Bioaccumulation Of Metal Substances by Aquatic Organisms
Transcript of Bioaccumulation Of Metal Substances by Aquatic Organisms
Bioaccumulation Of Metal Substances by
Aquatic Organisms Part 1
Bill Adams
OECD Meeting, Paris
September 7-8, 2011
Presentation Overview
• Bioaccumulation in aquatic organisms
• Inverse relationship between accumulation
factors (e.g., BCF/BAF/TTF) and exposure
concentration for metals
• Limitation on the use of BCFs and BAFs
• BCF and BAF comparisons
• Biomagnification summary for metals
• Trophic transfer factors (TTF)
• Proposed approach to assessing metal
bioaccumulation
Bioaccumulation Factors
Definition
Tissue Concentration
BCF/BAF = -----------------------------
Water Concentration
BCFs are based on water only exposures (lab data)
BAFs are derived from water and dietary exposure (field data)
Bioaccumulation Factors
• BCFs, BAFs, TTFs are inversely related to
exposure concentrations – they are not an intrinsic
property for metals
This identifies a problem for metal hazard assessment
• Big BCF/BAFs do not indicate hazard !!
• Larger values indicate low exposure and low
potential for chronic effects or secondary poisoning
• There is no one value above which hazard can be
ascribed
Bioaccumulation Factors
• BCF / BAF >1000 has been used to signify hazard
in many national regulatory schemes
• Such values have their origin with non-polar
organic compounds
• BCF / BAF >1000 for these substances denotes:
- significant and slow accumulation
- potential for chronic effects
- potential for food chain accumulation
• This is not the case for metal substances – why?
Bioaccumulation Factors
This is not the case for metal substances – why?
1.Nearly all metals (including iron) have BCF /BAFs
>1000 in natural ecosystems that are deemed to be
healthy and with aqueous concentrations at
background.
2.Extremely clean systems have even larger
BCF/BAFs
3.Metals accumulate different than organics
4.Metal regulation systems operate in most organisms
5.More………
Theoretical Basis - Metals
• Metals frequently occur as charged ions in
aqueous solutions and require active
transport to facilitate uptake for both
essential & non-essential elements
• Active transport mechanisms exhibit
saturable kinetics (i.e., rate limited & uptake
rates decline as exposure increases)
• Neutral lipophilic organics
– Uptake via passive diffusion across lipid bilayer
Pharmaco-Kinetic Model of Cu
Bioconcentration in Hyalella azteca Adapted from Borgmann et al. (1995)
1
10
100
1000
10000
100000
1000000
1 10 100 1000 10000 100000
Water Copper, µg/L
Tis
su
e C
op
per, µ
g/k
g
1
10
100
1000
10000
100000
1000000
BC
F
Tissue Burden
BCF
Bioconcentration Factor Concept – Non
Polar Organic Substances
Water Concentration
Tis
sue
Conce
ntr
atio
n
BCF
low high
BCF can be estimated
from Kow
Concentration (ug/L)
Tis
sue
con
c. (
ug/g
)
Homeostasis
1 10 100
Metal Regulation
0.01 0.1
Tissue Metal Concentration
Bioconcentration Factors (BCFs)
Supporting Data
Inverse relationship between tissue concentration
and exposure level for several metals
Bioconcentration Factors (BCFs)
Starting Point
- Fish metal BCFs often < 1000 in lab experiments
- Invertebrate BCF values are somewhat
larger than fish
- BCFs are derived in the laboratory via water
only exposures
- Lab tests that include diet show larger whole body
concentrations than water only exposures, i.e.,
BAFs > BCFs
Cadmium BCFs - Invertebrates
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0 -3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Amphipod (Hyalella azteca) Caddisfly (Hydropsyche betteni) Cladoceran (Daphnia magna) Crayfish (Orconectes propinquus) Grass shrimp (Palaemonetes pugio) Midge (Chironomus riparius) Grass shrimp (Palaemonetes vulgaris)
Lo
g B
CF
Log Cadmium, µg/L
Lead BCFs for Fish and
Invertebrates 4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Lo
g B
CF
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Log Lead, µg/L
Amphipod (Hyalella azteca)
Caddisfly (Brachycentrus sp.)
Snail (Physa integra)
Stonefly (Pteronarcys dorsata)
Brook trout (Salvelinus fontinalis)
Copper BCFs - Invertebrates
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Lo
g B
CF
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Log Copper, µg/L
Amphipod (Hyalella azteca)
Polychaete (Phyllodoce maculata)
Polychaete (Eudistylia vancouveri)
10000
1000
Nickel BCFs for Fish and
Invertebrates
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Lo
g B
CF
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Log Nickel, µg/L
Cockle (Cerastoderma edule)
Blue mussel (Mytilus edulis)
Eastern oyster (Crassostrea virginica)
Fathead minnow (Pimephales promelas)
Zinc BCFs for Fish
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Lo
g B
CF
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Log Zinc, µg/L
Atlantic salmon (Salmo salar)
Flagfish (Jordanella floridae)
Guppy (Poecilia reticulata)
Zinc BCFs - Invertebrates
4.5
4.0
3.5
3.0
2.5
2.0
1.5
1.0
0.5
0.0
-0.5
-1.0
Lo
g B
CF
-3.0 -2.0 -1.0 0.0 1.0 2.0 3.0 4.0 5.0 6.0
Log Zinc, µg/L
Amphipod (Allorchestes compressa)
Amphipod (Hyalella azteca)
Molybdenum BAFs
Literature data: indicate a decrease of the BAF with increasing Mo-levels in the environment: regulation/homeostasis (Van Tilborg, 2009)
The BCF at 12.7 mg/L (PNEC) has not been measured. Extrapolation of the BCF line results in a value of about 0.05. Measured value at 12.7 mg/L = 0.02-0.06 -BCFs in figure range from 90-0.02 -Mo is highly regulated
Bioaccumulation data
- OECD 305: FT fish test - Mo-levels in filets (muscle) and whole body were determined
• 60d uptake (Test concentrations: 0 – 1.0 – 12.7 mg Mo/L) • steady state reached at day 21
0
0.1
0.2
0.3
0.4
0.5
0.6
day 0 day 7 day 14 day 21 day 28 day 45 day 60 depuration
Mea
sure
d c
on
cen
trat
ion
(m
g M
o/L
)
Uptake phase
control filet
control whole body
1.0 mg/L filet
1.0 mg/L whole body
12.7 mg/L filet
12.7 mg/L whole body
Detection limit
Linear (Detection limit)
BCFs Cobalt: Note the phylogenetic differences
Species Phylogenetic Location BCF
Rhynchostegium riparioides FW Plant/moss 11005
Scapania undulata FW Bryophyte 8731
Fontinalis antipyretica FW Plant 7872
Cinclidotus aquaticus FW Plant 5000
Fissidens polyphyllus FW Plant 4800
Brachythecium rivulare FW Plant 4034
Lemna minor FW Plant 3935
Hyridella depressa Mollusk 1080
Velesunio ambiguus Mollusk 870
Mytilus galloprovincialis Mollusk 156
Mercenaria mercenaria Mollusk 3.5-73
Daphnia magna Zooplankton 265
Mixed zooplankton Zooplankton 3.9
Oncorhynchus mykiss FW Trout 4.6-11
Erynnis japonica Marine red sea bream 4.8
BAFs versus BCFs
- Field collected organisms
(dietary exposure)
- Species differences
- In depth look at bivalves
Zinc BAFs
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0.01 0.1 1 10 100 1000
Water, µg/L
BA
F
Mussels, calms, oysters
Amphipod (Allorchestes compressa)
Amphipod (Hyalella azteca)
Copper BAFs Vs BCFs
1
10
100
1000
10000
100000
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0.01 0.1 1 10 100 1000 10000
Water, µg/L
BA
F
Mussels, clams, oysters
Amphipod (Hyalella azteca)
Polychaete (Phyllodoce maculata)
Polychaete (Eudistylia vancouveri)
Lead BAFs
1
10
100
1000
10000
100000
1000000
10000000
0.001 0.01 0.1 1 10 100 1000 10000
Water, µg/L
BA
F
5000
500
Mussels, calms, oysters
Snails
Stoneflies
50000
Iron BAFs
1
10
100
1000
10000
100000
1000000
0.1 1 10 100 1000 10000 100000
Water, µg/L
BA
F
Mussels, clams, oysters
Amphipod (Hyalella azteca)
Polychaete (Phyllodoce maculata)
Polychaete (Eudistylia vancouveri)
Conclusions
• Bioaccumulation factors (BCFs, BAFs, TTFs) are not an intrinsic property for metals
• BCFs and other Accumulation Factors for metals are clearly inversely related to water (& sediment concentrations)
• Hazard and potential for chronic effects cannot be evaluated by magnitude of BCFs or BAFS