Abstracts of Annual Meeting of the Geochemical Society of Japan

Toyama Prefecture (Japan) has a variety of geographical environment where there is a high difference in 3000m in small areas. We determined δ¹³C and δ¹⁵N of the lipid-extracted muscles of largemouth bass, which is a top predator of aquatic creatures, from eight dam lakes and two ponds. The δ¹³C and δ¹⁵N of samples (nine or ten fish in each sampling point) were similar in a sampling point. On the other hand, the mean δ¹³C and δ¹⁵N values of each sampling point were scattered widely. The δ¹³C and δ¹⁵N showed large difference between two ponds. Furthermore the dam lakes were divided into two groups by the mean altitude and the flushing rate of the dam water, and we suggested that there were different food sources of food chain between two dam groups. We recommend using largemouth bass for monitoring and comparing the hydrosphere environment and food chain using δ¹³C and δ¹⁵N on similar species worldwide.

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Hydrogen isotopes and oxygen isotopes (water isotopes) of environmental water can be used as important tracer of water circulation cycle. In this study, we investigated analytical conditions of off-axis ICOS method, which is a kind of laser absorption spectroscopy. The long-term stability of measured oxygen isotopes is variable in comparison with that of hydrogen isotopes. The amount of injected water is strongly related to measured isotope ratios. On the other hand, salinity of water samples is not related to measured isotopic ratios.

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We measured the dissolved inorganic carbon (DIC), dissolved methane (CH₄) and nitrous oxide (N₂O) in the stream, estuary and coast of a river running through the dairy land.The greenhouse gas concentrations observed the spatial variation.From these concentrations, we calculated the air-water greenhouse gas fluxes.Result of the greenhouse gas fluxes was higher in the river than in the estuary or the coastal.Results suggest that fluxes of CH₄ is the highest, and N₂O the lowest, the estimated contribution of N₂O, by their global warming potential, was much more than that of CH⁴ and CO₂.Using results of CH₄ and CO₂ concentrations and fluxes, we could estimate the carbon cycle quantitatively, such as we could understood cycle production and consumption of the CH₄ and CO₂.

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Organic molecular compositions and source apportionments of suburban aerosols collected at Mangshan, north China China has been facing serious air pollution problems due to huge usage of fossil fuels. One fourth of global primary anthropogenic organic aerosols are generated in China, approximately 70% of which originate from coal burning. Beijing, the capital of China and one of the biggest mega-cities in the world, has been suffering a persistent air pollution problem. In this study, we investigated atmospheric aerosol samples collected from suburban site of Beijing for their molecular compositions and concentrations to better understand the diurnal variations and source apportionments of organic aerosols.Fifty eight aerosol samples (TSP) and 4 field blanks were collected at Mangshan (40° 16’ N, 116° 17’ E, 600m.s.l) from 15th September to 5th October 2007 using a high-volume air sampler and pre-combusted quartz fiber filters without any size-cut device. A filter aliquot was cut into pieces and extracted three times with dichloromethane/methanol (2:1, v/v) under ultrasonication for 10 min. The solvent extracts were filtered through quartz wool packed, concentrated by a rotary evaporator, and then blown down to dryness with pure nitrogen gas. The extracts were reacted with 50 µl of N,O-bis-(trimethylsilyl)trifluoroacetamide (BSTFA) with 1% trimethylsilyl chloride and 10 µl of pyridine at 70°C for 3 h. After the reaction, derivatives were diluted with 140 ml of n-hexane containing the internal standard (C13 n-alkane, 1.43 ng µl-1) and the samples were determined using a gas chromatography-mass spectrometry (GC-MS)Homologs of eight compound classes were detected in the Mangshan aerosol samples. Sugars, fatty acids, glycerol and polyacids were found as major organic compound classes, whereas n-alkanes, phthalate esters, biogenic SOA tracers and aromatic acids were detected as minor classes. Sugars (average 603 ng m^-3 in daytime and 447 ng m^-3 in nighttime) were found to be the dominant compound class. Mannitol (average 138 ng m^-3) and glucose (average 130 ng m^-3), as tracers of primary biological particles, were detected as two major single compounds, followed by levoglucosan (average 103 ng m^-3), a specific biomass burning (pyrolysis) product of cellulose, followed by fructose, arabitol, phthalic acid and malic acid.

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