Contributions to the study of organic-mineral complexes from hortic anthrosols

In this paper are presented the preliminary results of studies concerning the composition, structure and stability of organic-mineral complexes from hortic anthrosols. The separation of organic-mineral complexes has been performing by isodynamic magnetic method and by extraction in aqueous Na2SO4 –polyethylene glycol two-phase systems. The composition and structure of organic-mineral complexes have been studied by Raman, FT-IR and UV-VIS spectroscopy, optic microscopy, thermal and chemical analysis. In studied horthic antrosol, the content of organic-mineral complexes varied between 20.42-48.36 % [w/w], being evidenced a relative accumulation tendency in Ahok (48.36 %) horizon and in grain size fractions < 0.002 mm (63.62-86.30 %, from total determined organic-mineral complexes), respectively. The maximum weight (29.45-64.56 %) has been observed at grain size fractions < 0.001 mm. The high apparition frequencies and stability have organic-mineral complexes which include in their structures predominantly, the amorphous forms of clay minerals and of iron oxi-hydroxides. In function of clay mineral type from organic-mineral complexes composition, have been observed that the apparition frequency and stability follow the order: smectite > illite >> kaolinite (have been evidenced a special stabilization effect in case of Ca and Mg forms of clay minerals). In function of iron oxi-hydroxides type from organic-mineral complexes composition, has been observed that the apparition frequency and the stability follow the order: Fe(OH)3 (amorphous) > Fe(OH)3 (ferihidrite, amorphous) > -FeO(OH).nH2O (lepidocrocite) > -FeO(OH).nH2O (göethite) > -Fe2O3 (hematite). The separated and studied organic-mineral complexes have very complex compositions and structures (generally have 4- 5 structure levels), include over 65 % from mineral and organic components of anthrosol and are behaves as supra-molecular assembles very stable and with a high chemical-structural flexibility degree. In function of chemicalmineralogical composition and of their structure, the organic-mineral complexes from studied anthrosol have been classified in four main classes

Contributions to the study of mineralogy and geochemistry of hortic anthrosols from Bacău glasshouses

In this paper are presented the preliminary results of studies regarding the mineralogy and geochemistry of hortic anthrosol (profile BC. 1) from Bacău glasshouse (Romania). Have been special followed the aspects concerning to the distribution of occurrence forms of minerals and organic components, and genetic correlations between these in hortic antrosols conditions, respectively. According with the pedogeochemical characteristics, the studied soil is proxy-calcaric hortic anthrosol evolutes on fluviatil deposits with the following composition: Apk – Atpk – Ahok – Bvk1 – Bvk2 – Ck. The pedogeochemical characteristics of Ahok horizon are sensible different in comparison with the others horizons of studied profile, but rather similar with the pedogeochemical characteristics of horizons described in literature as frangipane horizons. Ours data not exclude the possibility that the Ahok horizon from studied profile to be admitted in frangipane horizons category, but it development way in profile, the chemical-mineralogical characteristics and formation conditions are not in agreement with the opinion of other researchers. Characteristics for the studied anthrosol are intense modifications of soil profile, relative large variability of mineralogy and chemism, and salinization processes of superior horizons. From chemical point of view, the hortic anthrosol is characterized by high values of bases saturation, accessible phosphorus and ration between humic and fulvic acids. From mineralogical point of view, the studied hortic anthrosol is characterized by a high heterogeneity degree, both as contents, and as occurrence and distribution forms of mineral and organic components in profile. Predominant quantitatively are clay minerals (39.86-48.75 %, average: 44.40 %), and as variety, the crystalline forms are most abundant (36.17-45.63 %, average: 40.49 %). As regard the clay minerals type, the kaolinite (14.97-25.19 %, average: 21.84 %) and illite Universitatea de Ştiinţe Agricole şi Medicină Veterinară Iaşi 136 9.58-17.57 %, average: 13.28 %) have dominant weights in comparison with smectite (4.55-8.49 %, average: 6.33 %) and the other mineral components

On spatial evolution of the solution of a non-standard problem in the bending theory of elastic plates

doi:10.1093/imamat/hxt04