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Single-crystal Raman spectra of marcasite-type FeS2, FeSe2, and FeTe2 and loellingite-type FeP2, FeAs2, and FeSb2 are presented and discussed with reference to the energies of the two X-X stretching modes v
x-x (A
g, B
1g) and the four X2 librations Rx2 (A
g, B
1g, B
2g, B
3g). The main results obtained are that (i) the intraionic X-X bonds of FeS2 marcasite and FeS2 pyrite are nearly equal in strengths (mean values of the S-S stretching modes 418 and 420 cm-1, respectively) and (ii) the interactions of the metal ions and the dumbbell-like X2 units increase on going from the chalcogenides to the respective pnictides and from FeS2 marcasite to pyrite (as shown from the frequencies of the X2 librations). 相似文献
13.
L. W. Fritz R. A. Lutz M. A. Foote C. L. van Dover J. W. Ewart 《Estuaries and Coasts》1984,7(4):513-518
Results of laboratory feeding experiments suggest that oyster (Crassostrea virginica) larvae select small phytoplanktonic organisms (<10 μm) over larger-celled forms from natural estuarine assemblages, but that little selection occurs within the small phytoplankton fraction. Laboratory-reared larvae grazed each of five small-celled phytoplankton groups enumerated (coccoids, centrate diatoms, pennate diatoms, dinoflagellates, and flagellates) at rates proportional to phytoplankton group densities in controls (no larvae added). Larval grazing rates (number of cells removed per larva per hour) were inversely proportional to both larval density and experimental duration. 相似文献
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From 1998 to 2002 investigations were carried out to estimate both the quantity and quality (heavy metal contents) of suspended matter loads discharged into a floodplain area measuring approx. 5 km2 of the Central German river Weiße Elster, a tributary of the river Saale in the Elbe river basin. Flood sediments, suspended particulate matter, and floodplain soils were investigated especially for the main pollutants Cd, Zn, Cu, Pb, Cr, and Hg. Supplementary gamma spectroscopy examinations were performed to help to identify the age of deposits in order to estimate sedimentation rates for last decades. The recent flood sediments are contaminated by up to 33 times the geogenic background (Cd). Up to 55% of the total annual SPM load of the river Weiße Elster is relocated into the investigated retention area in the flood‐stricken year 2002. The sedimentation rates for the last 50 years vary between 0.5 mm/a and 1 mm/a in far away and rarely flooded parts and between 1 mm/a and 2 mm/a in the frequently flooded parts of the inflow of the retention area. 相似文献
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From wind profile and wave measurements performed during the JONSWAP II experiment, relations between the dimensionless profile slope and the significant wave height are derived. It is shown that the wind profile is distorted by the waves especially in the vicinity of the water surface. The wave influence on the profile seems to be restricted to heights below about three wave heights. Above this level, the dimensionless profile slope is an approximately constant value corresponding to a drag coefficient of about 1.15 × 10–3. 相似文献
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