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31.
M. Yamada Y. Iwasaka A. Matsuki D. Trochkine Y. S. Kim D. Zhang T. Nagatani G.-Y. Shi M. Nagatani H. Nakata Z. Shen B. Chen G. Li 《Water, Air, & Soil Pollution: Focus》2005,5(3-6):231-250
Free tropospheric aerosol particles were collected using a balloon-borne particle impactor in August of 2002 and March of
2003 at Dunhuang in northwestern China (40°00′N, 94°30′E), and the morphology and elemental composition of the aerosol particles
were analyzed in order to understand the mixing state of coarse dust particles (diameter >1 μm) over the desert areas in the
Asian continent in spring. Electron microscopic experiments on the particles revealed that dust particles were major constituents
of coarse mode particles in the free troposphere over the Taklamakan Desert in spring and summer.
Si-rich or Ca-rich particles are major components of dust particles collected in the free troposphere over dunhuang and the
values of [number of Ca-rich particles]/[number of Si-rich particles] differs markedly between spring and summer, being about
0.3 in the spring of 2003 and about 1.0 in the summer of 2002 at heights 3–5 km above sea level. It is likely that the condition
of the ground surface and the strength of vertical mixing in source areas of Asian dust are potential factors causing the
difference in the chemical types of dust particles.
Comparison of the elemental compositions of these particles with those of particles collected over Japan strongly suggests
that these particles were chemically modified during their long-range transport in the free troposphere. Analysis of wind
systems shows that both the predominating westerly wind in the free troposphere and the surface wind strongly controlled by
the geographical structure of the Tarim Basin are important in the long-range transport of KOSA particles originating in the
Taklamakan Desert. 相似文献
32.
Evaluation of biological water purification functions of inland lakes using an aquatic ecosystem model 总被引:1,自引:0,他引:1
An effective measure to cope with eutrophication of lakes is to remove nutrients that can cause algal blooming by taking advantage of natural water purification processes. Here the term “purification” is defined, in a wide sense, as the potential role of a water body to contribute to the reduction of pollutants and thus controlling eutrophication. Also regarded as a kind of ecological regulating services, biological purification involves various processes concerning seasonal nutrient fixation, such as uptake by aquatic macrophytes, biofouling onto foliage substrates, feeding by organisms in higher trophic level, and eternal loss or removal of substance from the water. In order to evaluate the water purification ability, a numerical lake ecosystem model highlighting the role of macrophyte colonies in the shore zone was developed and applied to Lakes Suwa, Kasumi and Biwa, as well as five small lakes attached to Lake Biwa. 相似文献
33.
Interval between reproductive events is an important factor for iteroparous animals because it determines the number of clutches
throughout life. This study examined whether female size, clutch size, shell size and prenuptial molting affected the clutch
interval in the hermit crab Pagurus nigrivittatus. Precopulatory guarding pairs of P. nigrivittatus were sampled in the field and kept in the laboratory until the female extruded eggs. The clutch interval of each female was
assessed as one of two types of relatively “short” and “long” intervals by checking whether the guarded female had eggs and/or
egg cases from the preceding brood or not when the guarding pair was collected. The clutch interval was longer in females
with prenuptial molting than those without molting and these females usually grew larger at the prenuptial molt. This suggests
that female P. nigrivittatus with a long interval might allocate energy into growth at the expense of the number of clutches during the current reproductive
season. The allocation to growth is theoretically predicted to decrease with female size. Gastropod shell size is also known
to affect the reproductive activity in hermit crabs. However, female size did not significantly affect the clutch interval
in P. nigrivittatus, and the effect of gastropod shell size on clutch interval was not consistent with previous empirical studies. These results
may be caused by differences in the gastropod species of shell occupied by the females of P. nigrivittatus. 相似文献
34.
Iwasaka Y. Shi G.-Y. Shen Z. Kim Y. S. Trochkine D. Matsuki A. Zhang D. Shibata T. Nagatani M. Nakata H. 《Water, Air, & Soil Pollution: Focus》2003,3(2):129-145
Measurements of aerosol were made in August and October 2001, and January 2002, at Dunhuang, China (40°00N, 94°30E), to understand the nature of atmosphericparticles over the desert areas in the Asian continent. Balloon-borne measurements with an optical particle counter suggested that particle size and concentration had a noticeable peak in size range of super micron in not only the boundary mixing layer but also the free troposphere. Thickness of the boundary mixing layer, from distributions of particle concentration, was about 4 km in summer (17 August 2001), about2.5 km in fall (17 October 2001), and about 3 km in winter (11 January 2002), which suggest active mixing of particles near the boundary in summer. Number-size distribution of particleshowed a noticeable peak in the super micron particles size range inthe mixing boundary layer: 0.4–2 particles cm-3 at diameter>1.2 m in summer, 0.05–4 particles cm-3 at diameter >1.2 m in fall, and 0.1–5 particles cm-3 at diameter>1.2 m in winter. In winter strong inversion of atmospherictemperature was found in the height range from the boundary to about 3 km and vertical distribution of particle concentration well corresponded with the temperature distribution. Chemical elements of individual aerosols, which were collectedin the boundary layer atmosphere at Dunhuang (18 October 2001) were analyzed with an electron microscope equipped with EDX. Thosesingle particle analysis suggested that most of the particles with supermicron size were soil particles, and those particles had littlesulfate on its surface. This is a very important different point,comparing with the chemical state of soil particles, which weretransported from the desert area of China to Japan, and showed frequentlythe existence of sulfate on the particle surface. Therefore, it isstrongly suggested that dust particles can be chemically modifiedduring their long-range transport from desert areas to Japan. 相似文献