A new approach for measuring dissolution rates of silicate minerals by using silicon isotopes
A new approach for measuring dissolution rates of silicate minerals by using silicon isotopes
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利用硅同位素测量硅酸盐矿物溶解速率的新方法
DOI：
10.1016/j.gca.2012.11.022
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发表时间：
2013
影响因子：
5
通讯作者：
Ganor, Jiwchar
中科院分区：
文献类型：
--
作者：
Gruber, Chen;Harpaz, Liat;Zhu, Chen;Bullen, Tom D.;Ganor, Jiwchar
在实验室实验中测量接近自然条件下的溶解速率的两个主要问题是：（1）我们无法测量浓度相对较高的溶液之间的微小浓度差异；（2）溶液浓度的变化同时受到原生矿物溶解和次生矿物沉淀影响的固有问题。本手稿提出并测试了一种新方法，即“同位素比率法”，通过测量加标溶液中硅稳定同位素之间比率的变化来测量硅酸盐矿物的缓慢溶解速率。基于质量平衡计算，建立了两个方程来描述稳态下硅酸盐矿物在间歇式反应器和流通式反应器中的溶解速率。次生矿物的沉淀速率可以通过从使用所提出的同位素比率方法计算的速率减去使用同位素稀释计算的Si释放速率来计算。流通式和批量实验的数值模拟表明，“同位素比法”明显比传统方法更精确。发现对于报告的基于现场的溶出率的整个范围来说，确定溶出率的分析不确定度较低。计算表明，即使是相对较大的同位素分馏（高达 20% 的 ε 值），引入的不确定性也微不足道。初步的流通实验支持了上述结论，即使用所提出的“同位素比法”可以准确地获得溶解速率，且不确定性较小。
The two major problems in measuring dissolution rates under close-to-natural conditions in laboratory experiments are: (1) our inability to measure small differences in concentration between solutions with relatively high concentrations and (2) the inherent problem that the change in solution concentration is affected by both the dissolution of the primary mineral and the precipitation of secondary minerals. The present manuscript proposes and tests a novel method, “the isotope ratio method”, for measuring slow dissolution rates of silicate minerals by measuring the change in the ratios between stable isotopes of silicon of a spiked solution. Based on mass balance calculations, two equations that describe the dissolution rate of a silicate mineral in a batch reactor and in a flow-through reactor at steady-state are developed. The precipitation rate of the secondary mineral may be calculated by subtracting the release rate of Si that was calculated using isotope dilution from the rate that was calculated using the proposed isotope ratio method. Numerical simulations of flow-through and batch experiments demonstrate that the “isotope ratio method” is significantly more precise than conventional methods. The analytical uncertainty for the determination of dissolution rates was found to be low for the entire range of reported field-based dissolution rates. The calculation showed that even relatively large isotopic fractionations (up to ε values of 20‰), introduce insignificant uncertainties. Preliminary flow-through experiments support the above conclusion that dissolution rate may be obtained accurately and with small uncertainty using the proposed “isotope ratio method”.
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影响因子：
5
作者：
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通讯作者：
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DOI：
--
发表时间：
2007
期刊：
影响因子：
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通讯作者：
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DOI：
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发表时间：
1992
期刊：
影响因子：
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作者：
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DOI：
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发表时间：
1999
期刊：
影响因子：
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作者：
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