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Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters

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ABSTRACT

Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic + modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses.

No MeSH data available.


Related in: MedlinePlus

PARAFAC model and isolated components.(top) Three-dimensional fluorescence landscapes example of the measured, modeled and residual EEMs of the PARAFAC analysis. (bottom) The excitation (solid line) and emission (dashed line) spectra for the three fluorescent components identified by PARAFAC model for each of the cruises. Inset plots show the three-dimensional fluorescence landscapes for each of the final PARAFAC-derived component used in this work (with all cruises merged into one dataset).
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f5: PARAFAC model and isolated components.(top) Three-dimensional fluorescence landscapes example of the measured, modeled and residual EEMs of the PARAFAC analysis. (bottom) The excitation (solid line) and emission (dashed line) spectra for the three fluorescent components identified by PARAFAC model for each of the cruises. Inset plots show the three-dimensional fluorescence landscapes for each of the final PARAFAC-derived component used in this work (with all cruises merged into one dataset).

Mentions: Three fluorescent components (C1–C3) were identified during the different PARAFAC runs. C1 and C2 had broad emission and excitation spectra, with emission maxima at visible wavelengths, whereas C3 had an emission maximum at ultraviolet-A wavelengths (UV-A) (Fig. 5, bottom panel). The fluorescence intensities of C1 and C2 ranged from 0 to 0.1 and to 0.09 R.U., respectively, with highest values observed in the polar waters in Fram Strait (Figs 2g,h and 3g,h). In Davis Strait, C1 and C2 fluorescence values were notably lower, only reaching 0.05 and 0.04 R.U., respectively (Fig. 4g,h). In surface waters (depth <300 m) C1 and C2 were significantly correlated (C1 = 1.109 * C2 + 0.001; r2 = 0.99; p < 0.0001), however, this correlation was not apparent in Davis Strait deep waters (Fig. 4k). There was a clear addition of C1 in TrW and BBDW, without a proportional increase in C2.


Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters
PARAFAC model and isolated components.(top) Three-dimensional fluorescence landscapes example of the measured, modeled and residual EEMs of the PARAFAC analysis. (bottom) The excitation (solid line) and emission (dashed line) spectra for the three fluorescent components identified by PARAFAC model for each of the cruises. Inset plots show the three-dimensional fluorescence landscapes for each of the final PARAFAC-derived component used in this work (with all cruises merged into one dataset).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5035922&req=5

f5: PARAFAC model and isolated components.(top) Three-dimensional fluorescence landscapes example of the measured, modeled and residual EEMs of the PARAFAC analysis. (bottom) The excitation (solid line) and emission (dashed line) spectra for the three fluorescent components identified by PARAFAC model for each of the cruises. Inset plots show the three-dimensional fluorescence landscapes for each of the final PARAFAC-derived component used in this work (with all cruises merged into one dataset).
Mentions: Three fluorescent components (C1–C3) were identified during the different PARAFAC runs. C1 and C2 had broad emission and excitation spectra, with emission maxima at visible wavelengths, whereas C3 had an emission maximum at ultraviolet-A wavelengths (UV-A) (Fig. 5, bottom panel). The fluorescence intensities of C1 and C2 ranged from 0 to 0.1 and to 0.09 R.U., respectively, with highest values observed in the polar waters in Fram Strait (Figs 2g,h and 3g,h). In Davis Strait, C1 and C2 fluorescence values were notably lower, only reaching 0.05 and 0.04 R.U., respectively (Fig. 4g,h). In surface waters (depth <300 m) C1 and C2 were significantly correlated (C1 = 1.109 * C2 + 0.001; r2 = 0.99; p < 0.0001), however, this correlation was not apparent in Davis Strait deep waters (Fig. 4k). There was a clear addition of C1 in TrW and BBDW, without a proportional increase in C2.

View Article: PubMed Central - PubMed

ABSTRACT

Climate change affects the Arctic with regards to permafrost thaw, sea-ice melt, alterations to the freshwater budget and increased export of terrestrial material to the Arctic Ocean. The Fram and Davis Straits represent the major gateways connecting the Arctic and Atlantic. Oceanographic surveys were performed in the Fram and Davis Straits, and on the east Greenland Shelf (EGS), in late summer 2012/2013. Meteoric (fmw), sea-ice melt, Atlantic and Pacific water fractions were determined and the fluorescence properties of dissolved organic matter (FDOM) were characterized. In Fram Strait and EGS, a robust correlation between visible wavelength fluorescence and fmw was apparent, suggesting it as a reliable tracer of polar waters. However, a pattern was observed which linked the organic matter characteristics to the origin of polar waters. At depth in Davis Strait, visible wavelength FDOM was correlated to apparent oxygen utilization (AOU) and traced deep-water DOM turnover. In surface waters FDOM characteristics could distinguish between surface waters from eastern (Atlantic&thinsp;+&thinsp;modified polar waters) and western (Canada-basin polar waters) Arctic sectors. The findings highlight the potential of designing in situ multi-channel DOM fluorometers to trace the freshwater origins and decipher water mass mixing dynamics in the region without laborious samples analyses.

No MeSH data available.


Related in: MedlinePlus