Suspended Matter, Chl-a, CDOM, Grain Sizes, and Optical Properties in the Arctic Fjord-Type Estuary, Kangerlussuaq, West Greenland During Summer

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Lars Chresten Lund-Hansen, Thorbjørn Joest Andersen, Morten Holtegaard Nielsen, Morten Pejrup

Optical constituents as suspended particulate
matter (SPM), chlorophyll (Chl-a), colored dissolved
organic matter (CDOM), and grain sizes were obtained on
a transect in the arctic fjord-type estuary Kangerlussuaq
(66°) in August 2007 along with optical properties. These
comprised diffuse attenuation coefficient of downwelling
PAR (Kd(PAR)), upwelling PAR (Ku(PAR)), particle beam
attenuation coefficient (cp), and irradiance reflectance R
(-0, PAR). PAR is white light between 400 and 700 nm.
The estuary receives melt water from the Greenland Inland
Ice and stations covered a transect from the very high
turbid melt water outlet to clear marine waters. Results
showed a strong spatial variation with high values a s for
suspended matter concentrations, CDOM, diffuse attenuation
coefficient Kd(PAR), particle beam attenuation
coefficients (cp), and reflectance R(-0, PAR) at the melt
water outlet. Values of optical constituents and properties
decreased with distance from the melt water outlet to a
more or less constant level in central and outer part of the
estuary. There was a strong correlation between inorganic
suspended matter (SPMI) and diffuse attenuation coefficient
Kd(PAR) (r2=0.92) and also for particle beam
attenuation coefficient (cp; r2=0.93). The obtained SPMI
specific attenuation—Kd
*(PAR)=0.13 m2g-1 SPMI—and
the SPMI specific particle beam attenuation—cp
*=
0.72 m2g-1—coefficients were about two times higher
than average literature values. Irradiance reflectance R(-0,
PAR) was comparatively high (0.09-0.20) and showed a
high (r2=0.80) correlation with Ku(PAR). Scattering
dominated relative to absorption—b(PAR)/a(PAR)=12.3.
Results strongly indicated that the high values in the
optical properties were related to the very fine particle
sizes (mean=2–6 µm) of the suspended sediment. Data
and results are discussed and compared to similar studies
from both temperate and tropical estuaries.
Original languageEnglish
JournalEstuaries and Coasts
Volume33
Issue number6
Pages (from-to)1442-1451
ISSN1559-2723
DOIs
Publication statusPublished - 2010

ID: 32432943