Department of Chemistry and Biochemistry, Schmid College of Science and Technology, Chapman University, One University Drive, Orange, CA, 98266, USA.
Department of Chemistry, College of Science and Engineering, Western Washington University, 516 High Street, Bellingham, WA, 98225, USA.
Environ Sci Pollut Res Int. 2021 Jul;28(27):35811-35821. doi: 10.1007/s11356-021-13232-x. Epub 2021 Mar 6.
Acetaldehyde plays an important role in oxidative cycles in the troposphere. Estimates of its air-water flux are important in global models. Biological degradation is believed to be the dominant loss process in water, but there have been few measurements, none in estuaries. Acetaldehyde degradation rates were measured in surface waters at the inflow to the Upper Newport Back Bay estuary in Orange County, Southern California, USA, over a 6-month period including the rainy winter season. Deuterated acetaldehyde was added to filtered and unfiltered water samples incubated in glass syringes, and its loss analyzed by purge and trap gas chromatography mass spectrometry. Filtered samples showed no significant degradation, suggesting that particle-mediated degradation is the dominant removal process. Correlation between measured degradation rate constants in unfiltered incubations and bacteria counts suggests the loss is due to microorganisms. Degradation in unfiltered samples followed first-order kinetics, with rate constants ranging from 0.0006 to 0.025 min (k; average 0.0043 ± 0.006 min). Turnover (1/k) ranged from 40 to 1667 min, consistent with prior studies in coastal waters. Acetaldehyde concentrations in the estuary are estimated to range from 30 to ~500 nM (average ~250 nM). Results suggest the estuary is a source of acetaldehyde to the atmosphere.
乙醛在对流层的氧化循环中起着重要作用。其气-水通量的估计在全球模型中很重要。生物降解被认为是水中的主要损失过程，但测量很少，河口地区则没有。在美国加利福尼亚州奥兰治县的上纽波特后湾河口的入流处，在包括冬季多雨季节在内的 6 个月期间，测量了表层水中的乙醛降解速率。在装有玻璃注射器的过滤和未过滤水样中添加氘代乙醛，并通过吹扫捕集气相色谱质谱法分析其损失。过滤后的水样没有明显的降解，这表明颗粒介导的降解是主要的去除过程。未过滤孵育中测得的降解速率常数与细菌计数之间的相关性表明，损失是由于微生物造成的。未过滤样品中的降解遵循一级动力学，速率常数范围为 0.0006 至 0.025 min（k；平均值为 0.0043 ± 0.006 min）。周转率（1/k）范围为 40 至 1667 min，与沿海海域的先前研究一致。河口处的乙醛浓度估计范围为 30 至~500 nM（平均值约为 250 nM）。结果表明，河口是大气中乙醛的来源。
