Seasonal variability in CDOM absorption and fluorescence properties in theBarataria Basin, Louisiana, USA
Shatrughan Singh , Eurico D’Sa , Erick Swenson
DOI:
Received December 02, 2009,Revised February 03, 2010, Accepted , Available online
Volume 22,2010,Pages 1481-1490
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Absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) along a 124 km transect in the Barataria
Basin, a large estuary located in Louisiana, USA, were investigated during high and low flow periods of the Mississippi River in the
spring and winter of 2008–2009. Mean CDOM absorption at 355 nm from the marine to the freshwater end member stations ranged
from (3.25 0.56) to (20.76 2.43) m??1 for the three month high flow period whereas it varied from (1.48 1.08) to (25.45 7.03)
m??1 for the same stations during low flow period. Corresponding salinity values at these stations indicated the influence of river and
shelf exchanges in the lower basin and precipitation and runo in the upper basin. An inverse relationship of CDOM absorbance and
fluorescence with salinity observed in the basin could be a useful indicator of salinity. CDOM fluorescence also varied over a large
range showing an approximately 8 to 12-fold increase between the marine and freshwater end members for the two flow seasons.
Excitation-emission matrix spectral plots indicated the presence of various fluorescence components with highest being the A-peak,
lowest the T-peak, and the C and M-peaks showing similar trends along the transect. During low flow season the A/C ratio were well
correlated with station locations indicating increased terrestrial influence towards the upper basin. CDOM absorption and fluorescence
at 355 nm were highly correlated and independent of CDOM sources suggesting that fluorescence could be used to characterize CDOM
in the basin.
