Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia.
Isoprene photo-oxidation products quantify the effect of pollution on hydroxyl radicals over Amazonia.
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DOI：
10.1126/sciadv.aar2547
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发表时间：
2018-04
期刊：
影响因子：
13.6
通讯作者：
Martin ST
中科院分区：
文献类型：
--
作者：
Liu Y;Seco R;Kim S;Guenther AB;Goldstein AH;Keutsch FN;Springston SR;Watson TB;Artaxo P;Souza RAF;McKinney KA;Martin ST
异戊二烯氧化的观测证据表明，氮氧化物放大了亚马逊森林上空的OH浓度。人类活动排放的氮氧化物（NOx）被认为调节对流层的大气氧化能力。然而，对于污染地区以外普遍存在的低至中位数氮氧化物浓度，观测证据有限。直接测量氧化能力（主要由羟基自由基（OH）表示）是具有挑战性的，而且单个观测点的NOx浓度跨度通常不宽。用异戊二烯及其光氧化产物的浓度来推断正午的等效OH浓度。亚马孙河流域中部某观测点的取水经历了背景区域空气、城市污染和生物质燃烧的不同贡献。下午的活性氮氧化物（NOy）浓度介于十亿分之0.3至3.5之间，反映了前几个小时的氮氧化物暴露情况。随着NOy浓度的增加，推断的正午OH当量浓度从0.6 × 106增加到1.6 × 106 cm−3，至少增加了250%。综上所述，与亚马逊森林低NOx浓度的背景条件相比，污染增加了NOx浓度并放大了OH浓度，表明森林大气氧化能力容易受到人为影响，并强化了NOx在维持OH浓度中的重要作用。
Observational evidence of isoprene oxidation shows that nitrogen oxides amplify the OH concentrations over the Amazon forest. Nitrogen oxides (NOx) emitted from human activities are believed to regulate the atmospheric oxidation capacity of the troposphere. However, observational evidence is limited for the low-to-median NOx concentrations prevalent outside of polluted regions. Directly measuring oxidation capacity, represented primarily by hydroxyl radicals (OH), is challenging, and the span in NOx concentrations at a single observation site is often not wide. Concentrations of isoprene and its photo-oxidation products were used to infer the equivalent noontime OH concentrations. The fetch at an observation site in central Amazonia experienced varied contributions from background regional air, urban pollution, and biomass burning. The afternoon concentrations of reactive nitrogen oxides (NOy), indicative of NOx exposure during the preceding few hours, spanned from 0.3 to 3.5 parts per billion. Accompanying the increase of NOy concentration, the inferred equivalent noontime OH concentrations increased by at least 250% from 0.6 × 106 to 1.6 × 106 cm−3. The conclusion is that, compared to background conditions of low NOx concentrations over the Amazon forest, pollution increased NOx concentrations and amplified OH concentrations, indicating the susceptibility of the atmospheric oxidation capacity over the forest to anthropogenic influence and reinforcing the important role of NOx in sustaining OH concentrations.
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影响因子：
18.3
作者：
Fuchs, H.;Hofzumahaus, A.;Wahner, A.
通讯作者：
Wahner, A.
影响因子：
6.3
作者：
de Sa, Suzane S.;Palm, Brett B.;Martin, Scot T.
通讯作者：
Martin, Scot T.
影响因子：
6.3
作者：
Dusanter, S.;Vimal, D.;Holder, H.
通讯作者：
Holder, H.
影响因子：
6.3
作者：
Jenkin, M. E.;Young, J. C.;Rickard, A. R.
通讯作者：
Rickard, A. R.
影响因子：
6.3
作者：
Liu, Y. J.;Herdlinger-Blatt, I.;Martin, S. T.
通讯作者：
Martin, S. T.