Phytoplankton
Zooplankton
Polychaete sp.1
Polychaete sp.2
Blue mussel
Pacific oyster
Amphipod
Mysid shrimp
Dungeness crab
Crangon shrimp
Shiner surfperch
Pacific herring
Walleye pollock
Northern anchovyDove sole
Chum salmon
Gonatid squidCoho salmon
Lingcod
Sablefish
Halibut
Chinook salmon
Killer whale ()Killer whale ()
0.0001
0.001
0.01
0.1
1
10
100
1000
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000
137 C
s (B
q/kg
wet
wei
ght)
Time (days)
137Cs-Japan Consumption Guideline (100 Bq/kg)
137Cs-Canada Consumption Action Level (1000 Bq/kg)
Model Parameterization and Theory
Figure 4. Simulations showing predictions of the accumulation of 137Cs activities in organisms of the food web over time: A)
current scenario with seawater activity (CW) = 5.0 x 10-4 Bq/L; sediment activity (CS) = 0.05 Bq/kg dw; and, B) future scenario
with (CW) = 0.01 Bq/L; (CS) =1.0 Bq/kg dw (B). The simulations include the nuclear decay rate (kN = 6.33 x 10-5 d-1) for 137Cs.
The red solid line represents the Canadian Action Level for Consumption following a Nuclear Emergency of 1000 Bqkg-1; the
red dashed line represents the limit for radiocesium contamination in food (100 Bqkg-1) used currently in Japan.
While current 137Cs activities do not indicate a health concern for the consumption of fish products by human populations in the west coast of Canada, 137Cs activities may achieve levels in upper trophic levels that may pose health risks in wildlife species. A rigorous monitoring program would also support the further development of the model and improve the ability to forecast 137Cs activities in marine organisms and uptake in human populations that consume sea products.
A MARINE FOOD WEB BIOACCUMULATION MODEL FOR CESIUM 137 IN THE PACIFIC NORTHWEST
Juan Jos Alava & Frank A.P.C. Gobas 1 School of Resource and Environmental Management, Faculty of Environment, Simon Fraser University, Burnaby, BC, Canada (E-mail: [email protected]) November, 2014
Model Outcomes: Simulations
The area selected for the bioaccumulation modeling work is the resident killer whales outer coast habitat (i.e. offshore) in the Pacific Northwest coast (i.e. a region of the western coast of USA and Canada; Figs. 1-2).
A simplified oceanic food web, including Chinook salmon (Oncorhynchus tshawytscha) and killer whales, were constructed for the modeling work (Fig. 3).
Most of the data on feeding ecology, diet and trophic levels for fish and other aquatic biota were retrieved from Alava et al. (2012)
137Cs seawater activity data were obtained from Smith et al. (2013) to simulate current conditions (i.e. using 5.0 x 10-4 Bq/L), and from Rosi et al. (2013) for a future scenario over the 2014-2020 time period (i.e. 0.01 Bq/L).
137Cs sediment activity data are scarce for the study region, thus assumed activities were used as inputs in the model (Current scenario: 0.05 Bq/kg dw; Future scenario: 1.0 Bq/kg dw).
137Cs activities in the atmospheric air inhaled by air breathing organisms (i.e. killer whales) were assumed to be negligible in Pacific Northwest waters off the coast of Canada.
The Fukushima nuclear accident on 11 March 2011 emerged as a looming threat to the marine biodiversity in the Pacific Ocean and human health in coastal communities. Assessment of the long term consequences of radiocesium 137 (137Cs) releases from the Fukushima plant should consider the extent of ecological magnification in food-webs in addition to ocean dilution.
Pacific salmon are the major diet item of British Columbia resident killer whales (Orcinus orca), and therefore contribute to the accumulation of contaminants (e.g., POPs) found in this species (Fig. 1; Cullon et al., 2009).
137Cs cannot be ruled out as a potential bioaccumulative pollutant in regional food-webs, including the resident killer whale food-web in BC waters (Figs. 1 & 2).
Background Study Areas, Food web construction & Diet composition
Figure 2. Transport, fate and partitioning of 137Cs in a multi-media marine environment and in resident killer whales habitat and food-web.
Conclusion
137Cs-Bioconcentration Factor (BCF) in Phytoplankton: 20 L/kg, based on Vive i Batlle (2012) & IAEA (2004).
The basic kinetic mass balance, time dependent model for the bioaccumulation of 137Cs in aquatic biota is described as follows:
For air respiring organisms, the differential equation is:
Dietary Uptake Rate Constant (kD): Values for kD were derived from Alava et al. (2012) 137Cs-Elimination Rate Constant (kE) in invertebrates: kE values for zooplankton (0.053d-1), the
blue mussel, Mytilus edulis (0.04d-1) and Pacific giant oyster, Crassostrea gigas (0.01d-1) were calculated (using the biological half life:t = Ln/kE) or data reported elsewhere (Vive i Batlle 2012; IAEA 2004; Cranmore & Harrison 1975). For polychaetes (0.118 d-1) and benthic crustaceans (i.e. 0.130 d-1 for amphipods and mysid shrimp, Mysis sp., and 0.224 d-1 for Crangon shrimp and Dungeness crab, Metacarcinus magister), kE values were adopted from Topcuolu (2001).
Elimination Rate Constants (kE) in fish: because the apparent elimination of 137Cs in fish is predominantly due to growth dilution, the growth rate constant can be an adequate descriptor for the apparent elimination of 137Cs from fish (i.e. kE can be considered negligible).
Elimination Rate Constants (kE) in killer whale: the 137Cs-half life of 28d estimated for marine mammals by Watson et al. (1999) was used here to calculate a plausible elimination rate constant (kE) for resident killer whales (i.e. kE = Ln/t =0.693/t =0.693/ 28 d = 0.025 d-1).
Growth Rate Constant (kG) estimates for all species were retrieved from Alava et al. (2012).
Objective: To model the bioaccumulation of 137Cs in an offshore food web of the Pacific Northwest with the aims of improving our understanding of the bioaccumulation potential and health effects of 137Cs in top predators and of conducting an eco-toxicological risk assessment.
Nuclear fall out and long-range atmospheric transport
Muscle/Fat-soluble chemicals
- (137Cs)
-
Water - soluble (137Cs)
(137Cs)
-
- bound
chemicals (137Cs)
Water - soluble
-
Particle -
Water - soluble chemicals (
Phytoplankton
Zooplankton
Polychaete sp.1
Polychaete sp.2
Blue mussel
Pacific oyster
Amphipod
Mysid shrimp
Dungeness crab
Crangon shrimp
Shiner surfperch
Pacific herring
Walleye pollock
Northern anchovyDove sole
Chum salmon
Gonatid squidCoho salmon
Lingcod
Sablefish
Halibut
Chinook salmon
Killer whale ()Killer whale ()
0.0001
0.001
0.01
0.1
1
10
100
1000
0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000
137 C
s (B
q/kg
wet
wei
ght)
Time (days)
137Cs-Japan Consumption Guideline (100 Bq/kg)
137Cs-Canada Consumption Action Level (1000 Bq/kg)
Phytoplankton
ZooplanktonPolychaete sp.1
Polychaete sp.2
Blue musselPacific oyster
Amphipod
Mysid shrimp
Dungeness crab
Crangonshrimp
Shiner surfperchPacific herringWalleye pollock
Northern anchovy
Dove soleChum
salmon
Gonatid squid
Coho salmonLingcod
Sablefish
Halibut
Chinook salmon
Killer whale (male)
Killer whale (female)
Log 137Cs= 0.0231(TL) - 2.0655r = 0.0014, p > 0.05
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
90 days
Phytoplankton
Zooplankton
Polychaete sp.1Polychaete sp.2
Blue mussel
Pacific oyster
Amphipod
Mysid shrimp
Dungeness crab
Crangon shrimp
Shiner surfperch
Pacific herringWalleye pollock
Northern anchovy
Dove sole
Chum salmonGonatid
squidCoho salmon
LingcodSablefishHalibut
Chinook salmon
Killer whale (male)Killer whale (female)
Log 137Cs = 0.818(TL) - 3.3764r = 0.5099, p < 0.0001
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
730 days
Phytoplankton
Zooplankton
Polychaete sp.1Polychaete sp.2
Blue musselPacific oyster
Amphipod
Mysid shrimpDungeness crab
Crangon shrimp
Shiner surfperch
Pacific herringWalleye pollock
Northern anchovy
Dove sole
Chum salmonGonatid
squidCoho salmon
LingcodSablefish Halibut
Chinook salmon
Killer whale (male)Killer whale (female)
Log 137Cs= 1.1731(TL) - 4.129r = 0.6298, p < 0.0001
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
10950 days
N 60
50
40
180 150 120
Alaska
Vancouver I.
Gulf of Alaska
Strait of Georgia
Aleutian Is.
CANADA
USA
British Columbia
Puget Sound Pacific Ocean Washington 137Cs 137Cs
137Cs
Figure 1. Through the oceanic life stage cycle , Pacific salmon species are likely to deliver Fukushima associated 137Cs to the resident killer whales food-web in waters off the Pacific Northwest coast.
Trophic Magnification of 137Cs over time
Offshore
The Fukushima nuclear power plant lies within 200km of the core of the Kuroshio Current Extension
Position and direction of the
Kuroshio Current Extension
Resident Killer Whale TL =4.5
Chinook, Chum and Coho salmon
TL= 3.4-4.2Halibut & Sablefish
(Demersal fish) TL= 3.85-4.13
Small pelagic fish
TL=3
Zooplankton TL=2
Phytoplankton TL= 1
Benthic biota TL = 2.1-2.9
sediments
seawater
Gonatid squid TL =3
137Cs
137Cs
Salmon make up 96% of the killer whales diet, of which 71.5% is Chinook salmon (Ford and Ellis, 2006; Ford et al., 2010).
PhytoplanktonZooplankton
Polychaete sp.1Polychaete sp.2
Blue musselPacific oyster
Amphipod
Mysid shrimpDungeness crab
Crangonshrimp
Shiner surfperchPacific herring
Walleye pollock
Northern anchovy
Dove soleChum salmon
Gonatid squidCoho salmon
Lingcod
SablefishHalibut
Chinook salmon
Killer whale (male)
Killer whale (female)
Log 137Cs = -0.4029(TL) - 1.4306r = 0.3274; p =0.0035
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
30 days
Phytoplankton
ZooplanktonPolychaete sp.1
Polychaete sp.2
Blue musselPacific oyster
Amphipod
Mysid shrimp
Dungeness crab
Crangonshrimp
Shiner surfperchPacific herring
Walleye pollockNorthern anchovy
Dove sole
Chum salmon
Gonatid squid
Coho salmon
Lingcod
Sablefish
Halibut
Chinook salmon
Killer whale (male)
Killer whale (female)
Log 137Cs = -0.1371(TL) - 1.8221r = 0.0497, p > 0.05
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
60 days
Phytoplankton
Zooplankton
Polychaete sp.1Polychaete sp.2
Blue musselPacific oyster
Amphipod
Mysid shrimp Dungeness crab
Crangon shrimp
Shiner surfperch
Pacific herringWalleye pollock
Northern anchovy Dove
sole
Chum salmon
Gonatid squid
Coho salmon
LingcodSablefishHalibut
Chinook salmon
Killer whale (male)
Killer whale (female)
Log 137Cs= 0.5734(TL) - 2.9374r = 0.3743; p =0.0015
-6.00
-5.00
-4.00
-3.00
-2.00
-1.00
0.00
1.00
2.00
3.00
0 1 2 3 4 5
Log
137 C
s (B
qkg
-1w
et w
eigh
t)
Trophic Level (TL)
365 days
Figure 3.
BENGDDAAB CkkkCkCk
dtdC ).(.. +++=
BENGDDWWB CkkkCkCk
dtdC ).(.. +++=
Legends: CB = 137Cs-activity in biota; CW= 137Cs-seawater activity; CA= 137Cs-air activity ; CD= 137Cs-activity -diet; kW = 137Cs-water uptake rate; kA= air uptake rate; kN = 137Cs-nuclear decay rate.
A) Current scenario B) Future scenario
Figure 5. Linear regressions showing the bioaccumulation behavior and trophic magnification of 137Cs activities versus trophic
levels in the resident killer whales outer coast food web for a simulation with CW = 5.0 x 10-4 Bq/L; and, CS = 0.05 Bq/kg dw
at: A) 30 days, B) 60 days, C) 90 days, D) 365 days (1 year), E) 730 days (2 years); and, F) 10950 days (5 years), following the
the Fukushima nuclear accident in the North Pacific. 137Cs activities significantly increase in the food web after one year.
A) B) C)
D) E) F)
Slide Number 1