ALBERT

Description: 〈span class="paragraphSection"〉〈div class="boxTitle"〉Abstract〈/div〉In studies of the magnetic properties of soils, the frequency-dependent magnetic susceptibility percentage (〈span style="font-style:italic;"〉χ〈/span〉〈sub〉FD〈/sub〉%) is often used for the identification of ultrafine magnetically superparamagnetic/stable single-domain (SP/SSD) particles. This parameter is commonly used as an indicator for increased pedogenesis. In strongly magnetic soils, the SP/SSD magnetic signal (mostly bio-pedogenic) may be masked by lithological signals; making pedogenesis hard to detect. In this study, we compare results for the detection of ultrafine SP/SSD magnetic particles in andic soils using two instruments: a Bartington MS2B dual-frequency meter and an AGICO Kappabridge MFK1-FA. In particular, the study focuses on the effect of pedogenesis by investigating the relationship between specific soil magnetic and chemical properties (soil organic carbon and pH〈sub〉H2O〈/sub〉). The values of 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉FD〈/sub〉% obtained with the MS2B varied from 2.4 to 5.9 per cent, and mass-specific magnetic susceptibility (〈span style="font-style:italic;"〉χ〈/span〉〈sub〉LF〈/sub〉) from 283 to 1688 × 10〈sup〉−8〈/sup〉 m〈sup〉3〈/sup〉 kg〈sup〉−1〈/sup〉, while values of 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉FD〈/sub〉% and 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉LF〈/sub〉 obtained with the MFK1-FA varied from 2.7 to 8.2 per cent and from 299 to 1859 × 10〈sup〉−8〈/sup〉 m〈sup〉3〈/sup〉 kg〈sup〉−1〈/sup〉, respectively. Our results suggest that the detection of the SP/SSD magnetic fraction can be accomplished by comparing relative trends of 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉FD〈/sub〉% along the soil profile. Moreover, the discrimination between bio-pedogenic and lithogenic magnetic contributions in the SP/SSD fraction is possible by comparing the 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉FD〈/sub〉% and 〈span style="font-style:italic;"〉χ〈/span〉〈sub〉LF〈/sub〉 data determined in the fine earth (〈2 mm) and the coarse fraction (4–10 mm) samples down the soil profile.〈/span〉