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Compaction can seriously degrade soil in modern agriculture. Soil that has been temporarily removed and stored is particularly sensitive to compaction when restored, although little is known about the structural changes in such soils under mechanical loads. We investigated the structural changes in a restored soil that had been gently cultivated for several years and then was trafficked by a heavy combine harvester, analysing the macro-pore structure by quantitative morphometry of three-dimensional microcomputed tomography images. Increased trafficking caused decreases in both the porosity and connectivity of the macro-pores. The fraction of spherical pores (and thus the convexity of the pore space) and the mean pore separation were increased. Trafficking had no clear effect on the orientation of pores. While the mean pore diameter tended to decrease, biopores were more stable than interaggregate pores originating from the packing of soil aggregates. This is relevant for the development of structural stability in restored soils, as the macro-pores consist mainly of interaggregate pores initially, whereas biopores develop and increase in proportion only gradually over time. Quantitative morphometry provides valuable morphological indices for the objective assessment of the macro-pore structure and changes induced by compaction. [ABSTRACT FROM AUTHOR]

Abstract: A collaborative study on Raman spectroscopy and microspectrophotometry (MSP) was carried out by members of the ENFSI (European Network of Forensic Science Institutes) European Fibres Group (EFG) on different dyed cotton fabrics. The detection limits of the two methods were tested on two cotton sets with a dye concentration ranging from 0.5 to 0.005% (w/w). This survey shows that it is possible to detect the presence of dye in fibres with concentrations below that detectable by the traditional methods of light microscopy and microspectrophotometry (MSP). The MSP detection limit for the dyes used in this study was found to be a concentration of 0.5% (w/w). At this concentration, the fibres appear colourless with light microscopy. Raman spectroscopy clearly shows a higher potential to detect concentrations of dyes as low as 0.05% for the yellow dye RY145 and 0.005% for the blue dye RB221. This detection limit was found to depend both on the chemical composition of the dye itself and on the analytical conditions, particularly the laser wavelength. Furthermore, analysis of binary mixtures of dyes showed that while the minor dye was detected at 1.5% (w/w) (30% of the total dye concentration) using microspectrophotometry, it was detected at a level as low as 0.05% (w/w) (10% of the total dye concentration) using Raman spectroscopy. This work also highlights the importance of a flexible Raman instrument equipped with several lasers at different wavelengths for the analysis of dyed fibres. The operator and the set up of the analytical conditions are also of prime importance in order to obtain high quality spectra. Changing the laser wavelength is important to detect different dyes in a mixture. [Copyright &y& Elsevier]