Proceedings - Teaching and Learning Centre - Simon Fraser ...

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Fraser River Action Plan 3rd Research Workshop Modelling the Fate of Contaminant Discharges in the Fraser River Basin F.A.P.C. Gobas School of Resource and Environmental Management Simon Fraser University Abstract The objective of this project was to develop and test a simulation model of the environmental and ecological fate of organic chemical discharges in the Fraser-Thompson River basin. The main purpose of this model was to: 1. assess and verify the impacts of discharge of contaminants in the Fraser River from single and multiple sources and the resulting concentrations of these substances in water, sediments, benthic invertebrates and fish throughout the Fraser River basin as a function of time and during different seasons in the year; 2. determine whether existing contaminant loadings from point and non-point sources will meet environmental quality guidelines and standards and human consumption guidelines within the Fraser- Thompson River basin; 3. recommend targets for remediation on a whole-basin basis; 4. aid in the interpretation of data collected in monitoring programs; 5. establish guidelines with regards to the experimental design of contaminant and environmental effects monitoring (EEM) programs within the basin; 6. assess the time response of the contaminant concentrations throughout the Fraser River basin to changes in contaminant emissions under various loading scenarios; and, 7. identify data gaps and targets for research. Summary • We developed and tested a novel and truly time-dependent food chain bioaccumulation model, which, as far as we know, is the first truly time-dependent food chain bioaccumulation model for contaminants. In contrast to our earlier model, this new model is able to simulate the effect of seasonal and life-time changes in organism weight, lipid content and diet composition of fish and benthic invertebrate species. Each generation or age-class of organisms is now treated independently. This makes it possible to: (i) stimulate changes in chemical concentrations that occur seasonally and throughout the life-span of the organisms; (ii) compare contaminant levels between age-classes since several generations coexist at one time; and, (iii) represent inter-generational transfer of contaminants between adults and their respective offspring. • We compiled new data regarding the growth rates, changes in lipid content and age-dependent feeding behaviour for Rocky Mountain whitefish, rainbow trout and large-scale sucker in the Fraser and Thompson rivers and in Kamloops Lake. These data are used to build the food chain bioaccumulation model. • A new algorithm for simulating dietary uptake is included in the bioaccumulation model based on studies described in Gobas et al., 1993. • Emission records of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran from five pulp and paper mills were compiled. Effluent concentrations were multiplied by the reported average Page 43
Fraser River Action Plan 3rd Research Workshop pulp and paper mill effluent discharge rate to derive contaminant loadings in units of grams per day. These loadings were used to conduct model simulations. • Reported concentrations of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 2,3,7,8-tetrachlorodibenzofuran in water, sediments and fish of the Fraser and Thompson rivers for the period of 1989 to 1993 were compiled. These data were used to verify model predictions and to derive model uncertainty. • An initial model verification was conducted by comparing available observed and predicted concentrations for the time period from 1989 to 1993. The results were compiled and are graphically illustrated in Figures 1 and 2. Figure 1 illustrates the agreement between observed and predicted concentrations of TCDF in the organic carbon of sediments at various locations in the Fraser and Thompson rivers. The quality of agreement between observed and predicted TCDF concentrations in river bed sediments can be expressed by the mean ratio of the observed and predicted concentrations of TCDF in the sediments, which is 1.33, suggesting the model slightly under-predicts the observed concentrations. The 95% confidence limits of the model predictions range by a factor of 1.7 of the mean, suggesting that 95% of the observed sediment concentrations are approximately within a factor of 1.7 of the predicted concentrations. The uncertainty introduced in the model due to year-to-year variability in monthly river flow rates, river compartment widths and depths, concentration in suspended sediments, organic carbon content of suspended sediments and water temperature is represented in Figure 1 by the error bars which are 95% confidence limits of the mean derived through Monte Carlo Simulation. The 95% confidence limits range between a factor of 1.0 to 2.3 of the mean among the various compartments in the Fraser River and between a factor of 2.2 to 4.5 in the Thompson River. This means that year-to-year variability in the above mentioned model parameters is expected to cause variations in TCDF concentrations in the sediments that range between a factor of 2.0 to 4.5 depending on the location in the rivers. With the exception of the TCDF concentration observed in the Fraser River estuary (i.e., Compartment 18), all observed TCDF concentrations in the sediments of the Fraser and Thompson rivers are within the 95% confidence limits of the predicted concentrations. The higher TCDF concentration in the Fraser River estuary may be explained by local sources of TCDF, which are ignored in this study, as the Fraser River estuary is located in a highly industrialized part of Vancouver. Page 44
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PROCEEDINGS 3rd RESEARCH WORKSHOP F
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TABLE OF CONTENTS Participants ....
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Development of a Citizen’s Monito
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Fraser River Action Plan 3rd Resear
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SESSION 4 AGRICULTURAL ISSUES
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SESSION 5 BIOLOGICAL INDICATORS
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SESSION 6 ESTUARY ISSUES
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Fraser River Action Plan The Use of
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Fraser River Action Plan Concluding
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