Rainwater chemistry and carbon isotope composition at the Maldives Climate Observatory Hanimaadhoo, 2019 – 2023

Krishnakant Budhavant, S. K. Satheesh, Örjan Gustafsson

This dataset contains rainwater chemistry, water-insoluble organic carbon (WIOC), elemental carbon (EC, reported as black carbon), and dual-carbon isotope (Δ¹⁴C and δ¹³C) measurements from the Maldives Climate Observatory – Hanimaadhoo (MCOH) in the northern Indian Ocean.

The measurements were conducted to investigate seasonal variability in rainwater chemistry and to quantify contemporary and fossil-derived carbon contributions to wet-deposited carbonaceous aerosols under contrasting South Asian monsoon regimes.

Rainwater samples were collected between October 2019 and April 2023 at MCOH (6.78° N, 73.18° E), Maldives, using automated wet-only collectors. Major ions, carbonaceous components, and carbon isotope compositions were determined using ion chromatography, thermal-optical carbon analysis, accelerator mass spectrometry, and isotope-ratio mass spectrometry, respectively.

AtmosphereAerosolsRainwater chemistryWet depositionCarbon isotopesRadiocarbonBlack carbonSouth Asian monsoonMaldivesSource apportionment

Name

Version

Citation

References

Budhavant K, Satheesh SK, Gustafsson Ö (2026) Rainfall carbon sources across South Asia shift seasonally from biomass burning to fossil fuels. Communications Sustainability. Accepted manuscript; DOI pending.

Data description

This dataset contains rainwater chemistry, water-insoluble organic carbon (WIOC), elemental carbon (EC, reported as black carbon), and dual-carbon isotope (Δ¹⁴C and δ¹³C) measurements from the Maldives Climate Observatory – Hanimaadhoo (MCOH) in the northern Indian Ocean.

The data support the manuscript "Rainfall carbon sources across South Asia shift seasonally from biomass burning to fossil fuels", accepted for publication in Communications Sustainability.

The dataset contains 245 rainwater chemistry records and 34 radiocarbon measurements, of which 32 have paired stable carbon isotope measurements. Blank numerical cells mean missing or unavailable observations, not zero.

station_details.csv

Variables:

• field Metadata attribute name
• value Value of metadata attribute

isotopes.csv

Variables:

• collection_date Date of rainfall sample collection, in format DD-MM-YYYY
• delta13c_permil_vpdb Stable carbon isotope composition, delta-13-C (δ¹³C), relative to Vienna Pee Dee Belemnite (V-PDB), in ‰
• delta14c_permil Published/repository Δ¹⁴C reproduced from manuscript SI Table S1; pMC-derived values marked pending reconciliation, in ‰
• f_contemporary Contemporary (non-fossil) fraction of water-insoluble carbon (WIC)
• f_fossil Fossil carbon fraction of WIC

rain_chemistry

Variables:

• collection_date Rainwater sampling date, in format DD-MM-YYYY
• total_rain_volume_ml Total collected rainwater volume, in mL
• filtered_sample_volume_ml Volume of rainwater filtered for analysis, in mL
• wioc_ug_l Water-insoluble organic carbon (WIOC), in µg L⁻¹
• ec_ug_l Elemental carbon (EC), referred to as black carbon (BC) in manuscript, in µg L⁻¹
• ph Acidity expressed as pH
• hco3_ueq_l Bicarbonate (HCO₃⁻), in µeq L⁻¹
• conductivity_us_cm Electrical conductivity, in µS cm⁻¹
• cl_ueq_l Chloride (Cl⁻), in µeq L⁻¹
• no3_ueq_l Nitrate (NO₃⁻), in µeq L⁻¹
• so4_ueq_l Sulfate (SO₄²⁻), in µeq L⁻¹
• na_ueq_l Sodium (Na⁺), in µeq L⁻¹
• nh4_ueq_l Ammonium (NH₄⁺), in µeq L⁻¹
• k_ueq_l Potassium (K⁺), in µeq L⁻¹
• mg_ueq_l Magnesium (Mg²⁺), in µeq L⁻¹
• ca_ueq_l Calcium (Ca²⁺), in µeq L⁻¹
• nss_so4_ueq_l Non-sea-salt sulfate (nss-SO₄²⁻), in µeq L⁻¹
• nss_k_ueq_l Non-sea-salt potassium (nss-K⁺), in µeq L⁻¹
• nss_ca_ueq_l Non-sea-salt calcium (nss-Ca²⁺), in µeq L⁻¹
• nss_mg_ueq_l Non-sea-salt magnesium (nss-Mg²⁺), in µeq L⁻¹

Comments

Data creator roles

This dataset was generated through collaborative research involving the Indian Institute of Science, Bengaluru, India, and Stockholm University, Sweden. Krishnakant Budhavant coordinated field sampling, laboratory measurements, isotope analyses, and data processing. Örjan Gustafsson contributed to study design and scientific interpretation.

Data reuse

The dataset provides multi-year observations of rainwater chemistry and carbonaceous aerosol composition at a remote receptor site in the northern Indian Ocean. It can be used to investigate seasonal monsoon influences, atmospheric transport, carbon source apportionment, and aerosol wet deposition across South Asia.

Project

Örjan Gustafsson, FORMAS 2020-01917; Swedish Research Council VR 2017-05687

Publisher

Bolin Centre Database

License

Open Data Commons Attribution License (ODC-By) v1.0

First name

Örjan

Last name or organisation

Gustafsson

Email address

orjan.gustafsson@aces.su.se

Address

Department of Environmental Science; Stockholm University Bolin Centre for Climate Research; Stockholm University

Postal code

SE-106 91

City

Stockholm

Country

Sweden

GCMD science keyword

Earth science > Atmosphere > Aerosols > Carbonaceous aerosols

GCMD location

Continent > Asia > Southern Asia

Dataset language

English

Begin date

2019-10-15

End date

2023-04-30

DOI

Time