Chris M. Wood
(woodcm@mcmaster.ca)
McMaster University, Hamilton, Ontario, Canada
Rosenstiel School, University of Miami, U.S.A.

A Brief History of Agriculture
• 9500 B.C. - Domestication of wheat (Neolithic Age)
• 8500 B.C. - Domestication of Rice (Neolithic Age)
• 8000 B.C. - Cattle herding (Neolithic Age)
• 6500 B.C. - Domestication of sheep, goats, pigs, dogs
• 6500 B.C. - First irrigation canals (Neolithic Age)
• 2500 B.C. - First pesticide (elemental sulphur - Bronze Age * )
• 2000 B.C. - First windmills (Bronze Age- Iron age * )
• 200 A.D. - First seed drills *
• 1500's A.D. - "Columbian Exchange" - new world crops *
• 1800's A.D. - First chemical fertilizers *
• 1900 A.D. - Industrial agriculture *
• 1939 - DDT
• 1944 - H. Borlaug - "Green Revolution"
• 1996 - G.M.O.'s are introduced

since 1950 due to fertilizers, irrigation, and the green revolution
Dyson (1999)
PNAS
96:5929-5936
©1999 by The National Academy of Sciences

World Cereal* Production–Areas Saved
Through Improved Technology, 1950-2000
1,80
0
1,40
0
1,00
0
CEREAL PRODUCTION
1950 650 million tonnes
2000 1,900 million tonnes
LAND SPARED
1.1 billion ha
600
200
1950 1960 1970 1980 1990 2000
* Uses milled rice equivalents
Source: FAO Production Yearbooks and AGROSTAT
Borlag (2003) World Food Prize Address
LAND USED
660 million ha

But………
"Over 80% of the potentially arable land in the world was already being farmed in 1990!"
Cole et al. (1993) Water, Air, Soil Poll. 70: 111-122

From: "De Re Metallica"
Georgius Agricola (1556)

"Annaberger Bergaltar"
- a mining & smelting village in Saxony
-Hans Hesse (1521)

70 of the 92 naturally occurring elements are metals
- elements which are good conductors of electricity and heat, form cations by loss of electrons, and yield basic oxides and hydroxides
1 2
H
3 4
Li Be
11 12
Na Mg
19 20
The Periodic Table He
10 5 6 7 8 9
B C N O F Ne
13 14 15 16 17 18
Al Si P S Cl Ar
31 32 33 34 35 36 21 22 23 24 25 26 27 28 29 30
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
87 88 89 104 105 106 107 108 109 110
Fr Ra Ac Rf Ha Sg Ns Hs Mt Unn
58 59 60 61 62 63 64 65 66 67 68 69 70 71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
90 91 92 93 94 95 96 97 98 99 100 101 102 103
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

A Brief History of Metals
• 6000 B.C. - Gold - jewelry (Neolithic Age)
• 4200 B.C. - Copper - tools & weapons (Copper Age)
• 4000 B.C. - Silver - jewelry & coins
• 3500 B.C. - Lead - cookware, plumbing, tools
• 2500 B.C. -Tin - alloyed with copper (Bronze Age)
• 1500 B.C. - Iron - ornaments, weapons, tools (Iron Age)
• 750 B.C. - Mercury - gold & silver extraction
• 1400's A.D. - Antimony - alloyed with lead & tin --> printing!
• 1500's A.D. - Bismuth, Platinum
• 1700's A.D. - Cobalt, Manganese, Molybdenum, Zinc
• 1800's A.D. - Cadmium, Nickel, Chromium, Aluminum

Global annual production of most metals has increased dramatically since 1950
Han et al. (2002) Naturwisch. 89: 497-504

Cumulative global production of most metals has increased exponentially since 1850; the greatest cumulative dispersal into the environment has occurred since 1950
Approx. 50% of historical cumulative
Pb production was prior to 1850
Han et al. (2002) Naturwisch. 89: 497-504

Cumulative Global Environmental Metal Burden (kg) per Capita
80
Cu
60
Zn
Pb
40
20
0
Cr
Ni
1900 1950 2000 1900 1950 2000 1900 1950 2000 1900 1950 2000 1900 1950 2000
Han et al. (2002) Naturwisch. 89: 497-504

Cumulative Global Environmental Metal Burden (kg) per Capita
80
60
40
20
0
Cu
Zn
Pb
World Population
Cr
Ni
1900 1950 2000 1900 1950 2000 1900 1950 2000 1900 1950 2000 1900 1950 2000 1900 1950 2000
7
6
5
4
3
2
1
0
Han et al. (2002) Naturwisch. 89: 497-504

Every American born today will need -----
Copper
1179 lbs
Zinc
569 lbs
Lead
902 lbs
Iron
29,333 lbs
Aluminum
6534 lbs
Other Minerals and Metals
59,050 lbs
3.3 million pounds of minerals, metals
Mineral Information
Institute(2009)
& fuels in their lifetime

Cumulative Global Environmental Metal Burden (kg) per Capita
500
60
400
Cu
Cu
For one American born today
Zn
Pb
Pb
Zn
200
20
100
1900
1950 2000
2000 2000
1900
Current U.S. metal consumption per capita is 9 times greater than that of China and 15 times greater than that of India

100
80
60
40
20
0
Pb – 90% Recycling Efficiency
85
1st processing
2nd cycle
76.5
2nd processing
65 3rd cycle
58.5
3rd processing
49.7
4th cycle
44.7
4thprocessing
38
Zn – 30% Recycling Efficiency
85
1st processing
Time
2nd cycle
25.5
21.7
2nd processing
3rd cycle
6.5
5.5
3rd processing
Time

Global Mass Flow Budget for Copper
Copper
Rate of anthropogenic Cu mobilization is 10 6 fold greater that the natural renewal rate
Rauch & Pacina (In Press) Global Biogeochem. Cycles 23

Cu
Ag
Pb
Zn
15.6
6.9
6.2
3.5
Cr
Ni
1.8
0.9
Fe 0.5
Al
Anthropogenic Dispersal
Natural Weathering
0.04
Rauch & Pacina (In Press)
Global Biogeochem. Cycles 23

Estimated fold elevation in soil & sediment metal levels above historical background levels
12
10
Hg
8
6
Pb
Zn
4
2
Cu
Ni
Cr
0
1900 1955 2000 1900 1955 2000 1900 1955 2000 1900 1955 2000 1900 1955 2000 1900 1955 2000
Rauch & Pacina (In Press) Global Biogeochem. Cycles 23
Han et al. (2002) Naturwisch. 89: 497-504

Cu
Cd
Pb
Hg
Ni
Se
Zn
Ag
Current U.S. E.P.A. Criteria
Drinking Water Criterion
(ug/L)
Aquatic Life Criterion
(ug/L)
1,300
5.0
(50) 1
(6.0) 2
610
170
7400
(50) 1
88x more sensitive
5.1
0.25
2.5
0.7
52
5
120
1.5
1= Canada 2 = WHO

Bottom Line: Metals are an essential part of modern society. We must learn to use and control the dispersion of metals wisely.
For this we need environmental regulations that are scientifically sound and socioeconomically realistic.
Not the Precautionary Principle - widely legislated until recently - resulted in maximum allowable metal levels that were so low, they were often below natural background levels, and few labs could measure them
Not P.B.T. Criteria

• P ersistence in the environment
• B ioconcentration in aquatic organisms
• T oxicity (acute or chronic)

• Highly toxic acute effects caused by narcosis
• Diverse range of chronic toxic effects - e.g. reproductive inhibition
• Both acute and chronic toxicity appear to be related to BioConcentration Factor (BCF)
• Compounds persist in natural waters for greatly differing periods of time

The P. B. T. Criteria -
Persistence  ½ life in the environment
(scores assigned based on days to years)
Bioconcentration  exposure concentration
Toxicity  Acute or Chronic LC
50

Persistence?
Metals are elements - they persist forever!
1 2
H
3 4
Li Be
11 12
Na Mg
19 20
The Periodic Table He
10 5 6 7 8 9
B C N O F Ne
13 14 15 16 17 18
Al Si P S Cl Ar
31 32 33 34 35 36 21 22 23 24 25 26 27 28 29 30
K Ca Sc Ti V Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br Kr
37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54
Rb Sr Y Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sn Sb Te I Xe
55 56 57 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86
Cs Ba La Hf Ta W Re Os Ir Pt Au Hg Tl Pb Bi Po At Rn
87 88 89 104 105 106 107 108 109 110
Fr Ra Ac Rf Ha Sg Ns Hs Mt Unn
58 59 60 61 62 63 64 65 66 67 68 69 70 71
Ce Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
90 91 92 93 94 95 96 97 98 99 100 101 102 103
Th Pa U Np Pu Am Cm Bk Cf Es Fm Md No Lr

Toxicity ?
Only AgNO
3 yields significant amounts of free Ag + in solution
Hogstrand et al (1996) ETC 15: 1102 - 1108

900
For metals, toxicity depends entirely on speciation & water chemistry
600
Total Ag
Ionic Ag+
300
100
80
60
40
20
0
50 225 750 2500
Water [Cl ] (umol/L)
McGeer & Wood (1998). CJFAS 55: 2447-2454

BCF's for 42 elements in Daphnia magna collected from a pristine environment
Sr
Li
G
Sn
Cl
Zr
Ni
Ba
Fe
S
Ca
Na
As
Zn
Pb
Cs
Hf
Si
B
Mg
Ti
Al
F
I
Be
Br
Ge
Cu
Rb
Hg
Nb
Bi
Mn
K
Cr
Se
Cd
Ag
Co
P
V
Mo
10
1
10
2
Threshold Canada
10
3
BCF 10
4
Bioaccumulation factor
10
5
10
6
Cowgill (1976)
Sci. Tot. Environ.
6: 79-102.

Whole Body Accumulation
600
400 substance B
200 substance A
0
0 5 10 15 20 25 30 exposure concentration
BCF vs. Exposure
8000 substance B
6000
4000
Threshold
- Canada
2000 substance A
1.
BCF is independent of concentration.
*
2. BCF an intrinsic property of a substance.
Therefore can be used for comparison of substances, prioritization, hazard classification and etc.
0
0 10 20 30 exposure concentration

Canada WQG
)

Whole body
Cd burden
(mg • kg -1 )
1000
100
10
0.1
0.01
10
-5
10
-4
10
-3
10
-2
10
-1
10
1
10
2
BCF for Cd
100000
10000
1000
100
10
1
0.1
Canada WQG
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
10
Cd exposure concentration (mg •L -1 ) or •kg -1 )
1
10
2
Draves and Fox '98
Giesy & Wiener '77
Hamilton et al '87
Murphy et al '78
Benoit et al '76
Brown et al '86
Cope et al '94
Giles '88
Hollis et al '99
Hollis et al '00
Kumada '80
McGeer et al '00
Pascoe & Matty '77
Sephar '76
Cowgill '76;
Hare & Tessier '96;
Timmermans et al '92
Janssen et al '97
Porebski et al '99
Rule & Alden '98

Organisms have evolved in the presence of metals for millions of years - they are sometimes essential and all are homeostatically regulated to some degree.
The BCF approach is meaningless
The PBT approach is meaningless

Bioaccumulation is important:
- Metals have to bioaccumulate to cause impact.
- But metal bioaccumulation is very complex
& not all bioaccumulation results in impacts.
- BCF is not the way to measure it.
- What are the alternatives ?
1. B iotic L igand M odel Approach ( BLM )
2. Tissue Residue Approach
Cu
Cu
Gills
Organs &
Tissues gastrointestinal tract

• Computational approach for generating Water Quality
Criteria based on physiological understanding of gill function, toxic mechanism of a specific metal, & water geochemistry
• Uses sensitive reference species - e.g.
rainbow trout, fathead minnow, daphnia.
• Avoids further animal testing
• BLM evolves as knowledge changes

H +
NOM
.
.
Ca 2+ organic complexes inorganic complexes
M n+
Na + chlorides hydroxides carbonates sulphides
Chemistry
Gill or
Biotic ligand
Na +
H +
M
Ca 2+
Cl -
HCO
3
active influx passive efflux renal excretion
Physiology
Toxicology
Regulatory needs
Paul Paquin and 21 others (2002) Comp. Biochem. Physiol. 133C: 3-35

M 2+
Zn 2+ , Pb 2+ Cd 2+ , Co 2+
Ca 2+
M +
Ag + , Cu +
H
2
O (apical)
Na +
PVC
Ca 2+
ATP
H +
MRC
PVC
3Na +
ATP
+
Blood (basolateral)

Metals are “surface active” toxicants at the gills
For most metals, the “free cationic forms” are most toxic
Toxicity is proportional to early gill metal burden
Anionic Ligands in Water Cations
Gill
Anionic Ligands
NOM
“alkalinity”
Cl -
HCO
3
-
OH -
CO
3
=
S
2
O
3
-
S =
DOC
“hardness”
Me +
Me ++
Ca ++
Mg ++
H +
Na +
Concentration, Complexation, Competition

B max 100%
K
D
Free metal ion concentration in water
50%
Gill LA
50
0%
New gill metal burden at 3 or 24 h

100
Flow-through Exposures (96h)
80
60
40 r = 0.894
p < 0.05
20
Morgan & Wood (2004) ETC:23: 1261-1267
0
0 100 200 300
Gill silver accumulation (ng g-1)
3 h gill [Ag] predicts 96h mortality
400

1000
Ni 2+
Co 2+
100
10 Zn 2+
Pb 2+
1
Cu 2+
Cd 2+ Ag +
0.1
0.01
3 4 5 6 7 8 9
Gill-metal binding affinity (log K)
10 11
Niyogi & Wood (2004). EST 38:6177-6192.
The log K for gill metal binding directly correlates with 96 h LC50 for rainbow trout in Hamilton water (Lake Ontario)

FRESH WATER
Ca 2+ (4.0)
Na + (3.0)
H + (7.5)
Ni 2+ (4. 0)
Biotic Ligand
(GILL)
Allergic Reacti on Site?
Ca 2+ (2.3-3. 6)
Na + (2.3-3. 2)
H + (4.3-5.9)
Mg 2+ (3.6)
Cu 2+ (7.4-8.0)
Ag + (7.3-10. 0)
Na + Transport Site
BLOOD
Ca 2+ (5.0-5. 5)
Na + (2.4-3. 5)
H + (6.7-4.0)
Mg 2+ (3. 1-4.0)
Zn 2+ (5. 3-5.5)
Cd 2+ (8.6)
Pb 2+ (6.0)
Co 2+ (5.1)
Ca 2+ Transport Site
Niyogi & Wood (2004). EST 38:6177-6192.

S
2
O
3
FRESH WATER
HS
-
Ag(S
2
O
3
) n
S
Ag
2
S
=
Ca 2+
8.8
Cl AgCl
2
13.6
5.3
7.3 - 10.0
2.3
Cl -
AgCl
3.3
9.0
Ag +
2.9
Na +
Ag-DOM
5.9
4.0
H +
DOM H-DOM
Janes & Playle (1995) ETC 14: 1847-1858
Paquin et al. (1999) USEPA-822-E-99-001
Wood et al. (1999) ETC 18: 71-83
McGeer et al. (2000) EST 34: 4199-4207
Morgan & Wood (2004) ETC: 23: 1261-1267
Mann et al. (2004) ETC: 23:1204-1210
GILL
Tox-Ag
BLOOD
Na +
Mg 2+
ATP
K +

BLM successfully predicts acute toxicity of Ag to trout in 10 independent data sets in a variety of water qualities

Daphnia are 10-100 fold more sensitive to most metals & essentially “drive” environmental regulations in many jurisdictions
Does the BLM work in Daphnia?

Daphnia obtusa (Chile), Daphnia magna, Daphnia
pulex (USA) - BLM performance in natural Chilean waters and synthetic laboratory waters
BLM, Jenssen modifications
1000.00
Daphnia pulex (Chile)
Daphnia magna (US)
Daphnia pulex (US)
100.00
10.00
1.00
1.00
10.00
100.00
Observed LC50, Cu ug/L
1000.00
Villavicencio et al. (2005) ETC 24: 1287-1299

• Approved (2004, 2007) by U.S. EPA as the basis for
Cu Acute Criteria ,
• Ag next, then Zn, Cd, Pb, Co, & Ni by U.S. EPA.
• Ongoing incorporation into tiered approaches in
Canada, Australia/N.Z., & Chile.
• Acceptance (2003) of BLM concept by E.U, with planned incorporation into the Water Framework
Directive and REACH process.
• China MEP has agreed to use BLM in 2009-2010 revision of Acute Criteria .
• Eventual goal is to use BLM predictions as both Acute
& Chronic Criteria .

• The U.S. EPA are doing Chronic Criteria the wrong way - by multiplying the Acute
BLM output by the Chronic/Acute Ratio
- assumes toxic mechanism does not change.
• The EU are trying to do Chronic Criteria the correct way - by building Chronic
BLMs based on chronic toxicity testing.

The Tissue Residue Approach
Internal vs. External Threshold Concentrations
For Chronic Toxic Effects
External Conc.
(ug/L)
Internal Conc.
(ug/L)
Meador et al. (2010)
SETAC Press

Growth rate in trout vs. tissue Cu burden
Response is often graded
Hansen et al. (2002) Aquat. Toxicol. 58: 175-188

Useful for ecological surveys, if you use a "tough" organism as a biomonitor
Hydropsyche sp.
Cain, Luoma, Rainbow (unpubl.)

Organisms appear to have two internal metal pools

2.0
1.5
1.0
0.5
0.0
Time
Total Tissue Residue
Toxic Threshold

2.0
1.5
1.0
Small BIM
Total Tissue Residue
Small BIM
Toxic Threshold
Large BIM
0.5
Large BAM
Small BAM
Large BAM
0.0
Time
Only the metal in the BAM pool causes chronic toxicity

Acid mine drainage in the
Colorado River, U.S.A

A recent survey in Canada identified ~ 10,000 abandoned mine sites that are threatening drinking water supplies in nearby communities
7000 lakes have been polluted with Cu and Ni by just one smelting operation in Sudbury,
Canada

Oldest coal mine, Jharia-India
Exploitation of workers

Marinduque Mining Disaster -Phillipines:
- a Canadian Mining Company developed and then abandoned it 30 years later

"ecological catastrophe'
" loss of life"
"destruction of a way of life for 20,000 people"
" devastating health impacts"
"human rights abuses",
"lack of recourse",
"weak governance"
"corruption"

The Canadian Mining Company was bought out by another one, which denies responsibility
The Philippine Province of Marinduque has recently filed suit against the take-over company in the U.S. State of Nevada, where this company has its flagship assets.
The suit is being filed in the U.S. because any settlement would be unenforceable in Phillipines, and
Canadian law is too weak.
A private member's bill in Canada if passed, could impose sanctions on Canadian resource companies that violate good governance and environmental standards in foreign jurisdictions.

Alberta Tar Sands in Northern Canada

Alberta Tar Sands in Northern Canada
5% of Canada's CO
2 emissions from this one site

Massive Tailings Ponds - 50 km 2 at present

Recently 500 ducks died on the tailings pond

• Mining
• Pollution discharge
• Consumption of limited resources
• Acquisition of personal wealth at the expense of societal health
• Emissions of CO
2 greenhouse gases and other
• Population growth

• Garrett Hardin (1968) Science 162: 1243-
1248: The Tragedy of the Commons
• "The only kind of coercion I recommend is mutual coercion, mutually agreed upon by the majority of people affected"
• "Freedom is the recognition of necessity:
When men mutually agreed to pass laws against robbing, mankind became more free, not less free."

Physiology of Solute Homeostasis in
Freshwater Fish
Passive Na, Cl, & Ca loss
Freshwater
0.05-3 mM NaCl
0.02-2 mM Ca pH 4.5 to 9.0
Blood Plasma
~150 mM NaCl
~3 mM Ca pH ~7.8
Active Na, Cl, & Ca Uptake Copious dilute urine
Fish maintain constant blood pH & blood [Na] [Cl] & [Ca] at levels far above those found in the dilute environment.
Gills are the site of active ion & acid-base regulation, in addition to respiratory gas exchange

H
2
O (apical)
Ca 2+ Cl -
Na +
ATP
HCO
3
H +
PVC MRC PVC
CA
Ca 2+ Cl 3Na +
Cl -
Ca 2+
ATP
CO
2
ATP
2K +
Na +
Blood (basolateral)

The higher the log K , the more strongly the ligand binds Ag + log K nitrate chloride thiosulfate
-0.3
3.3 - 5.5
8.8 -14.2
dissolved organic carbon 9.0 -10.0
sulfide 8.0 -19.2

Structurally Complex:
 Pavement cells (PVC)
 Mitochondria-rich (MRC) or “chloride” cells
 Mucus cells
 Neuroepithelial cells
 Undifferentiated cells
Multi-functional organ:
 Involved in gas exchange, nitrogenous waste excretion, ion transport and acid-base regulation.

2.0
1.5
1.0
0.5
0.0
Total Tissue Residue
Small BIM
Large BIM
Toxic Threshold
Small BIM
Large BAM
Large BAM
Small BAM
Time

Mercury shows a different trend:
Han et al. (2002) Naturwisch. 89: 497-504

Salazar & Salazar (2006)
Mussel Toxicology
SETAC Press, 215-255

Aquatic Life Ambient Freshwater Criteria-Copper 2007 Revision
EPA-822-R-07-001 http://www.epa.gov/waterscience/criteria/copper/index.htm