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51.
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53.
Crinoids have been diverse organisms in marine epifaunal filter feeding communities at any level of tiering above the substrate
since they appeared in the Ordovician. Feeding is regarded as the most important factor in producing the crinoid tiering,
which is primarily defined by stalk length. The gut contents of five sympatric crinoid species (three isocrines and two comatulids)
were observed, and these were compared with the stalk length and the fan density. We have classified these crinoid species
into four groups based on the stalk length and fan density, e.g., long stalk with low fan density, long stalk with high fan
density, short stalk with low fan density, and short stalk with high fan density. In the gut contents, diatom crusts were
found mainly from species with longer stalks, and chlorophyll-like fluorescent material were only detected from the groups
with a shorter or no stalk. The group with lower fan density contained more inorganic particles than the group with higher
fan density. Therefore, the gut contents and their amounts depend on their stalk lengths and their fan densities. The results
imply that diversified morphologies in the crinoids have evolved through adaptations to different ecological factors such
as difference in their diets. 相似文献
54.
Tatsunori Yamagishi Tomoyuki Miyazaki Kazuyuki Akiyama Masatoshi Morita Junichi Nakagawa Shozo Horii Seiji Kaneko 《Chemosphere》1981,10(10):1137-1144
This paper describes the analyses of polychlorinated dibenzodioxins, dibenzofurans, and related compounds in diphenyl ether herbicides, CNP, NIP, and X-52. The levels of tetra-, penta-CDDs, and tetra-CDFs were about 150, 30, and 15 ppm, respectively in CNP formulations. NIP and X-52 contained lower chlorine alalogs. Isomer distribution of PCDDs in CNP agreed with an estimate from the reaction of chlorophenols. Freshwater fish samples heavily contaminated with CNP in the application season also contained 0.2 ppb of 1,3,6,8-tetra-CDD. 相似文献
55.
In this study, an electrochemical system was investigated to enhance abiotic dechlorination of chlorinated solvents in contaminated soil in situ. A potentiostatic electrolysis sand reactor was developed and tested to evaluate tetrachloroethene (PCE) dechlorination in saturated sand. When operated with recirculating nutrient-supplemented water the reactor sustained a low oxidation reduction potential (ORP) at the cathode (<-400 mV standard hydrogen electrode [SHE]), a pH less than 9.4, and electric current >5 mA at room temperature with the cathodic potential controlled at -950 mV SHE. Tetrachloroethene in the electrolysis reactor had a half-life of 6.8 d compared with the control bioreactor without electrolysis, which had a PCE half-life of 16.4 d. Ethane and ethene were the main dechlorination products in the test reactor, while trichloroethene (TCE) accumulated in the nutrient-amended control reactor without electrolysis. An electrolysis reactor operated with water not amended with nutrients showed a PCE half-life of 7.6 d, suggesting that most of dechlorination activity in the reactor was abiotic. Since complete dechlorination can be achieved under moderate pH and temperature, this type of electrolysis technology is attractive as a remedial method for subsurface chloroethene contamination. 相似文献
56.
Lead has caused serious environmental pollution due to its toxicity, accumulation in food chains and persistence in nature.In this paper, lead removal from aqueous solutions was investigated using condensed tannin gel adsorbent synthesized from a natural tannin compound. It is found that the adsorption is strongly affected by pH values of aqueous solutions.Within pH range of 3.5-6,when initial lead concentration is 100 mg/L, removal efficiency is more than 90%.Adsorption equilibrium is reached within 150 minutes.The adsorption isotherm fits well with the Langmuir equation, by which the saturated adsorption uptake of 190 mg Pb^2 /g dry tannin gel adsorbent is obtained.By means of thermodynamics analysis,it is revealed that the process is exothermic and the adsorption heat is up to 38.4kJ/mol.With respect to high efficiency, moderate pH requirement and minimized second pollution, the tannin gel adsorbent exhibits a promising potential in the removal of lead from wastewater. 相似文献
57.
The evolution of genome size has been discussed in relation to the evolution of various biological traits. In the present study, the genome sizes of 22 dictyopteran species were estimated by Feulgen image analysis densitometry and 6-diamidino-2-phenylindole (DAPI)-based flow cytometry. The haploid genome sizes (C-values) of termites (Isoptera) ranged from 0.58 to 1.90 pg, and those of Cryptocercus wood roaches (Cryptocercidae) were 1.16 to 1.32 pg. Compared to known values of other cockroaches (Blattaria) and mantids (Mantodea), these values are low. A relatively small genome size appears to be a (syn)apomorphy of Isoptera + Cryptocercus, together with their sociality. In some phylogenetic groups, genome size evolution is thought to be influenced by selective pressure on a particular trait, such as cell size or rate of development. The present results raise the possibility that genome size is influenced by selective pressures on traits associated with the evolution of sociality. 相似文献
58.
59.
Tatsuo Suzuki 《Chemistry and Ecology》2013,29(3-4):249-258
A new material with high content of fly ash named ‘Ashcrete’ has been developed. to examine the applicability of Ashcrete to marine structures, strength characteristics, resistance to sea water attack, and safety in the marine environment have been studied. the following results have been obtained: 1) the strength characteristics of high-volume fly ash concrete depend upon the type and proportions of chemical activators as well as curing conditions. 2) Ashcrete using sodium chloride (NaCI) as a chemical activator shows high initial strength and good strength development with age. 3) Ashcrete containing NaCI activator shows good resistance to sea water from the viewpoint of its strength characteristics, volume changes and microstructurcs. 4) Since 1980 many types of large-scale artificial reefs made of Ashcrete have been installed in the sea. As a result of long-term studies and underwater observations, the Japanese Government has demonstrated the durability of the material, safety in the marine environment and attractiveness to fish. 5) It is therefore proposed that Ashcrete might be used in constructing large-scale sea mounts in deep water for the purpose of generating upwelling. 相似文献
60.
Regular sea urchins show pentaradial symmetry: they have round bodies made of five almost identical sectors. There is no preference
in which sector should be anterior in their locomotion. Anthocidaris crassispina is exceptional among regular sea urchins. Morphometry showed that their tests had radial symmetry but the overall body shape
showed bilateral symmetry because of the uneven distribution of spine length. This bilateral axis did not correspond to the
ambulacrum III—interambulacrum 5 axis, which is the bilateral axis of irregular sea urchins. Their behavior in relation to
this bilaterality was observed in the aquarium. At rest, most of them stayed in the upper corner of the aquarium keeping the
sector with the shortest spine length (the shortest sector) toward the water surface. At walking, most of them moved on the
vertical wall just under the water surface keeping the shortest sector directing to the water surface. When they walked in
the open space, they moved in a random direction with respect to the bilaterality of the spines. The bilaterality and the
behavior of this sea urchin were interpreted as the adaptation to defense not to efficient locomotion. 相似文献