Renzo Kondo

Nitrate adsorption in some andisols developed under different moisture conditions

Abstract Nitrate leaching from agricultural lands is one of the most critical problems related to both environmental quality and human health. Although in many studies surfacecharge properties of and nitrate adsorption in soils have been analyzed in tropical and subtropical regions, fewer studies have been conducted on the nitrateretention properties of allo phanic Andisols. The objectives of the present study were to examine the potential nitrate adsorption capacity and the factors affecting nitrate retention in topsoils and subsoils of three Andisols Tokaachi, Hokkaido. Nitrate adsorption at pH 6.0 was found to be low or negligible even in the subsoil of a Haplic Wet Andisol (Melanaquands), despite the high clay content, Nitrate adsorption maxima calculated from the Langmuir equation were higher in the lower horizons of a Haplic Andisol (Melanudands) and a Lowhumic Andisol (Hap ludands), which were developed under moderate to moderately dry moisture conditions and displayed a high allophane content and a low total carbon content. The nitrate adsorption of the aliophanic Andisols was much higher than that reported from other studies conducted in Ultisols and Oxisols, which are rich in iron oxides. The potential capacity to adsorb nitrates and retard nitrate movement should be taken into account in predicting the fate of nitrate in soils and the consequent mitigation of groundwater contamination.

Composition of lignin-degradation products, lipids, and opal phytoliths in a peat profile accumulated since 32,000 years B. P. in Central Japan.

Abstract The compositions of lignin degradation products, fatty acids as well as opal phytoliths of peaty sediments were correlated with the environmental and climatic changes of a wetland which has been formed continuously since 32,000 yBP in Central Japan. Determination of phenolic and lipid compounds provided information on the aerobic and anaerobic conditions of the wetland as well as the types of vegetation. Palmitic and stearic acids were more decomposable and their contents reflected well the changes in the state of the wetland. These trends agreed well with the field-observation of the characteristics of the profile and with the results of opal phytolith analysis. The combination of organic chemical analysis and plant phytolith analysis was found to be effective for elucidating the paleo-environment surrounding the wetland.

Lignin-derived phenolic compounds in different types of peat profiles in Hokkaido, Japan

Abstract How is the composition of organic matter of peat related to the environment of the peatland? How does it change with the process of peat formation? How does it change when the peatland is affected by the lowering of the ground water table? What are the relationships between the organic matter composition of peat and peatland plants? These are problems which we attempted to address in this study. Peat samples were collected layer-wise from four different peat profiles formed under different environments in Hokkaido, Japan, The basic properties of the peat profiles, i.e. major peat-forming plants, contents of carbon and nitrogen, C/N ratio, pH, degree of humification analyzed by several methods, were described and compared. As one of the keys to answer the above-mentioned questions, we selected lignin-derived phenolic compounds that are released by CuO-NaOH oxidation. The composition of the phenolic compounds varied remarkably among the peat layers differing in peat-forming plants and in the mode o...

Determination of water-soluble low-molecular-weight organic acids in soils by ion chromatography

Abstract Low-molecular-weight organic acids (LOAs) widely occur in soils and affect the soil properties and processes. We developed a simplified and relatively rapid method to identify and quantify the water-soluble LOAs in soils by using ion chromatography with an exclusive column for organic acids, an ion exchange column for anions, and an electric conductivity detector. These combinations enabled to separate more than ten kinds of LOAs. Freeze-drying and passage through Sep-Pak Plus reverse-phase cartridge columns (Waters Corp., Milford, MA) were introduced as pretreatments to concentrate and purify the soil-water extracts. By applying this method, we investigated the vertical distribution of LOAs in two different adjacent soil profiles in Hamatonbetsu, Hokkaido, Japan. One profile consisted of a Sand-dune Podzol (Typic Haplorthods) and the other of a Sand-dune Regosol (Typic Udipsamments). Formic, lactic, oxalic, malic, and citric acids were detected in all the water-extracts from horizon-wise soil samples. In contrast, propionic, butyric, and succinic acids were not detected in any samples. Acetic acid was identified only in the surface horizons. The total amounts of LOAs ranged from 4.7 to 37.2 µmol kg-1 with a predominance of formic and oxalic acids. The total amounts of LOAs decreased with the increase in the depth in the Regosol. LOAs were abundant in the spodic Bh and Bsl horizons as well as in the surface horizon in the Podzol, suggesting that LOAs playa critical role in the podzolization process. The amounts of water-soluble LOAs were closely correlated with the soil acidity. These results indicated that further attention should be paid to the water-soluble LOAs determined by the simplified method using ion chromatography in the present study, in relation to their role in the soil formation processes and soil acidification.

Genesis of soils across a late Quaternary volcanic landscape in the humid tropical island of Leyte, Philippines

This study evaluated the characteristics and genesis of soils across a young volcanic landscape in the humid tropical island of Leyte, Philippines. Five representative soil pedons (P1-P5) derived from late Quaternary volcanoclastics (i.e. fragmental) on a hillslope sequence were examined and sampled. Results revealed that the soils have generally similar morphological characteristics particularly in terms of soil colour (10YR 3/3-10YR 5/6) and soil structure (granular to subangular blocky), but differed in terms of soil thickness and clay content, which was higher in P3 than the other pedons across the landscape. The high porosities of the soils were the results of high organic matter, the dominance of noncrystalline (short-range order) minerals, as well as the isovolumetric weathering in the subsoils. All soils have very similar chemical properties (e.g. acidic, high organic carbon, low exchangeable bases), except soils from the middle backslope position (P3), which have high cation exchange capacity because higher exchangeable Ca and K result in a higher base saturation. Allophane, goethite, ferrihydrite, and gibbsite are the dominant clay minerals in the soils. Principal component analysis revealed that P3 was distinct from pedons P1, P2, P4, and P5, suggesting that it was substantially different from all other soils across the landscape. Soil formation was relatively fast due to the easy weatherability of the parent materials, high rainfall, and good drainage of the soils along the landscape. This study revealed that on young volcanic soils under humid tropical condition, topography greatly influenced soil development.

Changes in fatty acid composition with age and environment in different types of peat profiles in Japan

Abstract Fatty acid composition of the crude lipid fraction of peat was investigated using several typical peat profiles in Japan. Fatty acid composition varied with the peat layers accumulated in a peat profile since 32,000 years BP. Deposition of long-range transported volcanic ash tephras also affected the composition remarkably due to the acceleration of decomposition. Fatty acid composition differed among high moor, transitional moor, and low moor peat profiles sampled in several locations in Hokkaido, Japan. The difference in the plants involved in the formation of peat was considered to be a very important factor determining the fatty acid composition. For example, arachidic acid was considered to be a good indicator for the presence of reed, while the percentage of stearic acid tended to be high in the high moor peat profiles dominated by sphagnum. As the fatty acids with a longer chain length were more stable than those with a shorter chain length, the percentage of longer fatty acids (C24 and C2...

HUMUS COMPOSITION OF PEAT LAND PLANT REMAINS

Abstract Plant remains of peat collected in Hokkaido were examined with regard to humus compositions by means similar to those used by Kumada et al. The examined samples of plant remains covered 34 species, 24 genera, and 19 families. The results were as follows: (1) HT, HE, and PQ varied considerably with the samples over a fairly large range, implying their relationships with the ash content or degree of humification of the samples to some extent. (2) On the basis of RF-Δlogk correlations and the humic acids spectra types, the plant remains may be grouped as follows: Group I: Remains of the organs, with the possible exception of the roots, of most grassy plants, several species such as Osmunda cinnamomea excepted ; remains of woody plant xylem and some woody plant leaves. Group I characterized by lignins. Group II: Remains of shrubby and woody plant organs with the exception of woody plant xylem and some exceptional woody plant leaves. Group II characterized by tannins. Group III: Remains of mosses. (3)...