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

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 + 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.


Schematic graphs for eastern Greenland.Schematic graphs showing the behavior during mixing of distinct waters defined in the text (Atlantic water, Eurasian and Canada basin polar waters, whose end members in this study are colored accordingly): for (a) C1 and salinity, (b) C1 and fmw, (c) temperature and salinity, (d) fsim and fmw. All data used in this study is shown with gray dots. Lines indicate the mixing between different waters, whose end-members for this study are tabulated below. Arrows represent the approximate direction of the deviation expected by dilution with sea-ice melt and precipitation (including glacial melt). The table shows information (range and average) on some parameters for the end members of each water type identified in this study.
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f8: Schematic graphs for eastern Greenland.Schematic graphs showing the behavior during mixing of distinct waters defined in the text (Atlantic water, Eurasian and Canada basin polar waters, whose end members in this study are colored accordingly): for (a) C1 and salinity, (b) C1 and fmw, (c) temperature and salinity, (d) fsim and fmw. All data used in this study is shown with gray dots. Lines indicate the mixing between different waters, whose end-members for this study are tabulated below. Arrows represent the approximate direction of the deviation expected by dilution with sea-ice melt and precipitation (including glacial melt). The table shows information (range and average) on some parameters for the end members of each water type identified in this study.

Mentions: The second exception to the correlation between C1 and C2 was in the surface waters of the western Davis Strait (Fig. 4k). If the DOM fluorescence signal in polar waters present in Davis Strait and Fram Strait would have common origins one would expect all data to lie on one relationship as dilution would influence both C1 and C2 in the same fashion. The fact that the DOM in the WGC has the same proportions of C1 and C2 as that found in polar waters of the EGC (Fig. 7d) strongly suggests that it represents here the same material transported along the Greenland shelf and gradually diluted. In contrast, the lower levels of C1 relative to C2 in polar waters in the western Davis Strait suggest a different DOM source (Fig. 7d). This could be reflecting the documented differences in DOM in polar waters originating from the Canada and Eurasian Basins, marine production and terrestrial material, respectively1. This is supported by the correlation of C1 fluorescence to fpw in Davis Strait (Fig. 7c) and to fmw in Fram Strait (Fig. 8b).


Using fluorescent dissolved organic matter to trace and distinguish the origin of Arctic surface waters
Schematic graphs for eastern Greenland.Schematic graphs showing the behavior during mixing of distinct waters defined in the text (Atlantic water, Eurasian and Canada basin polar waters, whose end members in this study are colored accordingly): for (a) C1 and salinity, (b) C1 and fmw, (c) temperature and salinity, (d) fsim and fmw. All data used in this study is shown with gray dots. Lines indicate the mixing between different waters, whose end-members for this study are tabulated below. Arrows represent the approximate direction of the deviation expected by dilution with sea-ice melt and precipitation (including glacial melt). The table shows information (range and average) on some parameters for the end members of each water type identified in this study.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f8: Schematic graphs for eastern Greenland.Schematic graphs showing the behavior during mixing of distinct waters defined in the text (Atlantic water, Eurasian and Canada basin polar waters, whose end members in this study are colored accordingly): for (a) C1 and salinity, (b) C1 and fmw, (c) temperature and salinity, (d) fsim and fmw. All data used in this study is shown with gray dots. Lines indicate the mixing between different waters, whose end-members for this study are tabulated below. Arrows represent the approximate direction of the deviation expected by dilution with sea-ice melt and precipitation (including glacial melt). The table shows information (range and average) on some parameters for the end members of each water type identified in this study.
Mentions: The second exception to the correlation between C1 and C2 was in the surface waters of the western Davis Strait (Fig. 4k). If the DOM fluorescence signal in polar waters present in Davis Strait and Fram Strait would have common origins one would expect all data to lie on one relationship as dilution would influence both C1 and C2 in the same fashion. The fact that the DOM in the WGC has the same proportions of C1 and C2 as that found in polar waters of the EGC (Fig. 7d) strongly suggests that it represents here the same material transported along the Greenland shelf and gradually diluted. In contrast, the lower levels of C1 relative to C2 in polar waters in the western Davis Strait suggest a different DOM source (Fig. 7d). This could be reflecting the documented differences in DOM in polar waters originating from the Canada and Eurasian Basins, marine production and terrestrial material, respectively1. This is supported by the correlation of C1 fluorescence to fpw in Davis Strait (Fig. 7c) and to fmw in Fram Strait (Fig. 8b).

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 + 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.