Source apportionment of sulphate aerosols and gaseous sulphur dioxide over the NW Atlantic during the spring SABINA cruise 2003 using stable sulphur isotopes

• Main Author: Eaton, Sarah Jane
• Format: Thesis
• Language: English
• Published: Memorial University of Newfoundland 2006
• Subjects: Newfoundland
• Online Access: https://research.library.mun.ca/6673/; https://research.library.mun.ca/6673/1/SarahJaneEaton.pdf; https://research.library.mun.ca/6673/3/SarahJaneEaton.pdf

Sulphate aerosols have the potential to alter climate, reducing the effect of increasing greenhouse gas emissions by scattering incident solar radiation back to space. Dimethylsulphide (DMS) is emitted from the surface ocean, and oxidized into methanesulphonic acid (MSA) aerosols, or gaseous sulphur dioxide (SO₂ ) in the atmosphere. Sulphur dioxide is further oxidized forming new sulphate aerosols. During the spring (2003) cruise of the NW Atlantic as part of the Canadian-Surface Ocean Lower Atmosphere Study (C-SOLAS), size segregated and total particulate sulphate aerosols and gaseous SO₂ samples were collected. Samples were collected diurnally using mass flow-controlled, high-volume air samplers. The cruise consisted of a Lagrangian study, following a phytoplankton bloom and a Transect study from 36°N to 54°N. Sulphur isotope abundance analyses were conducted on both the aerosol and SO₂ samples, while chemical characterisation of anions, cations, and MSA was conducted using ion chromatography. -- The Lagrangian study revealed relatively constant biogenic SO₂ concentrations, with variable anthropogenic SO₂ concentrations. Biogenic sulphate concentrations ranged from 0 to 1720ngm⁻³ with the largest average concentrations in the total particulate and 0.49μm size fraction. These were not coincident with higher than average biogenic SO₂ concentrations. Anthropogenic sulphate dominated the smaller size fractions, and concentrations were generally larger than the biogenic concentrations with the exception of the 3.0-1.5μm size fraction. The isotope data indicated that the smaller size fractions were dominated by anthropogenic emissions, likely derived from the ships emissions. Negative δ³⁴ SNSS values were present in the data set and are potentially linked to the combustion of Middle Eastern oil at a refinery in Newfoundland or H₂S flaring from the Sable Island gas fields.