Distribution and composition of dissolved extracellular polymeric substances (EPS) in Antarctic sea ice
Distribution and composition of dissolved extracellular polymeric substances (EPS) in Antarctic sea ice
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DOI：
10.3354/meps08557
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发表时间：
2010-04
影响因子：
2.5
通讯作者：
G. Underwood;S. Fietz;S. Papadimitriou;D. Thomas;G. Dieckmann
中科院分区：
文献类型：
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作者：
G. Underwood;S. Fietz;S. Papadimitriou;D. Thomas;G. Dieckmann
在2004年和2006年期间测定了南极洲威德尔海盐水、冰芯、海冰间隙层和相关地表水中溶解有机碳（DOC）和细胞外聚合物（EPS）中碳水化合物的浓度和化学组成。DOC浓度在45 ~ 669 μmol C kg-1之间，具有高度的空间异质性。DOC和碳水化合物的浓度在大块海冰盐水中测得最高。溶解碳水化合物的浓度在31 ~ 255 μmol C kg-1（葡萄糖-碳当量）之间，约占融化冰芯DOC的40%，占冰盐水DOC的10% ~ 20%。溶解碳水化合物和DOC浓度与chl a显著相关。在所有海冰栖息地中，以EPS形式存在的碳水化合物（通过选择性醇沉淀测定）占溶解碳水化合物的68%。不同海冰生境中不同EPS大小组分的浓度和相对重要性、脲酸含量和单糖组成（特别是葡萄糖的贡献）与chl - a浓度的关系以及两次取样巡航之间存在显著差异。高藻类生物量与高葡萄糖EPS的相对丰度相关。根据溶解度对EPS进行分馏，发现可溶性较低的EPS馏分含有大量的糖醛酸，甘露糖、木糖、焦糖和鼠李糖的比例高于可溶性较高的EPS馏分。这种相对不溶性的EPS组分具有有助于细胞周围疏水和结构化微环境的特性。EPS因此改变了海冰盐水通道的局部环境，并在冰融化时形成了一种化学多样性的DOC来源。©Inter-Research 2010。
Concentrations and chemical composition of carbohydrates in dissolved organic carbon (DOC) and in extracellular polymeric substances (EPS) from brines, ice cores, gap layers in sea ice and associated surface waters were determined during 2004 and 2006 in the Weddell Sea, Antarctica. High levels of spatial heterogeneity were a common feature in these habitats, with DOC concentrations ranging from 45 to 669 μmol C kg-1. The highest concentrations of DOC and carbohydrate were measured in bulk sea-ice brines. Concentrations of dissolved carbohydrate (>8 kDa in size) varied between 31 and 255 μmol C kg-1 (glucose-carbon equivalent), and consisted of ca. 40% of the DOC in melted ice cores, and 10 to 20% of the DOC in ice brines. Dissolved carbohydrate and DOC concentrations were significantly correlated to chl a. Carbohydrate present as EPS (determined by selective alcohol precipitation) made up >68% of dissolved carbohydrates in all sea ice habitats. There were significant differences in concentration and relative importance of different EPS size fractions, and in the uronic acid content and monosaccharide composition (especially for glucose contribution), of different sea ice habitats, in relation to chl a concentrations, and between the 2 sampling cruises. High algal biomass was associated with greater relative abundance of glucose-rich EPS. Fractionation of EPS on the basis of solubility found that the least soluble EPS fraction contained substantial amounts of uronic acids and higher proportions of mannose, xylose, fucose and rhamnose than the more soluble EPS fractions. This relatively insoluble EPS fraction had characteristics that could contribute to a hydrophobic and structured microenvironment surrounding cells. EPS thus modify the local environment in sea ice brine channels, and form a chemically diverse source of DOC to the water column upon ice melt. © Inter-Research 2010.