Comparative study of top soil magnetic susceptibility variation based on some human activities

Abstract

An investigation of the effect of some human activities on the magnetic susceptibility and frequency dependent susceptibility was conducted on top soil samples from, a commercial area, a motor park and a school environment in Jalingo, Taraba State, N-E Nigeria. The purpose was to assess the variation of magnetic susceptibility with different land use, detect pollution hotspots using magnetic proxy parameters and evaluate the contribution of superparamagnetic (SP) grain size contribution to the magnetic susceptibility from calculation of the frequency dependence of magnetic susceptibility (MS). The results of the mass specific low frequency magnetic susceptibility measurements showed significant enhancement with values ranging from 67.8 - 495.3 x 10-8 m3kg-1 with a mean value of 191.61 x 10-8 m3kg-1 for the Jalingo College of Education (JCOE) data; 520.1 - 1612.8 x 10-8 m3kg-1 with a mean value of 901.34 x 10-8 m3kg-1 for the Jalingo main Market (JMM) and 188.5- 1203.6 x 10-8m3kg-1 with an average value of 574 92 x 10-6 m3kg-1 for the Jalingo Motor Park (JMP). The significant magnetic enhancement indicates high concentration of ferrimagnetic minerals in the soil and hence increased pollution. The magnetic susceptibility of the different land use studied decreased in the order commercial area (market) > motor park > school premises. The results of the percentage frequency dependence susceptibility showed that most of the samples had a mixture of SP and coarse multi domain grains or SP grains < 0.05μm. The value of χfd% range from 2.68 to 13.80% with an average value of 8.67% in the JCOE samples, 0.49 to 10.04% with an a-verage of 5.05% in the JMM samples and 0.56 to 13.04% with an average value of 5.86% in the JMP samples.