Freshwater DOM quantity and quality from a two-component model of UV absorbance

Carter, Heather; Tipping, Edward; Koprivnjak, Jean-Francois; Miller, Matthew P.; Cookson, Brenda; Hamilton-Taylor, John. 2012 Freshwater DOM quantity and quality from a two-component model of UV absorbance. Water Research, 46 (14). 4532-4542.

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We present a model that considers UV-absorbing dissolved organic matter (DOM) to consist of two components (A and B), each with a distinct and constant spectrum. Component A absorbs UV light strongly, and is therefore presumed to possess aromatic chromophores and hydrophobic character, whereas B absorbs weakly and can be assumed hydrophilic. We parameterised the model with dissolved organic carbon concentrations, [DOC], and corresponding UV spectra for c. 1700 filtered surface water samples from North America and the United Kingdom, by optimising extinction coefficients for A and B, together with a small constant concentration of non-absorbing DOM (0.80 mg DOC L-1). Good unbiased predictions of [DOC] from absorbance data at 270 and 350 nm were obtained (r2=0.98), the sum of squared residuals in [DOC] being reduced by 66% compared to a regression model fitted to absorbance at 270 nm alone. The parameterised model can use measured optical absorbance values at any pair of suitable wavelengths to calculate both [DOC] and the relative amounts of A and B in a water sample, i.e. measures of quantity and quality. Blind prediction of [DOC] was satisfactory for 9 of 11 independent data sets (181 of 213 individual samples).

Item Type: Publication - Article
Digital Object Identifier (DOI):
Programmes: CEH Topics & Objectives 2009 - 2012 > Biogeochemistry > BGC Topic 1 - Monitoring and Interpretation of Biogeochemical and Climate Changes > BGC - 1.1 - Monitor concentrations, fluxes, physico-chemical forms of current and emerging pollutants ...
UKCEH and CEH Sections/Science Areas: Shore
ISSN: 0043-1354
Additional Information. Not used in RCUK Gateway to Research.: The attached document is the author’s version of a work that was accepted for publication in Water Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Water Research, 46 (14). 4532-4542. 10.1016/j.watres.2012.05.021
Additional Keywords: dissolved organic carbon, dissolved organic matter, model, UV absorbance
NORA Subject Terms: Ecology and Environment
Date made live: 24 Sep 2012 11:19 +0 (UTC)

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