Settleable and Non-Settleable Suspended Sediments in the Ogeechee River Estuary, Georgia, U.S.A. |
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| Authors: | M Alber |
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| Institution: | Department of Marine Sciences, University of Georgia, Athens, GA, 30602, U.S.A. |
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| Abstract: | Suspended particle dynamics were investigated in the Ogeechee River Estuary during neap tide in July 1996. Samples were operationally separated into ‘ truly suspended ’ (settling velocity <0·006 cm s−1) and ‘ settleable ’ (settling velocity >0·006 cm s−1) fractions over the course of a tidal cycle to determine whether these two fractions were comprised of particles with differing biological and chemical characteristics. Total suspended sediment, organic carbon and nitrogen, chlorophyll a and phaeopigment concentrations were measured in each fraction, as well as rates of bacterial hydrolytic enzyme activity β-1,4-glucosidase (βGase) and β-xylosidase (βXase)]. The majority of the suspended sediment (by weight) was in the truly suspended fraction; all measured parameters were largely associated with this fraction as well. When compared to the settleable material, the truly suspended material was significantly higher in % POC (5·7±0·6 vs. 3·9±1·8), % chlorophyll (0·07±0·02 vs. 0·03±0·01), % phaeopigment (0·030±0·006 vs. 0·018±0·012), and weight-specific maximal uptake rates (Vmaxper mg suspended sediment) of both enzymes (1·8±0·4 vs. 0·7± 0·2 nmol mg−1 h−1βGase and 1·1±0·3vs . 0·3±0·2 nmol mg−1 h−1βXase), providing clear evidence for a qualitative distinction between the two fractions. These results are interpreted to mean that the more organic-rich, biologically active material associated with the suspended fraction is likely to have a different fate in this Estuary, as ‘ truly suspended ’ sediments will be readily transported whereas ‘ settleable ’ sediments will settle and be resuspended with each tide. These types of qualitative differences should be incorporated into models of particle dynamics in estuaries. |
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| Keywords: | suspended sediments settling rates seston glycosides particulate matter estuaries Georgia coast |
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