Post on 09-Mar-2018
STRATUS CONSULTINGSTRATUS CONSULTING
Toxicity of Cadmium and Copper: Implications for Adverse Impacts to
Salmonids in Mining-Impacted Waters
Prepared for: Federal Review Panel
Prosperity Gold-Copper Mine Project
Prepared by:Jeff Morris, PhD
Stratus ConsultingBoulder, CO
April 26-30, 2010
STRATUS CONSULTING
Aquatic Toxicology Terminology
“Acute” effects– Adverse effects that occur during short-term
exposures (e.g., 1-96 hours)– Also refers to severity of effect, e.g., lethality is
often referred to as an “acute” effect
“Chronic” effects– Adverse effects that occur during longer
exposures (e.g., weeks – months).– Also refers to “sub-lethal” effects,
e.g., reduced growth, behavioral changes, impaired reproduction
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Terminology (cont.)
LCX = Concentration that results in X% mortality of exposed organisms over a given time
– “96-h LC50 ” = the concentration resulting in 50% mortality in the test organism population within 96 hours
– An LC50 is not a threshold for adverse effects: it implies that half the organisms are killed by the chemical exposure
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Terminology (cont.)
LC50 = a value determined from controlled experiments in a laboratory
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Terminology (cont.)
For metals such as copper and cadmium, a common convention in estimating an acute lethality “threshold” is to divide the LC50 by 2. This value roughly approximates 1-10% mortality level in the test organism population in most experiments (US EPA, 1996).
STRATUS CONSULTING
Toxicity of Copper and Cadmium to Fish
Both metals are highly toxic to fishToxic effects include:– Death– Impaired growth– Impaired behavior– Physiological alterations that can reduce
“fitness”
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Toxicity of Copper and Cadmium (cont.)
Direct effects from “dissolved” metal in water column
Indirect effects through invertebrate prey– Water column and sediment
• Toxic metal concentrations in prey (dietary exposure to fish)
• Decrease in overall available prey base
Young fish (swim-up fry) = most sensitive life stage
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Effects of Metals on Fish: Water
Geochemical interactions- hardness, pH, DOC, etc.
Uptake through gills
Mortality, cardiac arrest, suffocation, reduced growth, behavioral changes, physiological
impairment
Effects
Metals in water
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Metals Effects on Fish: Mechanisms
Lethality related to:– Ionoregulatory failure
• Fish take up ions (e.g., Na+) from the water through their gills
• Metals such as copper can impair this process leading to cardiac arrest
– Respiratory failure• Metals can cause thickening
of cell walls in gill tissues leading to reduced oxygen exchange and death
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Heavy Metals: Sublethal Effects
Reduced growthBehavioral avoidance– May impair
outmigration of smolts
– May impair returning adults
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Adverse Impacts to Salmonid Populations
MortalityDecreased recruitment– Young fish are the most sensitive– Spawning adults avoid contaminated areas– Social structures are disrupted and
population fitness suffers (olfactory impairment)
Reduced growth– Increased metabolic burden– Impaired olfactory system
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Water-Column Effects of Metals
Toxicity of both copper and cadmium is strongly influenced by water chemistry
– Hardness toxicity
– Dissolved organic carbon (DOC) toxicity • Dependent on chemical nature of the DOC
– pH: strongly influences toxicity, but relationship more complex than hardness, DOC
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Water Column Effects of Metals
Toxicity dependent on sensitivity of the exposed species– Salmonids (trout, salmon) among the
most sensitive species to copper and cadmium
– Many freshwater invertebrates that serve as food for juvenile salmonids (e.g., mayflies) also highly sensitive to metals
McCafferty 1981
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Potential Toxicity of Cadmium and Copper at the Prosperity Project
Examples based on published toxicity tests– Rainbow trout, including controlled laboratory
tests we have performed
Examples assume generalized relationships– No site-specific data available on relative
sensitivity of resident fish strains
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Potential Toxicity of Cadmium and Copper at the Prosperity Project
Examples focus solely on water column effects of metals to fish. Other potential effects include:
– Toxicity of contaminated sediments to fish eggs and prey species
– Toxicity of contaminated prey to fish (dietary)– Physical effects of sedimentation – Changes in hydrology (dewatering, increased
scouring)– Changes in thermal regime
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)
Hansen et al. 2002
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2
Hansen et al. 2002
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)
Hansen et al. 2002
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W Q G M axim um
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W Q G M axim umBC W Q G 30-day
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Prosperity Gold-Copper Project Estimates
Estimates of contaminant concentrations from the EIS for period corresponding to spring freshet on Fish Creek (March-May) and subsequent low-flow in Taseko RiverRelevant for:– Resident salmonid populations– Migrating/spawning steelhead and rainbow
trout– Early life-stage bull trout and Chinook and
sockeye salmon
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Prosperity Gold-Copper Project Estimates
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W Q G M axim umBC W Q G 30-dayProsperity prediction
Fish Creek
TSF (5%)
Taseko R iver
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W Q G M axim umBC W Q G 30-dayProsperity predictionBackground copper in the Taseko R iver in M ay
Fish Creek
TSF (5%)
Taseko R iver
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
10
20
30
40
50
60
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W Q G M axim umBC W Q G 30-dayProsperity prediction x10
Fish Creek TSF (5%)
Taseko R iver
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
20
40
60
80
100
120
140
160
96-h LC50 (m ortality, rainbow trout)96-h LC50/2IC20 (grow th, rainbow trout)BC W QG M axim umBC W QG 30-dayProsperity prediction x10
Fish Creek
TSF (5%)
Taseko River
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2Prosperity = LC50/2
TSF (5%)
4.0x
Factor increase in copper that could result in mortality
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Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)
1.3x
4.0x
Factor increase in copper that could result in mortality
STRATUS CONSULTING
Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)Taseko R iver
4.0x
1.3x
4.0x
Factor increase in copper that could result in mortality
STRATUS CONSULTING
Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)Taseko R iver
4.0x
8.4x1.3x
4.0x
Factor increase in copper that could result in mortality
STRATUS CONSULTING
Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2IC20 (grow th, rainbow trout)Prosperity = LC50/2
Fish Creek TSF (5%)Taseko R iver
4.0x
8.4x1.3x
4.0x
Factor increase in copper that could result in mortality
STRATUS CONSULTING
Toxicity of Copper
Hardness (m g/L as CaCO3)
0 25 50 75 100 125 150
Cop
per (μg
/L)
0
5
10
15
20
25
30
96-h LC50/2IC20 (grow th, rainbow trout)Prosperity = LC50/2
Fish Creek TSF (5%)Taseko R iver
8
1719
27
Concentration increase in copper that could result in
mortality
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Sub-Acute Effects (copper)
Mortality or changes in behavior after exposure to lower concentrations over a longer time (e.g., 30-60 days)
– Copper can accumulate in the olfactory system• Causes changes in behavior (social)
predator avoidance, and avoidance of contaminated waters (e.g., 0.8-1.6 µg/L)
– Other sub-acute effects include mortality and decreased growth
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Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0
1
2
3
4
96-h LC50 (mortality, rainbow trout)
Toxicity of Cadmium
Stratus Consulting 1999
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Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0
1
2
3
4
96-h LC50 (mortality, rainbow trout)96-h LC50/2
Toxicity of Cadmium
Stratus Consulting 1999
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0
1
2
3
4
96-h LC50 (mortality, rainbow trout)96-h LC50/2BC WQG 30-day
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.1
0.2
0.3
0.4
0.5
BC WQG 30-day
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.1
0.2
0.3
0.4
0.5
BC WQG 30-dayProsperity, predicted worst case
Fish Creek
TSF (5%)
Taseko River
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.1
0.2
0.3
0.4
0.5
BC WQG 30-dayProsperity, predicted worst caseBackground cadmium in the Taseko River in May
Fish Creek
TSF (5%)
Taseko River
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0
1
2
3
4
96-h LC50 (mortality, rainbow trout)96-h LC50/2Prosperity, predicted worst case x10
Fish Creek
TSF (5%)
Taseko River
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2
Toxicity of Cadmium
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2Prosperity = LC50/2
TSF (5%)
7.7x
Toxicity of Cadmium
Factor increase in cadmium that could result in mortality
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Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)
7.7x
3.7x
Toxicity of Cadmium
Factor increase in cadmium that could result in mortality
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)Taseko River
7.7x
3.7x
9.4x
Toxicity of Cadmium
Factor increase in cadmium that could result in mortality
STRATUS CONSULTING
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)Taseko River
7.7x
3.7x
9.4x
23x
Toxicity of Cadmium
Factor increase in cadmium that could result in mortality
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Toxicity of Cadmium
Hardness (mg/L as CaCO3)
0 20 40 60 80 100 120 140 160
Cad
miu
m ( μ
g/L)
0.0
0.5
1.0
1.5
2.0
2.5
3.0
96-h LC50/2Prosperity = LC50/2
Fish Creek TSF (5%)Taseko River
2.1
1.3
0.5
1.2
Concentration increase in cadmium that could result in
mortality
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Sub-Lethal Effects (cadmium)
Mortality or changes in behavior after exposure to lower concentrations (over a longer time, e.g., 30-60 days)
– Cadmium can accumulate in the olfactory system or affect the central nervous system
• Causes changes in behavior (social, foraging) predator avoidance, and avoidance of contaminated waters (0.2 – 0.5 µg/L)
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Evaluating Environmental Risks: Hazard Quotient Approach
The field of Ecological Risk Assessment employs a convention of calculating Hazard Quotients to evaluate potential risks to ecological receptors– Hazard Quotient (HQ) =
Environmental Concentration / Adverse Effects Concentration• Where HQ > 1 = "risk of adverse effects"
STRATUS CONSULTING
Hazard Index
For contaminants with a similar mode of action (e.g., metals) the convention is to sum HQs to calculate the Hazard Index (HI)– Therefore, individual HQs for copper and cadmium
(and other metals) should be summed to calculate the total HI
HI > 1 = "risk of adverse effects“
STRATUS CONSULTING
Hazard Index
Location
Hardness (mg/L as CaCO3) Cu HQ Cd HQ Cu+Cd HI
TSF (5%) 141 1.2 6.0 7.1
Fish Creek (mixing point B; waterfall) 92 3.8 11.7 15.5
Taseko River (after Fish Creek confluence) 33 1.0 3.9 4.9
Taseko River (after Fish Creek confluence) 81 1.0 1.8 2.8
Chronic (30-d)
Copper and Cadmium Hazard Index based on Prosperity Project estimates (in May) and BC WQGs (30-d)
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Conclusions
STRATUS CONSULTING
Copper
Taseko’s copper predictions for the Taseko River or Fish Creek in May:
– Meet or exceed concentrations resulting in significantly decreased growth in rainbow trout
– Would only need to increase by 1.3- or 4-fold to reach acutely lethal concentrations
STRATUS CONSULTING
Cadmium
Taseko’s cadmium predictions for the Taseko River or Fish Creek in May:– Would need to increase by 4- or 9-fold to
reach acutely lethal concentrations• These increases are equivalent to only
0.5 or 1.3 µg/L
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Other Factors to Consider…
Other metals and metalloids associated with this project are also toxic at elevated concentrations– E.g., arsenic, lead, nickel, selenium, zinc
Metal mixtures can increase toxicity through additive or synergistic effects
Dietary exposure to these contaminants can also cause toxicity to fish