Issue 5, 2021

Unraveling the complexity of atmospheric brown carbon produced by smoldering boreal peat using size-exclusion chromatography with selective mobile phases

Abstract

Boreal wildfires are a significant source of atmospheric brown carbon (BrC), a complex mixture of thousands of light-absorbing organic compounds that contributes to the warming effects of combustion particulate matter. Here, we use size-exclusion chromatography (SEC) coupled with photodiode array detection to characterize BrC collected from the controlled combustion of boreal peat. Importantly, rather than attempting to estimate the molecular weight of BrC chromophores through the minimization and correction of secondary interactions, we instead exploit these interactions to systematically explore BrC hydrophobicity, lability, and size-dependent light absorption properties. Using this new approach, which we corroborate using independent asymmetric flow field-flow fractionation (AF4) analysis, we show that the components of fresh wildfire BrC span a wide range of sizes, polarities, and light absorption characteristics. Unlike atmospherically aged wildfire BrC, which has previously been shown to resemble terrestrial humic substances in both its absorption profile and its retention behaviour, the fresh BrC sample studied here contains both higher-MW chromophores with “humic-like” featureless absorption and smaller-MW chromophores with structured absorption, and is more susceptible to hydrophobic interactions with the column matrix. Interestingly, we find that the contribution of the low-MW fraction to overall BrC absorption increases with increasing mobile phase acetonitrile content, which suggests that the high-MW fraction consists of metastable aggregates held together by easily disrupted intermolecular forces. Together, these results highlight the compositional diversity of atmospheric BrC and the challenge and potential of SEC for the characterization of complex, and poorly defined, environmental matrices.

Graphical abstract: Unraveling the complexity of atmospheric brown carbon produced by smoldering boreal peat using size-exclusion chromatography with selective mobile phases

Supplementary files

Transparent peer review

To support increased transparency, we offer authors the option to publish the peer review history alongside their article.

View this article’s peer review history

Article information

Article type
Paper
Submitted
18 feb. 2021
Accepted
07 jun. 2021
First published
18 jun. 2021
This article is Open Access
Creative Commons BY-NC license

Environ. Sci.: Atmos., 2021,1, 241-252

Unraveling the complexity of atmospheric brown carbon produced by smoldering boreal peat using size-exclusion chromatography with selective mobile phases

M. Lyu, D. K. Thompson, N. Zhang, C. W. Cuss, C. J. Young and S. A. Styler, Environ. Sci.: Atmos., 2021, 1, 241 DOI: 10.1039/D1EA00011J

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements