FN Archimer Export Format
PT J
TI Flocculation Potential of Estuarine Particles: The Importance of Environmental Factors and of the Spatial and Seasonal Variability of Suspended Particulate Matter
BT 
AF VERNEY, Romaric
   LAFITE, Robert
   BRUN-COTTAN, Jean-Claude
AS 1:1;2:2;3:3;
FF 1:PDG-DOP-DCB-DYNECO-PHYSED;2:;3:;
C1 IFREMER, DYNECO PHYSED, F-29280 Plouzane, France.
   Univ Rouen, CNRS, M2C, UMR 6143, F-76821 Mont St Aignan, France.
   Univ Caen, CNRS, M2C, UMR 6143, F-14000 Caen, France.
C2 IFREMER, FRANCE
   UNIV ROUEN, FRANCE
   UNIV CAEN, FRANCE
SI BREST
SE PDG-DOP-DCB-DYNECO-PHYSED
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 1.554
TC 70
UR https://archimer.ifremer.fr/doc/2009/publication-6631.pdf
LA English
DT Article
DE ;Seine estuary (France);Kolmogorov microscale;Diatom bloom;Floc structure;Cohesive sediment;Flocculation
AB Estuarine systems are complex environments where seasonal and spatial variations occur in concentrations of suspended particulate matter, in primary constituents, and in organic matter content. This study investigated in the laboratory the flocculation potential of estuarine-suspended particulate matter throughout the year in order to better identify the controlling factors and their hierarchy. Kinetic experiments were performed in the lab with a "video in lab" device, based on a jar test technique, using suspended sediments sampled every 2 months over a 14-month period at three stations in the Seine estuary (France). These sampling stations are representative of (1) the upper estuary, dominated by freshwater, and (2) the middle estuary, characterized by a strong salinity gradient and the presence of an estuarine turbidity maximum. Experiments were performed at a constant low turbulent shear stress characteristic of slack water periods (i.e., a Kolmogorov microscale > 1,000 A mu m). Flocculation processes were estimated using three parameters: flocculation efficiency, flocculation speed, and flocculation time. Results showed that the flocculation that occurred at the three stations was mainly influenced by the concentration of the suspended particulate matter: maximum floc size was observed for concentrations above 0.1 g l(-1) while no flocculation was observed for concentrations below 0.004 g l(-1). Diatom blooms strongly enhanced flocculation speed and, to a lesser extent, flocculation efficiency. During this period, the maximum flocculation speed of 6 A mu m min(-1) corresponded to a flocculation time of less than 20 min. Salinity did not appear to automatically enhance flocculation, which depended on the constituents of suspended sediments and on the content and concentration of organic matter. Examination of the variability of 2D fractal dimension during flocculation experiments revealed restructuring of flocs during aggregation. This was observed as a rapid decrease in the floc fractal dimension from 2 to 1.4 during the first minutes of the flocculation stage, followed by a slight increase up to 1.8. Deflocculation experiments enabled determination of the influence of turbulent structures on flocculation processes and confirmed that turbulent intensity is one of the main determining factors of maximum floc size.
PY 2009
PD JUN
SO Estuaries and coasts : Journal of the Estuarine Research Federation
SN 1559-2723
PU Estuaries Research Federation
VL 32
IS 4
UT 000266815300007
BP 678
EP 693
DI 10.1007/s12237-009-9160-1
ID 6631
ER

EF