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Volume 35 (2001)
- Issue 6 Pages 385-
- Issue 5 Pages 277-
- Issue 4 Pages 215-
- Issue 3 Pages 145-
- Issue 2 Pages 77-
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Volume 35, Issue 6
Displaying 1-7 of 7 articles from this issue
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Masanobu Yamamoto, Hajime Kayanne, Masumi Yamamuro2001 Volume 35 Issue 6 Pages 385-401
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSWe have applied organic carbon and total nitrogen analyses, Rock-Eval pyrolysis, and gas chromatography-mass spectrometric lipid analysis with in situ methylation with tetramethylammonium hydroxide (TMAH-pyrolysis-GC/MS) to characterize the organic matter in recent lagoonal sediments from the Great Barrier Reef (GBR). On a pyrogram, GBR sediments showed the unique feature that S1 and S3 values were anomalously high. The high S1 value presumably reflects a higher proportion of hydrolyzed lipids, and the high S3 value is due to the degradation of carbonate minerals in a low temperature range. Associated with a CaCO3 increase towards the offshore area, the organic carbon/total nitrogen ratio (C/N ratio) decreased, S1 and S2 values increased, and total fatty acid and phytol concentrations increased. These changes have negative correlations with the branched/total fatty acid ratio, implying that the changes reflect the degree of eubacterial activity. The higher preservations of lipids and lignin phenols in CaCO3-rich sediments are attributable to their higher preservation effect resulting from an impermeable carbonate matrix. The anteiso-/iso-fatty acid ratio has a significant negative correlation with the total fatty acid concentration and a positive correlation with the branched/total fatty acid ratio, indicating that the ratios are closely related to the degree of eubacterial degradation of organic matter.View full abstractDownload PDF (1231K) -
Jie-Dong Yang, Jun Chen, Xian-Cong Tao, Chun-Lei Li, Jun-Feng Ji, Yang ...2001 Volume 35 Issue 6 Pages 403-412
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSWe present 87Sr/86Sr ratios of acid-washed residues, Rb/Sr, magnetic susceptibilities and deposition rates of loess and paleosols from the Luochuan loess section, China, covering the last 2.5 Ma. Paleosol residues have consistently higher 87Sr/86Sr than loess residues. This is attributed to the paleoclimate-related differences in chemical weathering intensity of the source area. This study indicates that the 87Sr/86Sr ratio of residues of loess and paleosols may be a proxy for chemical weathering intensity. This investigation reveals a long-term decrease in residue 87Sr/86Sr ratios and a general increase in deposition rates from 2.5 Ma to the present. This may imply a general rise in mechanical erosion intensity coupled with a general decline in chemical weathering intensity over the past 2.5 Ma. The regular oscillations of residue 87Sr/86Sr, Rb/Sr, and magnetic susceptibilities of loess and paleosols began at ∼1.0 Ma and display a ∼100 Ka cyclicity, which is consistant with the climate change being associated with the eccentricity-driven insulation cycle of ∼100 Ka.View full abstractDownload PDF (141K) -
Mei-fu Zhou, John Malpas, Min Sun, Ying Liu, Xiao Fu2001 Volume 35 Issue 6 Pages 413-420
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSThe determination of low concentrations of the platinum-group elements (PGEs) in geological materials is of considerable importance and has attracted numerous studies using inductively coupled plasma mass spectrometry (ICP-MS) combined with a variety of preconcentration techniques. Among these techniques, the Ni-sulfide fire assay has proven the most convenient and efficient. However, Cu and Ni are also collected during the fire assay and cause serious isobaric interference by Cu- and Ni-argides with the light PGEs (Ru, Rh, and Pd). This problem is most pronounced in the analyses of sulfide-rich materials. Here, we report a new technique that involves a combination of standard addition with external and internal calibrations to make corrections for Cu- and Ni-argide interference. This study demonstrates that ICP-MS is suitable for the determination of the PGEs in sulfide-rich geological materials.View full abstractDownload PDF (139K) -
Giancarlo Cavazzini2001 Volume 35 Issue 6 Pages 421-438
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSEquations are derived giving the evolution of the 87Sr/86Sr ratio in mineral phases which crystallize from magmatic liquids with changing 87Sr/86Sr ratio, assuming continuous growth and no Sr diffusional exchange between crystals and residual liquid. The model shows, firstly, that separates of mineral phases which grow over the same range of residual liquid fraction from a magmatic liquid which crystallizes according to Rayleigh's distillation law, if characterized by different Rb/Sr ratios, define alignments in the 87Rb/86Sr vs. 87Sr/86Sr diagram. These alignments are not common isochrons: their slopes and y-intercepts change as crystallization proceeds and the slopes do not reflect the time-span elapsing from magma eruption or emplacement, but may give information about the time-span elapsing from the beginning of growth of the mineral phase., i.e., the time-scale of existence of the magma mass. Secondly, it shows that information may be inferred about the sequence of formation of mineral phases characterized by very low Rb/Sr ratios, simply by comparing the values of the 87Sr/86Sr ratio.View full abstractDownload PDF (190K) -
Detection of water extractable dipeptides and their characteristics in recent sediments of Tokyo BayRyo Ogasawara, Ryoshi Ishiwatari, Akira Shimoyama2001 Volume 35 Issue 6 Pages 439-450
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA total of 34 dipeptides was detected in water extract of the recent sediment core S8602 of Tokyo Bay by gas chromatography coupled to mass spectrometry. These dipeptides were indigenous to the sediments and showed predominance of the L or LL stereoisomers indicating that they were derived mainly from proteins. Alanylalanine, valylalanine, alanylleucine, and alanylaspartic acid were the four most abundant dipeptides, and their individual concentrations were about 5 nmol g-1 at 1.3 cm in depth. All dipeptides showed a maximum concentration at 1.3 or 6.3 cm in depth, which decreased rapidly with depth especially over a depth range from 6.3 to 13.8 cm. Total concentration of dipeptides at 1.3 cm in depth, corresponding to 160 nmol g-1 for amino acid residues, accounted for 2.8% of the hydrolyzed amino acids, and was about 1.2 times larger than that of free amino acids in the same water extract. Accordingly, dipeptides are one of the major products as well as free amino acids during the earliest stage of protein degradation in sediments. On the other hand, diketopiperazines were not found in the sediments. In addition, the sequential isomeric ratios of some dipeptides differed from the reported ratios at equilibria. Therefore, dipeptides were not derived through diketopiperazines and likely preserved their original amino acid sequences in their precursor proteins.View full abstractDownload PDF (324K) -
Yoshito Chikaraishi, Hiroshi Naraoka2001 Volume 35 Issue 6 Pages 451-458
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSStable isotopic compositions of organic hydrogen (δD) have positive correlations (r2 > 0.95) with those of carbon (δ13C) among several compound fractions of terrestrial plant leaves possessing distinctive photosynthetic pathways (C3, C4 and CAM). The δD/δ13C slopes of C3 plants vary from ∼25 to 42, which are larger than those of C4 plants (11 to 12). CAM plants have intermediate δD/δ13C slopes (∼17 to 20) between C3 and C4 plants. Using a δD-δ13C diagram, photosynthetic metabolisms are clearly discriminated, even though they sometimes cannot be distinguished from each other only by carbon isotopes. Relative to bulk organic matter, hydrogen and carbon of lipid fraction are more depleted in 13C than those of pigment fraction, respectively. Furthermore, δD values of lipid and pigment fractions relative to bulk organic hydrogen have negative correlations with δ13C values of corresponding fractions among the three photosynthetic pathways. This isotopic covariance among each fraction may be attributable to kinetically-controlled molecular biosyntheses using similar enzymes but with different isotope fractionations. Or the intermediate molecules for the biosyntheses have isotopically different pools in hydrogen and carbon.View full abstractDownload PDF (243K) -
Minoru Kusakabe2001 Volume 35 Issue 6 Pages 459-464
Published: December 20, 2001
Released on J-STAGE: April 08, 2008
JOURNAL FREE ACCESSA field-oriented, simple technique to determine the stable carbon isotopic ratio of the total dissolved carbonate in carbonate-rich natural water is proposed. The total dissolved carbonate is fixed in situ in a plastic syringe containing saturated Ba(OH)2 solution. The BaCO3 precipitate is purified without contact with atmospheric CO2. The dried precipitate is reacted with concentrated phosphoric acid in a capped, 5 ml glass syringe at 50°C overnight. A majority of the resulting CO2 is expanded into a vacuum line and purified in a trap before mass spectrometric δ13C determination. The effect of coexisting SO42- ion on δ13C determination becomes appreciable when the carbonate mole fraction in the precipitate, i.e., BaCO3/(BaCO3 + BaSO4), becomes smaller than 0.3. This technique can be applied for natural waters containing total carbonate waters down to <2.5 mmole/kg with the precision better than ±0.03‰.View full abstractDownload PDF (74K)
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