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

Carter, Heather T.; 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. 10.1016/j.watres.2012.05.021

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Abstract/Summary

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:	Article
Identification Number/DOI:	10.1016/j.watres.2012.05.021
Programmes:	CEH Topics & Objectives 2009 onwards > 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 ...
CEH Sections:	Shore
ISSN:	0043-1354
Additional Keywords:	dissolved organic carbon, dissolved organic matter, model, UV absorbance
NORA Subject Terms:	Ecology and Environment Chemistry
Date made live:	24 Sep 2012 11:19
URI:	http://nora.nerc.ac.uk/id/eprint/18745

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