| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1992: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1991: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Research Abstract |
Three humic acids (HAs) were extracted from volcanic ash soil at Shizuoka, brown forest soil at Aichi and sediment of Tokyo Bay. Sedimentary HA was fractionated into five molecular weight ranges. Surface pressure-area measurements were carried out on brown forest soil, volcanic ash soil and sedimentary HAs at an air-water interface. Surface pressure-area curves of the HAs exhibited a typical monolayer characteristic at the air-water interface. Limiting specific area of the sedimentary HAs decreased with the increase in molecular weight. A length of the sedimentary HAs was calculated as 3.1-8.7 nm and carbon number of the length was 23-67 from the lower molecular weight Ga to the higher one. A length of the brown forest soil and volcanic ash soil HAs were 3.8 and 12.1nm,respectively. Carbon number for the brown forest soil and volcanic ash soil HAs were 29 and 93, respectively. Size of the volcanic ash soil HA is appeared to be highly larger than the brown forest soil HA.
Then, HA is found to be a linear but not a spherical structure. Because, if such the thickness is a radius of a sphere, volume of the HA will become extremely high comparing to the molecular weight of the HA. These estimated values (thickness) are considered to be ascribed to a length of the molecule of HA, whose structure is a rod or linear shape.
Since there is no actual model compounds for HA, only relatively determined size has been known for HA. In this study, however, it is noteworthy that a length of the HAs was determined directly and absolutely. It will be continued to carry out the direct size determination of many kinds of HA macromolecules for the promotion of the chemical characterization of humic substances.
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