A laboratory study of ikaite (CaCO3·6H2O) precipitation as a function of pH, salinity, temperature and phosphate concentration
A laboratory study of ikaite (CaCO3·6H2O) precipitation as a function of pH, salinity, temperature and phosphate concentration
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水钙石 (CaCO3·6H2O) 沉淀随 pH、盐度、温度和磷酸盐浓度变化的实验室研究
DOI：
10.1016/j.marchem.2014.02.003
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发表时间：
2014
期刊：
影响因子：
3
通讯作者：
Nehrke
中科院分区：
文献类型：
--
作者：
Wolf-Gladrow;Dieckmann;Völker;Nehrke
Ikaite (CaCO3·6H2O) 最近才在海冰中被发现，这项研究也首次提供了海冰中 CaCO3 沉淀的直接证据。然而，目前人们对物理化学过程对海冰中伊卡石降水的影响知之甚少。我们的研究重点是 pH 值、盐度、温度和磷酸盐 (PO4) 浓度的变化如何影响伊卡石的沉淀。实验设置的条件为：pH 值从 8.5 到 10.0，盐度从 0 到 105（在人工海水 (ASW) 和 NaCl 介质中），温度从 0 到 − 4 °C，PO4 浓度从 0 到 50 μmol kg−1。结果表明，在 ASW 中，碳酸钙在所有条件下都会以藻石形式沉淀。在 NaCl 介质中，当 PO4 存在时，沉淀物为六方霰石；当 PO4 不存在时，沉淀物为球霰石。伊卡石沉淀开始的起始时间 (τ) 随着 pH 值的增加呈非线性下降。在 ASW 中，τ 随着盐度的增加而增加。在NaCl培养基中，τ首先随着盐度的增加而增加，直到盐度为70，随后随着盐度的进一步增加而减少；相同盐度下，ASW 中的时间比 NaCl 培养基中的时间长。 τ 不随温度或 PO4 浓度变化。这些结果表明，伊卡石很可能是海冰中形成的碳酸钙的唯一相。正如之前假设的那样，PO4 对于海冰中的伊卡石形成并不至关重要。 pH值和盐度的变化是海冰中伊卡石沉淀的控制因素。在本研究调查的范围内，温度和 PO4 浓度对伊卡石沉淀没有显着影响。
Ikaite (CaCO3·6H2O) has only recently been discovered in sea ice, in a study that also provided first direct evidence of CaCO3precipitation in sea ice. However, little is as yet known about the impact of physico-chemical processes on ikaite precipitation in sea ice. Our study focused on how the changes in pH, salinity, temperature and phosphate (PO4) concentration affect the precipitation of ikaite. Experiments were set up at pH from 8.5 to 10.0, salinities from 0 to 105 (in both artificial seawater (ASW) and NaCl medium), temperatures from 0 to − 4 °C and PO4concentrations from 0 to 50 μmol kg− 1. The results show that in ASW, calcium carbonate was precipitated as ikaite under all conditions. In the NaCl medium, the precipitates were ikaite in the presence of PO4and vaterite in the absence of PO4. The onset time (τ) at which ikaite precipitation started, decreased nonlinearly with increasing pH. In ASW, τ increased with salinity. In the NaCl medium, τ first increased with salinity up to salinity 70 and subsequently decreased with a further increase in salinity; it was longer in ASW than in the NaCl medium under the same salinity. τ did not vary with temperature or PO4concentration. These results indicate that ikaite is very probably the only phase of calcium carbonate formed in sea ice. PO4is not, as previously postulated, crucial for ikaite formation in sea ice. The change in pH and salinity is the controlling factor for ikaite precipitation in sea ice. Within the ranges investigated in this study, temperature and PO4concentration do not have a significant impact on ikaite precipitation.
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影响因子：
--
作者：
Nicolas-Xavier Geilfus;G. Carnat;G. Dieckmann;N. Halden;G. Nehrke;T. Papakyriakou;J. Tison;B. Delille
通讯作者：
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DOI：
--
发表时间：
1969
期刊：
影响因子：
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作者：
D. R. Kester;Ricardo M. Pytkowicx
通讯作者：
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影响因子：
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影响因子：
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