FTIR Photoacoustic and ATR Spectroscopies of Soils with Aggregate Size Fractionation by Dry Sieving.

Granulometric fractionation as a source of additional information on organic-matter and inorganic matrix components of soils using FTIR-photoacoustic spectroscopy (FTIR-PAS) supported by attenuated-total reflection FTIR spectroscopy (ATR-FTIR) for a wide range of aggregate fractions (10-5000 µm) was used to compare the sensitivity, reproducibility, information contents, and representativity of fractionated samples. For chernozem and sod-podzolic soils and different agricultural-use chernozem samples, differences in the composition were found, manifested in normalized spectra of microaggregate fractions, with the range of 10-100 µm bearing the complete information. Most changes are observed in the soil organic matter range (1900-1340 cm-1), although these changes are slight, and in the soil-matrix region (550-300 cm-1). The latter region increases the intensity of bands corresponding to amorphous silica and clay minerals in fine fractions, while the intensity of bands attributed to quartz lattice vibrations decreases. FTIR-PAS spectra do not differ considerably at high interferometer modulation frequencies as the signal-penetration depth is comparable with particle sizes. The soil fractions below 20 µm result in the maximum sensitivity, reproducibility, and signal-to-noise ratio, showing no changes from coarser fractions by the information content and, thus, providing representative samples for analysis. The fractionation shows more differences in the sod-podzolic and chernozem soil fractions than the whole soil spectra. FTIR-PAS provides better sensitivity and reproducibility in the 4000-2000 cm-1 region and ATR-FTIR in the 2000-100 cm-1 region.

La, Ce and Nd in the soil-plant system in a vegetation experiment with barley (Hordeum vulgare L.).

Rare earth elements (REEs) have received enormous attention in recent years. However, there are many gaps in the understanding of their behavior in the soil-plant system. The aim of this study is to investigate the behavior of three most common REEs (La, Ce, Nd) in the soil-plant system directly on soil samples using barley (Hordeum vulgare L.) in a vegetation experiment. We attribute the absence of significant changes in plant biomass and photosynthetic pigment content to the reduced availability of REEs in soil samples. The concentration of water-soluble forms of La, Ce and Nd didn't exceed 1 mg/kg, while the concentration of exchangeable forms varied and decreased in a row La > Ce > Nd. The transfer factor (TF) from soil to above-ground biomass was low for all three elements (<1). The stem-to-leaf TF increased with the increase in REEs concentration in soil. The concentration in plant material increased in the row Ce < Nd < La. REEs concentrations in barley leaves didn't exceed 1-3% of the corresponding element concentration in soil samples. REEs concentration in plant tissues is in close direct correlation with the REEs total concentration in soil, water-soluble and exchange forms. REEs concentration in barley leaves is 3-4 times higher than in the stems and for the group with extraneous concentration of 200 mg/kg for La, Ce and Nd was 6.20 ± 1.48, 2.10 ± 0.51, 6.90 ± 3.00 mg/kg, respectively. We show that there were no major changes in barley plants, but further study is needed of the relationship between the absorption of lanthanides by plants and the content of various forms of lanthanides in the soil.

FTIR photoacoustic spectroscopy for identification and assessment of soil components: Chernozems and their size fractions.

FTIR photoacoustic spectroscopy was used to approach inorganic matrix components and organic-matter constituents of chernozem size fractions (1-5000 µm, by dry sieving) with a different history of use (from intact steppe to permanent bare fallow, a continuous long-term field experiment). The conditions of FTIR photoacoustic measurements in continuous-scan modes were compared with attenuated total reflection measurements, the advantages of photoacoustic measurements resulting from a higher intensity of the incident radiation and signal-generating volume were discussed. Overtone peaks of quartz as a soil matrix component at 2000-1700 cm-1 were selected as a possible internal-standard (guide) bands for the comparison of photoacoustic spectra. For different land-use samples, differences in the composition were found, which are differently manifested in normalized spectra of size fractions, with millimeter-size, 20-100 µm, and silt fraction bearing the maximum information.

Photoacoustic and photothermal methods in spectroscopy and characterization of soils and soil organic matter.

Review sums up the application of photoacoustic and photothermal spectroscopies for the analysis and characterization of soils and soil organic matter and discusses the outlooks in this area.

Toxicity assay of lanthanum and cerium in solutions and soil.

Lanthanum (La) and cerium (Ce) are one of the most abundant rare earth elements (REEs). In spite of quite extensive studying of the effects of these lanthanides on biota, some contradictions remain in the results. Also little is known about the effect of lanthanum and cerium on plant cells and their mitotic cycle, especially in soils. In this study, the effects of La and Ce in solutions and soil samples on root growth, mitotic index (MI) and frequency of aberrant cells (FAC) were assayed using one of the most convenient objects for testing of cytotoxicity - onion Allium cepa L. Bulbs were germinated on media containing La and Ce in concentrations 0-200 mg/l and 0-50 mg/l respectively for solutions and 0-200 mg/kg for soil samples. After 5 days of germination in solutions, a significant decrease in root elongation and MI in apical meristem cells are shown. We have also observed an increase in the number of cells with aberrations at 50 mg/l La and Ce concentration. The number of observed stickiness and disturbed metaphase has increased significantly. Soil samples turned out to be less toxic compared to the solutions probably due to the decreased availability of REEs. In spite of this, significant cytotoxicity of soil samples containing the highest concentration of La and Ce (200 mg/kg) is observed. The latter may indicate the importance of considering the cytotoxicity of soils containing high lanthanides concentrations - in extraction and production areas and actively fertilized fields.

Binding polynomial in molecular self-assembly.

In the present work the concept of a binding polynomial is revisited for the most widely used case of self-assembly of identical molecular units and results in the re-construction of a link to the grand partition function of such a system. It is found that if the self-assembly process is not pronounced (i.e., the product of the equilibrium constant and the monomer concentration is close to zero), the binding polynomial has the meaning of a molecular partition function that is given by the summation over energy levels of any molecule in the system. In other cases the concept of a binding polynomial may be misleading.