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Exopolymeric secretions in HABs :
How flow, diffusion and bioengineering may depend on length scale
(as well as on rheology, turbulence, behaviour, chemistry, surface properties at membranes, etc)
Ian R. Jenkinson Tim Wyatt
Agence de Conseil et de Recherche Océanographiques,19320 La Roche Canillac, France.
Consejo Superior de Investigaciones Cientificas,Instituto de Investigaciones Mariñas36208 Vigo, [email protected]
Dry powder of grain“radius” rR << 5r
Two vessels with exit holes of radius R
R >> 5r
X Clogs
(Jams)Flows
Vessel with exit hole of radius R
Assuming no inertial effects
(low Re), flow rate
F ~ /where is hydrostatic pressure and is dynamic viscosity
Flows
Newtonian liquid
Two vessels with exit holes of radius R
Monodisperse liquid or paste
with yield stress Y
Y >> Y <<
X Flows F~-Y)/
GelsF = 0
1. Hard, dry suspensions (powders, sand, etc.)If hole diameter D >> ~5 . grain diameter, thenmaterial flows.Otherwise is jams however high τ.
Summary
1. Hard, dry suspensions (powders, sand, etc.)If hole diameter D >> ~5 . grain diameter, thenmaterial flows.Otherwise is jams however high τ.
2. Monodisperse materials (liquids, solids, gels...)
Summary
1. Hard, dry suspensions (powders, sand, etc.)If hole diameter D >> ~5 . grain diameter, thenmaterial flows.Otherwise is jams however high τ.
2. Monodisperse materials (liquids, solids, gels...)
Material properties (viscosity, elasticity, yield stress) constant across all length scales.
Summary
3. Suspensions of hard particles (spheres, plates, needles, etc.) in a liquid.
Like powders and sands, but they impart extra viscosity to that of the liquid, because of Brownian motion and repulsive charges
Summary
3. Suspensions of hard particles (spheres, plates, needles, etc.) in a liquid.Like powders and sands, but they impart extra viscosity to that of the liquid, because of Brownian motion and repulsive charges
4. Suspensions of soft particles and bubbles.
Summary
3. Suspensions of hard particles (spheres, plates, needles, etc.) in a liquid.
Like powders and sands, but they impart extra viscosity to that of the liquid, because of Brownian motion and repulsive charges
4. Suspensions of soft particles and bubbles.Same as above, but increasing τ can cause particles or bubbles to yield in the hole.
Summary
5. Suspensions of aggregates, flocs, etc. including soft particles aggregated in matricesof softer aggregates (lumpiness)
Summary
5. Suspensions of aggregates, flocs, etc. including soft particles aggregated in matricesof softer aggregates (lumpiness)
Very complex, but empirically viscosity andyield stress are a negative function of hole size(and probably of length scale in general)
Summary
5. Suspensions of aggregates, flocs, etc. including soft particles aggregated in matricesof softer aggregates (lumpiness)
Very complex, but empirically viscosity andyield stress is a negative function of hole size(and probably of length scale in general)Maybe natural waters are mostly like this, but with aggregates very dilute and tenuous, compared to, say, what we are used to in foodsor industrial reactors.
Summary
AiguillonCove
-
Pertuisd’Antioche
Pertuis Breton
Charente
Pertuis de Maumusson
La Rochelle Ré
Oléron
BrouageMudflat
Marennes-OléronBasin
Sèvre Niortaise
Pertuis SeaPampin Mudflat Fluff obtained
here
10 km
Mud flatswith fluid mud
Mud flatswith intertidalfluff
?? Harmful algae ??
Is this alga-rich fluff suffocating young sole ?
Mud flatswith fluid mud
Mud flatswith intertidalfluff
?? Harmful algae ??
Is this alga-rich fluff suffocating young sole ?
Between birds andsuffocation?
Didymosphenia geminata invading New Zealand rivers
Pictures received from Christina Vieglais via Diatom-L list
21 August 2006
Mud flatswith fluid mud
Mud flatswith intertidalfluff
The
Kasumeter
But sewage sludge, like pelagic and benthic marine organic aggregates, consist of a hierarchical (quasi-fractal) mixture of exopolymeric flocs, or aggregates
hY
The Kasumeter has been adopted as an EUstandard for measuring the « flowability »of sewage sludges (HORIZONTAL Report No. 21, 2004)
Mud flatswith fluid mud
Mud flatswith intertidalfluff
The
Kasumeter
Yield stress of sewage sludge for different sludge concentrations (%) as a function of tube diameter. (Drawn from data in Spinosa and Lotito (2003) Adv. env. Res. 7:655-659).
hY
Mud flatswith fluid mud
Mud flatswith intertidalfluff
Yield stress of sewage sludge for different sludge concentrations (%) as a function of tube diameter. (Drawn from data in Spinosa and Lotito (2003) Adv. env. Res. 7:655-659).
Y ~ d-2
The
Kasumeter
hY
Rheosole ichthyoviscometerJenkinson, Claireaux and Gentien, (2006) Mar. Biol., in press and published online
It gets the scales and measurement geometry right
Procedure:• A dead sole is arranged so that the tap nozzle fits in its mouth• Test material flows from SR to LR through a tap, into the mouth and through the gills of the dead sole• As the material flows, the hydrostatic pressure difference, H(t) (~water level difference) between the water in each cylinder is measured using a pressure probe, and recorded on computer every 0.5 s.
Rheosole ichthyo-viscometerPlots of hydrostatic pressure difference P vs. time t, obtained with the ichthyoviscometer.
P increased by 10 Pa
Pure seawaterLog-lin
Pure seawaterLin-lin
50% fluff [POM]=(8.4 g.L-1)Lin-lin
1 cm water ~ 100 Pa
50% fluff [POM]=(8.4 g.L-1)Log-lin
Rheosole ichthyo-viscometerPlots of hydrostatic pressure difference P vs. time t, obtained with the ichthyoviscometer.
P increased by 10 Pa
Pure seawaterLog-lin
Pure seawaterLin-lin
50% fluff [POM]=(8.4 g.L-1)Lin-lin
1 cm water ~ 100 Pa
50% fluff [POM]=(8.4 g.L-1)Log-lin
Straight line for log(Y) vs t
Juvenile sole (25 g)can produce a cross-gill hydrostatic pressure P of ~30 Pa
So if Y > P they can'tventilate
Rheosole ichthyo-viscometer
Mucus event in Adriatic, 1983. Giant mucus streamer in 5 m depth.
Field of view approx. 8 m2 (Stachowitsch, 1984)
Adriatic: Mare sporco mucus event, 1983. Sponge with mucus cover, and entangled crab. (Stachowitsch, 1984)
J. Plankt. Res., 17: 2251-2274 (1995)
Viscous modulus(µPa) (Viscosity at shear rate = 1/s)measured in aCouette rheometer
Mitigation of cytotoxicity, rheotoxicity and fish mortality caused by two species of
Gymnodinium
Ian R. Jenkinson, ACRO, Franceand Geneviève Arzul, IFREMER, France
HAB 2000, Hobart, 2000
Seabass: Seawater
0.1
1
10
-50 0 50 100 150 200 250 300
Water height difference(cm). Note log scale.
Pure seawater
1 cm water ~
100 Pa
t (s)
Pure seawater
1 cm water ~
100 Pa
Seabass: G. mikimotoi (Origin: Tinduff, France)
0.1
1
10
-500 0 500 1000 1500 2000 2500 3000
Time (s)
Waterheight diff .(cm) Notelog scale
1 cm water ~
100 Pa
Quasi yield-stress behaviour
“Error” bar is SD n = 3
Yield strength (cm water) of seawater and cultures before and after treatments (second batch of experiments)
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Yield strength (cm water)
G. mik + 0.01mM AC
G. mik + 0.1mM AC
G. mag (10,000/mL)
G. mag+ 0.01mM AC
G. mag + 0.01mM EC
G. mik (23,000/mL)
Yield strength (cm water) of seawater and cultures before and after treatments (second batch of experiments)
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Yield strength (cm water)
G. mik + 0.01mM AC
G. mik + 0.1mM AC
G. mag (10,000/mL)
G. mag+ 0.01mM AC
G. mag + 0.01mM EC
G. mik (23,000/mL)
“Error” bar is SD n = 3
Juvenile sole (25 g)can produce a cross-gill hydrostatic pressure P of ~30 Pa
So if Y > P they can'tventilate
Rheosole ichthyo-viscometer
Viscous modulus(µPa) (Viscosity at shear rate = 1/s)measured in aCouette rheometer
Yield strength (cm water) of seawater and cultures before and after treatments (second batch of experiments)
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 0.45 0.5
Yield strength (cm water)
G. mik + 0.01mM AC
G. mik + 0.1mM AC
G. mag (10,000/mL)
G. mag+ 0.01mM AC
G. mag + 0.01mM EC
G. mik (23,000/mL)
“Error” bar is SD n = 3
Juvenile sole (25 g)can produce a cross-gill hydrostatic pressure P of ~30 Pa
So if Y > P they can'tventilate
Rheosole ichthyo-viscometer
Viscous modulus(µPa) (Viscosity at shear rate = 1/s)measured in aCouette rheometer
POM ~Order 1-5 mg.L-1
Y is comparable in the intertidal fluffand in the Karenia mikimotoi culture,but the K.mikimotoi culture is around 1000 times less concentrated in POM
=
Karenia mikimotoitrapped intheir mucusin a 200µmnet.
The mucussticks to, and clogsa plankton net, but notfish gills.
-4
+3L
og k
olm
ogor
ov L
(m
)
Log rms shear rate (s -1) -4 +3
with 0.5 mm bubbles
With 0.1 mm bubbles
North Sea water
(off Heligoland)
Mediterranean water (off Villefranche)
newtonian
Redrawn from Jenkinson (1993) Oceanol. Acta, 16: 317-334
-4
+3L
og k
olm
ogor
ov L
(m
)
Log rms shear rate (s -1) -4 +3
with 0.5 mm bubbles
With 0.1 mm bubbles
North Sea water
(off Heligoland)
Mediterranean water (off Villefranche)
newtonian
Redrawn from Jenkinson (1993) Oceanol. Acta, 16: 317-334
The amount and timing of exopolymer production bydifferent algae is found to be extremely variable, both in culture and in the field: it's hard to deduce generalrules.
Some allelopathic algae may be using the changes in diffusion induced by exo-slime to reduce wastage ofallelopathic substances, and help deliver them to their targets