surface area/grain size relations figure 2.2.8.1, page 31; horowitz, a.j., 1991. a primer on...
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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/k
g)
0
20
40
60
80C
once
ntra
tion
(mg
/kg
)
0 20 40 60
Surface 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 Symbols
moles per liter mol/L or M moles per kg mol/kg
millimoles 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
2B
3 4
5
67
7B
7C 7D9 10
11
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 Miles
Km
95
Six Mile
Canyon Fan
Gold Canyon
Six M
ile Canyon
Fork
Reno Fallon
CarsonCity
Carson River
Watershed Boundary
Carson Lake
Carson Playa Stillwater
WildlifeRefuge
Lahontan Reservoir
LakePyramid
SIERRA NEVADA
NevadaCalifornia
ForkE
ast
Truckee R
.
Car
son
R.
Tru
ckee
R
.Wes
tF
ork
C
arso
n R. .
Lake Tahoe
Lahontan
Eureka Mill, Brunswick Canyon
Reservoir
0
1
1B2
2B
3 4
5
67
7B
7C 7D9 10
11
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 Miles
Km
95
Six Mile
Canyon Fan
Gold Canyon
Six M
ile Canyon
Fork
Reno Fallon
CarsonCity
Carson River
Watershed Boundary
Carson Lake
Carson Playa Stillwater
WildlifeRefuge
Lahontan Reservoir
LakePyramid
SIERRA NEVADA
NevadaCalifornia
ForkE
ast
Truckee R
.
Car
son
R.
Tru
ckee
R
.Wes
tF
ork
C
arso
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 59
aThe 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)