排序方式: 共有44条查询结果,搜索用时 203 毫秒
21.
Kimitaka Kawamura Leonard A. Barrie Desiree Toom-Sauntry 《Atmospheric environment (Oxford, England : 1994)》2010,44(39):5316-5319
Oxalate, the anion of oxalic acid, is one of the most abundant measurable organic species in atmospheric aerosols. Traditionally, this bifunctional species has been measured by gas chromatography (GC) after derivatization to butyl ester and by ion chromatography (IC) without derivatization. However, there are few published comparisons of the two techniques. Here, we report the results of an intercomparison study for the measurement of oxalic acid in Arctic aerosols (<2.5 μm, n = 82) collected in 1992 using GC and IC. The concentrations of oxalic acid by GC ranged from 6.5–59.1 ng m?3 (av. 26.0 ng m?3, median 26.2 ng m?3) whereas those by IC ranged from 6.6–52.1 ng m?3 (av. 26.6 ng m?3, median 25.4 ng m?3). They showed a good correlation (r = 0.84) with a slope of 0.96. Thus, observations of oxalate obtained by GC employing dibutyl esters are almost equal to those by IC. Because the accuracy of oxalic acid by GC method largely depends on the method used, it is important to strictly examine the recovery in each study. 相似文献
22.
Michihiro Mochida Kimitaka Kawamura Pingqing Fu Toshihiko Takemura 《Atmospheric environment (Oxford, England : 1994)》2010,44(29):3511-3518
Levoglucosan is considered as a useful molecular tracer of biomass-burning aerosols in the atmosphere. To characterize the seasonal variation of its concentrations over the Pacific Ocean and to assess its usefulness as a tracer after long-range transport, we investigated long-term variations of levoglucosan over Chichi-jima in the western North Pacific, from 2001 to 2004. Organic carbon (OC), elemental carbon (EC) and d-glucose were analyzed for comparison. The seasonal variation of levoglucosan concentrations showed a maximum in the winter, which is consistent with the enhanced Asian outflow to the Pacific indicated by backward air-mass trajectories. The concentration levels of levoglucosan estimated from global aerosol model outputs in the winter are, on average, comparable to the observed levels, suggesting that a considerable fraction of levoglucosan did not decompose during long-range transport from the Asian continent by westerly/northwesterly winds. This result is supported by comparable ratios of levoglucosan to EC in Chichi-jima and the East Asian coastal region. Conversely, the measured concentrations of levoglucosan in the summer were significantly lower than the modeled one. This implies a degradation of levoglucosan in the air masses that stagnated over the Pacific, although uncertainties in the model estimate may also be partly responsible for this discrepancy. One possible degradation pathway is oxidation by OH radicals; the contribution of acid-catalyzed reactions needs further investigation. 相似文献
23.
Pingqing Fu Kimitaka Kawamura 《Environmental pollution (Barking, Essex : 1987)》2010,158(10):3138-3143
Bisphenol A (BPA) is a suspected endocrine disruptor in the environment. However, little is known about its distribution and transport in the atmosphere. Here, the concentrations of BPA in the atmospheric aerosols from urban, rural, marine, and the polar regions were measured using solvent extraction/derivatization and gas chromatography/mass spectrometry technique. The concentrations of BPA (1-17,400 pg m−3) ranged over 4 orders of magnitude in the world with a declining trend from the continent (except for the Antarctica) to remote sites. A positive correlation was found between BPA and 1,3,5-triphenylbenzene, a tracer for plastic burning, in urban regions, indicating that the open burning of plastics in domestic waste should be a significant emission source of atmospheric BPA. Our results suggest that the ubiquity of BPA in the atmosphere may raise a requirement for the evaluation of health effects of BPA in order to control its emission sources, for example, from plastic burning. 相似文献
24.
Prashant?HegdeEmail author Kimitaka?Kawamura H.?Joshi M.?Naja 《Environmental science and pollution research international》2016,23(7):6102-6118
The aerosol samples were collected from a high elevation mountain site, Nainital, in India (1958 m asl) during September 2006 to June 2007 and were analyzed for water-soluble inorganic species, total carbon, nitrogen, and their isotopic composition (δ13C and δ15N, respectively). The chemical and isotopic composition of aerosols revealed significant anthropogenic influence over this remote free-troposphere site. The amount of total carbon and nitrogen and their isotopic composition suggest a considerable contribution of biomass burning to the aerosols during winter. On the other hand, fossil fuel combustion sources are found to be dominant during summer. The carbon aerosol in winter is characterized by greater isotope ratios (av. ?24.0?‰), mostly originated from biomass burning of C4 plants. On the contrary, the aerosols in summer showed smaller δ13C values (?26.0?‰), indicating that they are originated from vascular plants (mostly of C3 plants). The secondary ions (i.e., SO4 2?, NH4 +, and NO3 ?) were abundant due to the atmospheric reactions during long-range transport in both seasons. The water-soluble organic and inorganic compositions revealed that they are aged in winter but comparatively fresh in summer. This study validates that the pollutants generated from far distant sources could reach high altitudes over the Himalayan region under favorable meteorological conditions. 相似文献
25.
Jin YH Kawamura A Park SC Nakagawa N Amaguchi H Olsson J 《Journal of environmental monitoring : JEM》2011,13(10):2886-2894
Environmental monitoring data for planning, implementing and evaluating the Total Maximum Daily Loads (TMDL) management system have been measured at about 8-day intervals in a number of rivers in Korea since 2004. In the present study, water quality parameters such as Suspended Solids (SS), Biochemical Oxygen Demand (BOD), Dissolved Oxygen (DO), Total Nitrogen (TN), and Total Phosphorus (TP) and the corresponding runoff were collected from six stations in the Yeongsan River basin for six years and transformed into monthly mean values. With the primary objective to understand spatiotemporal characteristics of the data, a methodologically systematic application of a Self-Organizing Map (SOM) was made. The SOM application classified the environmental monitoring data into nine clusters showing exclusively distinguishable patterns. Data frequency at each station on a monthly basis identified the spatiotemporal distribution for the first time in the study area. Consequently, the SOM application provided useful information that the sub-basin containing a metropolitan city is associated with deteriorating water quality and should be monitored and managed carefully during spring and summer for water quality improvement in the river basin. 相似文献
26.
27.
Amanda D. Melin Linda M. Fedigan Chihiro Hiramatsu Shoji Kawamura 《Behavioral ecology and sociobiology》2008,62(5):659-670
Many species of platyrrhine primates are characterised by sex-linked color vision polymorphism. This presents an opportunity
to study the biology and ecology of individuals with different phenotypes living in the same group. Several evolutionary processes
could maintain polymorphic genes in populations. In this study, we evaluate the hypothesis that foraging niche divergence
among monkeys explains the presence of multiple color vision phenotypes. Specifically, we test whether dichromats and trichromats
differ in foraging time devoted to cryptic vs brightly colored resources. We did not find any differences in foraging time
spent on different food types by dichromatic and trichromatic monkeys in two groups of white-faced capuchins (Cebus capucinus) living in a tropical dry forest. We conclude that in so far as these variables are concerned, niche divergence does not
likely explain color vision polymorphism in our study population. 相似文献
28.
Yasuyuki Kitamori Michihiro Mochida Kimitaka Kawamura 《Atmospheric environment (Oxford, England : 1994)》2009,43(21):3416-3423
Aerosol water content (AWC) of urban atmospheric particles was investigated based on the hygroscopic growth measurements for 100 and 200 nm particles using a hygroscopicity tandem differential mobility analyzer in Sapporo, Japan in July 2006. In most of the humidogram measurements, presence of less and more hygroscopic mode was evident from the different dependence on relative humidity (RH). The volume of liquid water normalized by that of dry particle (Vw(RH)/Vdry) was estimated from the HTDMA data for 100 and 200 nm particles. The RH dependence of Vw(RH)/Vdry was well represented by a fitted curve with a hygroscopicity parameter κeff. The κeff values for 200 nm particles were in general higher than those for 100 nm particles, indicating a higher hygroscopicity of 200 nm particles. Based on the κeff values, the volume mixing ratios of water-soluble inorganic compounds (ammonium sulfate equivalent) were estimated to be on average 31% and 45% for 100 and 200 nm particles, respectively. The diurnal variation of κeff, with relatively higher values in the noontime and nighttime and lower values in the morning and evening hours, was observed for both particle sizes. The Vw(RH)/Vdry values under ambient RH conditions were estimated from κeff to range from 0.05 to 2.32 and 0.06 to 2.43 for 100 nm and 200 nm particles, respectively. The degree of correlation between κeff and Vw(RH)/Vdry at ambient RH suggests a significant contribution of the variation of κeff to atmospheric AWC in Sapporo. 相似文献
29.
Kimitaka Nishitani Shinji Kaneko Hidemichi Fujii Satoru Komatsu 《Journal of Cleaner Production》2011,19(17-18):1956-1964
This paper analyzes whether the reduction of pollution emissions improves a firm’s economic performance through the increase in sales to environmentally conscious customers and the cost reductions associated with the improvement in productivity. Because the selection of the control (end-of-pipe) or prevention (cleaner production) approach differently influences the effect through the improvement in productivity, this is also considered. Using panel data for Japanese manufacturing firms over the period 2002–2008, the findings indicate that firms that have reduced their pollution emissions can increase their economic performance through the increase in demand for their products and an improvement in productivity. However, the latter is conditional, and so the prevention approach is preferred. 相似文献
30.
Hiroyuki Katoh Takao Watanabe Hideaki Ohmori Kiyoshi Kawamura Yoshiaki Makino 《Journal of Material Cycles and Waste Management》2005,7(1):55-64
The carbonization of dehydrated johkasou sludge was examined using batch-type equipment. Based on the temperature changes in the carbonization room and the gas combustion room, the carbonization process was divided into three phases: phase I, drying the sludge; phase II, thermal decomposition of the dried sludge; phase III, after phase II. The times required for phases I and II were strongly correlated with the amounts of water and solid matter, respectively, in dehydrated sludge. The reduction rate of the sludge on completion of phase I was about 90% on average, and the decomposition rate of solid matter increased with time during phase II or phase II plus phase III until it reached about 50%. TOC concentration of the eluate from the carbonized sludge was used as an index to evaluate the progress of the carbonization process, and the highest temperature in the carbonization room was recognized as an important operational factor. The specific surface area and pore volume of carbonized sludge were smaller than those of charcoals and activated carbons by 1–3 orders of magnitude and 1–2 orders of magnitude, respectively. No elution of heavy metals was observed from any of the carbonized sludges examined. The reduced amount of carbon in dehydrated johkasou sludge was estimated to be about 25% of the decomposed organic matter. 相似文献