Canadian Environmental Modelling Centre

Progress Report: Summer 1997


Spring Meeting at The Irwin Inn

June 17 & 18, 1997


Attending the meeting were:

Front Row: J. Cole, E. Webster, H. Morrison, S. Wilkinson, K. Carr, R. Harris, L. Milford, D. Mackay; Middle Row: J. de Koning, J. Ridal, S. Scott, H. Eisler, K. Taylor, G. Coyle, J. Gannon, G. Cluett, H. Hintelmann, J. Argo, B. Hickie, E. Bentzen, J. Muldoon; Back Row: R. Beauchamp, D. Lasenby, D. Kane, A. McConnell, D. Lean, T. Scholtz, T. Parkerton. Missing from photo: J. Hewett, G. Klecka, L. Seeley, J. Soule.



D. Mackay opened the 5th meeting of the Environmental Modelling Centre's Partners by welcoming those present and a round of introductions followed. The purpose of the meeting was to provide the partners with an update on work at the Centre, exchange ideas, and to seek direction for future research through informal presentations and discussion.

The following is a brief synopsis of the presentations and discussions.

Physical Chemical Properties

D. Mackay presented an overview on Volume 5 of the Illustrated Handbook of Physical Chemical properties and Environmental Fate for Organic Chemicals, edited by D. Mackay, W.Y. Shiu and K.C. Ma. The 5th volume, treating pesticides, is complete and has been sent to the publisher, CRC Press.

Work continues jointly with Dr. Bob Boethling of US EPA, on editing a Handbook of Physical Chemical Property Estimation Methods. Some suggestions were made for additional content.

A paper co-authored by A. Finizio, T. Harner, T. Bidleman and D. Mackay on the use of the octanol-air partition coefficient has been published in Atmospheric Environment (Vol 31, No. 15, pp 2289-2296, 1997). Copies were distributed.

Collaboration is continuing with the groups at the University of Lancaster and the University of Bayreuth on chemical partitioning to vegetation from air and soil.

J. Cole presented a compilation of physical and chemical properties for chlorobenzenes. He also described his work on a novel approach to correlating the partitioning properties of organic chemicals by deducing the "three solubilities" ie. in air, water and octanol. Another summer student, J. Muncke, has been extending this to include solubility in organic carbon.

Multimedia Models

S. Scott gave a presentation of the status of his work on the spatial distribution of Volatile Organic Compounds. A paper describing how a statistical distribution function can be used to express the fraction of the population experiencing less than a specified concentration is nearing completion. This is being done in conjunction with the Ontario Ministry of Environment and Energy. It was suggested that closer dialogue with government would be desirable. Unfortunately, of the MOEE representatives invited, none were available to attend the meeting.

D. Mackay reviewed the status of the ChemCAN model which is undergoing a review with plans to revise its treatment of vegetation, including a sensitivity analysis and ultimately an unsteady state version.

E. Webster described her work on the concept of persistence. A draft paper was distributed which demonstrated that there are severe problems in defining persistence in an individual medium, eg. whether it is greater or less than 6 months in soil. Further, it is clear that mode of entry and partitioning tendencies strongly affect overall environmental persistence. This paper will be finalized in the next month.

J. Hewett gave a presentation of the "new generation" of Visual Basic Models. They will be easier to use and more readily understood. A Level I specimen model, which is nearly complete, was demonstrated. It should be on the web site for distribution by September.

H. Hintelmann, the newly appointed "Junior Chair" gave an account of his work on mercury cycling and particularly on the use of stable isotopes to determine the rates of processes such as mercury methylation. He also described plans to work on other metals such as zinc. This aspect of the overall program is funded jointly by INCO and NSERC and is a welcome addition to the primarily organic work to date.

Contributions by Partners

R. Harris of TetraTech described his modelling work of mercury cycling which includes fish bioenergetic components and is applicable to several types of lakes and reservoirs. Mechanisms are being sought by which the Centre can collaborate in this work.

J. Gannon of Dupont described his company's use of models, especially the Level I fugacity model, as part of screening for "greener" products. Intentions are to determine a product's life-cycle to avoid the development of persistent and bioaccumulative chemicals.

J. Argo discussed his involvement in the Canadian Cancer Surveillance Program as a consultant to Health Canada. Benzo[a]pyrene is being used as a standard for dose equivalence for relative toxicity and correlations are being sought between exposure and incidence of cancers.

S. Wilkinson of SENES Consulting presented her work on decision making models using water treatment as an example. Trade-offs between disinfection by-products and microbial contamination in drinking water were compared using public perception and cost as underlying concerns for the decision making process.

Water Quality

L. Milford gave an update on her model to quantify total PCBs in the Otonabee River/Rice Lake ecosystem. The model is a steady state, QWASI (Quantitative Water Air and Sediment Interaction) model. This model is being adapted to consider the dynamics of the river system. Presently the model predicts that PCB concentrations increase in the downstream segments as a result of discharge into Little Lake in Peterborough.

This model will be applied to the St. Lawrence River Area of Concern near Cornwall, Ontario. High regional PCB levels in all environmental media have come from local industrial sources. This project will be undertaken in collaboration with the St. Lawrence River Institute of Environmental Science.

D. Lean and J. Ridal from the St. Lawrence River Institute of Environmental Science (SLRIES) in Cornwall, Ontario described their work. D. Lean, the NSERC-Industry Chair at the University of Ottawa, discussed the balancing act between working with industry, while maintaining public confidence and satisfying academic demands. He also discussed a children's program set up by the Institute to promote environmental awareness. J. Ridal discussed gas transfer processes of chemicals using a-HCH as an example. There is seasonal variation in the direction of transfer between Lake Ontario water and the air above the lake.

Continuing on the water quality theme, D. Mackay discussed issues pertaining to virtual elimination. As detailed in a soon-to-be-published Atmospheric Environment paper with E. Bentzen, PCB concentrations in Lake Ontario are now close to equilibrium with the air above, having only seasonal fluctuations. Gas transfer of contaminants now greatly exceeds wet and dry deposition rates. Since the Lake is adjusting to conditions in the atmosphere, there is little that can be done to decrease the concentration in the lake. All we can do is wait for atmospheric concentrations to fall. It appears that we may already have reached "virtual elimination" of point discharges.

D. Mackay also discussed i) PAH modelling in the Saguenay Fiord which will be published in ET&C in the autumn, ii) the impact of PAH atmospheric emissions on the St. Lawrence and iii) contamination and remediation of a PCB storage site at Smithville, Ontario. The PCB storage site involved PCBs leaking into fractures in the bed rock, into an aquifer and eventually into nearby drinking water. A Level I and Level II analysis was conducted to determine concentrations of PCBs and chlorobenzene in the water.

Bioaccumulation

B. Hickie described his contaminant bioaccumulation modelling work for marine mammals, especially beluga whales and Arctic ringed seals. This work is driven by health concerns for northern people who rely on marine mammals as a food source, as well as concerns for health of marine mammals in more highly contaminated areas.

Models have been developed to examine detailed processes of contaminant accumulation, distribution and losses by individual beluga whales and ringed seals over their lifetime (~30 years), as well as at the level of whole populations. The individual-based models provide a highly detailed mass balance including losses by reproductive transfers to the fetus and newborn via milk. The population-based models allow examination of how contaminant levels in populations respond to changes in contaminant levels in their prey over extended periods of time. Retrospective analyses can be conducted and future trends forecasted. The models will be applied to other Arctic animal populations which are hunted. They are also being applied to the highly contaminated St. Lawrence beluga population where contaminants such as PCBs, DDT, and mirex could be impacting on the health of the population. The pollution reduction in the St. Lawrence River may be causing the gradual contaminant reduction seen in this beluga population.

The Windows-based "Visual Beluga" model was demonstrated by J. de Koning. This model provides an energetics driven lifetime prediction of organic contaminant uptake, accumulation and transfer in beluga whales. General features of both male and female contaminant accumulation profiles were illustrated, emphasizing the importance of contaminant offloading by nursing females, and the influence of the reproductive history of the adult female on relative dosing levels to neonates. The impacts of growth dilution and variable contaminant elimination rates were also illustrated. Visual Beluga will be made available on the Centre's website when testing and documentation is complete.

B. Hickie briefly discussed the project on Three Lake Classes. It has been hypothesized that the presence of the fresh water shrimp, Mysis relicta, in only class 3 lakes may be responsible for the higher lipid and contaminant levels seen in lake trout. A modified version of D. Mackay's fish model was used to examine the relative importance of water, sediment-pore water, and pelagic and benthic food concentrations to the mysid contaminant levels. Plans are underway to add reproduction and molting to this bioenergetics model. The model currently treats organic contaminants. It is hoped that metals can be added in the near future.

H. Morrison, a consultant to the Canada Centre for Inland Waters (CCIW), presented her work on the development of a system for quantifying environmental risks associated with halogenated aromatic hydrocarbons. This project which is primarily directed by C. Metcalfe and A. Niemi is supported by C4. Risk is assessed using both exposure and toxicity. Toxicity was estimated in terms of TCDD equivalents. A steady state bioenergetics foodweb model was used to estimate the concentration in sport fish from which fillet concentrations were estimated to determine human exposure. Lake Ontario anglers and their families were used to validate the developed modelling procedure. The lack of environmental concentration data and toxicity data have hindered progress on this project.

Impromptu Talks

H. Morrison discussed her recent work on zebra mussels, focussing on their effects on the PCB concentration in western Lake Erie. It was found that the mussels reduce particulate organic carbon in the water column which leads to an increase in chemical bioavailability of PCBs.

T. Scholtz from ORTECH discussed his modelling program on pesticide volatilization. This work is supported by AES as part of their assessment of agricultural sources of toxic chemicals to the atmosphere.

T. Parkerton from Exxon presented work on exposure assessment for DEHP in Western Europe. The modelling efforts have been successful and have yielded results which are particularly interesting in that release scenarios that result in longer overall environmental persistence actually reduce potential human exposure via the agricultural food chain due to bioavailability considerations. It is also important to note that when interpreting residue data for DEHP, one must not only consider possible contamination from food processing but also background lab contamination.

Administrative Issues

J. Muldoon, the Trent University Research Officer, brought attention to the upcoming 40-month progress report to NSERC regarding the performance of the Chair. Partners may be asked by NSERC to comment on the success of the partnership.

Mention was made concerning the Canadian Foundation for Innovation project. The Federal Government is allocating $800 million over 5 years, and the Provincial Government $500 million over 10 years, for research initiatives. The project is designed to support research infrastructure in the areas of health, environment, science and engineering.

D. Mackay closed the meeting with words of appreciation to all who attended. Approval of The Irwin Inn for next year's meeting was unanimous. The tentative dates for next year's partners' meeting are June 9th and 10th with a Fugacity Workshop to be held on the 8th.

A proposal was made to have a casual get together and progress review during the SETAC meeting in San Francisco, November 1997. This would provide a setting for an update on the proceedings of the Environmental Modelling Centre.


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