Anthropogenic enhancements to production of highly oxygenated molecules from autoxidation

Proceedings of the National Academy of Sciences, Год журнала: 2019, Номер 116(14), С. 6641 - 6646

Опубликована: Март 18, 2019

Atmospheric oxidation of natural and anthropogenic volatile organic compounds (VOCs) leads to secondary aerosol (SOA), which constitutes a major often dominant component atmospheric fine particulate matter (PM2.5). Recent work demonstrates that rapid autoxidation peroxy radicals (RO2) formed during VOC results in highly oxygenated molecules (HOM) efficiently form SOA. As NOx emissions decrease, the chemical regime atmosphere changes one RO2 becomes increasingly important, potentially increasing PM2.5, while oxidant availability driving formation rates simultaneously declines, possibly slowing regional PM2.5 formation. Using suite situ aircraft observations laboratory studies HOM, together with detailed molecular mechanism, we show although an archetypal biogenic system more competitive as decreases, absolute HOM production decrease due reductions, leading overall positive coupling between localized SOA from autoxidation. This effect is observed Atlanta, Georgia, urban plume where enhanced presence elevated NO, predictions for Guangzhou, China, HOM-RO2 coincides increases NO 1990 2010. These suggest added benefits abatement strategies come emission reductions have implications aerosol-climate interactions global resulting since preindustrial era.

Язык: Английский

---

The role of highly oxygenated organic molecules in the Boreal aerosol-cloud-climate system

Nature Communications, Год журнала: 2019, Номер 10(1)

Опубликована: Сен. 25, 2019

Abstract Over Boreal regions, monoterpenes emitted from the forest are main precursors for secondary organic aerosol (SOA) formation and primary driver of growth new particles to climatically important cloud condensation nuclei (CCN). Autoxidation leads rapid Highly Oxygenated Molecules (HOM). We have developed first model with near-explicit representation atmospheric particle (NPF) HOM formation. The can reproduce observed NPF, gas-phase composition SOA over forest. During spring, increases CCN concentration by ~10 % causes a direct radiative forcing −0.10 W/m 2 . In contrast, NPF reduces number at updraft velocities < 0.2 m/s, +0.15 Hence, while contributes climate cooling, result in warming

Язык: Английский

---

Hydroxyl radicals from secondary organic aerosol decomposition in water

Atmospheric chemistry and physics, Год журнала: 2016, Номер 16(3), С. 1761 - 1771

Опубликована: Фев. 15, 2016

Abstract. We found that ambient and laboratory-generated secondary organic aerosols (SOA) form substantial amounts of OH radicals upon interaction with liquid water, which can be explained by the decomposition hydroperoxides. The molar yield from SOA formed ozonolysis terpenes (α-pinene, β-pinene, limonene) is ∼ 0.1 % extraction pure water increases to 1.5 in presence Fe2+ ions due Fenton-like reactions. Upon samples photooxidation isoprene, we also detected yields around %, addition Fe2+. Our findings imply chemical reactivity aging particles strongly enhanced iron. In cloud droplets under dark conditions, compete classical H2O2 Fenton reaction as source radicals. Also human respiratory tract, inhalation deposition may lead a release radicals, contribute oxidative stress play an important role adverse health effects atmospheric aerosols.

Язык: Английский

---

Chemical Characterization of Secondary Organic Aerosol from Oxidation of Isoprene Hydroxyhydroperoxides

Environmental Science & Technology, Год журнала: 2016, Номер 50(18), С. 9889 - 9899

Опубликована: Июль 28, 2016

Atmospheric oxidation of isoprene under low-NOx conditions leads to the formation hydroxyhydroperoxides (ISOPOOH). Subsequent ISOPOOH largely produces epoxydiols (IEPOX), which are known secondary organic aerosol (SOA) precursors. Although SOA from IEPOX has been previously examined, systematic studies characterization through a non-IEPOX route 1,2-ISOPOOH lacking. In present work, authentic was systematically examined with varying compositions and relative humidity. High yields highly oxidized compounds, including multifunctional organosulfates (OSs) hydroperoxides, were chemically characterized in both laboratory-generated fine samples collected southeastern U.S. IEPOX-derived constituents observed all experiments, but their concentrations only enhanced presence acidified sulfate aerosol, consistent prior work. High-resolution mass spectrometry (HR-AMS) reveals that 1,2-ISOPOOH-derived formed routes exhibits notable spectrum characteristic fragment ion at m/z 91. This is strongly correlated factor recently resolved by positive matrix factorization (PMF) spectrometer data areas dominated emissions, suggesting pathway could contribute ambient measured Southeastern United States.

Язык: Английский

---

Multi-generation OH oxidation as a source for highly oxygenated organic molecules from aromatics

Atmospheric chemistry and physics, Год журнала: 2020, Номер 20(1), С. 515 - 537

Опубликована: Янв. 15, 2020

Abstract. Recent studies have recognised highly oxygenated organic molecules (HOMs) in the atmosphere as important formation of secondary aerosol (SOA). A large number focused on HOM from oxidation biogenically emitted monoterpenes. However, anthropogenic vapours has so far received much less attention. Previous identified importance aromatic volatile compounds (VOCs) for SOA formation. In this study, we investigated several compounds, benzene (C6H6), toluene (C7H8), and naphthalene (C10H8), their potential to form HOMs upon reaction with hydroxyl radicals (OH). We performed flow tube experiments all three VOCs detail Jülich Plant Atmosphere Chamber (JPAC). JPAC, also response NOx seed aerosol. Using a nitrate-based chemical ionisation mass spectrometer (CI-APi-TOF), observed reactor first OH attack. naphthalene, which were injected at lower concentrations, multi-generation seemed impact composition. tested more system allowed studying longer residence times. The results showed that apparent molar yield under our experimental conditions varied 4.1 % 14.0 %, strong dependence concentration, indicating majority formed through multiple OH-oxidation steps. composition spectrum supported hypothesis. By injecting only phenol into chamber, found cannot be solely responsible experiments. When was added changed many nitrogen-containing products CI-APi-TOF. Upon injection, loss rate higher than predicted by irreversible condensation, suggesting some undetected intermediates condensed onto aerosol, is line hypothesis oxidation. Based results, conclude systems strongly depend VOC concentration are needed fully understand effect and, consequently, SOA. suggest chamber may explain part variability yields reported literature advise monitoring future studies.

Язык: Английский

---