Study on Soil Sampling Methods from Different Attachments and Source Indication in Forensic Evidence
Soil plays an important role in traceability and comparison in forensic evidence due to its characteristics of extensiveness and easy adhesion.To clarify the role of sampling methods for different attachments on soil characteristics and source indication of soil,a simulation experiment was conducted for long route chosen in urban-suburbs.The original soils were collected in different road sections and under different environmental conditions.At the same time,soils attached fiber(gloves),metal(spades)and rubber(shoe soles)were simulated at each sampling point.Two methods of dry brushing and water washing/drip washing were used for sampling attached soils on different attachments.The X-ray fluorescence spectrometer(XRF)was used to analyze the element concentrations in soil samples.The results showed that the sampling methods had no significant effect on the elemental contents of soil samples attached to fiber and rubber.However,dry brushing method was more convenient and faster for operation than water washing.The drip washing was better than dry brushing for metal-attached soils.Based on soil element contents and principal component analysis,soils attached to fiber and metal had a better matching result with its source.After a longer route,soils attached to the sole reflected the combined information of the route passed,and sole samples were more similar to the last soil source passed more often.The principal component analysis combined with the Euclidean distance played a role in the indication of soil attached shoes and their sources.Therefore,the attachments of fiber,metal and rubber can provide a basis for inferring the sources of unknown soils and are helpful for soil source indication.However,proper selection and execution should be based on a variety of analytical methods combined with environmental information for comprehensive judgment.This simulation experiment can provide a basis for comparison and source indication of soil samples obtained from different attachments with proper sampling methods.
万方数据
维普
