Huffman, T., Ogston, R., Fisette, T., Daneshfar, B., Gasser, P-Y., White, L., Maloley, M. and Chenier, R. 2006. Canadian agricultural land-use and land management data for Kyoto reporting. Can. J. Soil Sci. 86: 431-439. The land use and management data requirements for assessing, monitoring and reporting on the impact of agricultural production practices on the environment, especially in a country as large as Canada, are considerable. In view of the fact that environmental assessments are a relatively new phenomenon, data collection activities targeted toward these needs are not widespread. As a result, we find it necessary to acquire and integrate a variety of data sources with differing time lines, spatial scales and sampling frameworks. This paper uses our current activities with respect to Kyoto reporting as a focus to present and discuss the types of data required and the spatial analysis and integration procedures being developed to provide them. The essential data for this activity include the area of crop and land use types, land use changes since 1990, farm and land management practices and biomass production. The spatial framework selected for national analysis is the Soil Landscapes of Canada, and the primary existing data sources are the Census of Agriculture, sample-derived yield estimates and satellite-based land cover products. These are supplemented with detailed, multi-season, multi-year satellite image interpretations conducted at an ecologically and statistically stratified sample of sites across the country. The use of these data in preparing an account of greenhouse gas sources and sinks identified a number of gaps and problems, and a brief outline of future work designed to improve the data inputs is presented.

This article summarizes discussions at the SETAC Pellston Workshop on "Science-Based Guidance and Framework for the Evaluation and Identification of PBTs and POPs" and provides an overview of other articles from that workshop that are also published in this issue. Identification of persistent, bioaccumulative, and toxic substances (PBTs) and persistent organic pollutants (POPs) and evaluation of their impact are more complicated than those for other chemicals and remain a challenge. The main reason for this is that PBT substance and POP assessment is associated with higher uncertainty and generally requires more data. However, for some data-rich PBTs and POPs, that identification and assessment of impact are feasible has been clearly demonstrated. New scientific developments and techniques are able to significantly increase the certainty of the various elements of PBT and POP assessment, and the current scientific literature provides many successful and illustrative examples that can be used as methodologies to build on. Applying multiple approaches for assessment is advisable, because it will reduce uncertainty and may increase confidence and improve the quality of decision-making.

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Transformer overloading capabilityPower transformers have inherently some margin of overloading capability. The rated power of a unit is basically the load level that will result in internal temperatures that are below the limits set forth by standard producing bodies such as IEEE and IEC. The normal life expectancy is a conventional reference basis for continuous duty under normal ambient temperature and rated operating conditions.The application of load in excess of nameplate rating involves a degree of risk and accelerated aging. These effects are discussed at length in the IEEE and IEC loading guides(l-2) and can be summarized as follows: For short term transformer failure, the main risk is the reduction of dielectric strength due to the release of gas bubbles in regions of high electrical stress. The probability of occurrence of these bubbles is closely related to winding insulation hot spot temperature and moisture content of insulating paper. Under overloading conditions, some components such as LTC contacts and bushing connections may develop high temperate leading to thermal runaway. High temperature may also occur in structures when the stray magnetic field increases beyond the saturation point of magnetic shields. For long duration overload, the main consequence is the thermal aging of solid insulation. With time, the cellulose chains undergo a depolymerization process thus reducing the average length of cellulose chains and consequently reducing the mechanical strength of paper. This deterioration of paper is a function of time, temperature, moisture content and oxygen content. This effect is irreversible and forms the basis for transformer life duration.