【国外标准】 Standard Practice for Use of Color in the Visual Examination and Forensic Comparison of Soil Samples

4.1 Color is an easily observable characteristic of soils and is integral to the taxonomic classifications of soils (6-8); factors including parent material, hydrology, vegetation, and extent of soil weathering, can affect soil color, making color a valuable diagnostic tool for forensic examination purposes.4.2 Soil color is sufficiently variable among soils to be used for differentiation of many soils in forensic examinations (9, 10) (see Section 6 for the test method for color determination and comparison criteria) as determined by visual characterization in the Munsell color system.4.3 Instrumental techniques are suitable for color determination of soil evidence but are not covered within this practice.4.4 Color determinations of soil samples are also used within soil provenance assessments to provide investigative leads or aid in searches. Interpretation of soil color for soil provenance is case-specific and beyond the scope of this practice, but the methods of color determination (6.5.1 to 6.5.2) and documentation (6.7) described here should be applied to soil color within soil provenance cases.1.1 This practice covers visual color determination of soil/geologic material within the context of a forensic examination and is intended for use by laboratory personnel.1.1.1 This practice recommends use of soil color for: the initial screening of soil samples in forensic casework, prioritization of known soil exemplars for detailed analysis, and includes a test method for color determination in the Munsell color system and comparison among samples.1.2 Units—Units in the Munsell color system are used throughout this document.1.3 This practice is intended for use by competent forensic science practitioners with the requisite formal education, discipline-specific training (see Practice E2917), and demonstrated proficiency to perform forensic casework.1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.