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

Abstract

Rachel; Jones, Timothy G.; 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 (6

Iron as a source of color in river waters

“…This agrees well with many earlier studies in which the link between COC (or absorbance of water) and TOC has been so intimate that it accurately predicts the concentration of TOC (Carter et al, 2012;Peacock et al, 2014). In our study, the a* of humic substances described color well, in agreement with earlier studies suggesting that humic substances comprise the majority of TOC in most freshwaters.…”

Changes in dissolved organic carbon quality in soils and discharge 10years after peatland restoration

“…This is consistent with the results of Wickland et al (2007) who observed lower SUVA in DOC samples derived from fresh plant material compared to soil water extracts. Peacock et al (2014) suggest that E2:E3 and SUVA may be good indicators of between site differences in DOC quality; however, despite higher productivity at the restored site, there were no significant difference between soil water E2:E3 and SUVA between restored and unrestored peat fields (Table 2). This was likely due to dry conditions during the study period and limited hydrologic connectivity between residual peat layers and the newly deposited peat (McCarter and Price, 2015) that limited contact between soil pore water and the new litter.…”

“…In contrast, Wallage et al (2006) observed an increase in E4:E6 following drain blocking. Peacock et al (2014) noted that E4:E6 ratios had greater temporal variation compared to E2:E3 and SUVA and suggest that this may make E4:E6 a good proxy for temporal change, but limit its utility for assessing treatment effects. GEP max was positively related to SUVA 254 indicating that more productive plots (large negative GEP) resulted in less aromatic DOC.…”

“…Peatland DOC chemistry can be investigated using spectrophotometric properties of the DOC including specific absorbance of ultraviolet wavelengths (SUVA), and ratios of absorbance at 250 and 365 nm (E2:E3) and 465 and 665 nm (E4:E6) (e.g. Höll et al, 2009;Austnes et al, 2010;Grayson and Holden, 2012;Peacock et al, 2014). SUVA has been shown to be positively correlated with aromaticity of DOC (Weishaar et al, 2003) and also to decrease in value as the proportion of low molecular weight compounds in colored DOC was increased by irradiation (Helms et al, 2008).…”

Peatland ditch blocking has no effect on dissolved organic matter (DOM) quality

“…DOC was measured as nonpurgeable organic carbon using an Analytical Sciences Thermalox Total Carbon analyser (Peacock et al, ). Samples were acidified (pH < 3), sparged with oxygen to remove inorganic carbon, and DOC concentrations calculated using a seven‐point calibration (0–60 mg L −1 ) curve with additional standards to check for drift, plus a quality control sample.…”