Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes
Macro-nutrient concentrations in Antarctic pack ice: Overall patterns and overlooked processes
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DOI：
10.1525/elementa.217
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发表时间：
2017-03-29
影响因子：
3.9
通讯作者：
Tison, Jean-Louis
中科院分区：
文献类型：
--
作者：
Fripiat, Francois;Meiners, Klaus M.;Tison, Jean-Louis
南极浮冰上居住着一个多样化的活跃的微生物群落，它们依赖营养物质生长。为了寻找模式和被忽视的过程，我们进行了大规模的汇编宏观营养数据（以下称为营养物质）在南极浮冰（306冰芯收集19个研究巡航）。溶解无机氮和草酸浓度随时间变化，从一个季节性生产的生态系统预期。在冬季，海冰中的盐度标准化硝酸盐和亚硝酸盐浓度（C*）接近海水浓度（C-w），表明很少或没有生物活性。在春季，硝酸盐和亚硝酸盐浓度相对于海水部分耗尽（C* < C-w），与增加的日照促进的冰微藻的季节性积累相称。较强和较早的硝酸盐比硝酸盐的消费表明，在海冰的初级生产力的一个显着的部分是由鞭毛虫。通过消耗和产生铵和亚硝酸盐，微生物群落在春季将这些营养素维持在相对较低的浓度。从夏末开始，随着日照的减少，溶解无机氮和碳酸盐浓度增加，表明海冰中无机氮和碳酸盐的生产（增加或不变）和消耗（减少）之间的不平衡。从春季到夏季，磷酸盐在海冰中积累，这与硝酸盐和亚硝酸盐浓度的耗尽不同（C* > C-w）。磷酸盐过量可以解释为一个更大的分配，以富磷的生物分子在冰藻水华加上对流损失过量溶解氮，优先的磷，和/或磷酸盐吸附到金属有机络合物。铵似乎也被有效地吸附到有机物上，可能对氮的流动性和可用性产生影响。这一数据集支持这样的观点，即海冰微生物群落在处理营养物质方面是高效的，但其动态与海洋表面沃茨中的动态完全不同，需要未来进行重点调查。
Antarctic pack ice is inhabited by a diverse and active microbial community reliant on nutrients for growth. Seeking patterns and overlooked processes, we performed a large-scale compilation of macro-nutrient data (hereafter termed nutrients) in Antarctic pack ice (306 ice-cores collected from 19 research cruises). Dissolved inorganic nitrogen and silicic acid concentrations change with time, as expected from a seasonally productive ecosystem. In winter, salinity-normalized nitrate and silicic acid concentrations (C*) in sea ice are close to seawater concentrations (C-w), indicating little or no biological activity. In spring, nitrate and silicic acid concentrations become partially depleted with respect to seawater (C* < C-w), commensurate with the seasonal build-up of ice microalgae promoted by increased insolation. Stronger and earlier nitrate than silicic acid consumption suggests that a significant fraction of the primary productivity in sea ice is sustained by flagellates. By both consuming and producing ammonium and nitrite, the microbial community maintains these nutrients at relatively low concentrations in spring. With the decrease in insolation beginning in late summer, dissolved inorganic nitrogen and silicic acid concentrations increase, indicating imbalance between their production (increasing or unchanged) and consumption (decreasing) in sea ice. Unlike the depleted concentrations of both nitrate and silicic acid from spring to summer, phosphate accumulates in sea ice (C* > C-w). The phosphate excess could be explained by a greater allocation to phosphorus-rich biomolecules during ice algal blooms coupled with convective loss of excess dissolved nitrogen, preferential remineralization of phosphorus, and/or phosphate adsorption onto metal-organic complexes. Ammonium also appears to be efficiently adsorbed onto organic matter, with likely consequences to nitrogen mobility and availability. This dataset supports the view that the sea ice microbial community is highly efficient at processing nutrients but with a dynamic quite different from that in oceanic surface waters calling for focused future investigations.