PARENT SESSION
3F Long-range transport of pesticides and other pollutants
9:00 AM to 7:00 PM, Monday, 07 May 2001

(M/EH098) GIS as a Tool in Continental Scale Multimedia Contaminant Fate Models .

Woodfine, David¹, MacLeod, Mattew¹, Mackay, Donald ¹, Brimacombe, Jennifer ¹, ¹

ABSTRACT- Continental-scale mass balance models seek to quantify the flux of chemicals over large spatial scales in the order of 100-1000s of kilometres. This type of model attempts to establish the link between emission sources and environmental concentrations in local and distant regions. Often distant regions suffer detrimental effects from pollutants emitted 1000s of km away. Our work addresses the movement of chemicals in Canada and in North America using linked regional models. Several challenges are faced when developing such mass balance models including: setting appropriate regional boundaries, parameterizing and collecting data for each region, including air and water flows as well as obtaining physico-chemical parameters, emission and monitoring data for the chemical(s) of interest. Air is a critical medium for long-range transport of a chemical. In these models we have calculated the long term overall mass balance for air using HYSPLIT trajectories, digital maps and an iterative air mass balance model. It has been shown that Geographical Information Systems (GIS) can be a valuable tool for both the parameterization steps and for interpreting model results. While developing the North American Continental Model (BETR) we have used GIS for four main purposes: 1) to assist with setting of regional boundaries, 2) to calculate the surface area and volume of various land/water types within regions, 3) to allocate geographical referenced direct emissions (eg. NPRI and TRI) and diffuse emissions data (eg. based on population), 4) to report results in one easy to understand spatially accurate graphical format. Overviews and examples are provided from work on our Canadian and North American continental-scale models. Possible future applications of GIS in continental-scale multimedia mass balance modelling are discussed.

Key words: long-range, transport, POPs, mass-balance