A b s t r a c t. The comparison of particle size distributions measured by sedimentation methods and laser diffraction shows the underestimation of the fine (clay) fraction. This is attributed mainly to the shape of clay particles being different than spherical. The objective of this study was to demonstrate differences in the results of particle size distributions of soils determined with the method of laser diffraction using two different dispersion units of the Malvern Mastersizer 2000.K e y w o r d s: particle size distributions, sedimentation, laser diffraction, Mastersizer 2000 INTRODUCTIONParticle size distribution (PSD) of soils is one of the fundamental parameters permamently used in soil science (Brzeziñska et al., 2011; Joó et al., 2010; Nosalewicz and Nosalewicz, 2011; S³awiñski et al., 2011; Tóth et al., 2009). More and more often the determinations of that parameter is made with the use of the method of laser diffraction (Blott and Pye, 2006; Pye and Blott, 2004; Sperazza et al., 2004). The method consists in measuring the intensity of laser light scattered on the particles measured. The intensity of scattered light depends on the size of the particles in the measurement system. The smaller the particle, the greater the angle at which the light is scattered/refracted.The method of laser diffraction has been compared many times with the earlier methods of PSD determinationthe sedimentation methods (Arriaga et al., 2006; Beuselinck et al., 1998; Ry¿ak and Bieganowski, 2010; Tauber et al., 2008). In certain of such reports one can encounter information about underestimation of the fine (clay) fraction content in measurements performed with the method of laser diffraction as compared to the sedimentation methods (Beuselinck et al., 1998; Eshel et al., 2004; Konert and Vanderberghe, 1997). The underestimation of the clay fraction content is attributed mainly to the shape of clay particles being different than spherical (Konert and Vendenberghe, 1997). Those authors pointed out that the divergent results might be also related to problems with the selection of optical parameters for the clay fraction (Eshel et al., 2004) or with the limited measurement range, especially of the older types of apparatus (Beuselinck et al., 1998).Apart from the above potential causes of the underestimated clay content in soils studied careful analysis of the literature on the determination of PSD with the method of laser diffraction leads also to further conclusions. One of the more important reasons for the lack of comparability of results lies in the use of laser diffractometers of various manufacturers or various models (generations) of equipment of this type from a single manufacturer. Another problem is the frequent lack of information -in research publications -on the type/model of apparatus used and/or on its equipment.The objective of this study was to demonstrate differences in the results of PSD of soils determined with the method of laser diffraction using two different dispersion units of the Malvern Masters...

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Background Humic substances (HS) are compounds with a complicated structure, present in the humus soil layer, water, lake sediments, peat, brown coal and shales. Due to their similar physicochemical properties to DNA, they may have an adverse effect on the subsequent use of the isolated material. The main aim of this research was to examine the effect of HS on DNA isolation depending on the soil type and land use, taking into account the spectroscopic full characteristics of HS fractions. Methods The research was conducted on eight types of soil sample. Soils represented the most important Soil Reference Groups for temperate climates: Fluvisols, Regosols, Cambisols, Arenosols, Histosols and Luvisols. Soil samples were also collected from areas diversified in terms of use: arable land, grassland and forest. The extraction of HS fractions was performed using the procedure recommended by the International HS Society. The fractional composition of HS was characterized by UV–Vis and fluorescence methods. Soil DNA is extracted by direct cell lysis in the using a CTAB-based method with a commonly-used commercial soil DNA isolation kit. The basis for assessing the quantity and quality of extracted DNA was the Polymerase chain reaction (PCR) reaction since the analysis of soil DNA often relies on the use of PCR to study soil microorganisms. Results Based on the results, it can be concluded that in the presence of a high concentration of HS, the isolated DNA was low quality and the additional purification procedure was necessary. Despite the differentiation of the internal structure of HS fractions, the decisive factor in the efficiency of DNA isolation from soil samples was the total carbon content in HS. Reduced DNA yields can significantly constrain PCR detection limits to levels inadequate for metagenomic analysis, especially from humus-rich soils.

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this paper presents preliminary results of the use of visible and near-infrared (Vis-nir) spectroscopy for soil classification and soil profile examination. three experiments involving (1) three different soil types (albic luvisol, Gleyic Phaeozem, brunic arenosol), (2) three artificial micro-plots with similar texture (loamy sand, Gleyic Phaeozem) but different soil organic carbon (soc) content and (3) a soil profile (Fluvisol) have been investigated using Vis-nir spectroscopy. results indicated that Vis-nir is a promising technique for preliminary soil description and can classify soils according to soil properties (especially soc) and horizons. instead of complex chemical and physical analyses involved in routine soil profile classification, Vis-nir spectroscopy is suggested as a useful, rapid, and inexpensive tool for soil profile investigation.

Activity concentrations, inventories and activity ratios of 137Cs, 238Pu, 239 + 240Pu and 241Am in soil profiles were surveyed in the dry tundra and the adjoining proglacial zones of glaciers at a High Arctic site on Svalbard. Vertical profiles of radionuclide activities were determined in up to 14-cm-thick soil sequences. Additionally, soil properties (pH, organic matter, texture, mineral composition and sorption capacity) were analyzed. Results obtained in this study revealed a large range of activity concentrations and inventories of the fallout radionuclides from the undetectable to the uncommonly high levels (inventories of 30,900 ± 940, 47 ± 6, 886 ± 80 and 296 ± 19 Bq/m2 for 137Cs, 238Pu, 239 + 240Pu and 241Am, respectively) found in two profiles from the proglacial zone. Concentration of these initially airborne radionuclides in the proglacial zone soils is related to their accumulation in cryoconites that have a large ability to concentrate trace metals. The cryoconites develop on the surface of glaciers, and the material they accumulate is deposited on land surface after the glaciers retreat. The radionuclide inventories in the tundra soils, which effectively retain radionuclides due to high organic matter contents, were comparable to the global fallout deposition for this region of the world. The 238Pu/239 + 240Pu activity ratios for tundra soils suggested global fallout as the dominant source of Pu. The 238Pu/239 + 240Pu and 239 + 240Pu/137Cs activity ratios in the proglacial soils pointed to possible contributions of these radionuclides from other, unidentified sources.Electronic supplementary materialThe online version of this article (doi:10.1007/s11356-014-3163-6) contains supplementary material, which is available to authorized users.