Airborne observations reveal elevational gradient in tropical forest isoprene emissions

Gu, Dasa; Guenther, Alex; Shilling, John E.; Yu, Haofei; Huang, Maoyi; Zhao, Chun; Yang, Qing; Martin, Scot T.; Artaxo, Paulo; Kim, Saewung; Seco, Roger; Stavrakou, Trissevgeni; Longo, Karla M.; Tóta, J.; Souza, Rodrigo Augusto Ferreira de; Vega, Oscar; Liu, Ying; Shrivastava, Manish; Alves, Eliane Gomes; Santos, Fernando C.; Leng, Guoyong; Hu, Zhiyuan

doi:10.1038/ncomms15541

Cited by 71 publications

(67 citation statements)

References 42 publications

(61 reference statements)

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“…1, much of the land cover outside of Manaus is tropical forest, with some pasture land interspersed. Significant isoprene emissions are expected and indeed measured from the forest (Gu et al, 2017;Guenther et al, 2006). Significant concentrations of methacrolein, methyl vinyl ketone, and isoprene hydroxyhydroperoxides (PTR-MS m/z 71), all first-generation oxidation products of isoprene, are also observed and have a more complicated structure (Liu et al, 2016).…”

Section: Wetmentioning

confidence: 94%

Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

et al. 2018

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Abstract. The Green Ocean Amazon (GoAmazon 2014/5) campaign, conducted from January 2014 to December 2015 in the vicinity of Manaus, Brazil, was designed to study the aerosol life cycle and aerosol–cloud interactions in both pristine and anthropogenically influenced conditions. As part of this campaign, the U.S. Department of Energy (DOE) Gulfstream 1 (G-1) research aircraft was deployed from 17 February to 25 March 2014 (wet season) and 6 September to 5 October 2014 (dry season) to investigate aerosol and cloud properties aloft. Here, we present results from the G-1 deployments focusing on measurements of the aerosol chemical composition and secondary organic aerosol (SOA) formation and aging. In the first portion of the paper, we provide an overview of the data and compare and contrast the data from the wet and dry season. Organic aerosol (OA) dominates the deployment-averaged chemical composition, comprising 80 % of the non-refractory PM1 aerosol mass, with sulfate comprising 14 %, nitrate 2 %, and ammonium 4 %. This product distribution was unchanged between seasons, despite the fact that total aerosol loading was significantly higher in the dry season and that regional and local biomass burning was a significant source of OA mass in the dry, but not wet, season. However, the OA was more oxidized in the dry season, with the median of the mean carbon oxidation state increasing from −0.45 in the wet season to −0.02 in the dry season. In the second portion of the paper, we discuss the evolution of the Manaus plume, focusing on 13 March 2014, one of the exemplary days in the wet season. On this flight, we observe a clear increase in OA concentrations in the Manaus plume relative to the background. As the plume is transported downwind and ages, we observe dynamic changes in the OA. The mean carbon oxidation state of the OA increases from −0.6 to −0.45 during the 4–5 h of photochemical aging. Hydrocarbon-like organic aerosol (HOA) mass is lost, with ΔHOA∕ΔCO values decreasing from 17.6 µg m−3 ppmv−1 over Manaus to 10.6 µg m−3 ppmv−1 95 km downwind. Loss of HOA is balanced out by formation of oxygenated organic aerosol (OOA), with ΔOOA∕ΔCO increasing from 9.2 to 23.1 µg m−3 ppmv−1. Because hydrocarbon-like organic aerosol (HOA) loss is balanced by OOA formation, we observe little change in the net Δorg∕ΔCO values; Δorg∕ΔCO averages 31 µg m−3 ppmv−1 and does not increase with aging. Analysis of the Manaus plume evolution using data from two additional flights in the wet season showed similar trends in Δorg∕ΔCO to the 13 March flight; Δorg∕ΔCO values averaged 34 µg m−3 ppmv−1 and showed little change over 4–6.5 h of aging. Our observation of constant Δorg∕ΔCO are in contrast to literature studies of the outflow of several North American cities, which report significant increases in Δorg∕ΔCO for the first day of plume aging. These observations suggest that SOA formation in the Manaus plume occurs, at least in part, by a different mechanism than observed in urban outflow plumes in most other literature studies. Constant Δorg∕ΔCO with plume aging has been observed in many biomass burning plumes, but we are unaware of reports of fresh urban emissions aging in this manner. These observations show that urban pollution emitted from Manaus in the wet season forms less particulate downwind as it ages than urban pollution emitted from North American cities.

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Section: Wetmentioning

confidence: 94%

Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

et al. 2018

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“…Measurements and models in Gu et al (2017) showed that isoprene emissions were approximately 2 times higher in the dry season than the wet season during this field campaign. We can make the assumption that other biogenic gases (including MT and SQT) also exhibited higher emissions in the dry season.…”

Section: Estimating Source Contributions To Potential Soa Using Multimentioning

confidence: 99%

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

Palm¹,

Sá²,

Day³

et al. 2018

Atmos. Chem. Phys.

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Abstract. Secondary organic aerosol (SOA) formation from ambient air was studied using an oxidation flow reactor (OFR) coupled to an aerosol mass spectrometer (AMS) during both the wet and dry seasons at the Observations and Modeling of the Green Ocean Amazon (GoAmazon2014/5) field campaign. Measurements were made at two sites downwind of the city of Manaus, Brazil. Ambient air was oxidized in the OFR using variable concentrations of either OH or O 3 , over ranges from hours to days (O 3 ) or weeks (OH) of equivalent atmospheric aging. The amount of SOA formed in the OFR ranged from 0 to as much as 10 µg m −3 , depending on the amount of SOA precursor gases in ambient air. Typically, more SOA was formed during nighttime than daytime, and more from OH than from O 3 oxidation. SOA yields of individual organic precursors under OFR conditions were measured by standard addition into ambient air and were confirmed to be consistent with published environmental chamber-derived SOA yields. Positive matrix factorization of organic aerosol (OA) after OH oxidation showed formation of typical oxidized OA factors and a loss of primary Published by Copernicus Publications on behalf of the European Geosciences Union. OA factors as OH aging increased. After OH oxidation in the OFR, the hygroscopicity of the OA increased with increasing elemental O : C up to O : C∼1.0, and then decreased as O : C increased further. Possible reasons for this decrease are discussed. The measured SOA formation was compared to the amount predicted from the concentrations of measured ambient SOA precursors and their SOA yields. While measured ambient precursors were sufficient to explain the amount of SOA formed from O 3 , they could only explain 10-50 % of the SOA formed from OH. This is consistent with previous OFR studies, which showed that typically unmeasured semivolatile and intermediate volatility gases (that tend to lack C=C bonds) are present in ambient air and can explain such additional SOA formation. To investigate the sources of the unmeasured SOA-forming gases during this campaign, multilinear regression analysis was performed between measured SOA formation and the concentration of gas-phase tracers representing different precursor sources. The majority of SOA-forming gases present during both seasons were of biogenic origin. Urban sources also contributed substantially in both seasons, while biomass burning sources were more important during the dry season. This study enables a better understanding of SOA formation in environments with diverse emission sources.

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“…Biogenic volatile organic compound (VOC) emissions from forests vary widely across plant species, ecosystem type, season, time of day, and environmental conditions at many scales, including from tens to hundreds of meters (Gu et al, 2017;Fuentes et al, 2000;Goldstein and Galbally, 2007;Alves et al, 2018;Greenberg et al, 2004;Guenther et al, 2006;Klinger et al, 1998;Kuhn et al, 2004;Pugh et al, 2011;Wang et al, 2011). These variations can have significant effects on and be affected by atmospheric chemistry, air quality, and climate (Chameides et al, 1988;Fuentes et al, 2000;Laothawornkitkul et al, 2009;Goldstein et al, 2009;Kesselmeier et al, 2013;Peñuelas and Staudt, 2010).…”

Section: Introductionmentioning

confidence: 99%

A sampler for atmospheric volatile organic compounds by copter unmanned aerial vehicles

McKinney

Wang

et al. 2019

Atmos. Meas. Tech.

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Abstract. A sampler for volatile organic compounds (VOCs) was developed for deployment on a multicopter unmanned aerial vehicle (UAV). The sampler was designed to collect gas- and aerosol-phase VOCs on up to four commercially available VOC-adsorbent cartridges for subsequent offline analysis by thermal-desorption gas chromatography. The sampler had a mass of 0.90 kg and dimensions of 19 cm ×20 cm ×5 cm. Power consumption was < 10 kJ in a typical 30 min flight, representing < 3 % of the total UAV battery capacity. Autonomous sampler operation and data collection in flight were accomplished with a microcontroller. Sampling flows of 100 to 400 sccm were possible, and a typical flow of 150 sccm was used to balance VOC capture efficiency with sample volume. The overall minimum detection limit of the analytical method for a 10 min sample was 3 ppt and the uncertainty was larger than 3 ppt or 20 % for isoprene and monoterpenes. The sampler was mounted to a commercially available UAV and flown in August 2017 over tropical forest in central Amazonia. Samples were collected sequentially for 10 min each at several different altitude–latitude–longitude collection points. The species identified, their concentrations, their uncertainties, and the possible effects of the UAV platform on the results are presented and discussed in the context of the sampler design and capabilities. Finally, design challenges and possibilities for next-generation samplers are addressed.

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Airborne observations reveal elevational gradient in tropical forest isoprene emissions

Cited by 71 publications

References 42 publications

Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

Aircraft observations of the chemical composition and aging of aerosol in the Manaus urban plume during GoAmazon 2014/5

Secondary organic aerosol formation from ambient air in an oxidation flow reactor in central Amazonia

A sampler for atmospheric volatile organic compounds by copter unmanned aerial vehicles

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