The use of PARAFAC modeling to trace terrestrial dissolved organic matter and fingerprint water masses in coastal Canadian Arctic surface waters

Abstract

The optical properties of chromophoric dissolved organic matter (CDOM) were investigated in the Canadian Archipelago and coastal Beaufort Sea surface waters using fluorescence spectroscopy coupled with parallel factor analysis (PARAFAC). Environmental dynamics of individual components were evaluated and compared to salinity, in situ fluorescence, absorption at 312 nm (a312), dissolved organic carbon, and lignin phenol concentrations. A positive linear relationship between four fluorescent components and lignin phenols suggests a terrestrial origin, whereas two components were unrelated to a river source, suggesting an autochthonous source. Elevated concentrations of terrestrial components were observed in the Mackenzie River plume near the coast of Alaska and decreased as water was transported to the Canadian Archipelago. The two nonterrestrial components exhibited only background levels in concentrations along the transect, suggesting minimal productivity within plume and archipelago surface waters. The relative abundance of terrestrial components in relation to nonterrestrial components allowed us to distinguish water masses including Atlantic, Archipelago, and Mackenzie River plume, respectively. This study illustrates the usefulness of PARAFAC to fingerprint water masses based on the optical characteristics of CDOM and shows promise to improve our understanding of upper Arctic Ocean ventilation.

Absorption and fluorescence properties of chromophoric dissolved organic matter of the eastern Bering Sea in the summer with special reference to the influence of a cold pool

“…It may result from biological activity and/or microbial reworking of plankton-derived DOM (Yamashita et al, 2008) and was found to be both sourced from land and produced in the ocean (Murphy et al, 2008). The fluorescence peaks of component 2 (C2) at excitation/emission wavelengths of < 260 (400)/475 nm is similar to previously identified terrestrial humic-like material or "A" peak (Coble, 1996;Stedmon et al, 2003Stedmon et al, , 2005bGueguen et al, 2012;Walker et al, 2009). Fluorescence of components 3 (C3) and 4 (C4) are of proteinaceous origin, namely tyrosine and tryptophan.…”

Warming increases carbon and nutrient fluxes from sediments in streams across land use

“…Temperature-enhanced P transformations and SRP fluxes from sediments have been widely observed in lab incubations (House and Denison, 2002;Suplee and Cotner, 2002;James and Barko, 2004;Schulz and Herzog, 2004) and field temperature manipulations (e.g., Zhang et al, 2012). The consistent temperature dependence of SRP fluxes across sites is related to the fact that organic P mineralization and MnO 2 /Fe 2 O 3 reduction (two processes contributing to SRP release from sediments) can be enhanced at higher temperatures with intensifying organic matter (OM) decomposition.…”

Technical Note: Comparison of storage strategies of sea surface microlayer samples

“…Sodium azide has been reported to have no effect (Ferrari et al, 1996;Astoreca et al, 2009) but also to cause up to 10 % increase in absorption (Tiltstone et al, 2002). Patel-Sorrentino et al (2002) found that sodium azide had no measurable effect on the EEMs of two humic-like fluorophores.…”

“…Hunter and Liss (1981) found small SA losses from samples dark-stored at 6 • C for up to a week, but an increase of 20 % after 34 days. Freezing of filtered samples at −20 • C is also widely used for CDOM storage (Coble et al, 1998;Murphy et al, 2008;Conmy et al, 2009;Walker et al, 2009;Gao et al, 2010;Spencer et al, 2010;Yamashita et al, 2010b) but again sample provenance appears to be important; highly coloured samples comprising mostly allochthonous OM tend to show greater changes during freeze/thaw than more optically clear autochthonousdominated OM samples. Two studies of a range of freshwaters found that after freeze/thaw, fluorescence intensities and adsorption coefficients showed both increases and decreases (Spencer et al, 2007a;Hudson et al, 2009), although overall CDOM loss was observed and protein-, humic-, and fulvic-like fluorophore intensities all declined (Hudson et al, 2009).…”

“…It contains unique microbial communities, is a site for the synthesis and concentration of organic matter components, including transparent exopolymer particles (TEP) implicated in marine snow formation, and surface active substances (SAS) that cause damping of surface turbulence and subsequent suppression of air-sea gas exchange (Ćosović, 2005;Upstill-Goddard et al, 2003;Cunliffe et al, 2011;Wurl et al, 2011;Salter et al, 2011). SAS in seawater are predominantly natural phytoplankton exudates, such as polysaccharides, proteins and lipids, and their degradation products (Gašparović, 2012), with additional contributions in coastal waters from terrestrial humic and fulvic acids.…”