Problems and potential of mineral magnetic measurements as a soil particle size proxy

Abstract

The use of mineral magnetic concentration parameters (cLF, cARM and SIRM) as a potential particle size proxy for soil samples collected from the Isle of Man (British Isles) is explored as an alternative means of normalizing particle size effects. Comparison of soil-related analytical data by correlation analyses between each magnetic parameter and individual particle size classes (i.e. sand, silt and clay), more discrete intervals within classes (e.g. fine sand or medium silt) and cumulative size fractions (e.g. clay + fine silt) are reported. Both cLF and cARM parameters reveal significant (p <0.05; n = 46), but relatively weak (rs = 0.297 and 0.369), associations with clay content, while cLF, cARM and SIRM parameters have no significant relationship with sand and silt content or any discrete or cumulative size fractions. Contrary to earlier research findings, this indicates that magnetic measurements are not always a suitable particle size proxy and it is only certain environments and/or specific settings that are appropriate for granulometric normalization by this technique. However, if future researchers working in other soil settings can identify a formal predictable relationship, the technique is known to offer a simple, reliable, rapid, sensitive, inexpensive and non-destructive approach that could be a valuable particle size proxy for normalizing particle size effects in soil contamination studies.