Systematic review of forsterite dissolution rate data
Systematic review of forsterite dissolution rate data
复制标题
镁橄榄石溶解速率数据的系统审查
DOI：
10.1016/j.gca.2012.09.019
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发表时间：
2012
影响因子：
5
通讯作者：
A. Olsen
中科院分区：
文献类型：
--
作者：
J. Rimstidt;S. Brantley;A. Olsen
本文以镁橄榄石溶解为例，介绍了一种系统分析已发表的矿物溶解速率数据的方法。该方法的步骤是：（1）识别数据源，（2）选择数据，（3）将数据制成表格，（4）分析数据以产生模型，以及（5）报告结果。该方法允许基于理论预期和实验陷阱的专家知识对数据进行关键选择，并使用统计方法对数据进行荟萃分析。将该方法应用于目前所有可用的镁橄榄石溶解速率（0<pH<14，且0<T<150°C）归一化为几何表面积，产生以下速率方程：对于pH<5.6和0 ° <T <150 ° C，基于519数据基于125个数据的R2值表明，r中的± 10%的变化不能由1/T和pH的变化解释。尽管速率测量的实验误差应该是± 30%，与logr值相关的观测误差为± 0.5logunits（±300%相对误差）。与报告速率相关的无法解释的方差和大误差可能源于以下假设：当速率实际上由表面位点的浓度和相对反应性控制时，速率与矿物表面积（几何或BET）成正比，这可能是反应持续时间的函数。与这些表面积术语相关的是其他可能的误差来源，包括矿物起始材料的组成和制备。从BET表面积归一化速率产生类似的速率方程。基于几何和BET归一化速率的速率模型的比较不支持选择一种归一化方法。然而，实际考虑支持使用几何表面面积归一化。Mg和Si释放速率的比较表明，它们产生了统计学上不可区分的溶解速率，因为在整个pH范围内的实验中溶解是化学计量的，即使已知Mg和Si的表面浓度随pH变化。来自添加碳酸盐的实验的速率的比较，来自大于大气压的CO2分压或添加的碳酸盐，表明现有的数据集不足以量化溶解的碳酸盐物种对镁橄榄石溶解速率的任何影响。
This paper demonstrates a method for systematic analysis of published mineral dissolution rate data using forsterite dissolution as an example. The steps of the method are: (1) identify the data sources, (2) select the data, (3) tabulate the data, (4) analyze the data to produce a model, and (5) report the results. This method allows for a combination of critical selection of data, based on expert knowledge of theoretical expectations and experimental pitfalls, and meta-analysis of the data using statistical methods. Application of this method to all currently available forsterite dissolution rates (0<pH<14, and 0<T<150°C) normalized to geometric surface area produced the following rate equations: For pH<5.6 and 0°<T<150°C, based on 519 data For pH>5.6 and 0°<T<150°C, based on 125 data The R2values show that ∼10% of the variance in r is not explained by variation in 1/T and pH. Although the experimental error for rate measurements should be±∼30%, the observed error associated with the logr values is ∼0.5logunits (±300% relative error). The unexplained variance and the large error associated with the reported rates likely arises from the assumption that the rates are directly proportional to the mineral surface area (geometric or BET) when the rate is actually controlled by the concentration and relative reactivity of surface sites, which may be a function of duration of reaction. Related to these surface area terms are other likely sources of error that include composition and preparation of mineral starting material. Similar rate equations were produced from BET surface area normalized rates. Comparison of rate models based on geometric and BET normalized rates offers no support for choosing one normalization method over the other. However, practical considerations support the use of geometric surface area normalization. Comparison of Mg and Si release rates showed that they produced statistically indistinguishable dissolution rates because dissolution was stoichiometric in the experiments over the entire pH range even though the surface concentrations of Mg and Si are known to change with pH. Comparison of rates from experiments with added carbonate, either from CO2partial pressures greater than atmospheric or added carbonate salts, showed that the existing data set is not sufficient to quantify any effect of dissolved carbonate species on forsterite dissolution rates.