Accuracy of methods for reporting inorganic element concentrations and radioactivity in oil and gas wastewaters from the Appalachian Basin, U.S. based on an inter-laboratory comparison
Accuracy of methods for reporting inorganic element concentrations and radioactivity in oil and gas wastewaters from the Appalachian Basin, U.S. based on an inter-laboratory comparison
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基于实验室间比较的美国阿巴拉契亚盆地石油和天然气废水中无机元素浓度和放射性报告方法的准确性
DOI：
10.1039/c8em00359a
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Johnsen, A. M.
中科院分区：
文献类型：
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作者：
Tasker, T. L.;Burgos, W. D.;Ajemigbitse, M. A.;Lauer, N. E.;Gusa, A. V.;Kuatbek, M.;May, D.;Landis, J. D.;Alessi, D. S.;Johnsen, A. M.
准确准确地分析油气废水和固体（如沉积物和污泥）对于油气开发的监管监测和追踪环境中潜在的油气污染非常重要。在这项研究中，15个实验室参与了对来自Appalachian盆地的三种油气废水和四种受油气开发影响的固体的化学特性的实验室间比较，目的是评估数据的质量和各种分析物的测量准确性。使用各种不同的方法，高浓度（即bbb50 mg L−1）废水中的分析物易于检测，准确度相对较高，通常在最可能值（MPV）的±10%以内。相比之下，通常15个实验室中只有不到7个能够报告可检测的痕量金属（样蛋白）浓度（即Cr、Ni、Cu、Zn、As和Pb），准确度约为±40%。尽管大多数实验室使用电感耦合等离子体质谱（ICP-MS）进行痕量金属分析，但仪器检测能力较低，样品制备过程中的稀释系数大，废水中痕量金属浓度低，限制了可量化测定的数量，并可能影响分析准确性。相比之下，所有测量废水中Ra的实验室都能够使用各种方法报告可检测的浓度，包括伽马光谱和湿化学方法，这些方法遵循美国环境保护局（EPA）的标准方法。然而，报告的镭活度与MPV的差异通常大于±30%，这可能是由于实验室之间的校准不一致、氡泄漏或未能纠正自衰减。固体材料中报告的镭活度变化较小（MPV±20%），但通过使用经认证的镭标准并考虑基体干扰或校准标准物与未知样品之间的密度差导致的自衰减，准确度可能会提高。这种实验室间的比较表明，有许多方法可以用于测量油气废水中的主要阳离子、次要阳离子和阴离子浓度，准确度相对较高，而液体中的痕量金属（样蛋白）和放射性分析通常与MPV的误差超过±20%。
Accurate and precise analyses of oil and gas (O&G) wastewaters and solids (e.g., sediments and sludge) are important for the regulatory monitoring of O&G development and tracing potential O&G contamination in the environment. In this study, 15 laboratories participated in an inter-laboratory comparison on the chemical characterization of three O&G wastewaters from the Appalachian Basin and four solids impacted by O&G development, with the goal of evaluating the quality of data and the accuracy of measurements for various analytes of concern. Using a variety of different methods, analytes in the wastewaters with high concentrations (i.e., >5 mg L−1) were easily detectable with relatively high accuracy, often within ±10% of the most probable value (MPV). In contrast, often less than 7 of the 15 labs were able to report detectable trace metal(loid) concentrations (i.e., Cr, Ni, Cu, Zn, As, and Pb) with accuracies of approximately ±40%. Despite most labs using inductively coupled plasma mass spectrometry (ICP-MS) with low instrument detection capabilities for trace metal analyses, large dilution factors during sample preparation and low trace metal concentrations in the wastewaters limited the number of quantifiable determinations and likely influenced analytical accuracy. In contrast, all the labs measuring Ra in the wastewaters were able to report detectable concentrations using a variety of methods including gamma spectroscopy and wet chemical approaches following Environmental Protection Agency (EPA) standard methods. However, the reported radium activities were often greater than ±30% different to the MPV possibly due to calibration inconsistencies among labs, radon leakage, or failing to correct for self-attenuation. Reported radium activities in solid materials had less variability (±20% from MPV) but accuracy could likely be improved by using certified radium standards and accounting for self-attenuation that results from matrix interferences or a density difference between the calibration standard and the unknown sample. This inter-laboratory comparison illustrates that numerous methods can be used to measure major cation, minor cation, and anion concentrations in O&G wastewaters with relatively high accuracy while trace metal(loid) and radioactivity analyses in liquids may often be over ±20% different from the MPV.