GIS in Environmental Contamination
GIS in environmental contamination is the use of GIS software in mapping out the contaminants in soil and water using the spatial interpolation tools from GIS. Soil and water contamination by metals and other contaminants have become a major environmental problem after the industrialization across many parts of the world. As a result, environmental agencies are placed in charge in remediating, monitoring, and mitigating the soil contamination sites. GIS is used to monitor the sites for metal contaminants in the soil, and based on the GIS analysis, highest risk sites are identified in which majority of the remediation and monitoring takes place. GIS is used in making spatial interpolations of contaminants in the soil and water. Spatial interpolation allows for more efficient approach to remediation and monitoring of soil and water contaminants.
Soil contamination from heavy elements can be found in the urban environments, which can be attributed to the transportation and industries along with the background levels (minerals-leaching heavy elements from weathering). Also, some of the most soil contaminated areas are around the mines such as the ones in Slovenia, Bosnia and Herzegovina, and in United States (Sulphur Bank Superfund Site, in California). In a study area, GIS is used for the analysis of spatial relationship of the contaminants within the soil.
In Idrija, Slovenia, where the world’s second largest mercury (Hg) mine operated has a significant amount of Hg emissions into the atmosphere by a surface process of adsorption of Hg from and to soil particles surfaces, which results in a diffusion of Hg through the pores of soil. To calculate the emission flux for Hg, a Hg emission model was developed:
in which the FHg is the flux of Hg emission, Ea is the activation energy, R is the gas constant, Ts is the soil temperature, n and m are constants, [Hg]s is the Hg concentration, and 0.003* Rz accounts for the solar radiation since the solar radiation has the effect on the temperature, hence the solar radiation has the effect on the emission flux of Hg. Once the Hg concentration data was gathered, a schematic model has been prepared for GIS input, which consisted of a digital elevation model (DEM), a satellite land use map, and EARS data. Using the inverse distance weighted (IDW) method from geostatistical tools in ArcGIS 9.3, a raster model of the Hg concentration has been produced for the Idrija area.
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