Estimation of atmospheric total organic carbon (TOC) – paving the path towards carbon budget closure

Abstract. The atmosphere contains a rich variety of reactive organic compounds, including gaseous volatile organic carbon (VOCs), carbonaceous aerosols, and other organic compounds at varying volatility. Here we present a novel and simple approach to measure atmospheric non-methane total organic carbon (TOC) based on catalytic oxidation of organics in bulk air to carbon dioxide. This method shows little sensitivity towards humidity and near 100 % oxidation efficiencies for all VOCs tested. We estimate a best-case hourly precision of 8 ppb C during times of low ambient variability in carbon dioxide, methane, and carbon monoxide (CO). As proof of concept of this approach, we show measurements of TOC+CO during August–September 2016 from a coastal city in the southwest United Kingdom. TOC+CO was substantially elevated during the day on weekdays (occasionally over 2 ppm C) as a result of local anthropogenic activity. On weekends and holidays, with a mean (standard error) of 102 (8) ppb C, TOC+CO was lower and showed much less diurnal variability. TOC+CO was significantly lower when winds were coming off the Atlantic Ocean than when winds were coming off land if we exclude the weekday daytime. By subtracting the estimated CO from TOC+CO, we constrain the mean (uncertainty) TOC in Atlantic-dominated air masses to be around 23 (±≥8) ppb C during this period. A proton-transfer-reaction mass spectrometer (PTR-MS) was deployed at the same time, detecting a large range of organic compounds (oxygenated VOCs, biogenic VOCs, aromatics, dimethyl sulfide). The total speciated VOCs from the PTR-MS, denoted here as Sum(VOC), amounted to a mean (uncertainty) of 12 (±≤3) ppb C in marine air. Possible contributions from a number of known organic compounds present in marine air that were not detected by the PTR-MS are assessed within the context of the TOC budget. Finally, we note that the use of a short, heated sample tube can improve the transmission of organics to the analyzer, while operating our system alternately with and without a particle filter should enable a better separation of semi-volatile and particulate organics from the VOCs within the TOC budget. Future concurrent measurements of TOC, CO, and a more comprehensive range of speciated VOCs would enable a better characterization and understanding of the atmospheric organic carbon budget.

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Estimation of atmospheric total organic carbon (TOC) – paving the path towards carbon budget closure

10.5194/acp-2018-1055 ◽

2018 ◽

Author(s):

Mingxi Yang ◽

Zoë L. Fleming

Keyword(s):

Organic Carbon ◽

Total Organic Carbon ◽

Organic Compounds ◽

Carbon Budget ◽

Dimethyl Sulfide ◽

Proton Transfer Reaction ◽

Anthropogenic Activity ◽

Carbonaceous Aerosols ◽

Diurnal Variability ◽

Marine Air

Abstract. The atmosphere contains a rich variety of reactive organic compounds, including gaseous volatile organic carbon (VOCs), carbonaceous aerosols, and other organic compounds at varying volatility. Here we present measurements of atmospheric non-methane total organic carbon plus carbon monoxide (TOC+CO) during August-September 2016 from a coastal city in the southwest United Kingdom. TOC+CO was substantially elevated during the day on weekdays (occasionally over 2 ppm C) as a result of local anthropogenic activity. On weekends and holidays, with a mean (standard error) of 102 (8) ppb C, TOC+CO was lower and showed much less diurnal variability. Excluding weekday daytime, TOC+CO was significantly lower when winds were coming off the Atlantic Ocean than when winds were coming off land. By subtracting the estimated CO from TOC+CO, we constrain the mean (uncertainty) TOC in marine air to be around 19 (±≥8) ppb C during this period. A proton-transfer-reaction mass spectrometer (PTR-MS) was deployed at the same time, detecting a large range of organic compounds (oxygenated VOCs, biogenic VOCs, aromatics, dimethyl sulfide). The total speciated VOCs from the PTR-MS, denoted here as Sum(VOC), amounted to a mean (uncertainty) of 11(±≤3) ppb C in marine air. We assess the possible contributions from a number of known organic compounds present in marine air that were not detected by the PTR-MS. Future concurrent measurements of TOC, CO, and a more comprehensive range of speciated VOCs would enable a better characterization and understanding of atmospheric organic carbon budget.

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Carbocentric limnology: looking back, looking forward

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f08-011 ◽

2008 ◽

Vol 65 (3) ◽

pp. 543-548 ◽

Cited By ~ 102

Author(s):

Yves T Prairie

Keyword(s):

Carbon Dioxide ◽

Organic Matter ◽

Microbial Community ◽

Organic Carbon ◽

Dissolved Organic Carbon ◽

Carbon Budget ◽

Metabolic Balance ◽

Lake Ecosystems ◽

Looking Back ◽

Landscape Level

In this perspective article, I argue that dissolved organic carbon occupies a central role in the functioning of lake ecosystems, comparable in importance to that played by nutrients. Because lakes receive so much dissolved organic carbon from the terrestrial landscape, its accumulation in water bodies usually represents the largest pool of lacustrine organic matter within the water column. The transformation of even a small fraction of this external carbon by the microbial community can alter significantly the metabolic balance of lake ecosystems, simultaneously releasing carbon dioxide to the atmosphere and burying organic carbon in lake sediments. At the landscape level, even if they occupy a small fraction of the landscape, lakes play a surprisingly important role in the regional carbon budget, particularly when considered at the appropriate temporal scale.

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Treatment Efficiency by means of a Nonthermal Plasma Combined with Heterogeneous Catalysis of Odoriferous Volatile Organic Compounds Emissions from the Thermal Drying of Landfill Leachates

Journal of Engineering ◽

10.1155/2014/831584 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 1

Author(s):

Daniel Almarcha ◽

Manuel Almarcha ◽

Elena Jimenez-Coloma ◽

Laura Vidal ◽

Montserrat Puigcercós ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Carbon ◽

Total Organic Carbon ◽

Organic Compounds ◽

Nonthermal Plasma ◽

Sulphur Compounds ◽

Odor Concentration ◽

Volatile Organic ◽

Thermal Drying ◽

Urban Solid Waste

The objective of the present work was to assess the odoriferous volatile organic compounds depuration efficiency of an experimental nonthermal plasma coupled to a catalytic system used for odor abatement of real emissions from a leachate thermal drying plant installed in an urban solid waste landfill. VOC screening was performed by means of HRGC-MS analysis of samples taken at the inlet and at the outlet of the nonthermal plasma system. Odor concentration by means of dynamic olfactometry, total organic carbon, mercaptans, NH3, and H2S were also determined in order to assess the performance of the system throughout several days. Three plasma frequencies (100, 150, and 200 Hz) and two catalyst temperatures (150°C and 50°C) were also tested. Under conditions of maximum capacity of the treatment system, the results show VOC depuration efficiencies around 69%, with average depuration efficiencies between 44 and 95% depending on the chemical family of the substance. Compounds belonging to the following families have been detected in the samples: organic acids, alcohols, ketones, aldehydes, pyrazines, and reduced sulphur compounds, among others. Average total organic carbon removal efficiency was 88%, while NH3and H2S removal efficiencies were 88% and 87%, respectively, and odor concentration abatement was 78%.

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