No abstract

No abstract

There is a need to develop a wider empirical research base to expand the scope for utilising the organic fraction of soil in forensic geoscience, and to demonstrate the capability of the analytical techniques used in forensic geoscience to discriminate samples at close proximity locations. The determination of wax markers from soil samples by GC analysis has been used extensively in court and is known to be effective in discriminating samples from different land use types. A new HPLC method for the analysis of the organic fraction of forensic sediment samples has also been shown recently to add value in conjunction with existing inorganic techniques for the discrimination of samples derived from close proximity locations. This study compares the ability of these two organic techniques to discriminate samples derived from close proximity locations and finds the GC technique to provide good discrimination at this scale, providing quantification of known compounds, whilst the HPLC technique offered a shorter and simpler sample preparation method and provided very good discrimination between groups of samples of different provenance in most cases. The use of both data sets together gave further improved accuracy rates in some cases, suggesting that a combined organic approach can provide added benefits in certain case scenarios and crime reconstruction contexts.

Bentgrass (Agrostis capillaris) and clover (Trifolium repens) were grown as pure swards and mixtures in pots containing soil from the NERC Soil Biodiversity field site located in Scotland. Six weeks after plant establishment leatherjacket larvae (Tipula paludosa) were added at field density to half the pots and the impacts of their feeding on plant shoot and root biomass and soil microbial communities was determined after 10 days. Plate counts and community level physiological profiles (CLPP) were used to characterise the microbial communities. Larval herbivory had a significant negative effect on shoot growth of both grass and clover and root biomass of grass. In mixed swards, larvae preferentially fed on clover. Soil microbial community structure was altered in the presence of larvae with populations of pseudomonads being significantly increased. These community differences may be attributed to increased quantity and qualitative changes in carbon flux to the soil as a result of root herbivory, as indicated by differences in the CLPPs of microbial communities in the presence and absence of larvae. This was mainly due to increased utilisation of some sugars, carboxylic and amino acids in the presence of larvae.

No abstract