1. Some Uses of Channel Bed Sediment Concentration Data
Determine the spatial distribution of trace metals
Identify point and non-point sources of pollution
Assessment of the rates and patterns of contaminant dispersal
First approximation of potential ecological and human health effects (and regional water quality surveys)
Monitoring of potential impacts of waste waters from industrial or municipal sites
Geochemical exploration (surveys)

2. Downstream Trends in Channel Bed
From Salomons
& Forstner, 1984
Where point sources are present the concentrations generally decline from the point of input.

3. Concentrations of Cu and Ni in the <63 um fraction of channel bed sediments from the Po River, Italy. Samples were collected in the summer (grey bars) and winter (black bars). Acronyms along x-axis represent successive downstream sampling sites. Note minimal variations in concentration between seasons.
Viganò, L., and 14 others, Quality assessment of bed sediments of the Po River (Italy). Water Research, 37: (from 2 of 8 graphs from figure 3, page 507)

4. Downstream Trends in Channel Bed
From Salomons
& Forstner, 1984
Where point sources are present the concentrations generally decline from the point of input.

5. Bedload temporarily at rest
Scale
Characteristic
Transitory deposits
Micro-forms
Meso-forms
Bedload temporarily at rest
Coherent structures such as ripples with λ ranging from 10-2 to 100 m
Features with λ from 100 to 102 m; includes dunes, pebble clusters and transverse ribs
Alluvial bars
Macro-forms
Mega-forms
From by lag deposition of coarse-grained sediment
Structures with λ from 101 to 103 m such as riffles, point bars, alternate bars, and mid-channel bars
Structures with λ > 103 m such as sedimentation zones
Characteristics of channel deposits (adapted from Knighton 1998; Church and Jones 1982; Hoey 1992)

6. Figure from Huggett, J.R., Fundamental of Geomorphology, Routledge Fundamentals in Physical Geography, Routledge, London, fig. 7.7, p. 185.

7. Straight Channel (A) Meandering Channel (B) (C) Longitudinal Profile
Elevation
Distance Downstream
Riffle
Pool
Mean Water Surface Slope
(A)
(B)
(C)
Meandering Channel
Straight Channel
Longitudinal Profile

8. Secondary
Flow Directions
Point Bar
Super Elevated
Water Surface
From Markham, A.J. and Thorne, C.R., Geomorphology of gravel-bed river bends. In: P. Billi, R.D. Hey, C.R. Thorne, and P. Tacconi, (eds.), Dynamics of Gravel-bed Rivers, pp , New York, Jonh Wiley and Sons, Ldt., figure 22.2, p. 436.

9. From Thompson, A., Secondary Flows and the Pool-Riffle, Earth Surface Processes and Landforms, 11: , Figure 4, p. 636.

10. Reading, H.G., 1978. Sedimentary Environments and Facies, Blackwell Publications,
New York, Fig. 3.26, page 34. Company may have been purchased by Elsevier?

11. Figure 20. Laremie River, Wyoming (photo by J. R
Figure 20. Laremie River, Wyoming (photo by J.R. Balsley); obtained from USGS Photo Library

12. Knighton, D., 1998. Fluvial Form and Processes: A New Perspective, Arnold, London.
Fig. 5.23, p. 233.

14. Grain-Size & Compositional Variations
Ladd et al. 1998
Examined trace metal concentrations in 7 morphological units in Soda Butte Creek, Montana
(lateral scour pools, eddy drop zones, glides, low gradient riffles, high gradient riffles, attached bars, and detached bars)
Highest concentrations in eddy drop zones and attached lateral bars with largest amount of fine sediment

15. Density-Dependent Variations
Slingerland and Smith (1986) define a placer as “a deposit of residual or detrital mineral grains in which a valuable mineral has been concentrated by a mechanical agent,”
A contaminant placer is defined here as a concentration of metal enriched particles by the hydraulic action of the river. Where they occur, trace metal concentrations will be locally elevated in comparison to other areas (Miller & Orbock Miller, 2007)

16. Guilbert, J. M. and Park, C. F. , Jr. , 1986
Guilbert, J.M. and Park, C.F., Jr., The Geology of Ore Deposits. New York, W.H. Freemand and Company, figures 16-1, p. 746 and 16-4b p.749.

17. Bateman, A. M. , 1950. Economic mineral deposits, 2nd edition
Bateman, A.M., Economic mineral deposits, 2nd edition. New York, Wiley and Sons.

18. Lahontan Reservoir Virginia City 15 11 18 13 14 9 10 16 17 7C 7D 12M i l e i x C S a n y o n
Table
Fort 95 15
Churchill
Six Mile
Mtn. 11
Canyon Fan 18 13 14 9 10 16 17
Mineral 7C 7D 12
Canyon
Gaging
Station
Gold Canyon 7B 7 6
Dayton 5
Reno
Fallon 3 4
Pyramid
Lake 2B
Canyon
Carson
(Brunswick)
City 2 1B T r
Carson u c
Playa k e
Stillwater 1 e R .
Wildlife
Refuge R . o n s
395 C a r
Gaging R . e e
Lahontan
station u c k
Reservoir
Carson r T
Lake R . .
Lake n
Tahoe o
Carson River a r s C
Carson
Watershed Boundary k
City o r F E t a 1 2 3 4 5 W e s s t
Miles F F 1 2 3 4 Km o o r r k k
SIERRA NEVADA
Nevada
California

20. Eureka Mill, Brunswick Canyon

24. Variations Dependent on Time and Frequency of Inundation
Examples
Queens Creek, Arizona
Rio Pilcomayo, Bolivia

25. Graf, W. L. , Clark, S. L. , Kammerer, M. T. , Lehman, T. , Randall, K
Graf, W.L., Clark, S.L., Kammerer, M.T., Lehman, T., Randall, K., Tempe, R., and Schroeder, A., Geomorphology of heavy metals in the sediments of Queen Creek, Arizona, USA. Catena, 18: , figures 2, p. 572 and 6, p. 578.

26. Study
Area

27. “Modern Mine”
Floatation Process
Pb & Zn Concentrate
Ball Mill

28. Floatation Mill, Potosi
Sampling Site RP-1
~1.5 miles from Mills
Floatation Mill, Potosi
Effluent
You want me to
live where?
20 miles from Mills

29. ~60 miles from Mills
20 miles from Mills

30. Yikes!

31. High-Water
Channel Deposits
Low-Water
Rio Pilcomayo, southern Bolvia near Uyuni. Photo taken in July during the dry season.

32. Implications to Sampling
Local variations – referred to as small scale or field variance (Birch et al. 2001)
Can be on the order of 10 to 25 % relative standard deviation and may be significantly greater than analytical variation (error)
May hinder ability to decipher differences in contaminant levels between sample sites
Reconnaissance level surveys and sample stratification by morphological units ?
Sampling of specific units only?
Composite sampling to minimize within unit variations

33. Changes in Sediment Composition Can:
Influence the spatial and temporal concentration patterns observed in aquatic systems
Hinder the determination of localized inputs of trace metals from either natural sources (e.g., ore bodies) or anthropogenic sources (e.g., mining operations or industrial complexes).
Changes in grain-size have a particularly significant influence on metal concentrations.

34. Types of Mathematical Manipulations Commonly Applied to Bulk Metal Data After Horowitz, 1991
Corrections for Grain-size differences
Normalization to a single grain-size range
Carbonate content corrections
Recalculation of concentration data on a carbonate-free basis
Normalization to a conservative elemental
Use of multiple Normalizations

35. Methods of Handling the Grain Size Effect
Analysis of a specific grain-size fraction which is considered to be the chemical active phase
Does not provide for an understanding of the actual concentrations that exist in the bulk sample
Inhibits the calculation of total trace metal transport rates
Normalize the metal concentration data obtained for the bulk (< 2mm or sand) sized fraction using some form of mathematical equation and grain size data obtained from a separate sample
Provides actual concentration found in bulk sample
Poorly documents the concentrations that would actually be measured in the finer-grain size fractions

36. Designation of Chemical Active Sediment Phase
Numerous size fractions have been used as the chemical active phase including <2 µm, <16 µm, <20 µm, <63 µm, <70 µm, <155 µm, <200 µm (Horowitz, 1991)
Argument for using < 63 µm fraction
It can be extracted from the bulk sample via sieving, a process which does not alter trace metal chemistry
It is the particle size most commonly carried in suspension by rivers and streams and may therefore be the most readily distributed through the aquatic environment

37. Grain Size Normalization
Normalized
Concentration =
(DF *Bulk Metal Concentration)
Where,
DF = Dilution Factor
= 100/(100 - % of sediment > size range of Interest)

38. Concentration vs. Quantity of Fine Sediment
Sizes Frequently Used
2 μm
16 μm
62.5 μm
63 μm
70 μm
125 μm
200 μm
Data from deGroot et al., 1982

39. Data from Horowitz and Elrik, 1988

40. Differences between Measured and Normalized Values
Selected chemical active phase (grain size fraction) may not contain all of the trace metals
Differences in concentration are not solely due to grain size variations
Data contain analytical errors associated with grain size or geochemical analyses

41. Fractional Contributions of Selected Metals in Suspended Sediments
Concentration
Percent Contribution
Constituent
(mg/kg)
<63 μm
fraction
>63 μm
Total Sample
Arkansas River (sampled 5/11/87)a,b Mn
1100
600
800 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 55 45 Co 15 11
12.5
Cowlitz River (sampled 4/20/87)a,c
650
670
660 40 60 62 68 59 12 10
10.8 19 53 47 14 41
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 %.
Fractional Contributions
of Selected Metals in
Suspended Sediments
(modified from Horowitz et al., 1990)

42. Carbonate Correction Normalized Concentration
Assumes: Carbonate does not contain substantial quantities of trace metals and, thus, acts as a diluent. May not be true of Cd and Pb.
Generally applied to streams in calcareous terrains, particularly those in areas with karst.
Normalized
Concentration
(DF *Bulk Metal Concentration) =
Where,
DF = Dilution Factor
= 100/(100 - % of carbonate in sample)

43. Conservative Element Corrections
Assumes that some elements have had a uniform flux from crustal rocks. Thus, normalization to these elements provides a measure (or level) of dilution that has occurred.
Elements most commonly used are Al, Ti, and to a lesser extent, Cs and Li.
Normalized
value = (Concentration of Trace Metal)
(Concentration of conservative element)
Note: this generates a ratio, not a concentration as did the previous
procedures