CONTAMINATED SOILS NEAR AN OLD COPPER SMELTER,
ANACONDA, MONTANA: METAL DISTRIBUTION AND PARTITIONING
WITH IMPLICATIONS FOR TRANSPORT
by
DEBORAH J.AGENBROAD, B.S.
A THESIS
IN
GEOSCIENCE
Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of
MASTER OF SCIENCE
Approved -^3 ACKNOWLEDGEMENTS
Y\o.i\ I would like to thank my advisor. Dr. Moira K. Ridley, for her guidance and C support. Thanks also to the rest of my committee. Dr. Tom Lehman and Dr. Necip
Guven, for their assistance and advice. Thanks to James Browning for his help wdth
setting up the flow through columns (oops!). Dr. Melanie Barnes for her help with
analysis on the ICP, and Blakely Adair for going out of her way to provide graphite
fiimace AA analysis on some samples. Thanks to David Jacobi for the X-ray scans, Mike
Hooper for the greatest opportimity, and Mike Gower for the thin sections. Thanks to
Blakely Adair and Toby McBride for help in the field. Special thanks to my family and
fiiends for their support. Partial financial support from NIEHS grant number ES 04696
and the Brand Scholarship.
u TABLE OF CONTENTS
ACKNOWLEDGEMENTS ii
ABSTRACT vi
LIST OF TABLES vii
LIST OF FIGURES viii
CHAPTER
L INTRODUCTION 1
1.1 Problem Statement 1
1.2 Goals 3
1.3 Use of Terminology 4
IL BEHAVIOR OF METALS IN SOILS 5
2.1 Overview 5
2.2 Arsenic 7
2.3 Cadmium 8
2.4 Copper 9
2.5 Lead 9
2.6 Zinc 10
IIL SITE HISTORY 11
3.1 Setting 11
3.2 Smelter History 14
3.3 Waste Areas 15
m 3.4 Waste Management 15
IV. METHODS AND PROCEDURES 18
4.1 Sample Collection 18
4.2 Site Descriptions 18
4.3 Sample Preparation and Laboratory Work 21
4.3.1 Extraction and Analysis 21
4.3.2 Petrology 23
4.3.3 X-Ray Diffraction 24
V. RESULTS 25
5.1 Sample Description 25
5.1.1 Field Description 25
5.1.2 Petrography 26
5.1.3 X-Ray Diffraction Results 27
5.2 Extraction Results 27
5.2.1 Variations Between Cores 28
5.2.2 Variations Between Elements 39
5.2.3 Variations with Depth 40
VL DISCUSSION 42
6.1 Redox Boundaries 42
6.2 Sequential Extractions 43
6.2.1 Exchangeable Fraction 44
6.2.2 Bound to Carbonates 46
IV 6.2.3 Bound to Fe and Mn Oxides 47
6.2.4 Bound to Organic Matter 48
VIL CONCLUSIONS 50
7.1 Summary of Metal Partitioning 50
7.2 Conclusion 51
REFERENCES 52
APPENDIX
A: TESSIER SEQUENTIAL EXTRACTION PROCEDURE 54 B: ICP-AES AND GRAPHITE FURNACE AA RESULTS TABULATED 57 ABSTRACT
Nine decades of copper smehing operations in Anaconda, Montana have generated 5.7x10* m^ of waste material and 16x10^ m^ of tailings material. These operations resuhed in severe degradation of the surrounding soils (777 km), contamination of groundwater and the adjacent Clark Fork River, and posed human health risks, prompting the U.S. Envu-onmental Protection Agency to place the area on its
National Priority List. Resuhing from this listing, numerous studies have been conducted to identify the principal metal contaminants, which mclude As (ISOOppm), Cd (41ppm),
Cu (5200ppm), Pb (800ppm), and Zn (1900ppm).
In this study, the chemical and mineralogical characteristics of soils proximal to the tailings ponds were examined in order to identify the hydrogeochemical processes responsible for controlling the bioavailability and mobility of the contaminants. Soil cores up to 2.5m depth were collected from three sites. Sequential extractions were performed on samples taken from the cores at 30-50cm intervals. The extraction procedure followed that of Tessier et al. (Analytical Chemistry, 1979). This procedure is designed to differentiate between the adsorbed and coprecipitated metal fractions.
Extractions were performed on samples dried at 60°C, then sieved to 0.25mm. The
<0.25mm fraction was selected as being the most likely fraction to have readily adsorbed the metals of mterest, and to provide suflQcient material for the sequential extraction analyses. Extracts were analyzed for Al, As, Ca, Cd, Cu, Fe, K, Mg, Mn, Pb, Zn by ICP-
AES. In addition, the residual metal concentrations were determined following standard
Uthium-metaborate fusions.
vi LIST OF TABLES
3.1: Characterization of wastes found at Anaconda 16
B. 1: Exchangeable Fraction 56
B.2: Bound to Carbonates 57
B.3: Bound to Iron and Manganese Oxides 58
B.4: Bound to Organic Matter 59
vu LIST OF FIGURES
3.1: Location map of Anaconda 12
3.2: Areas of mterest at the Anaconda Superfimd Site 13
4.1: Location of sample sites 19
4.2: Cross-section illustrating samples cores, estimated water table,
and estimated redox boundary 20
5.1: Partitioning of Arsenic 29
5.2: Partitioning of Cadmium 30
5.3: Partitioning of Copper 31
5.4: Partitioning of Lead 32
5.5: Partitioning of Zinc 33
5.6: Arsenic with depth 34
5.7: Cadmium with depth 35
5.8: Copper with depth 36
5.9: Lead with depth 37
5.10: Zinc with depth 38
vm CHAPTER I
INTRODUCTION
1.1 Problem Statement
Copper smehing at Anaconda, Montana began m 1884 and ended in 1980, producing millions of cubic meters of waste material, including flue dust, fiimace slag, and mill tailings. These wastes were disposed of on-site, e.g., mill tailings were transported as slurries to a series of impoundments named the Anaconda and
Opportunity Ponds (Tetra Tech, 1986), which now cover approximately 6,000 acres and contain 185 million cubic yards of material. Mill tailings are highly varied in their characteristics due to differences in processing methods, types of ores, and reworking.
Water and sewage were applied to the ponds from the late 1950's through 1982 to prevent wind erosion of the tailings (Tetra Tech, 1986). The ponds have all dried since operations have ceased.
The Anaconda smelter site has been under examination since it attracted the attention of the Environmental Protection Agency and was deemed a Superfimd site in
1983. Studies have been contracted to several environmental companies including Titan
Engineering, Tetra Tech, CH2M Hill, to assess the extent of contamination, effects on animals and vegetation, and the possible migration of metal contaminants.
The Anaconda smelter site is not restricted to the immediate vicinity of the smelter, but includes an affected area in excess of 700km . Metal concentrations in soils may be elevated near a smelter enough to pose a significant health hazard, but decrease
exponentially with distance from a smeher (Kuo et al., 1983).
Local and surrounding soil and water systems have been degraded by the
presence and migration of tailings material containing high levels of arsenic (1800ppm),
cadmium (41ppm), copper (5200ppm), lead (800ppm), and zinc (1900ppm). The local
aquifer system shows levels of the metals of concern in this study occurring in plumes
directly beneath and adjacent to the tailings material (Titan Engineering, 1996).
Most of the material processed at the smelter was copper porphyry ore including
the mmerals chalcocite (CuS), bomite (CuFeS), and enargite (CuAsS). The tailings that
are impounded in the ponds are rich in sulfide minerals - both primary and those formed
in situ. Although most metal contamination of surface and groundwaters is due to
mining activities exposing sulfides to oxygen-rich waters (Carroll et al., 1998), the
contamination at the Anaconda site is due to the long-term oxidation of sulfides and the
presence of toxic metals in the primary material.
In order to effectively manage metal contaminated dramage from mine waste it is
important to understand the mechanisms controlling metal solubility (Shum and
Lavkulich, 1999). The mobility of trace elements and metals is an important factor in
determining their bioavailability (Boisson et al., 1999). Bioavailability (or bioaccessibility) of metal contaminants is of concern at the Anaconda Smelter site since there are natural wetlands within the area with abundant bird and animal populations that may be adversely affected by the presence of these metals. Determination of total metal concentration in soil can provide information for
superficial comparisons and the identification of areas of significant contamination, but
it does not provide any information regarding the mobility, plant availability, chemical
reactivity, and biological effects of the metals (Narwal et al., 1999). This study was
designed to examine the mechanisms controlling metal concentrations found in the
sediments and tailings material since the majority of a potentially toxic element or metal
is bound in solid phases (Hesterberg, 1998).
The method used in this study employs a sequential extraction procedure
published by Tessier et al. (1979). This procedure allows the determination of the
partitioning of trace elements into five different chemical fractions: (1) exchangeable,
(2) bound to carbonates, (3) bound to Fe and Mn oxides, (4) bound to organic matter,
and (5) residual. The exchangeable fraction refers to metals found in easily soluble
complexes or minerals that are liberated through simple leaching mechanisms. Bound to
carbonates refers to metals that are associated with sediment carbonate minerals. Metals
bound to iron and manganese oxides are adsorbed onto the amorphous surfaces of these
materials. Bound to organic matter refers to metal associated with various forms of
organic matter: living organisms, detritus, and coatings on mineral particles. Residual
metals are retained within the crystal structures of primary and secondary minerals.
1.2 Goals
The research presented here describes the fate and transport of the toxic contaminants As, Cd, Cu, Pb, and Zn at the Anaconda Smelter site. Parameters controlling the mobihty of the contaminants of concern include sediment texture, organic content, sedunent mineralogy, pore fluid chemistry, and the oxidation state of the sediments. The approach used in this study includes: (1) sequential extraction as outlined by Tessier et al. (1989), (2) petrographic description using thin section samples, and (3) mineralogic description using X-ray diffractometry. The sequential extraction procedure provided data to aid in the determination of the chemical fractions responsible for the adsorption of metal cations onto sediments. Mineralogic data were used to fiirther quantify the nature of the chemistry and metal contamination in the sediments.
1.3 Use of Terminologv
"Soil" or "soils" describes the unconsolidated material being investigated, which includes mine tailings, disturbed sediments, and natural soils. Disturbed sediments are those affected either by mine tailings or application of soil amendments, such as lime and clay. "Contamination" or "contaminants" refers to the high concentration of certain elements above background levels established by the Environmental Protection Agency, namely arsenic, cadmium, copper, lead, and zinc. "Metal" or "metals" refers to the set of elements including arsenic, copper, cadmium, lead, and zinc, although it is well known that arsenic is a metalloid. "Toxic" is used to imply the potential health hazard that an element or situation may pose. CHAPTER II
BEHAVIOR OF METALS IN SOILS
2.1 Overview
The partitioning and stability of metal species are evaluated in this study to determine the extent of contamination at the Anaconda site. Rather than looking at the bulk metal concentrations found in soils, this study focuses on the specific chemical form binding various metal cations to the sediments. Sequential extractions can provide information on the partitioning of metals in various mineral phases in mine wastes, providing valuable information regarding the availability of metals to the environment
(Leinz et al, 1999). Metals in the environment are of concern because of their potential reactivity, toxicity, and mobility in natural soils. Toxicity may occur when metal levels become concentrated above natural background levels (Selim and Amacher, 1997). The fate of trace elements in soils depends on soil chemical and physical properties, such as alkalinity or acidity, pH, redox potential, mineralogy, predominant grain size, and soil moisture (Kabata-Pendias and Pendias, 1992).
Soils that have many sorption sites favorable for precipitation will decrease the mobility of metal ions (McBride, 1994). The clay-sized fraction of a soil is the primary provider for the surface sites necessary for metal-soil reactions (Sposito, 1984). In general, soils that contain high fractions of clays, oxides, and/or organic matter tend to retain most natural levels of trace metals (McBride, 1994). Clay material has been added to many of the tailings ponds as an immobilizer, so the clay fraction of these sediments may contain a large portion of the metals being studied.
Metals occur in different forms in soils - as free ions, complexed with inorganic or organic hgands, or associated with inorganic and organic colloidal material (McLean and Bledsoe, 1992). Shuman (1979) defined several soil fractions where metals may be located:
1. Dissolved in soil solution,
2. Occupying exchange sites on morganic soil constituents,
3. Specifically adsorbed on inorganic soil constituents,
4. Associated with insoluble soil organic matter,
5. Precipitated as pure or mked solids,
6. Occupying structures of primary or secondary minerals.
All occurrences of metals in the forms listed above are of concern when studying metal concentrations that have been affected by anthropogenic activity (McLean and Bledsoe,
1992). Furthermore, the sequential extraction procedure used in this study enables the fractions listed above to be identified. The partitioning of metals by sequential extraction can be compared to the fractions determined by Shuman is as follows:
"Exchangeable" metals as outlined by Tessier include fractions 1 and 2 listed by
Shuman; metals "bound to carbonates" and "bound to Fe and Mn oxides" include fractions 3 and 5 listed by Shuman; metals "bound to organic matter" include fraction 4 listed by Shuman; and "residual" metals include fraction 6 Usted by Shuman. The extent and nature of contamination at the Anaconda Smelter site is still under investigation and a variety of remediation techniques are being tested, including clay capping, revegetation, and construction of wetlands. Reclamation of contaminated soils is a complicated problem, requiring a good understanding of soil chemical and physical properties, and of the extent and nature of contamination (Kabata-Pendias and Pendias,
1992). The contamination at the Anaconda Smelter site includes metals that are relatively immobile but are phytotoxic in nature, so it is important to fully understand the fate and transport mechanisms controlling these contaminants. The mobility of metal contaminants due to anthropogenic activity can be so low that their presence is permanent unless action is taken to remediated the soils (McBride, 1994). An overview of the occurrence and behavior of each metal studied is presented here, including possible implications regarding their occurrence at the Anaconda Site.
2.2 Arsenic
The mean concentration of arsenic in U.S. surficial materials is 5.8ppm (Kabata-
Pendias and Pendias, 1992), where arsenic is found up to 1800ppm m surface soils surrounding the Anaconda Smelter site.Arsenic, a metalloid, occurs in soils as either arsenate or arsenite. As (V) in As04^", and As (III) in ASO2", respectively. Arsenite is the more toxic and mobile form of arsenic (McLean and Bledsoe, 1992). In this study, only total arsenic was determined because it is relatively difficult to analyze for individual As species. Arsenate predominates in oxidizing conditions, whereas arsenite becomes predominant in reducing or high pH conditions. The mobility of arsenic is greatly limited due to strong sorption to clays, hydroxides, and organic matter (Kabata-Pendias and Pendias, 1992). Boisson et al. (1999) however, state that there is no correlation between arsenic and the organic carbon or the cation exchange capacity of a soil, reiterating the fact that the distribution of metals in the solid phase depends on the concentrations, their nature and origin (Narwal, 1999).
2.3 Cadmium
The worldwide mean concentration of cadmium in soils is 0.53ppm (Kabata-
Pendias and Pendias, 1992), where cadmium is found up to 5ppm in soils surrounding the Anaconda Smelter site. Cadmium is found in soils predominantly as cadmiimi carbonate, cadmium hydroxide, or cadmium phosphate.
Cadmium forms soluble complexes with inorganic and organic ligands, CI" in particular and the chemistry of Cd m soils is primarily controlled by pH (McLean and
Bledsoe, 1992). Adsorption of cadmium in polluted soils is also sensitive to the presence of otavite (CdCOs) (McLean and Bledsoe, 1992), due to the ease of substitution of Ca^"^ for Cd^^ (Hickey and Kittrick, 1984). Calcite is found at the Anaconda site either primary, secondary, or both, in the tailings and surrounding soils, increasing the likelihood of finding cadmium bound into a carbonate form.
8 2.4 Copper
Copper is widely distributed geographically and geologically, with an average concentration of 13-24ppm in soils worldwide (Kabata-Pendias and Pendias, 1992)
N\1iereas copper is found up to 5200ppm in soils surrounding the Anaconda Smelter site.
Green and blue salt crusts are abundant on and around the tailings ponds and in adjacent areas where no visible tailings materials are present. This suggests the occurrence of copper as a soluble salt.
Copper is relatively immobile corq)ared to other trace elements and there is typically httle variation in total Cu concentration with depth in a soil column (McBride,
1981). The greatest amounts of adsorbed copper have been found associated with Fe and Mn oxides, amorphous Fe and Al hydroxides, and clays (Kabata-Pendias and
Pendias, 1992). Copper has a high affinity for soluble organic ligands (McLean and
Bledsoe, 1992), and may be foimd up to 25% total Cu associated with the organic fi-action of a soil (Stevenson, 1981).
2.5 Lead
The worldwide mean concentration of lead in soils is 32ppm (Kabata-Pendias c and Pendias, 1992) where it is found up to 800ppm in soils surrounding the Anaconda
Smeher site. Lead poisoning in children is the primary reason for the demolition of Mill
Town, an old community adjacent to the smeker (Titan Engineering, 1996). Lead occurs as galena (PbS) or as Pb^^ in its natural state, although it may be oxidized to a valence of
+4. Lead minerals are quite insoluble in natural waters. Lead is reported to be the least mobile among the heavy metals, however, its mobility is enhanced through its high affinity for soluble organic ligands. On the other hand, lead readily adsorbs to clays and a number of Fe, Mn, and Al oxides and oxyhydroxides, which decrease its mobility (Kabata-Pendias and Pendias, 1992).
2.6 Zinc
The worldwide mean concentration of zinc in soils is 64ppm (Kabata-Pendias and Pendias, 1992) where it is found up to 1900ppm in soils surrounding the Anaconda
Smelter site. Zinc occurs primarily as a sulfide mineral (ZnS), but may substitute in silicate minerals for Mg^"^.
Zinc is more soluble than the other heavy metals in soils, but is readily adsorbed by clay minerals, carbonates, and hydrous oxides (Kabata-Pendias and Pendias, 1992).
The bulk percent of zinc in polluted soils was associated with iron and manganese oxides (14-38%, McLean and Bledsoe, 1992), and clay minerals (24-63%, Kabata-
Pendias and Pendias, 1992).
10 CHAPTER III
SITE HISTORY
3.1 Setting
The Anaconda Smelter site is located in southwestern Montana, in Deer Lodge
County (Figure 3.1). The town of Anaconda is approximately 25 miles northwest of
Butte, Montana on the western margin of Deer Lodge Valley. The smelter stack is approximately 5200 feet above sea level and set at the edge of a valley bound to the
south by the Pintlar Mountains and to the northwest by the Flint Creek Range.
Three communities surrounding the smelter: (1) Anaconda (population 8,000),
(2) Opportimity (population approximately 1,000), and (3) Warm Springs (population approximately 1,000). Milltown was a small community adjacent to the smelter site that was destroyed in the early 1980's due to lead poisoning in the human population.
Surface water systems that outline the southern border of the site include Mill
Creek, Willow Creek, and Silver Bow Creek; outlining the northern border include
Warm Springs Creek, Dutchman Creek, and Lost Creek (Figure 3.2). Silver Bow Creek, flowing out of Butte, combines with Warm Springs Creek to form the Clark Fork River,
The Clark Fork is heavily laden with metal contaminants from its headwaters near
Anaconda downstream to Missoula due to activities at the Anaconda smelter and other mining areas including Butte.
The groundwater system in the area is comprised of an upper unconfined
Quaternary alluvium aquifer, and a Tertiary aquifer of alternating sands, clayey sands.
11 Anaconda _« SmeitBT
v.---»»
/'»-' *».-' 10 ' J »H I I Wlc—ttn 0 to
Figure 3.1: Location of Anaconda and vicinity.
12 Figure 3.2: Areasof interest at the Anaconda Superfimd site.
13 and clay layers (Tetra Tech, 1986). The groimdwater flow is to the northeast, following the surface water drainage.
Quaternary unconsolidated alluvial sediments, including glacial gravel till,
dominate the surfece geology at Anaconda. The alluvium is underlain by Tertiary
fluvial and lacustrine deposits, boulder conglomerates, and shales (Tetra Tech, 1986).
The bedrock is well lithified and consists of a variety of granitic, volcanic, sedimentary,
and metamorphic rocks including packages of pre-Cambrian Beh Supergroup sequences
and igneous rocks related to the Tertiary Idaho Batholith (Ah and Hyndman, 1986).
3.2 Smelter History
The copper smelter at Anaconda was established by the Anaconda Minerals
Con^any to process the ores mined out of the Berkeley Pit in Butte. Smelting took
place at two locations during two significant periods: The Old Works area operated from
1884 through 1902, and the Washoe Smelter ("Smeher Hill") operated from 1903
through 1980 (Figure 3.2).
In 1884, copper smelting commenced with 26 fiimaces with their own
smokestacks, with a total capacity of 500 tons of ore per day. Smehing began at the
Washoe Smeher in 1903 using a single 300 foot smokestack with a capacity of 12,000
tons of ore per day. In 1919, the mam flue stack at the Washoe Smeher was built up to
585 feet. All smelter operations were closed down in 1977 (Tetra Tech, 1987). Smeher
Hill was officially closed in September 1980 and all structures were demolished except
for the smeher stack.
14 3.3 Waste Areas
Figure 3.2 illustrates the general waste zones at the smelter site:
The Old Works, initial location for copper smehing (1884-1902),
Smeher Hill, location of the Washoe Smelter (1903-1980),
Opportunity Ponds, most of the mine tailings are contained here,
Anaconda Ponds, an impoundment of mine tailings.
Granulated slag pile, a Ikm^ pile of inert slag.
These wastes are described in Table 3.1.
The tailings characteristics vary considerably because of differences in the ores
mined, processing methods used, and extensive reworking of the materials (Tetra Tech,
1986). A 19-hole golf course has been constructed over most of the soUd waste material
located in the Old Works area. Smeher Hill, Opportunity Ponds, and Anaconda Ponds,
are contaminated primarily with aerially deposited and stored flue dust. Moreover,
Opportunity and Anaconda Ponds are filled wkh fine-grainedmil l tailings. Granulated
slag is sold for commercial use.
3.4 Waste Management
During the Old Works smehing operations, wet mill tailings were dunq)ed onto the land surrounding the Old Works hill (Figure 3,2) and tailings sediments found in
Warm Springs Creek can be traced to eictivity at the Old Works, When operations began at the Washoe Works, the tailings waste materials were contained in ponds constructed
15 Table 3,1: Characterization of wastes foimd at Anaconda (Tetra Tech, 1986).
Location Waste Type Area Approximate Condition (acres) Volume (yd^
Old Works Tailmgs 287 1,75x10* Spread out; Uncontained
Slag 39 7,75x10^ Piled up; Uncontained
Fhiedust 0,02-0,1 40-400 Dispersed over hillsides; concentrated in old flues
Anaconda Ponds Tailings 560 3x10' Impounded; covered with hme and clay
Opportimitv Ponds Tailings 3,390 4,3x10' Impounded; covered with lime and clay
SlagPUe Slag 130 1,6x10^ Piled up; Uncontained
Deer Lodge County Smeker stack 67,700 Metal saks soils &llout dispersed on sur&ce soils overawkie area
16 north of Smeker Hill; unfortunately these ponds were inadequately maintained resuking in tailings spilling onto the adjacent land.
Opportunity Ponds were begim in 1914, receiving tailings in the form of 25-30 percent soUds, Tailings waste deposkion into Opportunity Ponds ceased in 1980, but municipal sewage from the town of Anaconda was dumped here until 1982, Anaconda
Ponds were begim in 1943 and ceased also in 1980, receiving municipal sewage from
Anaconda and Butte (Tetra Tech, 1986), In addkion to disposal in the tailings ponds, smeking wastes were also used to construct pond dikes, railroad berms, roads, and line drainage dkches. Remediation efforts mclude the application of lime, clay capping, vegetative covering, and waste removal
17 CHAPTER IV
METHODS AND PROCEDURES
4.1 Sample Collection
All samples for this study were collected during summer 2000, May through
August. Cored soil samples were collected fromthre e sites (Figure 4.1), on three separate occasions during the summer. A hand-operated stamless steel augur was used to collect soil core san^les to depths up to 2.5 meters (Figure 4.2). The cores were double bagged in Ziploc bags, and refrigerated if visible soil moisture was present.
Three sample sites were chosen in order to assess the effect of tailings material adjacent to partially "undisturbed" soils. She 1 was chosen as a reference core, comprised entk-ely of tailings material. Ske 2 was chosen due to ks proximity to the tailings material and surfeice water and relatively undisturbed appearance. Site 3 was chosen to test the extent and nature of metal contamination distal to the tailings material.
4.2 Site Descriptions
Ske 1 was located at the eastern edge of Opportunity Ponds directly on the tailings material. There was no vegetation covering the tailings material, although some decayed plant material was encountered at various depths during sampling. Three 2,5m cores were collected within a 1ft area at this site on separate occasions spread over a period of 3 weeks during the course of the summer.
18 I / f'y Warm (Springs Creek
SCALE 1:24 000
MUS
QUMMtAMSLE lOCATION
Figure 4.1: Location of sample sites.
19 NE
Site 3
26 cm
" 60 cm- 225 cm -U
93 cm- Tailings Material 100 cm Undisturbed soils"
0 Indicates sample used in extraction •"-• Inferred redox boundary zone - - • Approxirrxjte water saturation level ** Illustration not drawn to scale
Figure 4.2: Cross-section illustrating sanq)le cores, estimated water table, and estimated redox boundary.
20 Site 2 was located 250 meters northeast of site 1 in a ditch off the edge of Opportunity
Ponds, just over the vegetated berm that outlines the eastern border of Opportunity
Ponds, The dkch contains intermittent water. There were scattered grasses and
wildflowers covering the area, along with abundant salt crusts covering the soil surfece.
Three 0,75m cores were collected within a Ift^ area at this ske on three separate
occasions spread over a period of 3 weeks,
Ske 3 was located 100 meters northeast of ske 2 in a floodbankarea , created by
flooduig of the dkch where ske 2 is located. Like ske 2, there were abimdant scattered
grasses and wildflowers. In addkion, imidentified salt crusts were observed at this ske.
Three 1.0m cores were collected within a Ift^ area at this ske on three separate occasions
spread over a period of 3 weeks.
4.3 Sample Preparation and Laboratory Work
Initially all soil san^les were dried at 60°C and homogenized with a mortar and pestle, then sieved to < 60 mesh (0.25mm). In order to compare the effects of grain size on metal partitioning throughout the sequential extractions, some samples were sieved to different grain sizes.
4.3,1 Extraction and Analysis
Select samples (Figure 4.2) were sequentially extracted following the procedure of Tessier et al, (1979), which is outlined m Appendix A. Extractions were performed
21 on l.Og dried samples m 50mL HDPE centrifuge tubes. Each extraction step was followed by a KhnL aliquot of deionized water as a rinse.
The metal fractioni n exchangeable form was obtained by adding 8mL (1 .OM)
MgCl2 to a l.Og dried san^le and lettmg the reaction proceed at room temperature for 1 hour at a neutral pH. This step provided the metals easily soluble in neutral condkions.
The metals bound to carbonates were obtained by addmg 8mL (l.OM) Na-
Acetate to the residue from step one and lettmg the reaction proceed at room temperature for 5 hours at a pH « 5, which was adjusted with acetic acid. This step provided the metals adsorbed onto carbonate mineral surfaces or into the mineral lattices.
The metal fractionboun d to Fe and Manganese oxides was obtained by adding a combmationof 5mL (0,3M) Na2S204, 5mL (0,025M) H-Citrate, and lOmL (0.175M)
Na-Citrate to the residue from step two and letting the reaction proceed at room temperature for 1 hour at a pH « 2, adjusted with nitric acid. This step provided the metals adsorbed to the surface of these amorphous confounds.
The metals bound to organic matter were determined after two steps: (1) adding
3mL (0,02M) HNO3 and 5mL (30% v/v pH=2) H2O2 to the residue from step three and letting the reaction proceed m an 85°C water bath for 2 hours at a pH « 2, adjusted with nitric acid, then (2) addmg another 3mL of the H2O2 and reactmg under the same conditions for another 3 hours. This step provided the metals adsorbed onto the surfeces of or chelated by various types of organic matter, such as Uving organisms, detritus, and coatings on mineral particles (Tessier, 1979),
22 The extraction leachates were fikeredthroug h 0,2 micron MilUpore fikers, acidified wkh nitric acid to pH <2 and subsequently analyzed by inductively coupled plasma atomic emission spectrometry (ICP-AES), The "exchangeable" fraction from step 1 was analyzed for Fe, Mn, Zn, Pb, As, Cd, Cu, Al, K, and Na; the "bound to carbonates" and "bound to Fe and Mn oxides" fractions were analyzed for Fe, Mn, Zn,
Pb, As, Cd, Cu, and K; and the "bound to organic matter" fractionwa s analyzed for Mn,
Zn, Pb, As, Cd, and Cu. A few sanq)les were analyzed using graphite furnace AA to conq)are with ICP-AES results and provide more accurate data for As, Cd, and Pb at low concentrations. For the purpose of this study, only the values obtamed for the contammants of interest. As, Cd, Cu, Zn, and Pb, are reported m Appendbc B. The ICP-
AES data were corrected using a linear regression equation and have an associated error of<10%.
Three grain sizes were extracted for a sanple from both ske 1 and site 3 sanqjles:
(1) bulk sanqjle, (2) < 0.25mm, and (3) < 0.045mm, to assess any grain size effects on metal partitioning. Results are tabulated in Appendix B,
4.3.2 Petrology
Select samples (Table 4.1) were mounted in epoxy and made into thin sections in order to examine the mineralogy using a petrographic microscope. The sUdes are described in section 5.1.2.
23 4.3.3 X-Ray Diffraction
Some samples were analyzed as bulk powders using an X-ray diffractometer, using a Cu lamp set to 0.154184nm, to provide additional details on sample mineralogy.
X-Ray reflections were used in conjunction with the petrographic results and are described in section 5.1.3.
24 CHAPTER V
RESULTS
5.1 Sanyle Description
Site and sample descriptions were noted in the field during each samphng event.
The following section describes the visual appearance of the sedunent cores, thki sections, and x-ray diffraction resuks. Redox boundaries were mferred in terms of color transkions and mmeralogy.
5.1.1 Field Description
Site 1. All three sediment cores were obtained from this site had similar characteristics. Surface samples from 0-12cm were iron-oxide stained very-fine sand, grading downward into a light yellow very-fine sand/silt. At approximately 140cm there was a color change to medium to Ught gray very-fine sand/silt with yellow mottled clay lunqjs. Visible pyrite crystals from 140cm to the bottom of the borehole indicate a correlation between the color transition and mferred redox boundary. Soil moisture was present toward the bottom of the borehole, but no water saturation boundary was reached.
Site 2. The different sedunent cores obtamed from this ske all had similar characteristics. Surface samples from 0-15cm were light yellow very-fine sand/silts with mottled dark brown/kon-stamed chunks. The remainder of the core was a medium to
25 Ught gray brown clay. The water saturation level was poskioned at approxunately 30-
40cm, correlatmg with the mferred redox boundary.
Ske 3. The different sediment cores obtained from this site all had sunilar characteristics. Siuface samples 0-15cm were yellow very-fine sand/clay, gradmg downward to rusty brown very fine sand. The next portion of the core, from 15-80cm was Ught to medium gray clay with gravel clasts; with the remamuig depth of the core was a medium gray-brown silt/clay. The water saturation level was at approxunately
85cm, correlating with the inferred redox boundary zone.
5.1.2 Petrography
Site 1. Sample 15-21cm fromth e surface cont£iined abimdant quartz and highly altered (serickized) feldspar grains, with thm hematke coatmgs existing on most grains.
There were oxidized pyrite grams and a few scattered accessory minerals. Sample 51-
61cm contained abundant quartz, sericitized feldspar grains and some carbonate grains with a few smaU scattered pyrite grams. Sample 221-23 8cm contamed abundant opaque minerals - predominantly pyrite which may have formed in-situ. Clay aggregates were present with opaque grams mcorporated.
Site 2, Sample 0-17cm contained abundant quartz, weU-cleaved feldspar grains, and fine-grainedhematke . There were scattered ferromagnesian minerals and some clay coatmgs on aU grams. Sample 44-58cm contained very fine-grainedplagioclas e feldspar and quartz grams. There were abundant carbonate fragments and scattered accessory muierals.
26 Site 3. Sample 0-13cm contained coarse-grained quartz and fresh feldspar grains with abundant oxidized iron oxide grains and gram coatings. There were clay aggregates containuig organic material. Sample 26-51cm contained fine-gramed peUetized clay grains with a few quartz grams also present. Sample 95-104cm contained very fine-gramed quartz and calcke grams with calckic sheU fragments. There were
scattered ferromagnesian minerals found m clumps.
5,1.3 X-Ray Diffraction Results
Site 1. Sample 15-21cm fromth e surface showed predominantly quartz with
lesser amounts of gypsum, ilUte, kaoUnite, and perhaps potassium feldspar. Sample 51-
61cm showed predominantly quartz with lesser amoimts of ilUte, kaoUnite, and perhaps
cerrusite. Sample 221-23 8cm showed predominantly quartz and gypsum with lesser
amounts of ilUte and kaoUnite.
Site 2. Sample 44-58cm showed predominantly quartz and calcite with lesser
amounts of ilUte and kaoUnite.
Site 3, Sample 0-13cm showed predominantly quartz with lesser amounts of
illke and kaoUnite, Sample 95-104cm showed predominantly quartz and calcite with
smaU amounts of pyrite.
5.2 Extraction Resuks
Each of the three skes yielded highly varied resuks, an artifact of the
heterogeneity of the area. Although buDc and residue samples were extracted and
27 independent extractions were performed, this study focuses on the sequential extraction results in terms of site variation, chemical fraction variation, and depth variation. The results are plotted in figures 5.1 through 5.10, Data that are below detection Umits are not shown on the plots, leavmg some gaps in the figures. Note that the data for each element at each ske are plotted using different scales.
5.2.1 Variations between Cores
Site 1 resuks show most As and Cd were bound to the organic fraction,wherea s
Cu, Pb, and Zn were predommantly m the exchangeable fraction. Trace amounts of As were bound to the Fe and Mn oxide fraction, and trace Zn was bound to carbonates.
Metals were found at this ske in varied concentrations (up to 7ppm for any one element).
Ske 2 resuks show As, Cd, and Zn bound to organic matter, especiaUy in the
surface samples. Most Pb, some Cu, and trace Cd, Zn were bound to carbonates. The
Fe and Mn oxide fractioncontai n some As, Cu, Pb, and Zn. The concentrations of metals found at this site are low (< 4ppm for any one element) relative to sites 1 and 3.
Site 3 results show that aU contammants, except Pb, were concentrated in the top
40cm of the core. As and Pb were the only metals bound by organic matter, while Cu,
Zn, and trace amounts of As were boimd to carbonates. The Fe and Mn oxide fraction contained most of the Pb, and trace amounts of As and Zn, Metal concentrations at this site were high relative to skes 1 and 2 (up to 140ppm for any one element).
28 Site 1 Arsenic Concentration (ppm) 0.00 0.10 0.20 0.30 0.40 0.50 0.60
^c/j, ^^9«a6/e
Sot/,"Qf/ o ^^rton^ afes • 12-23cm ^, ^C'/O; •««S/Wo • 56-67cm Oxides nl18-131cm a'ot^oc y nl42-153cm ^OQr'9ani., c/lf.afte r
1- '-.;•,;rf-'yyWit^:-''; •::-,'•'•SV-^;|:'':--.V..'i:'' -^ , i ••^/••'-:-V' .j 4-A.- Ai^rim,
Site 2 Concentration (ppm) 0.00 0.05 0.10 0.15 0.20 0.25 0.30 0.35 ^^ch, '^''deetL fi.°una toe^rbo; '^a^es m: • 14-32cm e,°una fopf. • 32-50cm O^c^'e, s 8, r • 50-61 cm • ':-•-' -f • • 61-70cm ^''te/i,, ^er
^^,•^•^-.•^-^4:••^- ,-...; /I- -' -vvt ;,.
Site 3 Concentration (ppm) 0.00 2.00 4.00 6.00 8.00 10.00 12.00 ^c/7, , ^""Seebie
^, w• - - . na ^th • ^^'i'oo,afe s ^ria • 15-26cm ^th p. ^***'0«^ • 26-37cm ^, n49-60cm nd "^th Q ''"Sao, D 81-93cm 'oMatt, er mmmmmuHm
Figure 5.1: Partitioning of Arsenic,
29 Site 1 Cadmium Concentration (ppm) O.OE+O 5.0E- 1.0E- 1.5E- 2.0E- 2.5E- 3.0E- 0 04 03 03 03 03 03 ^c^, '^"eea^e ^; na ^th C^rton^ a^es • 12-23cm ^nd ^thp. • 56-67cm ^^Mn °^ctes ni18-131cm fioo,nd ^th • 142-153cm Or9ani,, ""^att, er
Site 2
Concentration (ppm) 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0 12 3 4 5 6 7 8
• 14-32cm • 32-50cm n50-61cm n61-70cm
"'^'^mer .^^ , 1
Site 3 Concentration (ppm) 0.00 0.05 0.10 0.15 0.20 0.25 0.30
^"^^angeab/e
fioo,ndto ^arboi'nates • 15-26cm fiou ndto • 26-37cm ^^Mn Oxidi es n49-60cm Boo, • 81-93cm ndto Orgat '^'c/lfaft, er I
Figiu-e 5.2: Partitioning of Cadmium.
30 Site 1 Copper Concentration (ppm)
0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00
^C^. ^""deebL
e,oo/7c y toe.3^ , "^afes • 12-23cm a,°ond to p. • 56-67cm ni18-131cm a°und ni42-153cm to Or, 9anicu after
. . I- .1 • —r- t-;kf!^i^ihfmS!^;:r:'i C
Site 2 Concentration (ppm) 0.00 1.00 2.00 3.00 4.00 ^-^c/,.ar), ^6/, a'ouna, toC; ^^, ">a/
Site 3 Concentration (ppm) 40 80 120 160
^1 '^"^eab/e
^i '"C/fo Oarton^ ates
- • • 15-26cm aoui '^C^/OA ^^Mn • 26-37cm Oxides n49-60Gm ^ ^i '"^dto • 81-93cm On9ani, 'cMiatter
- . • - .- • -,•••> .-.L-l ^..A,i ,-..J
Figure 5.3: Partitioning of Copper.
31 Site 1 Lead Concentration (ppm) 0,00 0.10 0.20 0.30 0.40 0.50 0.60 ev< •^/'ao, '^^bie —+ Sou, I ^fo, -arbon, 'ates • 12-23cm Sou, • 56-67cm Oxid,'es nl18-131cm Sou, '''CI to nl42-153cm On'9ani, ""^att, er ^ r- J
Site 2 Concentration (ppm) 0.00 0.10 0.20 0.30 0.40 0.50 0.60
^('^^ao , 'deabie
Sou, ''CI to Oarb, '°natie s a • 14-32cm ^nd toA= ^Mr) • 32-50cm Oxid,'e s n50-61cm a^nd too- 'dam, • 61-70cm '""^att, er
Site 3 Concentration (ppm) 0.00 0.10 0.20 0.30 0.40 ef( ''^/'ao, yeabie 1 Sou, "'CTfo Oarb, '°nat es • 15-26cm Sou, '^fo ^^Mn • 26-37cm Oxid,'es ^^^•^^^ 1 • 49-60cm Sou, 1 " n81-93cm •^tffo O, ''yam, '""^att, er \
Figure 5.4: Partitioning of Lead.
32 Site 1 Zinc Concentration (ppm) 0.00 0.40 0.80 1.20 1.60 2.00 ^C/). '^^^eabfe a°und r toe. w^^^d ^'tOi'"ates a • 12-23cm °(Jnd top. e«SyWn • 56-67cm Q^c/, a 'es nl18-131cm "^"dto • 142-153cm On9anic^^ atter
• :. ..• :v,..-,„ ^
Site 2 Concentration (ppm) 0.00 0.40 0.80 1.20 1.60 ^^c 'c^.'an, a '^«^6/e ""^nd to, I ''^QO. St '^fes • 14-32cm '°^nd to p ^"S/lfr, • 32-50cm O^c^, fib. 'es 0 50-61 cm '"^cr/b, ^'9ar,/c • 61-70cm 1^, '^tter
Site 3 Concentration (ppm) 0.0 20.0 40.0 60.0 80.0 ^^Ch. '^"deabie •
a^nd tor 3^i "ates a ™ • 15-26cm °«^n(/ top. e«S/Wr • 26-37cm Oxidte s n49-60cm B, ^na r ^°Orrto„- n81-93cm ^"^/i^, ^er 3
Figure 5.5: Partitionuig of Zmc.
33 Site 1 Arsenic Concentration (ppm) -0.20 0.00 0.20 0.40 0.60
•Exchangeable E u Bound to Fe & Mn Q. Oxides Q •Bound to Organic Matter
Site 2 Concentration (ppm) -0.10 0.00 0.10 0.20 0.30 0 10 Bound to Organic ^20 Matter 3, 30 Bound to Carbonates "S. 40 r Bound to Fe&Mn ° 50 Oxides 60 \ 70
1
Site 3 Concentration (ppm) -5.00 0.00 5.00 10.00 15.00 n U 10 - 20 - ? 30 - / •^-^"""'^ —•— Exchangeable / ^^^""^"''^^ ^ 40 i 1 y^y^ i. 50 - Y Bound to Fe & Mn tS 60 - 1 Oxides 70 - • Bound to Organic Matter 80 - I yU
Figure 5.6: Arsenic with depth. Note: Trend lines are only for reference and may not be accurate.
34 Site 1 Cadmium Concentration (ppm) 0 0.001 0.002 0.003
O III u • ',__ • 20 ^.,,^^^, f '°- ^^"'^'^N. o. 60 - J • Bound to Organic 5 80 - y/ Matter S 100 - y/^ 120 - y^ ^^ 140 -
Site 2 Concentration (ppm) 0.001 0.003 0.005 0.007 0 10 ^ 20 E ii 30 Bound to Organic Q. 40 Matter ° 50 60 70
Site 3 Concentration (ppm) -0.05 0.05 0.15 0.25 0.35 0 10 20 E 30 o 40 Exchangeable Q. 50 Q 60 Bound to Organic 70 Matter 80 90
Figure 5.7: Cadmimn with depth. Note: Trend Unes are only for reference and may not be accurate.
35 Site 1 Copper Concentration (ppm) 1.00 3,00 5.00 7.00 0 20 40 E o 60 80 •A Fraction Q. 0) Q 100 •D Fraction 120 140
Site 2 Concentration (ppm) 0.00 2.00 4.00
Bound to Carbonates
Bound to Fe & Mn Oxides Bound to Organic Matter
Site 3 Concentration (ppm) C0 00 2 00 4.00 6.00 0 10 20 E 30 o^ 40 Bound to Fe & Mn .c a 50 Oxides 0) Q 60 •Bound to Organic 70 Matter 80 90
Figure 5.8: Copper with depth. Note: Trend lines are only for reference and may not be accurate.
36 Site 1 Lead Concentration (ppm) 0.00 0.20 0.40 0.60
E o Exchangeable a. 0) Bound to Organic Q Matter
Site 2 Concentration (ppm) 0.00 0.20 0.40 0.60 0 10 ^20 Bound to Fe & Mn Oxides ii 30 ••—Bound to Organic a 40 Matter ° 50 -Ar—Bound to Carbonates 60 70
Site 3 Concentration (ppm) 0.00 0.10 0.20 0.30 0.40 n U 10 - 20 - c on ^ C VJU ^ ^ 4ADU Bound to Fe & Mn .C •*-" en Oxides Q. JU Q 60 - • Bound to Organic i 70 - Matter 80 - 90 -^
Figure 5.9: Lead with depth. Note: Trend lines are only for reference and may not be accurate.
37 Site 1 Zinc Concentration (ppm) 0.00 0.50 1.00 1.50 2.00
0 , 1 ' 1 , 20 40 Exchangeable E u 60 80 -*—Bound to Carbonates Q. 0) -I 00 20 -•—Bound to Organic Matter 40
Site 2 Concentration (ppm) 0.00 0.50 1.00 1.50
-•—Exchangeable
Bound to Fe & Mn Oxides -•—Bound to Organic Matter -A—Bound to Carbonates
Site 3 Concentration (ppm) 0.00 5.00 10.00
-•—Exchangeable
Bound to Fe & Mn Oxides -•—Bound to Organic Matter -*—Bound to Carbonates
Figure 5.10: Zinc with depth. Note: Trend lines are only for reference and may not be accurate.
38 5.2.2 Variations between Elements
Arsenic (Figure 5.1) in sites 1 and 2 was predominantly (0.35-0.6ppm) bound to organic matter, whereas in site 3 it was found in all four fractions(2-lOppm ) in the 15-
40cm depth zones.
Cadmium (Figure 5.2), hke arsenic, was bound to organic matter (0.003-
O.OOSppm) in sites 1 and 2, whereas in site 3 it was in the exchangeable fractioni n the
15-40cm depth zones.
Copper (Figure 5.3) in site 1 was in both exchangeable form (2.5ppm) and bound to organic matter (6ppm). In site 2 copper was found mostly in the 14-32cm depth zone predominantly bound to organic matter (4.5ppm) and Fe and Mn oxides (4ppm), with a trace amount (Ippm) bound to carbonates. Copper in site 3 was boimd to carbonates
(140ppm).
Lead (Figure 5.4) was found in site 1 to be in the exchangeable fraction
(0.55ppm) and boimd to organic matter (0.2ppm). In site 2 lead was bound to carbonates
(0,3ppm), Fe and Mn oxides (0.2ppm), and organic matter (0.6ppm). Lead in site 3 was bound to Fe and Mn oxides (0.15ppm) and organic matter (0,37ppm),
Zinc (Figure 5.5) in site 1 was predominantly in exchangeable form (1.6ppm), but also bound to carbonates (0.2ppm) and organic matter (0.4ppm). In site 2, zinc was bound to carbonates (0.3ppm), Fe and Mn oxides (0.55ppm), and organic matter
(1.6ppm), with trace amounts (0. Ippm) in exchangeable form. Zinc in site 3 was predominantly boimd to carbonates (60ppm) in the 15-40cm depth zones.
39 5.2.3 Variations with Depth
The concentration of arsenic in site 1 (Figure 5.6) increased with depth for the exchangeable and organic bound fractions,wherea s the As bound to Fe and Mn oxides decreased with depth. In site 2, As concentration decreased at a shallow depth for the fraction bound to organic matter but increased for the Fe and Mn oxide bound fraction.
The fractionboun d to carbonates was unchanged with depth for this core. Arsenic in she 3 decreased at the redox boundary for the exchangeable and organic bound fractions and increased gradually with depth for the fraction bound to Fe and Mn oxides.
Cadmium was only bound to organic matter in sites 1 and 2 (Figure 5.7) with the maximum concentration in she 1 at 60cm and at 20cm depth in site 2. Cadmium in site
3 was at maximum concentration in the exchangeable form at 20cm and the fraction bound to organic matter remained unchanged with depth.
The concentration of copper in site 1 (Figure 5.8) increased at 120cm for the
fraction bound to organic matter whereas the exchangeable fractionremaine d constant with depth. In site 2, the copper concentrations decreased at 40cm for all three fractions.
Copper in site 3 reached a maximum at 30cm for the Fe and Mn oxide bound fraction, and gradually increased for the fraction bound to organic matter.
Lead concentrations m site 1 (Figure 5.9) mcreased at 120cm consistently for both the exchangeable and organically bound fractions. In site 2, lead reached a maximum concentration in the surface sanq)les for all three fractions with a gradual decrease in depth. Lead in site 3 reached a maximum at 30cm for the fraction bound to
40 organic matter, whereas the fractionboun d to Fe and Mn oxides was relatively constant with depth.
Zinc concentrations ui site 1 (Figure 5.10) were relatively consistent for the fractions bound to carbonates and organic matter but there was a maximum concentration at 60cm for the exchangeable fraction. In site 2, there was a consistent decrease in zinc concentrations at 40cm for all four chemical fractions. Zinc in site 3 shows consistently decreasing concentrations at 55cm for the exchangeable, bound to carbonates, and organic matter fractions.
41 CHAPTER VI
DISCUSSION
6.1 Redox Boundaries
The redox potential of an environment affects the solubiUty of a number of soil
con^nents. The downward migration of the oxidation zone in and around the tailings ponds at Anaconda, as noted by Tetra Tech (1987), presents a mechanism for the
liberation of metals. In general, oxidizing conditions fevor metal retention in soils,
while reducing conditions enhance their mobilization (McLean and Bledsoe, 1992).
At she 1, a redox boundary at 120cm depth (Figure 4.2) is suggested by changes
in the concentrations of arsenic, lead, and copper. Unoxidized pyrite grakis noted in a
thin section from a depth of 55cm may in:q)ly that the redox zone starts at a much
shallower depth.
The redox boundary at site 2 was inferred at 35 cm from a significant change in
the chemical partitioning of arsenic, copper, lead, and zinc; this corresponded to the
water level encountered at 32cm (Figure 4.2). The thin sections showed no oxidized
minerals below a depth of 44cm, but significant oxidized iron minerals were present to a
depth of at least 17cm. A decrease in the concentrations of the above mentioned metals at depths below 35cm suggests either that the soils below the 35cm horizon are undisturbed, or protected from metal concentrations nearby, or that the availability of the metals below the redox zone is limited.
42 At she 3, a change in the chemical partitioning of all metals of interest indicated
a redox boundary at 55cm depth. The apparent decreased availability of metals below
the redox boundary suggests the soils are undisturbed, or the reduced form of the metals
makes them relatively immobile.
6.2 Sequential Extractions
Parameters to account for in the determination of trace metal partitioning in soils
include organic content, soil properties and chemistry, and the nature of contamination.
The approach used here provides insight into the partitioning of metal contaminants into
four different fractions:(1 ) Exchangeable, (2) Bound to carbonates, (3) Bound to Fe and
Mn oxides, and (4) Bound to organic matter. The mobility and bioavailability of metals
decrease following the extraction sequence (Hickey and Kittrick, 1984). Not all
chemical and physical characteristics of the soils studied were examined, therefore, the
sequential extraction resuks reported in this study may be used only to infer general
trends.
Calvet et al, (1990) suggest that sequential extraction procedures do not provide
an unequivocal distribution of the metals in soils; as the extraction order may affect the concentrations of metals released. For example, usmg MgClz in the first extraction step may liberate metals fromth e carbonate fraction (Tessier, 1979), however, minimizing the extraction time in this step may decrease this effect.
Specific aflSnities inherent to metals such as lead, copper, and zinc may affect their parthioning in an extraction procedure. For example, soil affinities for zinc and
43 copper are greater than that of magnesium, therefore, MgCl2 may not be an ideal sah to exchange metals in a sequential extractwn (Calvet et aL, 1990).
Sequential extractions of different grain size fi*actions yielded little variations within the accuracy of the technique and analysis, vvliich is consistent with the results of
Lemz, et aL (1999) and Carroll, et aL (1998). However, only shght differences were noted for copper.
The occurrence of clay globules, or peds, m thin sections from all three sites suggests reduced reactivity of clay material in the soils. Clay materials are highly mfluential in the partitioning of metals in soils due to their sur&ce areas, so the clumpy nature of the clays in the Anaconda soils may keep the clays from releasing a possibly significant concentration of metals. Clay globules may account for the lack of variation in concentration with grain size.
6.2.1 Exchangeable Fraction
Metals found in the firstextractio n step are most readily leached and likely to be affected by local mobilization agents such as rainfell percolation, and aerial redeposition.
Arsenic was found (up to 10% total As) m the exchangeable fi-action in sites 1 and 3, v^ereas no arsenic was detected in the exchangeable fiaction in site 2. Therefore, a fiaction of the elevated As concentrations (up to 18(X) ppm) is not readily mobile in the environments seen at all three shes at Anaconda.
Cadmium was in an exchangeable form at shes 1 (10% total Cd), and 3 (50% total
Cd), concurrent with Narwal, et aL (1999), WIK) found significant (14-46%) Cd
44 associated with the exchangeable fi-actioni n acidic soils. Exchangeable cadmium is
most Hkely due to the acidic nature of the tailings material and adjacent soils, as
cadmium is more mobile in acid environments (Kabata-Pendias and Pendias, 1992). The
lack of exchangeable Cd at she 2 suggests a low soil acidity or that another soil fi-action
controls the availability of cadmium at site 2.
Copper was in the exchangeable fi-action (45% total Cu) m site 1, contrary to Hickey
and Kittrick (1984), and EUiot et aL (1986) who report Cu as bemg primarily bound by
the organic and residual fi-actionso f a soiL Considering the elevated levels (up to
5200ppm) of copper at the Anaconda she, it is uiQX)rtant to recognize the mobility of
copper in a readily leached form.
Lead was found exchangeable in site 1 (45% total Pb), but not m sites 2 or 3, perh^s
due to the uptake of Pb by carbonate and iron hydroxide phases (Carroll et aL, 1998).
The occurrence of exchangeable lead suggests lead is readily mobilized and available at
site 1 contrary to the findmgs reported by Elliot et aL (1986) stating that Pb is strongly retamed by soils and phytotoxic effects from Pb uptake are rare.
Zinc was in the exchangeable fi-action(10-75 % total Zn) in all three sites, agreeing with McLean et al. (1992) and Elliot et al. (1986), and reiterating the idea that zmc is relatively more soluble and mobile than other heavy metals in soils. Zinc is predominantly found in the readily exchangeable fi-action of a soil (Elliot et aL, 1986) and is therefore a concern in terms of mobility and availability at the Anaconda site.
45 6.2.2 Bound to Carbonates
Metals bound to carbonate minerals are susceptible to acid leaching due to their high solubility at tow pHs. Many carbonate mmerals were visible m the sections. In addition to naturally occurring carbonate minerals, it is possible that carbonates have formed in-situ, resuhing from the heavy liming of the Superfimd site.
Arsenic was bound to carbonate minerals in small amounts (10-17% total As), at shes 2 and 3 suggesting the in-situ formation of arsenic-carbonate phases in soils surrounding the tailings materiaL The solubility of any arseno-carbonates would therefore control the mobility of arsenic bound to the carbonate fi-action.
Cadmium was associated with the carbonate fi-action at all three sites (up to 14% total Cd), agreemg with Hickey and Kittrick (1984) who found Cd in the carbonate bound fiaction up to 23%, The ease of substitution of Cd forCa in calcite suggests octavite (CdCOs) is a significant sink for cadmium as noted by Carroll et al. (1998).
Copper was found in the carbonate bound fi-action at sites 2 and 3 (up to 30% total
Cu) inferring the formation of copper carbonate phases which is likely considering the high concentrations of copper found at the site, accounting for the occurrence of Cu in this fi-action.
Lead occurred in the carbonate bound fi-action at sites 2 and 3 (up to 24% total Pb) suggesting the possibility of siderite (PbCOs) formation in the soils surrounding the tailings material, providing an appropriate sink for lead, as suggested by Carroll et aL
(1998).
46 Zmc (up to 15% total Zn) was bound to carbonates at all three sites. Carroll, et aL
(1998) have shown zinc to be easily taken up by carbonates, accountmg for the abundant zinc found in this fi-action.
6.2.3 Bound to Fe and Mn Oxides
Iron and manganese oxides and amorphous phases are stable metal retainers, however, metals will be Hberated at low pHs.
Arsenic (15-25% total As) was associated with Fe and Mn oxides at all three sites, a resuh of the strong sorption of As onto oxides and ox>iiydroxides as noted by Kabata-
Pendias and Pendias (1992), Hickey and Kittrick (1984), and McBride (1981). The adsorption of As onto Fe oxides is at a maximum at pH 3-4 (McLean and Bledsoe,
1992), suggesting these oxide phases may be significant retainers of As under moderately acidic conditions as seen around Anaconda.
Copper was bound to Fe and Mn oxides at sites 2 (25% total Cu) and 3 (40% total
Cu), an artifect of the ease of sorption onto iron hydroxides (McLean and Bledsoe, 1992, and Narwal, et aL, 1999) and the common substitution of Cu for Fe or Mn in the oxide structure (McBride, 1981; Hickey and Kittrick, 1984). The adsorption of Cu onto Fe and
Mn oxides is an irrqwrtant mechanism in the mobility of copper at Anaconda, but mfers a dependence on the pH conditions.
Zuic (10-30% total Zn) was found m this fiaction at shes 2 and 3, concurrent whh results of Narwal, et al. (1999), Hickey and Kittrick (1984), and McLean and Bledsoe
(1992), \^K) state that the majority of Zn was partitioned into the oxide fi-action. The
47 zinc retauied in this oxide fraction is not likely to be very mobile or bioavailable at the
Anaconda site.
Lead (10-20% total Pb) was bound to Fe and Mn oxides at sites 2 and 3, with only minor amounts at site 1 uidicatmg this fraction of Pb to be immobile and not bioavailable, concurrent with resuks of EUiot, et al. (1986), who note the preferential adsorption of Pb onto sinq)le oxides over Cu, Cd, and Zn.
6.2.4 Bound to Organic Matter
Organic matter content can be usefiil in explaining differences in retention between surface and subsurface samples of the same soil (EUiot et al., 1986). Organic matter is an important adsorbent for many inorganic soU contaminants (Hesterberg,
1998). Organic matter uicludes plant matter, humic and formic acid compounds, and microbial organisms. SoU organic matter is of particular interest in the retention of metals m soils because of the tendency for these elements to form stable complexes with organic Ugands (EUiott et aL, 1986). Metals bound to organic matter are susceptible to mobUization upon oxidation or degradation of plant material. The occurrence of vegetation at skes 2 and 3 accounts for the metals bound in this fraction ui the shaUowest layers.
At aU three skes the elements of concern were concentrated m the fraction bound to organic matter: arsenic (60-70% total As), cadmium (60-80% total Cd), copper (30-
45% total Cu), lead (40-50% total Pb), and zmc (15-5-% total Zn), Organic matter is not the dominant contributor to the partkioning of copper in ske 1, perhaps due to the lack of
48 surfece vegetation (Figure 4.2), akhough decayed plant material was encountered m ske
1 samples at various depths. Any copper bound by organic matter may have been released during the breakdown and oxidation of the plant material, providing a source of mobUe copper. The lack of plants at ske 1 and significant organic material in the thin sections from ske 1 indicate the retention of these metals by organic matter other than plant material, such as humic and formic acids or microbial organisms.
Plant material is abundant at skes 2 and 3, therefore the root zone, which may penetrate to significant depths, provides an environment conducive to the stabUization of metals bound to this fiaction. Migration of the redox boundary in the tailings material and adjacent soils provides a mechanism that may oxidize and hence liberate toxic metals that are presently m reduced forms.
49 CHAPTER VII
CONCLUSIONS
7.1 Summary of Metal Partkioning
Metals at ske 1 were predominantly bound by two fractions:exchangeable , or bound
to organic matter. The Zn and Pb m exchangeable forms at this ske are most Ukely to be
mobUe and bioavaUable regardless of the location of the redox boundary, suggestmg aU
tailings material resembling that found at ske 1 are a potential source of Zn and Pb
contamination \^iien e?qx>sed to simple leaching mechanisms. The metals bound to
organic matter (As, Cd, and Cu) at this ske are relatively hnmobUe fromth e tailings
material and are only likely to mobilize under oxidizing condkions.
Metals at ske 2 were predominantly bound to organic matter, with minor amounts
bound to carbonate minerals. The presence of plant material (Figure 4.2) at ske 2
promotes the immobilization of metals in the soils, therefore the major mechanism that
may release metals from this ske is the oxidation of the soils, and/or degradation of the
plants.
Metals at ske 3 were predominantly bound to organic matter, with significant
amounts bound to oxides and carbonates. Plant material at ske 3 (Figure 4.2) is the
controUer of the stabilization of metals bound to so Us surroundmg roots and plant
matter, therefore oxidation or degradation of the plants or root system wiU mobUize any retauied metals, making them bioavailable and transportable. The metals bound to oxides and carbonates at ske 3 wiU only become bioavailable and/or mobUe with a
50 change of pH toward more acidic condkions, which is a possibUity at the Anaconda ske surrounding the taUuigs materials.
7.2 Conclusion
Chemical partkioning of metals at the Anaconda ske is important when studying the effects of contamination and possible remedial techniques. The partkioning of metals m soUs exammed m this study is more significant than total metal concentration values in terms of evaluatuig the mobUity and fate of contaminants. The sequential extraction procedure used in this study provided data that made k possible to determine the changes m environmental parameters that might Uberate metal contammants from the taUing materials and soUs surroundmg the Anaconda Smeker Superfimd ske.
51 REFERENCES
Ah, D., and Hyndman, D.W., 1986. Roadside Geologv of Montana. Mountam Press, Missoula, MT, 427p.
Boisson, J., Mench, M., Vangronsveld, J., Ruttens, A., Kopponen, P., and De Koe, T., 1999, ImmobUization of Trace Metals and Arsenic by Different SoU Addkives: Evaluation by Means of Chemical Extractions. Communications m SoU Science and Plant Analysis, v. 30, p. 365-387.
Calvet, R., S. Bourgeois, and J.J. Msaky. 1990. Some experiments on extraction of heavy metals present in soU. International Journal of Envkonmental Analytical Chemistry,v. 39,p. 31-45.
CarroU, S.A., O'Day, P.A., and Piechowski, M., 1998. Rock-Water Interactions ControUmg Zmc, Cadmium, and Lead Concentrations m Surfece Waters and Sedunents, U.S., Tri-State Minmg District. 2. Geochemical Interpretation. Environmental Science & Technology, v. 32, p. 956-965.
EUiott, H.A., Liberati, M.R., and Huang, C.P., 1986. Competkive Adsorption of Heavy Metals by SoUs. Journal of Environmental Quality, v. 15, p. 214-219.
Hesterberg, D., 1998. Biogeochemical cycles and processes leading to changes in mobUity of chemicals m soils. Agriculture Ecosystems & Environment, v. 67, p. 121-133.
Hickey, M.G., and Kittrick, J.A., 1984. Chemicsil Partkioning of Cadmium, Copper, Nickel and Zinc m Soils and Sediments Containing High Levels of Heavy Metals. Journal of Environmental Quality, v. 13, p. 372-376.
Kabata-Pendias, A., and Pendias H., 1992. Trace Elements in Soils and Plants. CRC Press, Boca Raton, 365p.
Kuo, S,, HeUman, P.E,, and Baker, A.S., 1983. Distribution and Forms of Copper, Zmc, Cadmium, Iron, and Manganese in SoUs Near a Copper Smeker. SoU Science, V, 135, p, 101-109,
Lemz, R.W., Sutley, S.J., and Briggs, P.H., 1999. The use of sequential extractions for the chemical speciation of mine wastes. Tailings and Mine Waste '99. Balkema, Rotterdam, p. 555-561.
52 McBride, M.B., 1981. Forms and Distribution of Copper m SoUd and Solution Phases of SoUs. In Loneragan, J.F., Robson, A.D., and Graham, R.D., 1981. Copper m SoUs and Plants. Academic Press, Sydney, 380p.
McBride, M.B., 1994. Envkonmental Chemistry of SoUs. Oxford University Press, New York, 406p.
McLean, J.E., and Bledsoe, B.E., 1992. Behavior of Metals m SoUs. EPA Ground Water Issue, Internet PubUcation, 25p.
Narwal, R.P., Smgh, B.R., and Salbu, B., 1999. Association of Cadmium, Zmc, Copper, and Nickel with Components m NaturaUy Heavy Metal-Rich SoUs Studied by ParaUel and Sequential Extractions. Communications m SoU Science and Plant Analysis, v. 30, p. 1209-1230.
SeUm, H.M., and Amacher, M.C., 1997. Reactivity and Transport of Heavy Metals m Soils. Lewis Publishers, Boca Raton, 201 p.
Shum, M., and Lavkulich, L., 1999. Speciation and Solubility Relationships of Al, Cu and Fe in Solutions Associated With Sulfiuic Acid Leached Mine Waste Rock. Environmental Geology, v. 38, p. 59-68.
Shuman, L.M., 1979. Zinc, Manganese, and Copper in SoU Fractions. SoU Science, V. 127, p. 10-17.
Sposko, G., 1984. The Surface Chemistry of SoUs. Oxford University Press, New York, 234p.
Stevenson, F.J., and Fkch, A., 1981. Reactions With Organic Matter. In Copper m Soils and Plants. Academic Press, Sydney, 380p.
Tessier, A., P.G.C. Campbell, and M. Bisson. 1979. Sequential extraction procedure for the speciation of particulate trace metals. Analytical Chemistry v. 51, p. 844-850.
Tetra Tech, Inc., 1986. Geochemistry Report. Prepared for Anaconda Minerals Con^any.
Tetra Tech, Inc. 1987. Anaconda Smelter Remedial Investigation/FeasibUity Study, Master Investigation Draft Remedial Investigation Report.
Than Environmental Corporation, 1996. Anaconda Smelter NPL Site, Anaconda Regional SoUs Operable Unk Remedial Investigation Report. Prepared for ARCO.
53 APPENDIX A
TESSIER SEQUENTL\L EXTRACTION PROCEDURE
54 Tessier Extraction
Godi Obtam metal fractions bound into the foUowmg partkions:
1. Exchangeable 2. Bound to carbonates 3. Bound to Mn-Fe oxides 4. Bound to organic matter 5. Residual
Sample: Sample size = Igram of homogenized material (mortar ground)
Chemicals:
MgCl2 (IM) NaO-Acetate (IM) Acetic acid (IM) Na2S204 (0.3M) Na-Citrate (0.175M) H-Ckrate (0.025M) HNO3 (0.02M) H2O2 (30%v/v) NFLjOAc (3.2M) m 20%HNO3 Digestion chemicals - HF, HCIO4
Procedure:
1. Extract with 8mL(*10mL)MgCl2 • Time = I hour • pH = 7 • Temperature = room temperature
2. Extract residue from step 1 with 8mL (* lOmL) NaO-Acetate • Time = 5 hours • pH = 5 - adjusted with acetic acid • Temperature = room temperature
3. Extract residue from step 2 wkh 20mL NH20H*HCl + HO Ac • Tune = 6 hours • pH = 2 • Temperature = 96°C
55 4. a. Extract residue from step 3 with 3mL HNO3 and 5mL H2O2 Tune = 2 hours • pH = 2 - adjust wkh HNO3 • Temperature = 85°C b. Add 3 mL H2O2 (*+HN03) Tune = 3 hours (*2 hours) • pH = 2 - adjust wkh HNO3 • Temperature = 85°C • Intermittent agitation c. Cool, then agitate for 30 minutes m 20mL NH4OAC
5. Digest residue from step 4 for residue analysis
56 APPENDEXB
ICP-AES ANT) GRAPHITE FLT^ ACE AA
RESULTS TABULATED
57 Table B.l: Exchangeable Fraction
Grain Site Samplins Depth (cm) Size Zn Pb As Cd Cu Date (mm) 1 7/1/00 31-42 bulk 1 7/1/00 31-42 0.25 2.490 0.140 bd' bd 3.764 1 7/1/00 31-42 0.045 4.771 6.525 bd 0.041 10.650
I 7/6/00 16-25 0.25 1.014 bd bd bd 1.902
1 7/23/00 12-23 0.25 0.704 bd bd bd 2.045 I 7/23/00 56-67 0.25 1.573 0.127 bd bd 2.624 1 7/23/00 118-131 0.25 0.888 0.100 0.063 bd 2.425 1 7/23/00 142-153a" 0.25 0.884 0.580 0.335 bd 2.474 1 7/23/00 142-I53b" 0.25 0.828 0.508 0.314 bd 2.342
2 7/6/00 37-49 0.25 0.065 bd bd bd bd
2 7/23/00 14-32 0.25 0.067 bd bd bd bd 2 7/23/00 32-50 0.25 0.058 bd bd bd bd 2 7/23/00 50-61 0.25 0.049 O.lOl bd bd bd 2 7/23/00 61-70a 0.25 0.050 bd bd bd bd 2 7/23/00 6I-70b 0.25 0.050 bd bd bd bd
3 7/2/00 36-51 bulk 3 7/2/00 36-51 0.25 0.549 0.097 0.796 0.173 1.279 3 7/2/00 36-51 0.045 0.649 bd 0.870 0.172 1.789
3 7/7/00 91-96 0.25 0.054 0.120 bd bd bd
3 7/22/00 15-26 0.25 2.236 bd 1.797 0.250 1.063 3 7/22/00 26-37 0.25 0.371 bd 1.064 0.196 0.851 3 7/22/00 49-60 0.25 0.051 bd 0.075 bd bd 3 7/22/00 81-93 0.25 0.052 0.113 bd bd bd
AU values m ppm *bd indicates value below detection limk of instrument **a/b indicates first and second repUcates, respectively
58 Table B.2: Bound to Clarbonates
Sampling Depth Grain Site Date (cm) Size 7M Pb As Cd Cu (mm) 1 7/1/00 31-42 bulk 0.252 bd' bd bd bd I 7/1/00 31-42 0.25 0.228 bd bd bd bd 1 7/1/00 31-42 0.045 0.454 bd bd bd 0.343
1 7/6/00 16-25 0.25 0.198 bd bd bd bd
1 7/23/00 12-23 0.25 0.188 bd bd bd bd I 7/23/00 56-67 0.25 0.202 bd bd bd bd 1 7/23/00 118-131 0.25 0.193 bd bd bd bd 1 7/23/00 142-153a'' 0.25 0.1873 bd bd bd bd 1 7/23/00 142-153b 0.25 0.1944 bd bd bd bd
2 7/6/00 37-49 0.25 0.514 0.320 0.042 bd 0.556
2 7/23/00 14-32 0.25 0.274 0.306 0.053 0.0004 1.113 2 7/23/00 32-50 0.25 0.161 0.298 0.051 0.001 0.416 2 7/23/00 50-61 0.25 0.080 0.230 0.042 bd 0.161 2 7/23/00 61-70a 0.25 0.042 0.240 bd bd 0.138 2 7/23/00 61-70b 0.25 0.048 0.247 0.052 bd 0.145
3 7/2/00 36-51 bulk 13.385 bd 2.04 84.702 8.754 3 7/2/00 36-51 0.25 10.423 bd 1.522 64.400 9.585 3 7/2/00 36-51 0.045 13.478 bd 1.796 76.766 8.425
3 7/7/00 91-96 0.25 0.378 bd bd 0.545 5.491
3 7/22/00 15-26 0.25 58.114 bd 5.157 137.963 4.981 3 7/22/00 26-37 0.25 10.475 bd 2.413 79.383 8.818 3 7/22/00 49-60 0.25 0.229 bd bd bd 4.397 3 7/22/00 81-93 0.25 0.195 bd bd bd 4.024 AU values in ppm *bd indicates value below detection hmk of mstrument **a/b indicates firstan d second replicates, respectively
59 Table B.3: Bound to Iron and Manganese Oxides
Sampling Depth Grain Site Date (cm) Size Zn Pb As Cd Cu (mm) 1 7/1/00 31-42 buDc 1 7/1/00 31-42 0.25 bd* bd 0.106 bd 0.131 1 7/1/00 31-42 0.045 bd 0.129 bd bd 0.285
1 7/6/00 16-25 0.25 bd bd bd bd bd
1 7/23/00 12-23 0.25 bd bd 0.066 bd bd 1 7/23/00 56-67 0.25 bd bd 0.085 bd bd 1 7/23/00 118-131 0.25 bd bd 0.135 bd bd I 7/23/00 142-153a" 0.25 bd bd 0.059 bd bd I 7/23/00 142-I53b 0.25 bd bd 0.056 bd bd
2 7/6/00 37-49 0.25 0.701 0.119 0.051 bd 1.301
2 7/23/00 14-32 0.25 0.547 0.180 bd bd 3.894 2 7/23/00 32-50 0.25 0.189 O.llO bd bd 1.031 2 7/23/00 50-61 0.25 0.082 0.097 0.09 bd 0.285 2 7/23/00 61-70a 0.25 0.096 0.066 0.06 bd 0.351 2 7/23/00 61-70b 0.25 0.089 0.065 0.13 bd 0.314
3 7/2/00 36-51 buUc 3 7/2/00 36-51 0.25 35.006 0.075 0.570 0.056 2.611 3 7/2/00 36-51 0.045 27.190 1.030 3.738 bd 206.422
3 7/7/00 91-96 0.25 1.583 0.242 0.391 bd 5.391
3 7/22/00 15-26 0.25 0.189 0.112 bd bd 1.034 3 7/22/00 26-37 0.25 38.247 0.138 5.185 0.118 6.617 3 7/22/00 49-60 0.25 0.677 0.173 0.394 bd 2.948 3 7/22/00 81-93 0.25 0.400 0.132 0.185 bd 1.030 AU values in ppm *bd indicates value below detection limk of mstrument **a/b mdicates first and second repUcates, respectively
60 Table B.4: Bound to Organic Matter
SampUng Depth Grain Site Date (cm) Size Zn Pb As Cd Cu (mm) 1 7/1/00 31-42 buUc 1 7/1/00 31-42 0.25 0.246 0.306 0.105 bd* 2.069 I 7/1/00 31-42 0.045 0.598 0.128 0.112 bd 5.483
1 7/6/00 16-25 0.25 0.423 bd 0.131 bd 2.097
1 7/23/00 12-23 0.25 0.256 0.095 0.307 0.001 2.336 1 7/23/00 56-67 0.25 0.377 0.087 0.278 0.003 1.425 1 7/23/00 118-131 0.25 0.276 0.067 0.436 0.002 1.470 1 7/23/00 142-153a" 0.25 0.522 0.208 0.664 0.002 7.238 1 7/23/00 142-I53b 0.25 0.309 0.184 0.452 0.002 5.034
2 7/6/00 37-49 0.25 1.247 0.242 0.187 bd 0.777
2 7/23/00 14-32 0.25 1.573 0.583 0.347 0,007 4.320 2 7/23/00 32-50 0.25 0.590 0.207 0.167 0,003 0.622 2 7/23/00 50-61 0.25 0.561 0.186 0.175 0.002 0.167 2 7/23/00 6I-70a 0.25 0.500 0.200 0.174 0.003 0.135 2 7/23/00 61-70b 0.25 0.497 0.186 0.175 0.003 0.191
3 7/2/00 36-51 buUc 3 7/2/00 36-51 0.25 13.070 0.182 4.757 bd 18.528 3 7/2/00 36-51 0.045 50.824 2.616 9.876 bd 84.544
3 7/7/00 91-96 0.25 0.510 0.022 0.2875 bd 0.340 0.265 3 7/22/00 15-26 0.25 21.051 0.163 10.471 bd 50.502 3 7/22/00 26-37 0.25 10.376 0.359 6.327 bd 24.182 3 7/22/00 49-60 0.25 0.663 0.072 0.439 bd 0.344 3 7/22/00 81-93 0.25 0.415 0.066 0.150 bd 0.184 All values in ppm *bd indicates value below detection limit of instrument **a/b indicates firstan d second repUcates, respectively
61 PERMISSION TO COPY
In presenting this thesis in partial fulfillment of the requkements for a master's degree at Texas Tech University or Texas Tech University Health Sciences Center, I agree that the Library and my major department shaU make k freely avaUable for research purposes. Permission to copy this thesis for scholarly purposes may be granted by the Dfrector of the Library or my major professor. It is understood that any copymg or publication of this thesis for financial gain shaU not be allowed without my ftirther written permission and that any user may be liable for copyright mfiingement.
Agree (Permission is granted.)
Disagree (Permission is not granted.)
Student Signature Date