Degradation of polyethylene glycols and polypropylene glycols in microcosms simulating a spill of produced water in shallow groundwater
Degradation of polyethylene glycols and polypropylene glycols in microcosms simulating a spill of produced water in shallow groundwater
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DOI：
10.1039/c8em00291f
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发表时间：
2019-02-01
影响因子：
5.5
通讯作者：
Ryan，Joseph N.
中科院分区：
文献类型：
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作者：
Rogers，Jessica D.;Thurman，E. Michael;Ryan，Joseph N.
聚乙二醇（peg）和聚丙烯乙二醇（PPGs）是常用的水力压裂液，在多个盆地的水力压裂油气井返地水中都检测到了聚乙二醇和聚丙烯乙二醇。在模拟采出水向浅层地下水溢出的条件下，我们确定了peg和PPGs的降解途径和动力学。采用Denver-Julesburg盆地两口井的4口采出水样进行了早期和后期的沉积物-地下水微观实验。采用高分辨率质谱法分别鉴定了PEG和PPG生物降解产物单羧基化和双羧基化PPGs的形成。在氧条件下，peg的一级半衰期（< 0.4-1.1 d）比PPGs （2.5-14 d）更快。PEG和PPG的降解与16S rRNA基因宏基因组分析预测的初级醇脱氢酶基因的相对丰度增加相对应。在缺氧条件下未观察到进一步的降解。我们的研究结果揭示了聚乙二醇（peg）和聚乙二醇（PPGs）降解速率和途径之间的差异，这可以用来更好地表征采出水释放后浅层地下水污染。
Polyethylene glycols (PEGs) and polypropylene glycols (PPGs) are frequently used in hydraulic fracturing fluids and have been detected in water returning to the surface from hydraulically fractured oil and gas wells in multiple basins. We identified degradation pathways and kinetics for PEGs and PPGs under conditions simulating a spill of produced water to shallow groundwater. Sediment-groundwater microcosm experiments were conducted using four produced water samples from two Denver-Julesburg Basin wells at early and late production. High-resolution mass spectrometry was used to identify the formation of mono- and di-carboxylated PEGs and mono-carboxylated PPGs, which are products of PEG and PPG biodegradation, respectively. Under oxic conditions, first-order half-lives were more rapid for PEGs (<0.4–1.1 d) compared to PPGs (2.5–14 d). PEG and PPG degradation corresponded to increased relative abundance of primary alcohol dehydrogenase genes predicted from metagenome analysis of the 16S rRNA gene. Further degradation was not observed under anoxic conditions. Our results provide insight into the differences between the degradation rates and pathways of PEGs and PPGs, which may be utilized to better characterize shallow groundwater contamination following a release of produced water.