Abiotic reduction of contaminants in iron-based laboratory model systems has been studied extensively, but the resulting understanding is not sufficient to allow prediction of reaction rates under field conditions. This study demonstrates that rates of contaminant reduction by aquifer sediments can be predicted by combining several recent methodological innovations into an integrated protocol that is amenable to use on field samples. The protocol involves (i) cryogenic collection of core samples to preserve redox conditions, (ii) contaminant reduction rate measurements, (iii) oxidation–reduction potential measurements of sediments using electron shuttle-mediated potentiometry, and (iv) regression analysis of mass-normalized rate constants for contaminant reduction and reduction potential. The protocol was demonstrated using carbon tetrachloride as the model contaminant and 43 aquifer sediment samples from nine locations at four sites. The abiotic rate of degradation covers 5 orders of magnitude and a 450 mV potential range. The 95% confidence interval was used to represent the minimum reactivity that would be observed at each of the field sites under the measured reduction potentials. This provides a novel and effective protocol for screening abiotic reduction capabilities or establishing site specific rates.

中文翻译：

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使用低温收集的土壤核和介导的还原电位测量预测非生物还原速率

已经对铁基实验室模型系统中污染物的非生物还原进行了广泛的研究，但由此产生的认识不足以预测田间条件下的反应速率。这项研究表明，可以通过将几种最新的方法学创新结合到一个适用于田间样品的综合方案中，来预测含水层沉积物减少污染物的速度。该协议涉及（i）低温收集核心样品以保存氧化还原条件，（ii）污染物减少率测量，（iii）使用电子梭介导的电位计测量沉积物的氧化还原电位，以及（iv）质量回归分析。归一化的速率常数，用于减少污染物和还原电位。使用四氯化碳作为模型污染物并从四个地点的九个地点的43个含水层沉积物样本中证明了该方案。非生物降解速率涵盖5个数量级和450 mV的电位范围。95％的置信区间用来表示在测得的还原电位下在每个现场所观察到的最小反应性。这为筛选非生物还原能力或确定特定部位的速率提供了一种新颖有效的方案。95％的置信区间用来表示在测得的还原电位下在每个现场所观察到的最小反应性。这为筛选非生物还原能力或确定特定部位的速率提供了一种新颖有效的方案。95％的置信区间用来表示在测得的还原电位下在每个现场所观察到的最小反应性。这为筛选非生物还原能力或确定特定部位的速率提供了新颖有效的方案。