PPT Slide

Table C-2

Summary of Characteristic Times of Sediment Fate and Transport Processes

Process

Characteristic Time

Relationship

Typical Range of Key

Parameter Values

Illustrative Value of

Characteristic Time

1

Diffusion

D

R

H

4

=

eff

f

2

2

diff

p

t

R

f

> 1,000

(Hydrophobic

organics)

D

eff

~ 10

-6

cm

2

/s

1,280 years

Advection

v

R

H

=

f

adv

t

Groundwater velocity,

v

,

widely variable

100 years

Sediment Erosion

U

H

=

ero

t

Bed erosion rate, U,

widely variable

10 years

Bioturbation

D

H

4

=

bio

2

2

bio

p

t

0.3 cm

2

/yr<D

bio

ណ

cm

2

/yr

13 years

Reaction

k

1

=

rxn

fate

t

Reaction rate,

k

rxn

,

widely variable

100 years

*

Assumes a 10 cm thick

surficial layer contaminated with a hydrophobic organic with an effective

retardation factor of 1,000. A groundwater velocity of

1 meter/

yr, a bed erosion rate of 1 cm/

yr, an effective

bioturbation diffusion coefficient of 3 cm

2

/yr and a reaction rate of 0.01 yr

-1

are assumed for purposes of

illustration.

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