scholarly journals Supplementary material to "Physicochemical uptake and release of volatile organic compounds by soil in coated-wall flow tube experiments with ambient air"

2018 ◽  
Author(s):  
Guo Li ◽  
Yafang Cheng ◽  
Uwe Kuhn ◽  
Rongjuan Xu ◽  
Yudong Yang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Ambient Air ◽  
Flow Tube ◽  
Volatile Organic ◽  
Supplementary Material ◽  
Wall Flow ◽  
Uptake And Release

scholarly journals Physicochemical uptake and release of volatile organic compounds by soil in coated-wall flow tube experiments with ambient air

2019 ◽  
Vol 19 (4) ◽  
pp. 2209-2232 ◽  
Author(s):  
Guo Li ◽  
Yafang Cheng ◽  
Uwe Kuhn ◽  
Rongjuan Xu ◽  
Yudong Yang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Soil Surface ◽  
Ambient Air ◽  
Flow Tube ◽  
Heterogeneous Oxidation ◽  
Volatile Organic ◽  
Wall Flow

Abstract. Volatile organic compounds (VOCs) play a key role in atmospheric chemistry. Emission and deposition on soil have been suggested as important sources and sinks of atmospheric trace gases. The exchange characteristics and heterogeneous chemistry of VOCs on soil, however, are not well understood. We used a newly designed differential coated-wall flow tube system to investigate the long-term variability of bidirectional air–soil exchange of 13 VOCs under ambient air conditions of an urban background site in Beijing. Sterilized soil was investigated to address physicochemical processes and heterogeneous/multiphase reactions independently from biological activity. Most VOCs revealed net deposition with average uptake coefficients (γ) in the range of 10−7–10−6 (referring to the geometric soil surface area), corresponding to deposition velocities (Vd) of 0.0013–0.01 cm s−1 and soil surface resistances (Rc) of 98–745 s cm−1, respectively. Formic acid, however, was emitted at a long-term average rate of ∼6×10-3 nmol m−2 s−1, suggesting that it was formed and released upon heterogeneous oxidation of other VOCs. The soil–atmosphere exchange of one individual VOC species can be affected by both its surface degradation/depletion caused by surface reactions and by competitive uptake or heterogeneous formation/accommodation of other VOC species. Overall, the results show that physicochemical processing and heterogeneous oxidation on soil and soil-derived dust can act as a sink or as a source of atmospheric VOCs, depending on molecular properties and environmental conditions.

scholarly journals Physicochemical uptake and release of volatile organic compounds by soil in coated-wall flow tube experiments with ambient air

2018 ◽  
Author(s):  
Guo Li ◽  
Yafang Cheng ◽  
Uwe Kuhn ◽  
Rongjuan Xu ◽  
Yudong Yang ◽  
...  
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Chemistry ◽  
Soil Surface ◽  
Ambient Air ◽  
Flow Tube ◽  
Heterogeneous Oxidation ◽  
Volatile Organic ◽  
Wall Flow

Abstract. Volatile organic compounds (VOCs) play a key role in atmospheric chemistry. Emission and deposition on soil have been suggested as important sources and sinks of atmospheric trace gases. The exchange characteristics and heterogeneous chemistry of VOCs on soil, however, are not well understood. We used a newly designed differential coated-wall flow tube system to investigate the long-term variability of bidirectional air-soil exchange of 13 VOCs at ambient air conditions of an urban background site in Beijing. Sterilized soil was investigated to address physicochemical processes and heterogeneous/multiphase reactions independently from biological activity. Most VOCs revealed net deposition with average uptake coefficients (γ) in the range of 10-7–10-6 (referring to the geometric soil surface area), corresponding to deposition velocities (Vd) of 0.0013–0.01 cm s-1 and soil surface resistances (Rc) of 98–745 s cm-1, respectively. Formic acid, however, was emitted at a long-term average rate of ~ 6 × 10-3 nmol m-2 s-1, suggesting that it was formed and released upon heterogeneous oxidation of other VOCs. The soil-atmosphere exchange of one individual VOC species can be affected by both its surface degradation/depletion caused by surface reactions and by competitive uptake or heterogeneous formation/accommodation of other VOC species. Overall, the results show that physicochemical processing and heterogeneous oxidation on soil and soil-derived dust can act as a sink or as a source of atmospheric VOCs, depending on molecular properties and environmental conditions.

scholarly journals Seasonal and Spatial Variation of Volatile Organic Compounds in Ambient Air of Almaty City, Kazakhstan

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1592
Author(s):  
Olga P. Ibragimova ◽  
Anara Omarova ◽  
Bauyrzhan Bukenov ◽  
Aray Zhakupbekova ◽  
Nassiba Baimatova
Keyword(s):  
Air Pollution ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Power Plants ◽  
Ambient Air ◽  
Spatial Variations ◽  
Primary Sources ◽  
Volatile Organic ◽  
Seasonal And Spatial Variations ◽  
Before And After

Air pollution is one of the primary sources of risk to human health in the world. In this study, seasonal and spatial variations of multiple volatile organic compounds (VOCs) were measured at six sampling sites in Almaty, Kazakhstan. The seasonal and spatial variations of 19 VOCs were evaluated in 2020, including the periods before and after COVID-19 lockdown. The concentrations of 9 out of 19 VOCs had been changed significantly (p < 0.01) during 2020. The maximum concentrations of total VOCs (TVOCs) were observed on 15, 17, and 19 January and ranged from 233 to 420 µg m−3. The spatial distribution of TVOCs concentrations in the air during sampling seasons correlated with the elevation and increased from southern to northern part of Almaty, where Combined Heat and Power Plants are located. The sources of air pollution by VOCs were studied by correlations analysis and BTEX ratios. The ranges of toluene to benzene ratio and benzene, toluene, and ethylbenzene demonstrated two primary sources of BTEX in 2020: traffic emissions and biomass/biofuel/coal burning. Most of m-, p-xylenes to ethylbenzene ratios in this study were lower than 3 in all sampling periods, evidencing the presence of aged air masses at studied sampling sites from remote sources.

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