Plant wax compounds and soil microbial DNA profiles to ascertain urban land use type

Soil material found on questioned items (such as footwear, tools or vehicles) during a police enquiry can provide powerful forensic intelligence (and evidence) relating to geographical origin. We evaluated the potential of organic biomarkers (i.e. plant wax compounds n-alkanes and fatty alcohols) and microbial community DNA profiles (bacterial and fungal) in providing land-use-based intelligence within two geographically separated urban study areas. Our results demonstrate the limited potential of basic soil physico-chemical analysis, mineralogy (X-ray diffraction) and spectroscopic (colour and Fourier transform infrared) methods in providing land-use intelligence within these specific localized urban environments. Our results also demonstrate the complementary nature of biochemical/biological analysis to mineralogy, providing important information about the variability of analysis in localized urban environments. However the n-alkane compounds proved variable within land-use types. Bacterial DNA profiles were influenced by both land use and the urban/geographical origin. Fatty alcohol compounds and fungal DNA profiles provided characteristic analyses that discriminated grass-dominated, flowerbed, woodland and roadside soils, regardless of urban/geographic origin. Supported by appropriate knowledge of landscape variability (e.g. spatial, temporal), these methods demonstrate potential to provide rapid and cost-effective land-use-based intelligence to complement soil inorganic information over a greater definition of scale relevant to a contact point location at a locus.