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1.
Proc Natl Acad Sci U S A ; 110(19): 7550-5, 2013 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-23620519

RESUMO

The production, size, and chemical composition of sea spray aerosol (SSA) particles strongly depend on seawater chemistry, which is controlled by physical, chemical, and biological processes. Despite decades of studies in marine environments, a direct relationship has yet to be established between ocean biology and the physicochemical properties of SSA. The ability to establish such relationships is hindered by the fact that SSA measurements are typically dominated by overwhelming background aerosol concentrations even in remote marine environments. Herein, we describe a newly developed approach for reproducing the chemical complexity of SSA in a laboratory setting, comprising a unique ocean-atmosphere facility equipped with actual breaking waves. A mesocosm experiment was performed in natural seawater, using controlled phytoplankton and heterotrophic bacteria concentrations, which showed SSA size and chemical mixing state are acutely sensitive to the aerosol production mechanism, as well as to the type of biological species present. The largest reduction in the hygroscopicity of SSA occurred as heterotrophic bacteria concentrations increased, whereas phytoplankton and chlorophyll-a concentrations decreased, directly corresponding to a change in mixing state in the smallest (60-180 nm) size range. Using this newly developed approach to generate realistic SSA, systematic studies can now be performed to advance our fundamental understanding of the impact of ocean biology on SSA chemical mixing state, heterogeneous reactivity, and the resulting climate-relevant properties.


Assuntos
Aerossóis/química , Atmosfera/química , Bactérias/metabolismo , Fitoplâncton/metabolismo , Água do Mar/química , Clorofila/química , Clorofila A , Ecologia , Oceanografia , Oceanos e Mares
2.
Proc Natl Acad Sci U S A ; 107(15): 6640-5, 2010 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-20080572

RESUMO

Isoprene is a significant source of atmospheric organic aerosol; however, the oxidation pathways that lead to secondary organic aerosol (SOA) have remained elusive. Here, we identify the role of two key reactive intermediates, epoxydiols of isoprene (IEPOX = beta-IEPOX + delta-IEPOX) and methacryloylperoxynitrate (MPAN), which are formed during isoprene oxidation under low- and high-NO(x) conditions, respectively. Isoprene low-NO(x) SOA is enhanced in the presence of acidified sulfate seed aerosol (mass yield 28.6%) over that in the presence of neutral aerosol (mass yield 1.3%). Increased uptake of IEPOX by acid-catalyzed particle-phase reactions is shown to explain this enhancement. Under high-NO(x) conditions, isoprene SOA formation occurs through oxidation of its second-generation product, MPAN. The similarity of the composition of SOA formed from the photooxidation of MPAN to that formed from isoprene and methacrolein demonstrates the role of MPAN in the formation of isoprene high-NO(x) SOA. Reactions of IEPOX and MPAN in the presence of anthropogenic pollutants (i.e., acidic aerosol produced from the oxidation of SO(2) and NO(2), respectively) could be a substantial source of "missing urban SOA" not included in current atmospheric models.


Assuntos
Aerossóis/química , Monitoramento Ambiental/métodos , Oxigênio/química , Ácidos/química , Atmosfera , Butadienos/química , Cromatografia Gasosa-Espectrometria de Massas/métodos , Hemiterpenos/química , Luz , Modelos Químicos , Nitratos/química , Pentanos/química , Fotoquímica/métodos , Espectrometria de Massas por Ionização por Electrospray/métodos , Sulfatos/química
3.
Inhal Toxicol ; 24(11): 689-97, 2012 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-22954394

RESUMO

The biological response to inhalation of secondary organic aerosol (SOA) was determined in rodents exposed to SOA derived from the oxidation of toluene, a precursor emitted from anthropogenic sources. SOA atmospheres were produced to yield 300 µg·m(-3) of particulate matter (PM) plus accompanying gases. Whole-body exposures were conducted in mice to assess both pulmonary and cardiovascular effects. ApoE(-/-) mice were exposed for 7 days and measurements of TBARS and gene expression of heme-oxygenase-1 (HO-1), endothelin-1 (ET-1), and matrix metalloproteinase-9 (MMP-9) were made in aorta. Pulmonary inflammatory responses in both species were measured by bronchoalveolar lavage fluid (BALF) cell counts. No pulmonary inflammation was observed. A mild response was observed in mouse aorta for the upregulation of ET-1 and HO-1, with a trend for increased MMP-9 and TBARS, and. Overall, toluene-derived SOA revealed limited biological response compared with previous studies using this exposure protocol with other environmental pollutants.


Assuntos
Aerossóis/química , Aerossóis/toxicidade , Poluentes Atmosféricos/toxicidade , Tolueno/química , Tolueno/toxicidade , Poluentes Atmosféricos/química , Animais , Apolipoproteínas E/genética , Apolipoproteínas E/metabolismo , Câmaras de Exposição Atmosférica , Gases , Regulação da Expressão Gênica , Exposição por Inalação , Masculino , Camundongos , Camundongos Knockout , Estrutura Molecular , Oxirredução
4.
Contemp Clin Trials ; 108: 106520, 2021 09.
Artigo em Inglês | MEDLINE | ID: mdl-34332159

RESUMO

BACKGROUND: Near highway residents are exposed to elevated levels of traffic-related air pollution (TRAP), including ultrafine particles, which are associated with adverse health effects. The efficacy of using in-home air filtration units that reduce exposure and potentially yield health benefits has not been tested in a randomized controlled trial. METHODS: We will conduct a randomized double-blind crossover trial of portable air filtration units for 200 adults 30 years and older who live in near-highway homes in Somerville, MA, USA. We will recruit participants from 172 households. The intervention periods will be one month of true or sham filtration, followed by a one-month wash out period and then a month of the alternate intervention. The primary health outcome will be systolic blood pressure (BP); secondary outcome measures will include diastolic and central BP, C-Reactive Protein (CRP) and D-dimer. Reasons for success or failure of the intervention will be evaluated in a subset of homes using indoor/outdoor monitoring for particulate pollution, personal monitoring, size and composition of particulate pollution, tracking of time spent in the room with the filter, and interviews for qualitative feedback. RESULTS: This trial has begun recruitment and is expected to take 2-3 years to be completed. Recruitment has been particularly challenging because of additional precautions required by the COVID-19 pandemic. DISCUSSION: This study has the potential to shed light on the value of using portable air filtration in homes close to highways to reduce exposure to TRAP and whether doing so has benefits for cardiovascular health.


Assuntos
COVID-19 , Doenças Cardiovasculares , Adulto , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Estudos Cross-Over , Fatores de Risco de Doenças Cardíacas , Humanos , Pandemias , Fatores de Risco , SARS-CoV-2
5.
Sci Data ; 5: 180026, 2018 02 27.
Artigo em Inglês | MEDLINE | ID: mdl-29485627

RESUMO

Airborne measurements of meteorological, aerosol, and stratocumulus cloud properties have been harmonized from six field campaigns during July-August months between 2005 and 2016 off the California coast. A consistent set of core instruments was deployed on the Center for Interdisciplinary Remotely-Piloted Aircraft Studies Twin Otter for 113 flight days, amounting to 514 flight hours. A unique aspect of the compiled data set is detailed measurements of aerosol microphysical properties (size distribution, composition, bioaerosol detection, hygroscopicity, optical), cloud water composition, and different sampling inlets to distinguish between clear air aerosol, interstitial in-cloud aerosol, and droplet residual particles in cloud. Measurements and data analysis follow documented methods for quality assurance. The data set is suitable for studies associated with aerosol-cloud-precipitation-meteorology-radiation interactions, especially owing to sharp aerosol perturbations from ship traffic and biomass burning. The data set can be used for model initialization and synergistic application with meteorological models and remote sensing data to improve understanding of the very interactions that comprise the largest uncertainty in the effect of anthropogenic emissions on radiative forcing.

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