrient limitation of ice algal primary production, with silicon limitation likely being most prevalent, although uncertainties remain around the affinities of sea-ice algae for each nutrient. Remineralisation of organic matter and nutrient recycling drive substantial accumulations of inorganic nitrogen, phosphate and to a lesser extent silicic acid in some ice cores to concentrations far in excess of those in surface waters. Nutrient supply to fast ice is enhanced by brine convection, platelet ice accumulation and incorporation into the ice matrix, and under-ice tidal currents, whilst nutrient adsorption to sea-ice surfaces, formation of biofilms, and abiotic mineral precipitation and dissolution can also influence fast-ice nutrient cycling. Concentrations of nitrate, ammonium and silicic acid were generally higher in fast ice than reported for Antarctic pack ice, and this may support the typically observed higher algal biomass in fast-ice environments.