Isotopic composition of carbon monoxide in South Asia

Peng Yao, Henry Holmstrand, Carina van der Veen, Maria Elena Popa, Chloe A. Brashear, Krishnakant Budhavant, Mohanan Remani Manoj, Joakim Romson, Abdus Salam, Thomas Röckmann, Örjan Gustafsson

We collected wintertime atmospheric samples from South Asia starting in 2017 and measured both CO concentrations and its dual isotopes (δ¹³C and δ¹⁸O).

The samples were obtained through continuous observations at two key sites: the Bangladesh Climate Observatory at Bhola (BCOB) — a receptor site located at the outflow of the Indo-Gangetic Plain (IGP), and the Maldives Climate Observatory at Hanimaadhoo (MCOH) — a receptor site in the northern Indian Ocean that provides a broad regional footprint for South Asia.

These datasets form the basis for CO source apportionment constrained by isotopic measurements.

AtmosphereGas phaseCarbon monoxideCOIsotopeδ13Cδ18OSouth Asia

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Version

Citation

Data description

The dataset comprises nine UTF-8 encoded CSV (csv) files, including three from BCOB and six from MCOH, together with one summary Excel spreadsheet (xlsx):

• bcob2019.csv
• bcob2023.csv
• bcob2024.csv
• mcoh2018.csv
• mcoh2019.csv
• mcoh2021.csv
• mcoh2022.csv
• mcoh2023.csv
• mcoh2024.csv
• co_south_asia.xlsx

Each row in the dataset sheets for CO isotopic composition represents one sample collected and analyzed. All data and metadata are organized as columns in the data tables. The files contain the following variables:

• No Sequential sample number
• Sample_ID Unique identifier for each sample
• Batch_Flask Batch and flask number
• Batch Number of dual-sample sets
• Flask Indicates whether the sample is the first or second flask in a paired sample
• Site_ID Sampling site identifier
• Box_No Box or container number used for storing the collected samples
• Sampling_Date Date of sampling
• Start_Time Start time of sample collection (hh:mm)
• Stop_Time End time of sample collection (hh:mm)
• Flush_time_start Start time of flushing before sampling (UTC)
• Pressure_in_flask Air pressure measured in the flask after sampling (Bar)
• Operator Name of the colleague who conducted the sampling
• Analysis Series number assigned for isotopic analysis
• Analysis_datetime Date and time of isotopic analysis
• CO Measured CO concentration (ppb)
• δ13C Measured δ¹³C value of CO (‰ VPDB)
• δ18O Measured δ¹⁸O value of CO (‰ VSMOW)
• CO_final CO concentration averaged from the paired samples (ppb)
• δ13C_final δ¹³C value averaged from the paired samples (‰ VPDB)
• δ18O_final δ¹⁸O value averaged from the paired samples (‰ VPDB)
• Flag_CO Quality or status flag noted for this sample (0 = normal sample; 1, 2 = minor issues; 5 = blank sample)
• File Filename or reference for the isotopic analysis record
• Pressure_isotopic_analysis Flask pressure measured during isotopic analysis (mbar)
• No_isotopic_analysis Sample number within the isotopic analysis batch
• Comments Additional notes or remarks

Comments

Campaigns

The sampling campaigns, termed the South Asian Pollution Experiment (SAPOEX-year), covered winter periods (e.g., SAPOEX-2024 corresponds to late 2023 – early 2024). Air samples were collected at two receptor sites in South Asia. MCOH samples are available for 2018, 2019, 2021, 2022, 2023, and 2024, while BCOB samples were collected in 2019, 2023, and 2024; continuous sampling was interrupted during the COVID-19 lockdowns. As the campaigns were conducted by different colleagues over several years, the original records were not fully consistent. Nevertheless, the key information required for data interpretation is retained, and the measurement methodology is consistent throughout (see below).

Methods

Air was collected in 1-L borosilicate glass flasks (Normag, Germany) sealed with glass spindle valves. After a 20-minute flushing, samples were filled at 2 L min⁻¹ to ~1.7 bar. CO mixing ratios and isotopic compositions were measured at the Institute for Marine and Atmospheric Research Utrecht (IMAU) using a continuous-flow IRMS (Thermo Scientific Delta V Advantage). Isotope values are reported in δ notation relative to V-PDB (δ¹³C) and V-SMOW (δ¹⁸O). Calibration used an atmospheric reference gas (NAT-307; CO = 180 ppb; δ¹³C = −30.25‰; δ¹⁸O = +7.10‰). Measurement precision (1σ) is 0.12‰ for δ¹³C and 0.16‰ for δ¹⁸O.

Data creator roles

The dataset is curated by scientists at the Bolin Centre for Climate Research and will continue to be updated.

• dataset curation
  • Örjan Gustafsson
  • Peng Yao
  • Henry Holmstrand
• acquired funding and conceived the study
  • Örjan Gustafsson
• design and conducting of field campaigns
  • Örjan Gustafsson
  • Peng Yao
  • Henry Holmstrand
  • Krishnakant Budhavant
  • Mohanan Remani Manoj
  • Joakim Romson
  • Abdus Salam
• isotope analyses
  • Carina Van der Veen
  • Maria Elena Popa
  • Chloe A. Brashear
  • Thomas Röckmann
• data analysis and interpretation
  • Peng Yao
  • Henry Holmstrand
  • Thomas Röckmann
  • Maria Elena Popa
  • Carina Van der Veen
  • Örjan Gustafsson

Project

This work was supported by the Swedish Research Council VR (Distinguished Professor Grant No. 2017-01601), the Swedish Research Council for Sustainable Development Formas (Grant No. 2023-01234), and the European Union’s Horizon 2020 research and innovation programme through the ATMO-ACCESS Integrating Activity (Grant Agreement No. 101008004, project No. 0000000110).

Publisher

Bolin Centre Database

License

Creative Commons Attribution 4.0 International License (CC BY 4.0)

First name

Örjan

Last name or organisation

Gustafsson

Email address

Orjan.Gustafsson@aces.su.se

Address

Department of Environmental Science; Stockholm University

Postal code

SE-106 91

City

Stockholm

Country

Sweden

GCMD science keyword

Earth science > Atmosphere > Air quality > Carbon monoxide

GCMD location

Continent > Asia > Southern Asia

Dataset language

English

Begin date

2017-12-15

End date

2024-04-10

DOI

Time