Using GIS to understand the environmental chemistry of manganese contaminated soils, Kgwakgwe area, Botswana

摘要

This study aimed at establishing the spatial distribution of manganese (Mn) and iron (Fe) within the periphery of a manganese oxide (Mn oxide) ore abandoned mine. Four hundred soil samples were obtained from a 4 km~2 area close to the Kgwakgwe Mn oxide ore abandoned mine, Kanye, South eastern Botswana. The determination of Fe and Mn concentrations after acid digestion of samples was performed on a Varian Spectra AA-220 FS atomic absorption spectrometer (Varian, Australia) equipped with a deuterium background correction. Laboratory results were processed using Geographical Information Systems (GIS), and Remote Sensing (RS) techniques with the integrated Land and Water Information System (1LWIS), Geosoft Oasis Montaj and ArcGIS software packages. Microsoft Excel was used for statistical and graphical presentation of data analyses. The range of concentration levels of Fe in soils was from 1116 μg g~(-1) to 870766 μg g~(-1) with a mean of 17593 μg g~(-1) and for Mn in soils was 35 μg g~(-1) to 24907 μg g~(-1) with a mean of 1088 μg g~(-1). The gridded soil maps for Fe and Mn show anomalies in different parts of the study area. Where Mn is high, the Fe is low and vice versa. Manganese was high at the mine workings and in the northwestern part of the study area. Iron on the other hand is very low in the mine working area and is high on the northern part of the study area. Suggestions are advanced for the Mn interplay in the soils and environment around the Kgwakgwe abandoned Mn oxides ore mine.