Geospatial Analysis of Zinc Contamination in Lake Ontario Sediments

Abstract

This study analyzed zinc contamination concentrations in Lake Ontario sediments. While trace amounts of zinc are important for overall biotic health, large quantities can lead to toxic ecosystem contamination. The data that were utilized in this research were collected as part of the Environment Canada Gr eat Lakes Sediment Assessment Program. Geospatial analysis has become increasingly important when examining spatial trends. A GIS-based kriging technique was utilized to interpolate contamination estimates between sampling locations. The Canadian federal government specifies the Threshold Effect Level (TEL) and Probable Effect Level (PEL) for sediment contamination. The TEL refers to the concentration below which adverse biological effects are expected to occur rarely, while the PEL defines the level above which adverse biological effects are expected to occur frequently. The historical and contemporary results indicate that areas of the lake have zinc concentrations that are above the PEL and represent a degree of enrichment of roughly twice the historical background levels. These are mostly associated with the major depositional basins in Lake Ontario with the southern parts of lake having higher concentrations than those in the north. This is related to the eastward flowing current along the southern shore which act s to transport contaminants from Canadian and American industrial estates towards the depositional basins, and bathymetry as the three primary deep-water depositional basins extend much closer to the southern shoreline, compared to the northern shoreline. The kriging analysis has provided an additional communication tool and means of influencing management options and decisions.

Keywords: GIS, lake Ontario, log-normalization, ordinary kriging, sediment contamination, zinc