Tropical Soils and Landmine Detection--An Approach for a Classification System

摘要

Electromagnetic induction is the most common technique used in landmine detection. In soils exhibiting high magnetic susceptibility, metal detectors based on this method may become useless for landmine detection. Currently, no soil classification system exists that allows a prediction of negative effects on metal detectors. A total of 511 tropical soil samples from 15 different countries were investigated with regard to their susceptibility and some basic chemical parameters. Samples were separated into six classes based on their chemistry and their parent material. Soils derived from ultrabasic to basic parent material, on average, exhibited the highest susceptibilities because both rock types often contain a large amount of weathering-resistant magnetite. Independent of the origin, the variance of the susceptibilities is large. Even in soils derived from rocks initially low in magnetite, high susceptibilities may develop with pedogenesis. This may be due to either the enrichment of residual magnetite or the formation of maghemite. In addition to a soil's parent material, its degree of weathering should also be considered in a proper classification scheme. We used a coefficient based on soil chemistry that correlates with the degree of weathering. Based on this coefficient and the soil parent material, we determined the median and the 90th percentile of the corresponding distribution of soil susceptibilities for each combination of the classification factors. The resulting classification scheme has the form of a matrix and may serve as a first approximation of expected susceptibilities when only parent material and degree of weathering are known.