The Open UniversitySkip to content
 

UV-visible absorbance spectroscopy as a proxy for peatland dissolved organic carbon (DOC) quantity and quality: considerations on wavelength and absorbance degradation

Peacock, Mike; Evans, Chris D.; Fenner, Nathalie; Freeman, Chris; Gough, Rachel; Jones, Timothy G. and Lebron, Inma (2014). UV-visible absorbance spectroscopy as a proxy for peatland dissolved organic carbon (DOC) quantity and quality: considerations on wavelength and absorbance degradation. Environmental Science: Processes & Impacts, 16 pp. 1445–1461.

DOI (Digital Object Identifier) Link: https://doi.org/10.1039/C4EM00108G
Google Scholar: Look up in Google Scholar

Abstract

Absorbance in the UV or visible spectrum (UV-vis) is commonly used as a proxy for DOC concentrations in waters draining upland catchments. To determine the appropriateness of different UV-vis measurements we used surface and pore water samples from two Welsh peatlands in four different experiments: (i) an assessment of single wavelength proxies (1 nm increments between 230–800 nm) for DOC concentration demonstrated that 254 nm was more accurate than 400 nm. The highest R2 values between absorbance and DOC concentration were generated using 263 nm for one sample set (R2 = 0.91), and 230 nm for the other three sample sets (respective R2 values of 0.86, 0.81, and 0.93). (ii) A comparison of different DOC concentration proxies, including single wavelength proxies, a two wavelength model, a proxy using phenolic concentration, and a proxy using the area under a UV spectrum at 250–350 nm. It was found that both a single wavelength proxy (≤263 nm) and a two wavelength model performed well for both pore water and surface water. (iii) An evaluation of the E2:E3, E2:E4, E4:E6 ratios, and SUVA (absorbance at 254 nm normalised to DOC concentration) as indicators of DOC quality showed that the E4:E6 ratio was subject to extensive variation over time, and was highly correlated between surface water and pore water, suggesting that it is a useful metric to determine temporal changes in DOC quality. (iv) A repeated weekly analysis over twelve weeks showed no consistent change in UV-vis absorbance, and therefore an inferred lack of degradation of total DOC in samples that were filtered and stored in the dark at 4 °C.

Item Type: Journal Item
Copyright Holders: 2014 Royal Society of Chemistry
ISSN: 2050-7895
Project Funding Details:
Funded Project NameProject IDFunding Body
Not SetSP1202DEFRA (Department for Environment Food and Rural Affairs)
Academic Unit/School: Faculty of Science, Technology, Engineering and Mathematics (STEM) > Environment, Earth and Ecosystem Sciences
Faculty of Science, Technology, Engineering and Mathematics (STEM)
Item ID: 47900
Depositing User: Michael Peacock
Date Deposited: 24 Nov 2016 17:19
Last Modified: 07 Dec 2018 10:46
URI: http://oro.open.ac.uk/id/eprint/47900
Share this page:

Metrics

Altmetrics from Altmetric

Citations from Dimensions

Actions (login may be required)

Policies | Disclaimer

© The Open University   contact the OU