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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Nonequilibrium atmospheric secondary organic aerosol formation and growth
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Nonequilibrium atmospheric secondary organic aerosol formation and growth

机译:非平衡大气次级有机气溶胶的形成与生长

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Airborne particles play critical roles in air quality, health effects, visibility, and climate. Secondary organic aerosols (SOA) formed from oxidation of organic gases such as α-pinene account for a significant portion of total airborne particle mass. Current atmospheric models typically incorporate the assumption that SOA mass is a liquid into which semivolatile organic compounds undergo instantaneous equilibrium partitioning to grow the particles into the size range important for light scattering and cloud condensation nuclei activity. We report studies of particles from the oxidation of α-pinene by ozone and NO_3 radicals at room temperature. SOA is primarily formed from low-volatility ozonolysis products, with a small contribution from higher volatility organic nitrates from the NO_3 reaction. Contrary to expectations, the paniculate nitrate concentration is not consistent with equilibrium partitioning between the gas phase and a liquid particle. Rather the fraction of organic nitrates in the particles is only explained by irreversible, kinetically determined uptake of the nitrates on existing particles, with an uptake coefficient that is 1.6% of that for the ozonolysis products. If the nonequilibrium particle formation and growth observed in this atmospherically important system is a general phenomenon in the atmosphere, aerosol models may need to be reformulated. The reformulation of aerosol models could impact the predicted evolution of SOA in the atmosphere both outdoors and indoors, its role in heterogeneous chemistry, its projected impacts on air quality, visibility, and climate, and hence the development of reliable control strategies.
机译:空气中的微粒在空气质量,健康影响,能见度和气候中起着关键作用。由有机气体(例如α-pine烯)氧化形成的二次有机气溶胶(SOA)占了空气中颗粒物总量的很大一部分。当前的大气模型通常包含以下假设:SOA质量是一种液体,半挥发性有机化合物会在其中进行瞬时平衡分配,以使粒子生长到对光散射和云凝结核活性重要的尺寸范围内。我们报告了在室温下臭氧和NO_3自由基对α-pine烯氧化产生的颗粒的研究。 SOA主要由低挥发性的臭氧分解产物形成,而NO_3反应的较高挥发性的有机硝酸盐贡献很小。与预期相反,颗粒状硝酸盐的浓度与气相和液相之间的平衡分配不一致。而是仅通过不可逆的,动力学确定的现有颗粒上硝酸盐的吸收来解释颗粒中有机硝酸盐的比例,其吸收系数是臭氧分解产物的吸收系数的1.6%。如果在这一对大气重要的系统中观察到的非平衡颗粒形成和生长是大气中的普遍现象,则可能需要重新制定气溶胶模型。气溶胶模型的重新制定可能会影响SOA在室外和室内大气中的预测演变,其在异质化学中的作用,对空气质量,能见度和气候的预测影响,从而影响可靠控制策略的发展。

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