The Impact of Acid Rain on the Aquatic Ecosystems of Eastern Canada

In the past environmental management practices have been based on disparate analysis of the impacts of pollutants on selected components of ecosystems. However, holistic analysis of emission reduction strategies is necessary to justify that actions taken to protect the environment would not unduly punish economic growth or vice versa. When environmental management programs are implemented, it would be extremely difficult for the industry to attain the targeted emission reduction in a single year in order to eliminate impacts on ecosystems. It means that targets have to be established as increments or narrowing the gap between the desired level of atmospheric deposition and actual deposition. These targets should also be designed in a way that would balance the impacts on the economy with improvements in environmental quality. Environment Canada in partnership with other organizations has developed an Integrated Assessment Modeling Platform. This platform enables to identify an emission reduction strategy(ies) that is(are) able to attain the desired environmental protection at a minimum cost to the industry. In this study, an attempt is made to examine the impact on the industry when the level of protection provided to the aquatic ecosystems is implemented using environmental and environmental-economic goals as objectives using Canadian IAM platform. The modeling platform takes into account sources and receptor regions in North America. The results of the analysis indicated that reductions of at least 50% of depositions of SO2 would require complete removal of emissions from all sources. However, this is not compatible with the paradigm of balancing economy with the environment. Therefore, gradual reductions in emissions as well as depositions were found to be plausible strategy. When depositions are reduced by 80% and maximum emission reduction is set at 90%, the number of lakes with pH>6 as well as the presence of fish increased significantly compared to current level. These improvements in acidification in lakes are particularly visible for a strategy that incorporates both environmental and economic goals. Furthermore, optimization using only a single receptor at a time resulted in significantly higher reduction in emissions compared to optimization that incorporates all the twelve Canadian receptors in a single run. It implies that globally optimal emission reduction strategy (i.e., multi-receptor optimization) would not penalize the sources of emission compared to locally optimal emission reduction strategy (i.e., single receptor optimization). It is hoped that with this kind of analysis of feasible environmental targets can be put in place without jeopardizing the performance of the economy or industry while ensuring continual improvements in environmental health of ecosystems.