High winter ozone pollution from carbonyl photolysis in an oil and gas basin
High winter ozone pollution from carbonyl photolysis in an oil and gas basin
复制标题
DOI：
10.1038/nature13767
复制
发表时间：
2014-10-16
期刊：
影响因子：
64.8
通讯作者：
Zamora, Robert
中科院分区：
文献类型：
--
作者：
Edwards, Peter M.;Brown, Steven S.;Zamora, Robert
美国目前正在经历四十年来最快速的石油和天然气生产扩张，这在很大程度上要归功于水平钻井与水力压裂相结合等新开采技术的实施。这一发展对环境的影响，从对水质的影响(1)到甲烷泄漏增加对气候的影响(2)，一直是一个激烈争论的问题。空气质量影响与氮氧化物(3,4) (NOx = NO + NO2) 和挥发性有机化合物(5-7) (VOC) 的排放有关，其光化学作用会导致臭氧的产生，臭氧是一种对健康产生负面影响的二次污染物(8)。最近对美国西部石油和天然气生产盆地的观察发现，臭氧混合比远远超过目前的空气质量标准，但仅限于冬季(9-13)。了解这些地区冬季臭氧的产生具有科学挑战性。它发生在冰雪覆盖的寒冷时期，此时气象倒转使石油和天然气活动产生的空气污染物集中，但此时太阳辐照度和绝对湿度（这两者都是启动臭氧产生所必需的常规光化学所需的）处于最低水平。在这里，我们利用来自犹他州东北部石油和天然气盆地偏远地区的数据和箱模型，对导致这些极端冬季臭氧污染事件的光化学进行了定量评估，并确定了在这种独特环境中控制臭氧产生的关键因素。我们发现，与夏季城市相比，臭氧产生的氮氧化物浓度较低，挥发性有机化合物浓度高得多，导致羰基（具有 C=O 部分的含氧挥发性有机化合物）光解作用成为主要氧化剂源。极端的 VOC 浓度可优化 NOx 的臭氧生产效率。全球页岩油气开采增长潜力巨大。该分析可以帮助制定监测和减轻空气质量影响的策略，并为冬季臭氧对主要污染物的反应提供更广泛的见解。
The United States is now experiencing the most rapid expansion in oil and gas production in four decades, owing in large part to implementation of new extraction technologies such as horizontal drilling combined with hydraulic fracturing. The environmental impacts of this development, from its effect on water quality(1) to the influence of increased methane leakage on climate(2), have been a matter of intense debate. Air quality impacts are associated with emissions of nitrogen oxides(3,4) (NOx = NO + NO2) and volatile organic compounds(5-7) (VOCs), whose photochemistry leads to production of ozone, a secondary pollutant with negative health effects(8). Recent observations in oil-and gas-producing basins in the western United States have identified ozone mixing ratios well in excess of present air quality standards, but only during winter(9-13). Understanding winter ozone production in these regions is scientifically challenging. It occurs during cold periods of snow cover when meteorological inversions concentrate air pollutants from oil and gas activities, but when solar irradiance and absolute humidity, which are both required to initiate conventional photochemistry essential for ozone production, are at a minimum. Here, using data from a remote location in the oil and gas basin of northeastern Utah and a box model, we provide a quantitative assessment of the photochemistry that leads to these extreme winter ozone pollution events, and identify key factors that control ozone production in this unique environment. We find that ozone production occurs at lower NOx and much larger VOC concentrations than does its summertime urban counterpart, leading to carbonyl (oxygenated VOCs with a C=O moiety) photolysis as a dominant oxidant source. Extreme VOC concentrations optimize the ozone production efficiency of NOx. There is considerable potential for global growth in oil and gas extraction from shale. This analysis could help inform strategies to monitor and mitigate air quality impacts and provide broader insight into the response of winter ozone to primary pollutants.