Size characteristics of chromophoric dissolved organic matter in the Chukchi Sea

Abstract

With the Arctic warming, terrestrial input plays a more important role in carbon cycle in the Arctic Ocean than before. Chromophoric dissolved organic matter (CDOM) as a tracer of terrestrial dissolved organic matter (tDOM) becomes more valuable in elucidating the source and compositions of DOM. Although measurements of DOM in the Arctic Ocean have been widely reported, characteristics of high molecular weight colloids are still poorly understood. In this study, the bulk absorbance and size fractograms of CDOM were measured in the Chukchi Seas using an asymmetrical flow field‐flow fractionation (AF4) coupled online with UV‐vis detectors. Both CDOM a254, absorption coefficient at 254 nm, and the integrated UV254 (from AF4 UV‐vis detector) of three colloidal fractions (1–10, 10–100, and >100 kDa) significantly correlated with the fraction of meteoric water (fmw) calculated from δ18O in seawater, which indicates that the CDOM was mainly derived from terrestrial input and a254 is a potential tracer of tDOM in the Chukchi Sea. Compared with the larger colloidal fractions (10–100 and >100 kDa), the smaller colloidal fraction (1–10 kDa) showed a stronger correlation with the fmw, suggesting the smaller colloids were of mostly terrigenous origin. Values of field measured spectral slope at 275–295 nm (s275–295), a tDOM proxy, were significantly lower than the model‐estimated s275–295 calculated from the MODIS Aqu satellite remote sensing data, which indicated that terrestrial input of CDOM derived from model calculation was likely underestimated in the Chukchi Sea.

Size distribution of absorbing and fluorescing DOM in Beaufort Sea, Canada Basin

“…(1.62-2.52 kDa) were reported for colloidal DOM in Chukchi Sea (Lin et al, 2016). The average MW reported in Beaufort Sea agreed with values reported for fulvic acids (Beckett et al, 1987;Guéguen and Cuss, 2011), confirming that fulvic acids are good proxy for marine DOM (Tipping et al, 2015).…”

“…The simultaneous multi wavelength measurements of the online absorbance detector allow us to accurately determine of each of the four macromolecules in a single injection. The retention time at 254 nm was used to estimate the CDOM MW at peak maximum intensity (Guéguen and Cuss, 2011;Lin et al, 2016;Stolpe et al, 2010Stolpe et al, , 2014. For example, a typical calibration recorded at 254 nm was log (Time) = (0.1634 ± 0.0086) * Log (MW) + (0.4831 ± 0.0228) (r 2 = 0.999).…”

“…Dainard and Guéguen, 2013;Guo et al, 2011;Murphy et al, 2008). Asymmetrical flow field-flow fractionation (AF4) is a chromatographic-like method that has been recently applied to investigate the sources and dynamics of DOM in aquatic systems (Boehme and Wells, 2006;Guéguen and Cuss, 2011;Lin et al, 2016;Stolpe et al, 2010Stolpe et al, , 2014. For example, Lin et al, (2016) showed that the 1-10kDa CDOM fraction was influenced by terrestrial input.…”

“…Asymmetrical flow field-flow fractionation (AF4) is a chromatographic-like method that has been recently applied to investigate the sources and dynamics of DOM in aquatic systems (Boehme and Wells, 2006;Guéguen and Cuss, 2011;Lin et al, 2016;Stolpe et al, 2010Stolpe et al, , 2014. For example, Lin et al, (2016) showed that the 1-10kDa CDOM fraction was influenced by terrestrial input. Stolpe et al, (2014) concluded that the small MW DOM (2-3nm) in surface northern Gulf of Mexico originated from terrestrial sources whereas the larger MW DOM (>6 nm) was protein-rich and freshly produced.…”

Association of Seawater Nanoparticle Size Distribution With Diversity of Marine Plankton

“…The outflow time of nanoparticles (Figure 3) was mainly concentrated at 10-16 min, corresponding to the outflow interval of C 1 , which further verified that seawater nanomaterials were mainly composed of small-sized particles. This is consistent with an earlier study which showed that, in the Chukchi Sea, the colloidal materials were primarily dominated by small-sized particles (55.4%) (Lin et al, 2016). Stolpe et al (2014) and Zhou et al (2016) obtained similar findings in the Mississippi River and in small rivers in the Gulf of Mexico, which they attributed to the important contribution of small-sized terrestrial humus to river nanoparticles.…”