A Study On The Applications Of Geospatial Engineering Techniques In Mineral Mapping And Geotoxicological Risk Assessment Of Mining Land Contamination In Ulu Johan, Kinta Valley Tinfield
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Date
2008
Authors
ABU-LIBDA, OSAMA AHMAD MUSTAFA
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Abstract
Natural mineralization and intermittent mining operations in Ulu Johan, Kinta Valley
tinfield have resulted in generating enormous quantities of contaminants of potential
hazard in the environment, thereby contaminating the land asset and imposing significant
risk to human health and ecosystem. A geoenvironmental characterization and
assessment of soil contamination planned in Environmental Site Assessment Phase I and
Phase II, had been carried out in this study by the integration of state-of-the-art techniques
of mining geoscience and geospatial engineering. The preliminary risk assessment phase
revealed deterioration of land quality due to natural and anthropogenic disturbances of
regolith materials. In the quantitative risk assessment phase, a geochemical exploration
procedure was undertaken to collect, prepare and analyze a total of 25 GPSgeoreferenced
soil samples extracted at average depth <40 cm by random sampling. The
10-mesh-sized samples were analyzed by ICP-OES for elements As, Zn, Mn, Pb, TI, Sb
and Zr then mapped-out using geostatistical spatial interpolation modeling by kriging and
geovisulaized thematically in GIS. Geochemical mapping showed generally a spatial
distribution pattern extending NNE-SSW, parallel to the zone of mineralization and mining
activities. The anomalous environmental concentration levels above the global background
values implied to the extent and severity of pollution levels on the contaminated land. GIS
hazard mapping using geostatistical spatial interpolation modeling by kriging of
geotoxicological indices of target contaminants of potential hazard revealed that As, Zn,
Mn and Pb impose high potential to hazard exposure probabilities exceeding 80% to occur
in ecological receptors located atinear hot spot sites, and that As and Pb impose high
potential to hazard exposure probabilities exceeding 65% and 80%, respectively, to occur
in human receptors located at/near hot spot sites. Geomedical inference of geotoxicity was
supported by geobotanical remote sensing image processing of Landsat TM 5 and
IKONOS multispectral data and a ground truth study, as a spatial qualitative approach
supporting the GIS-quantitative ecological risk assessment. Geomedical inference of
geotoxicity was also supported by environmental epidemiology study of human disease
etiology as a spatial qualitative approach supporting the GIS-quantitative human health
risk assessment. False-color composite infrared geobotanical data enabled distinguishing
between stressed and healthy vegetation, and therefore identifying contaminated and noncontaminated
lands. Modeling vegetation index of TNDVI revealed information on stressed
vegetation was associated with contaminated land areas by increasing grades of pixel
darkness. Tasseled Cap modeling showed the stressed vegetation cover associated with
contaminated land areas characterized by high Soil Brightness Index and low Greenness
Index. Epidemiological disorders were detected in inhabiting centers spatially proximal to
contaminated areas; suggesting thereby a concealed linkage between local geology
conditions and human health incidents. The geospatial results of geochemical mapping
and geotoxicological risk analysiS suggested the decision to the need for applying urgency
methodology at defined contaminated sites as priority to manage the contamination risk to
an acceptable level before re-developing Ulu Johan's land asset. Geovisualizing these
results cartographically in thematic maps will enable communicating risk to different
concerned parties. The study suggested further the need to go on for conducting the
Environmental Site Assessment Phase III in future
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Keywords
A Study On The Applications Of Geospatial Engineering Techniques In Mineral Mapping , And Geotoxicological Risk Assessment Of Mining Land Contamination In Ulu Johan, Kinta Valley Tinfield