First estimates of the contribution of CaCO3 precipitation to the release of CO2 to the atmosphere during young sea ice growth
First estimates of the contribution of CaCO3 precipitation to the release of CO2 to the atmosphere during young sea ice growth
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DOI：
10.1029/2012jc007980
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发表时间：
2013
影响因子：
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通讯作者：
Nicolas-Xavier Geilfus;G. Carnat;G. Dieckmann;N. Halden;G. Nehrke;T. Papakyriakou;J. Tison;B. Delille
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文献类型：
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作者：
Nicolas-Xavier Geilfus;G. Carnat;G. Dieckmann;N. Halden;G. Nehrke;T. Papakyriakou;J. Tison;B. Delille
[1]我们报道了霜花(FF)和薄陆冰的pH、总碱度、空气-冰CO2通量(室法)和CaCO3含量的测量。随着温度的降低，卤水脱脂中的溶质浓度增加。在这个逐渐浓缩的过程中，一些盐达到了它们的溶解阈值并开始沉淀。拉曼光谱和X-射线分析证实，在浮冰和整个冰层中都有伊开石(CaCO3.6H2O)的析出。据估计，在FF中，伊卡伊石的沉淀量为25微摩尔·kg·−-1熔融的Ff，在冰层的上部和底部分别从19-15µm o l·kg-−-1融化的冰减少。碳酸钙沉淀产生的二氧化碳释放量估计为50微摩尔公斤−-1熔融样品。盐度归一化为10的溶解无机碳(DIC)在冰的上层和浮冰中表现出显著的耗竭。这一DIC损失量估计为2069微摩尔·公斤−-1熔融样品，相当于从冰到大气的二氧化碳释放量为20-40mmolm-−-2d−-1。我们的测量证实了之前的实验室发现，不断增长的年轻海冰是大气中二氧化碳的来源。早期冰生长期间的CaCO3降水似乎促进了二氧化碳向大气的释放；然而，它对新形成的冰的总体释放的贡献很可能很小。
[1] We report measurements of pH, total alkalinity, air-ice CO2 fluxes (chamber method), and CaCO3 content of frost flowers (FF) and thin landfast sea ice. As the temperature decreases, concentration of solutes in the brine skim increases. Along this gradual concentration process, some salts reach their solubility threshold and start precipitating. The precipitation of ikaite (CaCO3.6H2O) was confirmed in the FF and throughout the ice by Raman spectroscopy and X-ray analysis. The amount of ikaite precipitated was estimated to be 25 µmol kg−1 melted FF, in the FF and is shown to decrease from 19 to 15 µmol kg−1 melted ice in the upper part and at the bottom of the ice, respectively. CO2 release due to precipitation of CaCO3 is estimated to be 50 µmol kg−1 melted samples. The dissolved inorganic carbon (DIC) normalized to a salinity of 10 exhibits significant depletion in the upper layer of the ice and in the FF. This DIC loss is estimated to be 2069 µmol kg−1 melted sample and corresponds to a CO2 release from the ice to the atmosphere ranging from 20 to 40 mmol m−2 d−1. This estimate is consistent with flux measurements of air-ice CO2 exchange. Our measurements confirm previous laboratory findings that growing young sea ice acts as a source of CO2 to the atmosphere. CaCO3 precipitation during early ice growth appears to promote the release of CO2 to the atmosphere; however, its contribution to the overall release by newly formed ice is most likely minor.