AN ECOLOGICAL RISK ASSESSMENT FOR BROWN TROUT IN LAKE SUPERIOR Howard Kung REM 445 at Simon Fraser U

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AN ECOLOGICAL RISK ASSESSMENT FOR BROWN TROUT IN
LAKE SUPERIORHoward Kung REM 445 at Simon
Fraser University Presented December 12th 2003
ABSTRACT
A ecological risk assessment of Hexachlorobenzene
(HCB) concentration in Lake Superior is
conducted. The development and the evaluation of
a multimedia compartment model Fugacity level
lII model which can predict the concentration
and the distribution of chemicals in Lake
Superior in multiple environmental media
simultaneously is used for risk assessment. The
model assumes that the compartments are at steady
state. The attenuation mechanisms include
advection, transformation reactions, and
diffusive/non-diffusive intermedia transport
between compartments. Input Parameters include
the physical properties of the environmental
media, emission rates, and chemicail properties
of HCB. The question of this assessment is to
determine whether or not current HCB
concentrations in Lake Superior are a hazardous
risk to rainbow trout. The predictioted
concenrations of HCB in brown trout (a top
predator) in the lake are within 1 order of
magnitude of its LC50 and greatly exceeds the
water quality guideline set by the New Great
Lakes Initiative (NGI) which is set at 0.45 ng/L.
This suggest that the HCB concentration in the
lake is of hazarddois risk to the Brwon Trout.
The fugacity level III results are compared with
Zhang et als Multimedia Compartment Model
(CHEMGL) results.
Ecological Risk Assessment

CONCLUSIONS
BACKGROUND
The Level III fugacity model in this project was
not to predict the fate of chemicals precisely
in a specific environmental compartment, but to
estimate the concentration of HCB for the sole
purposes of conducing a ecological risk
assessment.
Problem Formulation Phase
Analysis Phase

What is Brown Trout?

Determination of HCB in Surface Water
Equilibration time
Rapid initial uptake
Slow prolonged uptake
The calculated HCB concentration in Fish (with
BMF) using the fugacity level output did not
reach the LC50 of brown trout assuming a normal
distribution but greatly exceeded the NGL water
quality guideline suggesting that there is
hazardous risk

2
1
Csurface water
(no BMF/BMF)
2.
The calculated HCB concentrations in Fish (with
BMF or BCF) using Zhang et al.s CHEMGL model
either reached or exceeded the LC50 of brown
trout assuming a normal distribution suggesting
the Lake Superior is toxic to Brown Trout
Uptake of PCBs (1), and Chlorobenzenes (2) into
EVA in (mol/m3) over time
What is Lake Superior?

• Lake Superior is located on the northern edge of
  Wisconsin and stretches between the Upper
  Peninsula of Michigan north to Ontario Canada.

STEP 4 Hexane extraction and analysis
3.
The fugacity level II model only considers 4
environmental compartments while the CHEMGL model
considers 10 environment compartments. Thus, more
compartments can employed into my model for a
more valid comparison. However, the modeling
capacities of fugacity level III are more limited
than CHEMGL.
At Equilibrium (approx. 80 hours) fEVA fSED
68 mPa

• Conceptual Models

Risk Characterization
My fugacity level III results
Zhang et al.s CHEMGL model results

4.

• Holds 10 percent of the worlds fresh water.
• Population living around the lake 629,825 (US
  Canada)

Model predictions are highly uncertain because
accurate emission rates are rarely known and some
model inputs such as transport rates and reaction
rates are highly uncertain.
CEVA Chexane x Vhexane VEVA
What is Hexachlorobenzene (HCB)?

• HCB is a white, needle-like solid used as a wood
  preservative and a fungicide for treating seeds

Error bars represent 1 standard deviation above
and below the mean concentration
0.5 ml hexane
MAJOR REFERENCES

• Persistent environmental chemical due to its
  chemical stability and resistance to
  biodegradation

Chemical structure of HCB

• Coefficients of variation (for all chemicals)
  ranged from 2 to 24, with an average of 11
  variation

Cook, R., Suter II, G., and Sain, E. 1999.
Ecological risk assessment in a large
river-reservoir Clinch River. Environmental
Toxicology and Chemistry. 18(4)
581-598. Meloche, L., Otton, V., and Gobas, F.
2003. Use of thin-film solid-phase extraction to
measure frugalities of hydrophobic organic
chemicals in sediment samples. Zhang, Q.,
Crittenden, J., Shonnard, D., and Mihelcic J.
2003. Development and evaluation of an
environmental multimedia fate model CHEMGL for
the Great Lakes region. Chemosphere. 50
1377-1397.

• HCB is bioaccumulative in fish

Results for Tetrachlorobenzene uptake into EVA
over time (each time step conducted in triplicate)

• HCB can cause confusion, weakness, convulsions or
  even death in Aquatic species

Zhang et al, Csurfacewater is 30ng/L, this
accounts for the major differences in fish HCB
concentration relative to my fugacity level III
results
HCB under a microscope