Dear colleagues,
I hope this message finds
you well.
I
am pleased to share two new contributions on food-web bioaccumulation modeling
for anthropogenic pollutants using marine mammalian food webs. Please, see
below:
Modeling 137Cs bioaccumulation in
the salmon–resident killer whale food web of the Northeastern Pacific following
the Fukushima Nuclear Accident
Juan José Alava
& Frank A. P. C. Gobas
Abstract
To track the long
term bioaccumulation of 137Cs in marine organisms off the Pacific
Northwest coast of Canada, we developed a time dependent bioaccumulation model
for 137Cs in a marine mammalian food web that included fish-eating
resident killer whales. The model outcomes show that 137Cs can be
expected to gradually bioaccumulate in the food web over time as demonstrated
by the increase of the apparent trophic magnification factor of 137Cs,
ranging from 0.76 after 1 month of exposure to 2.0 following 30 years
of exposure. 137Cs bioaccumulation is driven by relatively rapid
dietary uptake rates, moderate depuration rates in lower trophic level
organisms and slow elimination rates in high trophic level organisms. Model
estimates of the 137Cs activity in species of the food web, based on
current measurements and forecasts of 137Cs activities in oceanic
waters and sediments off the Canadian Pacific Northwest, indicate that the long
term 137Cs activities in fish species including Pacific herring,
wild Pacific salmon, sablefish and halibut will remain well below the current 137Cs-Canada
Action Level for consumption (1000 Bq/kg) following a nuclear emergency.
Killer whales and Pacific salmon are expected to exhibit the largest long term 137Cs
activities and may be good sentinels for monitoring 137Cs in the
region. Assessment of the long term consequences of 137Cs releases
from the Fukushima aftermath should consider the extent of ecological
magnification in addition to ocean dilution.
Alava, J. J., Gobas, F. A. 2016. Modeling 137Cs bioaccumulation in the salmon-resident killer
whale food web of the Northeastern Pacific following the Fukushima Nuclear
Accident. Science of the Total Environment 544: 56-67
doi:10.1016/j.scitotenv.2015.11.097
Alternatively,
it can be found at:
Food Web Bioaccumulation
Model for Resident Killer Whales from the Northeastern Pacific Ocean as a Tool
for the Derivation of PBDE-Sediment
Quality Guidelines.
Juan José Alava, Peter S. Ross & Frank A. P. C. Gobas
Abstract
Resident
killer whale populations in the NE Pacific Ocean are at risk due to the
accumulation of pollutants, including polybrominated diphenyl ethers (PBDEs).
To assess the impact of PBDEs in water and sediments in killer whale critical
habitat, we developed a food web bioaccumulation model. The model was designed
to estimate PBDE concentrations in killer whales based on PBDE concentrations
in sediments and the water column throughout a lifetime of exposure. Calculated
and observed PBDE concentrations exceeded the only toxicity reference value
available for PBDEs in marine mammals (1500 μg/kg lipid) in southern
resident killer whales but not in northern resident killer whales. Temporal
trends (1993–2006) for PBDEs observed in southern resident killer whales showed
a doubling time of ≈5 years. If current sediment quality guidelines
available in Canada for polychlorinated biphenyls are applied to PBDEs, it can
be expected that PBDE concentrations in killer whales will exceed available
toxicity reference values by a large margin. Model calculations suggest that a
PBDE concentration in sediments of approximately 1.0 μg/kg dw produces
PBDE concentrations in resident killer whales that are below the current
toxicity reference value for 95 % of the population, with this value
serving as a precautionary benchmark for a management-based approach to
reducing PBDE health risks to killer whales. The food web bioaccumulation model
may be a useful risk management tool in support of regulatory protection for
killer whales.
Alava, J.J., Ross, P.S., Gobas, A.P.C. 2015. Food web bioaccumulation
model for resident killer whales from the Northeastern Pacific Ocean as a tool
for the derivation of PBDE-Sediment Quality Guidelines. Archives of Environmental
Contamination and Toxicology. doi: 10.1007/s00244-015-0215-y
Best Wishes!!!
Juan José Alava
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