Effects of the soil on the activity of pentachlorophenol

There is little doubt that pesticides have contributed in no small measure to modern agriculture. However, it is apparent that many pesticides pollute agricultural products, soils, and water, affecting ecosystems. Pesticides should be examined not only from the standpoint of expanding agricultural production but also the aspect of environmental pollution should be considered. The major fractions of the pesticides applied to crops are known to enter the soil eventually, where they follow various fates, such as; absorption by organisms including crop plants, adsorption by soil colloids, chemical and biological degradation and decomposition, leaching from soils with gravitational water, all according to the properties of the pesticide, the nature of the soil and climate.     

Adsorption of silica in river waters by soils in central Chile

The adsorption of the silica in water by soils was investigated using principal river waters and soils collected in central Chile from about 34° to 41° south latitude. The adsorption of silica in water (y) was linearly proportional to the silica concentration in river waters (x) as shown by the following equation:

y=bx-a

where a and b were constants being subject to the nature of the soils. The silica contentration in river waters appeared to relate closely to the rocks in the catchment area. and was high in rivers from volcanic ash areas. However, the salt concentration had no correlation with the silica concentration, and tended to lower to the southward with an increase in annual precipitation and a decrease in annual mean temperature. Sulphate appreciably lowered the adsorption of silica by soils, although chloride and nitrate had little effect on the adsorption. The a-value, dissolution of silica in pure water, was the largest in paddy and alluvial soils, and both the a- and b-values were less in surface soils .in comparison with those of lower horizons. Soils caused neither adsorption nor dissolution of silica at a certain silica concentration. This silica zero adsorption concentration differed greatly from soil to soil, and the largest value which was observed in the surface soil of an irrigated paddy soil was so large that it could not adsorb silica from any river water in the central Chile. In contrast to this soil, an imogolitic subsoil of an Ando soil exhibited the highest adsorption concentration, i.e. it was possible to adsorb silica from every river water in the central Chile. Humus seemed to protect soil silica from dissolution and at the same time to prevent adsorption of silica by soils. Allophanic colloids were labile in water without humic-material, readily releasing silica into the water.     

Mechanisms of pentachlorophenol adsorption by soils

The precipitation and adsorption of pentachlorophenol (PCP) on allophane was confirmed by adsorption experiments carried out at various pll values. The precipitation of PCP took place around base-unsaturated clay particles when the concentration of PCP exceeded solubility. The adsorption of PCP involves anion exchange reaction as well as physical adsorption due to van der Waals' force, and the PCP adsorbed as anions is released with greater when washed with deionized water.

Allopbane of Andosols appears to adsorb PCP largely as anions, while humus, balloysite, and allophane (molar SiO₂/Al₂O₃ ratio about 2) seem to adsorb PCP mostly as molecules. The precipitation of PCP in mlcell might participate in the adsorption. PCP mixed with layer silicate day minerals such as illite, montmorillonite, and kaolinite sublimated by about 200°C. In contrast to this, PCP mixed or adsorbed on allophane did not sublimate by 200°C but burnt out between 250 and 500°C showing a strong exothermic reaction.     

Antioxidant activity of polyphenols in carob pods.

We extracted polyphenols from carob (Ceratonia siliqua L.) pods, and evaluated the in vitro antioxidant activity of the crude polyphenol fraction (CPP). The total polyphenol content in CPP determined by the Folin-Ciocalteu method was 19.2%. The condensed tannin content determined by the vanillin and proanthocyanidin assay systems was 4.37% and 1.36%, respectively. beta-Carotene bleaching, 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, inhibition of lipid peroxidation by the erythrocyte ghost, and microsomal assay systems were used to evaluate the antioxidant activity. CPP showed a stronger inhibitory effect against the discoloration of beta-carotene than other polyphenol compounds such as catechins and procyanidins. CPP had weaker antioxidant activity in the DPPH free radical scavenging, the erythrocyte ghost, and microsomal systems than authentic polyphenol compounds at the same concentrations. The activity adjusted by the polyphenol concentration was, however, comparable to that of authentic polyphenol compounds. Considering most carob pods are discarded and not effectively utilized at present, these results suggested that carob pods could be utilized as a functional food or food ingredient.     

切花月季芽变品种的分子标记与鉴别研究

现代月季的基因型高度杂合，目的基因的定位如同大海捞针，形态指标模棱两可的描述比比皆是。为此，特别收集了组别17个，品种45个及相对的芽变品种进行随机增护多态DNA（Random Amplified Polymorphic DNA,RAPD）基因分析。结果表明：11个经筛选的人工全盛随机引物（10－base）共增扩出基因位点143个，其中多态性位点93个，平均多型性比率高达66.0％；切花月季品种与品种之间，特异性RAPD图带清晰稳定，极易识别；由同一品种变异而来的芽变品种之间，特异性位点极少，相似性遗传距离非常接近，最小为0.8607，最大为1；幼叶DNA双步CTAB提取法有助于提高基因指纹图谱的重现性。这为表型性状较为相近的切花月季芽变品种的分子鉴别提供了可靠的技术手段，也为转基因品种的育成奠定了基础。     

Vermiculite in Some Japanese Soils

Since Gruner's pioneer work in 1934¹⁾, vermiculite has been attracting the attention of mineralogists and soil scientists with much interest, probably because of its unique behaviour on cation exchange and of a component common in most soils derived from various parent rocks. A number of papers thereafter dealt with the mineral, revealing its properties, diagenesis, and distribution in soils. However, as information has been accumulated on vermiculite, especially on clay vermiculite, it became evident that the difference between vermiculite and montmorillonite is due simply to the difference in layer charge and that the division is essentially an arbitrary one²⁾. Walker suggested that the Mg plus glycerol test would be the only one which appeared to be universaIlY valid in the identification of vermiculite, and that although the K test was still of value as an aid in the differentiation, it could no longer be reo commended as of universal validity. In recent years, several workers^4-12) indicated that interlayer materials, especially Al-hydroxyls, prevented vermiculite from contracting to 10 Å in the K test and prevented montmorillonite from expanding to 18 Å in the Mg-glycerol test. This suggests that in the light of new evidences the 14 Å mineral hitherto believed as vermiculite, chlorite, or montmorillonite by the classical test should be reexamined after removal of interlayer materials.     

Hydroxy-Al complexes of montmorillonite and vermiculite and identification of intergrades of montmorillonite-chlorite and vermiculite-chlorite in soils

Much evidence has indicated that the occurrence of montmorillonite and vermiculite containing Al-interlayers is very common in solis, particularly acid soils. Viewed in the light of soil clay minerology, it would be required to investigate the properties of their original minerals. For the latter purpose, the Al-interlayer has been removed prior to the Mg-glycerol,K-saturation and heating tests for identification of montmorillonite and vermiculite. Its removal has been accomplished in sevsral ways; KOH plus KCl (1), NH₄F, KCl plus HCl (2), Na-citrate (3),400C de hydroxylation-NaOH (4) dissolution. Although these methods are effective for the removal of Al-interlayers, they seem drastically to affect the minerals or are time-consuming. Inthe course of the study of hydroxy-Al interlaid complexes of expanding 2:1 layer lattice clay minerals, the authors have noticed the difference between the (001) spacings of hydroxy-Al complexes of montmorillonite and vermiculite; the former exhibited the 20 A basal spacing at room temperature against the 14 A spacing of the latter. This difference might be useful for differentiating montnmorillonite-chlorite intergrades in soils.     

Adsorption of pentachlorophenol by soils

The adsorption studies using soils various in the species of clay minerals and organic matter content indicate:

1) That apparent adsorption occurs to the greatest extent on the strong acid soil system compared to the moderate acid soil system, regardless of the species of clay mineral and organic matter content. And there is no adsorption on the slightly acid or neutral soil system.

2) The apparent adsorption involves adsorption of molecules and/or anions and precipitation of molecules in the micell and the external liquid phase.

3) The magnitude of adsorption occurs in the decreasing order of humus-allophanic, allophanic, montmorillonitic, and halloysitic soils.

4) The major factor governing the magnitude of apparent adsorption is pH.     

Imogolite of Imogo-Layers in Kyushu

A distinct, brownish yellow soil layer often intervenes between dark colored layers in the profiles of Ando soil in Kyushu, particularly in central east and southern Kyushu. The layer is called “imogo” in the Hitoyoshi district and “akahoya” in the Miyazaki district. The soil is characterized by a very low bulk density such as 0.4, and bears glassy particles in abundance, which are colorless and shard-shaped. It often displays exchange-neutrality or exchange-alkalinity. Plant roots are very few in the layer, and most roots are observed to make a bend along the layer surface, from perpendicular to horizontal. It seems that the plant root has trouble intruding the layer, probably because of its special structure (1, 2).