Surface Area/Grain Size Relations

Figure 2.2.8.1, page 31; Horowitz, A.J., 1991. A Primer on SedimentTrace Element Chemistry, 2nd edition, Lewis Publishers, Chelsea, Michigan.

0 20 40 600

20

40

60

80

Copper

Surface Area (m/g)

Con

cent

ratio

n (m

g/kg

)

0

20

40

60

80C

once

ntra

tion

(mg/

kg)

0 20 40 60Surface Area (m/g)

Nickel

Forstner, U, and Witmann, GTW. Figure 39a and b. page 127. Metal Pollution in the Aquatic Environment; Springer Verlag, Berlin.

Changes in Surface Area as aFunction of Grain Size

Table from Horowitz, 1991; data from Jackson, 1979

Influence of Grain Mineralogy on Surface Area

Table from Horowitz, 1991; data fromForstner and Wittmann, 1981

Influence of Coatings on Surface Area

• Sand-sized and Larger seds.: grain coatings composed of carbonates, Fe & Mn oxides and hydroxides, and organic matter are rough in comparison to surface of the underlying particles.– Coatings may comprise <5% by weight, but account for

significant portion of the total surface area.

Based on Horowitz and Elrick, 1987

•Silt and clays sized particles: coatings fill in surface irregularities. Also, cement grains together, creating larger agglomerated grains. Combination of processes reduces surface area.

Grain Size vs. Concentration• Semi-systematic increase

in concentration with finer-grained material

Forstner, U, and Witmann, GTW. Figure 36. page 123. Metal Pollution in the Aquatic Environment; Springer Verlag, Berlin.

•Decrease in conc. In finest fraction due to coatings, composition, and agglomeration of grains

•Increase in fine sand due to dentrital minerals. Also to influx of metal enriched sediments from pollutant sources.

Grain Size vs. Concentration

Data from Forstner and Wittman, 1979

Concentration vs. Quantity of Fine Sediment

Sizes Frequently Used•16 μm

•62.5 μm

•63 μm

•125 μm

Data from deGroot et al., 1982

Units of Concentration

Concentrations (volume) Concentrations (weight)

Unit Symbols Unit Symbolsmoles per liter mol/L or M moles per kg mol/kgmillimoles per liter

mmol/L or mM

milliequavlents per kilogram

meq/kg

micromoles per liter

µmol/L or µM

micrograms per kg or ppbn

µg/kg or ppb

micrograms per liter

µg/L milligrams per kg orparts per billion

g/kg = ppm

Metals per unit Mass

• Some deposits may contain so little fine-grained material that the bulk of the metal contaminant per unit mass is found in the sand-sized fraction.

Reservoir

0

1

1B2

2B3 4

56

77B7C 7D

9 1011

1213 14

15

16 1718

Gagingstation

GagingStation

MineralCanyon

Dayton

CarsonCity

VirginiaCity

TableMtn.

Canyon

(Brunswick)

FortChurchill

395

0

0 1 2 3 4

1 2 3 4 5 MilesKm

95

Six Mile

Canyon Fan

Gold Canyon

Six Mile Canyon

Fork

Reno Fallon

CarsonCity

Carson RiverWatershed Boundary

Carson Lake

Carson Playa Stillwater

WildlifeRefuge

Lahontan Reservoir

LakePyramid

SIERRA NEVADA

NevadaCalifornia

ForkE

ast

Truckee R.

Cars

on R

.

Truc

kee R

.Wes

tFo

rk

Carso

n R. .

Lake Tahoe

Lahontan

Eureka Mill, Brunswick Canyon

Reservoir

0

1

1B2

2B3 4

56

77B7C 7D

9 1011

1213 14

15

16 1718

Gagingstation

GagingStation

MineralCanyon

Dayton

CarsonCity

VirginiaCity

TableMtn.

Canyon

(Brunswick)

FortChurchill

395

0

0 1 2 3 4

1 2 3 4 5 MilesKm

95

Six Mile

Canyon Fan

Gold Canyon

Six Mile Canyon

Fork

Reno Fallon

CarsonCity

Carson RiverWatershed Boundary

Carson Lake

Carson Playa Stillwater

WildlifeRefuge

Lahontan Reservoir

LakePyramid

SIERRA NEVADA

NevadaCalifornia

ForkE

ast

Truckee R.

Cars

on R

.

Truc

kee R

.Wes

tFo

rk

Carso

n R. .

Lake Tahoe

Lahontan

Fractional Contributions of Selected Metals in Suspended Sediments

ConcentrationPercent Contribution

Constituent(mg/kg)

<63 μmfraction

>63 μmfraction

Total Sample

<63 μmfraction

>63 μmfraction

Arkansas River (sampled 5/11/87)a,b

Mn 1100 600 800 50 50

Cu 51 22 33 58 42

Zn 325 110 190 63 37

Pb 52 25 35 54 46

Cr 56 44 49 43 57

Ni 32 16 22 55 45

Co 15 11 12.5 45 55

Cowlitz River (sampled 4/20/87)a,c

Mn 650 670 660 40 60

Cu 63 33 46 57 43

Zn 62 68 59 42 58

Pb 12 10 10.8 45 55

Cr 35 19 25 56 44

Ni 25 16 19 53 47

Co 14 14 14 41 59aThe represents the mean of the initial and final composite samples obtained at these sampling sites. b<63 μm fraction equaled 37 %, >63 μm fraction equaled 63 %, c <63 μm fraction equaled 41 %, >63 μm equaled 59 %.(modified from Horowitz et al., 1990)