Study of Asian Dust Phenomena in 2001–2003 Using A Network of Continuously Operated Polarization Lidars

We have conducted dust observations at a number of locations including Beijing, Hefei, Suwon, Fukue, Nagasaki, Tsukuba, and Sapporo using automated two-wavelength polarization lidars o study Asian dust phenomena, including generation, transport, and change during transport. We developed a method using the depolarization ratio for estimating the contributions of Asian dust and spherical air-pollution aerosols in observed aerosol mixtures. We analyzed the dust profiles statistically to derive climatological characteristics and year-on-year variations. We also studied dust source and transport path for each dust event using the regional chemical transport model CFORS. The statistical analysis clearly demonstrated the year-on-year variation of dust phenomena and the characteristics depending on the locations of the observational sites. Most major dust events in 2001 and 2002 originated in Inner Mongolia and/or Mongolia at the southern edge of a low-pressure area located in Siberia and were transported by strong westerlies. In 2003, the typical meteorological pattern for heavy dust cases accompanying a strong low in Siberia was not seen, except for one case in April. Furthermore, the lidar observation in Beijing suggests that less dust was generated in the source regions in Inner Mongolia and/or Mongolia, probably due to higher precipitation in 2003.     

Aerosol concentrations observed at Mt. Haruna,Japan, in relation to long-range transport of Asian mineral dust aerosols

As a part of the effort to understand the structure of long-range transported aerosol plumes and local pollution, aerosol observations monitored the mass concentrations and number-size distributions during the period August 2006 to July 2009 near the top of Mt. Haruna (1365 m), an isolated mountain in the Kanto Plain in Japan. The mass concentrations observed at Mt. Haruna and plain sites showed a seasonal variation with a maximum in spring and summer, respectively. The spring peaks in aerosols at Mt. Haruna were probably caused by long-range transport of mineral dust and anthropogenic particles from the Asian continent. The summer peaks at the plain sites was attributed to local pollution from the Tokyo metropolitan area. Three examples of 2007 Asian dust events were investigated to show that aerosols may be dispersed in a complicated three-dimensional structure and that delayed arrivals of the dust plumes at plain sites compared to Mt. Haruna were not a rare case. Because of the boundary layer being stable at night, the dust layer was advected eastward without the vertical mixing before sunrise. This study suggests that after thermal convection activated by sunlight during daytime Asian dust transported in the free troposphere may be brought down into the atmospheric boundary layer, increasing the dust concentration there.     

Influence of a botanical pesticide,azadirachtin, on ultimobranchial gland of the freshwater catfish Heteropneustes fossilis

Freshwater catfish, Heteropneustes fossilis, were subjected to 42 mg L^?1 of azadirachtin for short-term exposure (96 h) and to 10.5 mg L^?1 for long-term exposure (28 days). Six fishes were sacrificed on each time interval from control and experimental groups after 24, 48, 72, and 96 h in the short-term exposure and after 7, 14, 21, and 28 days in the long-term experiment. The calcium regulating endocrine gland, viz. the ultimobranchial gland, was fixed for histological studies. Up to 72 h of azadirachtin treatment, there was no histological alteration in the UBG (ultimobranchial gland) of H. fossilis. After 96 h exposure, the ultimobranchial cells stain feebly and the nuclear volume of these cells were slightly decreased. No histological alterations have been observed in the UBG cells up to 14 days following azadirachtin exposure. After 21 days, the cytoplasm of ultimobranchial cells was feebly stained and the nuclear volume exhibits a decrease. The nuclear volume of these cells was further decreased and the gland shows vacuolization and degeneration at certain places after 28 days azadirachtin treatment. Hence, it can be concluded that azadirachtin severely affects the physiology of calcium homeostasis in H. fossilis. Therefore, the botanical pesticides should be used carefully near aquatic reservoirs.     

Catalytic decomposition of polychlorinated biphenyls (PCBs)

In this study, polychlorinated biphenyls (PCBs) were decomposed by low‐temperature heat treatment with metallic catalyst, and with metallic catalyst and a hydrogen source. Of the catalysts used, iron (Fe) was the most active catalyst for the decomposition of PCBs, and the decomposition was due to dechlorination. The addition of hydrogen sources accelerated the decomposition of PCBs in the presence of catalyst. Surface analysis of the catalyst using X‐ray photoelectron spectroscopy (XPS) suggested that the emitted chlorine was presumed to form metal chloride. The reactions of each homolog can be expressed by a successive first‐order reaction model. This means that a substituted chlorine is successively detached during this reaction. The overall decomposition rate in this reaction system was controlled by that of the lower chlorinated homologs. The decomposition rates with Fe and NaBH₄ for the lower chlorinated homologs were about 10 times as fast as the rates with only Fe.     

A new class of mealybug pheromones: a hemiterpene ester in the sex pheromone of Crisicoccus matsumotoi

Mealybugs, which include several agricultural pests, are small sap feeders covered with a powdery wax. They exhibit clear sexual dimorphism; males are winged but fragile and short lived, whereas females are windless and less mobile. Thus, sex pheromones emitted by females facilitate copulation and reproduction by serving as a key navigation tool for males. Although the structures of the hitherto known mealybug pheromones vary among species, they have a common structural motif; they are carboxylic esters of monoterpene alcohols with irregular non-head-to-tail linkages. However, in the present study, we isolated from the Matsumoto mealybug, Crisicoccus matsumotoi (Siraiwa), a pheromone with a completely different structure. Using gas chromatography–mass spectrometry and nuclear magnetic resonance spectroscopy, we identified the pheromone as 3-methyl-3-butenyl 5-methylhexanoate. Its attractiveness to males was confirmed in a series of field trapping experiments involving comparison between the isolated natural product and a synthetic sample. This is the first report of a hemiterpene mealybug pheromone. In addition, the acid moiety (5-methylhexanoate) appears to be rare in insect pheromones.     

Human milk survey for dioxins in the general population in Japan

BACKGROUND: Much attention has been paid to the level of dioxins in breast milk in Japan but few large-scale studies have been conducted on the subject. METHODS: From 1997 to 2002, we collected 839 samples of breast milk from primiparas residing throughout Japan. Starting in 1999, breast milk was also collected from secundiparas. Seven isomers of polychlorinated dibenzo-p-dioxins (PCDDs), 10 of polychlorinated dibenzofurans (PCDFs), 4 of coplanar polychlorinated biphenyls (Co-PCBs) and 8 of mono-orthochlorinated polychlorinated biphenyls (mono-ortho PCBs) were analyzed by employing gas chromatography and mass spectrometry. A correlation between the level of dioxins in human milk and the age of the mothers was noted for the primiparas and the secundiparas; and the levels were compared between the first and the second deliveries. Grouped by parity and prefecture in each year, observations were also made on the trends in these levels. Dioxin levels are shown by using geometric means because their distributions were skewed to the left. RESULTS: The sum of PCDDs and PCDFs, Co-PCBs, mono-ortho PCBs, and total dioxins in the breast milk of primiparas were 13.9, 5.4, 3.4, and 22.7 pg TEQ/g fat, respectively. In the samples obtained from secundiparas, these levels were 63-68 percents of those taken from the primiparas. The correlation coefficients between the PCDDs/DFs, Co-PCBs, mono-ortho PCBs, and total dioxins and the age of the primiparas were 0.19, 0.17, 0.36, and 0.24, respectively. All these correlations were statistically significant (p < 0.001). The positive correlations between these contaminants and the age of the secundiparas were also examined. The total dioxins as well as PCDDs/DFs, Co-PCBs, and mono-ortho PCBs in the breast milk of the primiparas declined significantly between 1998 and 2002 (regression coefficients: -0.04, -0.05, -0.03, and -0.03, respectively). However, no significant decline in these levels was observed when sorted by prefectures. CONCLUSIONS: Much attention should be paid to the age and parity of nursing mothers when investigating the relationship between the level of dioxins in breast milk and the body burden of infants.