Geostatistical analysis and integration of soil chemistry data with remote sensing information in the Sudbury area, Ontario.

Abstract

The presence of anomalous concentrations of metals within the soil profile can strongly affect its biological availability to plants, causing potential toxicity when exceeding threshold concentrations, and favoring numerous chemical exchanges. These interactions further facilitate metal dispersion in the hydrogeological and ecological systems, in response to weathering and erosion. Studies of the geospatial distribution of trace metal contaminants in Sudbury soils is thus important to unravel the dominant processes controlling dispersion patterns, contributing to sustainability of mining practice. A kriging geostatistical approach was applied to geochemical data obtained from the Sudbury Soil Survey to map multiscale geographic, enrichment trends in metal concentrations. Ordinary kriging prediction maps were developed to re-evaluate the multiscale spatial distribution of the chemicals of concern. Results show an anomalous distribution of metals centered on historical smelters, forming dominant northeast and southwest enrichment trends. The existence of these trends was validated by implementing a geostatistical Gaussian conditional simulation method, which reproduced the same spatial variability observed in the ordinary kriging maps and efficiently replicated the observed trends. The correlation analysis of the trends with remote sensing data, suggests that prevailing wind directions are likely one of the dominant driving forces controlling the trends. Integrating these results with satellite data showed improved vegetation regrowth patterns consistent with the geochemical northeast-southwest trend providing further, independent validation of the kriging results. Re-evaluation of the regional, geospatial distribution of the measured trace element concentrations will assist the monitoring and improved understanding of soil contamination trends and their impact on vegetation and other aspects of the biosphere in the Greater Sudbury area.