Yoshinari Ambe

Characterization of a humic acid-like brown substance in airborne particulate matter and tentative identification of its origin

Abstract A brown substance having the solubility characteristics of humic acid was extracted from airborne particulate matter sampled in a rural area of Japan. This brown substance contributed 0.6–3% of the total carbon in airborne particulate matter. This fraction also contained pollen protein in samples collected during the pollen season. Patterns of elution from gel permeation chromatography suggested a molecular weight range from 500 to 10,000, with a still higher upper limit for one sample. The infrared spectra were compared with those of humic acid from the local soil, extracts from dead leaves, smoke from burning plant matter, and soot from automotive exhaust, all possible sources of the brown substance. The closest similarity was with the extract smoke. This identification is strengthened by lack of correlation of the brown substance with aluminum, a tracer for soil content, and a value of K/Fe ratio in the associated particulate matter higher than any plausible source other than combustion. It is probable that the primary source of this brown, high molecular weight acidic materials is agricultural burning.

Characterization of polar organics in airborne particulate matter

Abstract The methanol-extractable highly polar organics in atmospheric aerosol were characterized using GC-MS. Dicarboxylic acids having 2–16 carbon numbers were detected with a total concentration of 172 ng m −3 . Azelaic acid ( C 9 ) was the most abundant diacid and it possibly originated from the ozonolysis of unsaturated carboxylic acids such as oleic acid and linoleic acid, which mainly originate from terrestrial plants. A compound, which was tentatively identified as tetrahydrofuroic acid, contributed to about 10% of the highly polar organics. Other polyfunctional compounds found in the samples included some ketocarboxylic acids and aromatic acids such as phthalic acids, anisic acid and vanillic acid.

Long-term variation of chemical composition of atmospheric aerosol on the Oki Islands in the Sea of Japan

Abstract Chemical composition in aerosols collected on the Oki Islands, which are located in the Sea of Japan, were measured for 4 1 2 years (1983–1988) and their variations were investigated from the viewpoints of aerosol background level and transport of aerosols from both the mainland of Japan and the Asian Continent. Kosa, which is soil dust from the Asian deserts, strongly influenced the variations of the concentration of soil-derived components in aerosol, which showed high concentrations every spring and November. Sulfate had a good correlation with V in the variation and their concentrations increased in summer as the result of the transport of the aerosol from the mainland of Japan. Whereas high Pb concentration in winter was presumed to be attributed to the contribution of lead-enriched aerosol transported from the Asian Continent by the northwest monsoon. The differences of aerosol composition between summer and winter were seen in the ratios of Pb/Zn and Sulfate/V, which may be good indicators for the characterization of aerosol in Asian region. Long-term trends of changing of aerosol composition were also studied, and only C indicated a slight increase for 4 years.

Seasonal variation of monoterpenes in the atmosphere of a pine forest

Abstract Seasonal variation of monoterpene concentration in the atmosphere of a pine forest was measured and is discussed in relation to various environmental factors. The concentration of monoterpenes was low in winter, and higher and more variable in summer and autumn. Rough seasonal variation may be explained by temperature differences, but changes from day to day are anticorrelated with ozone concentration. The emission rate of monoterpenes from a pine forest was estimated on the basis of atmospheric concentration, going on the assumption that the disappearance of monoterpenes in the forest is governed by atmospheric reactions.

Semi-volatile aldehydes as predominant organic gases in remote areas

Abstract The atmospheric organics in two remote islands and in an inland local city in Japan were measured, and it was found that semi-volatile aldehydes (C 5 –C 11 ) are present ubiquitously. The mixing ratios of these aldehydes often amounted to a ppb(10 −9 ) level, and nonanal (C 9 H 18 O) was always the most abundant of them. These aldehydes were considered to be naturally-derived.

Seasonal variation of monoterpene emission rate in a pine forest

Abstract A technique to observe terpene emission rate in a forest without disturbing the environment of plant, was developed, and the seasonal variation of monoterpene emission rate from a branch in a pine forest was measured.

Gas chromatographic-mass spectrometric analysis of formaldehyde in ambient air using a sampling tube

A gas chromatographic-mass spectrometric technique for the analysis of trace concentrations of formaldehyde in air is described. Molecular Sieve 13X was found to be an excellent adsorbent. The collected samples were thermally desorbed onto the analytical column (Porapak T) for separation, and quantified by mass fragmentography (m/e 29 and 30). Advantages of the technique include ppb sensitivity, selectivity and quantitative recovery. Experimental results are given for air samples in a rural area.

Temporal variation of trace element concentrations in selected rainfall events at Tsukuba, Japan

Abstract Using ICP emission spectrometry, the temporal variation of the concentration of dissolved Al, Fe. Si, Mn, Zn. Cu and B in rain-water during an event was observed at Tsukuba, Japan. The relationships between trace element variations and rainfall characteristics were compared with those for major elements such as Na, K, Ca and Mg. In many cases, the concentration of minor elements was highest in the initial stage. The exception was in rain with very short duration or very strong intensity at the initial stage of rainfall. No significant relationship was observed between rainfall intensity and soluble elemental concentration, although in a few cases AI, Zn, Na and Fe showed an inverse correlation with rainfall intensity. It was found that the concentration of minor elements such as Fe, Al and Zn fluctuated, whereas those of Na and other major elements changed smoothly. This difference is considered to be caused by differences in the scavenging process of the elements as well as the heterogeneous and varying distribution of atmospheric particles which supply minor elements in rain-water.

Detection of monomethylarsenic compounds originating from pesticide in airborne particulate matter sampled in an agricultural area in Japan

Abstract Alkylarsenic species in airborne particulate matter sampled in an agricultural area in Japan were investigated. The monomethyl form of arsenic, which has not been found so far in the air, was detected in a concentration as much as 1.4 ng m −3 in a sample collected on a sunny summer day. It had a different size distribution from that of di- and tri-methyl forms of arsenic. The mean particle diameter containing monomethylarsenic compound was 2–4 μm, while those of the di- and/or tri-methyl forms of arsenic were 0.2–0.5 μm. This monomethyl form is thought to originate from the alkylarsenic pesticide spread over rice fields, based on the relation between variation in its concentration and meteorological conditions. Alkylarsenic pesticide appears to be blown up by the wind when the land surface is dry. Further, the methylation of arsenic in nature was found to be influenced by humidity and temperature.

The relationship of the monoterpene composition in the atmosphere, the foliar emission gas and the leaf oil of Pinus densiflora

Abstract Monoterpene compositions in the atmosphre in a pine forest, the foliar emission gas and the leaf oil of pine needles were compared. The emission rate of each monoterpene from pine needles was proportional to the product of the amount in the leaf oil and the approximate vapor pressure. The composition of monoterpenes in the atmosphere is rather well explained by considering foliar emission rates with the supposition that the terpenes emitted into the atmosphere react with ozone and photochemically with nitrogen oxides.