Soil Evidence Determination And Application Study

Since the criminal activities becoming more and more intelligent and professional,fewer an fewer traces of traditional fingerprints, shoe prints, as well as regular physicalevidence are left at the scene, thus, trace evidence play an increasing role in the in thecases detected. The fingerprints can not be leaved, the footprint can be destroyed, the bloodstains can be wipe, however, the imperceptible, ubiquitous trace evidence can not bedestroded. As a kind of trace evidence, soil physical evidence, has many features, such asextensive, dispersed, hidden and so on. Therefore. Much attention should be payed on thevalue of soil evidence in the case, which can provide a reference and basis for the casedetection.There are many examination items in the soil physical evidence, such as somephysical and chemical examination of soil particle density, bulk density (soil density),porosity, soil particle size, soil moisture and so on. In this paper, on the basis of the testpprogect of soil physical evidence can provide good basises and clues for case detection,scientific collection and preparation of soil samples, soil pH, organic matter, and theimprovement of digestion parameters in soil pretreatment were shown, besides,13heavymetals in the soil of Gansu region were measured.There are four chapters in this dissertation.In the first chapter：the soil pH，organic matter detection method，research progressand basic principle were introduced：we maily focused on the sample pretreatment methodsbefore the determination of heavy metal elements in the soil, the test instruments, methods,basic principles and application for heavy metals in soils; different methods for the samplepretreatment methods before the determination of heavy metal were also reviewed.In the second chapter：the collection and preparation of the soil sample were shown.Because the test results of the heavy metal elements are directly related to the scientificof the soil collection and preparation, we mainly introduced the soil sample collection andpreparation; preparatory work before sampling, note in the sampling, and handler after sampling were shoem in detail.In the third chapter：Determination of acidity in the soil samples and organic mattercontent. We introduced the instruments, reagents and conditions in the experiment, andfocused on soil acidity and organic matter content in the Gansu region, which can beimportant for the detection clues and range in the case.In the fourth chapter： Optimization and determination of heavy metal elements in thesoil sample of Gansu region were presented. The optimal digestion ratio of digestionsolution in Sample pretreatment before determination of heavy metal elements wre foundin the experiment. The foundation can provide reference and help for soil pretreatment infuture. Analysis and determination the soil sample in Gansu Province with the optimizedsoil sample pretreatment conditions.It will be helpful in the soil evidence cases to make acomprehensive analysis and judgment for the results.