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Spatial distribution patterns of Crustacea in the floodplain aquifer of an alluvial river (1994)

Ward, J. V. ; Stanford, J. A. ; Voelz, N. J.

Springer

Hydrobiologia 287 (1994), S. 11-17

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ISSN: 1573-5117

Keywords: hyporheic ; floodplain aquifer ; interstitial

Source: Springer Online Journal Archives 1860-2000

Topics: Biology

Notes: Abstract Interstitial crustaceans were collected from a grid of shallow sampling wells penetrating the alluvial floodplain aquifer (ca. 10 m × 5 km × 10 km) of the Flathead River, Montana, USA. Eighteen taxa were identified, which collectively encompassed a range of hypogean-epigean affinities. The subterranean amphipod Stygobromus spp., the most common crustacean, occurred in all wells but was rare in the channel well. When well data were pooled into ‘habitat types’ (channel, bank, near-, central-, and far-floodplain), distinct faunal patterns were apparent. Crustaceans constituted an increasing percentage of the total interstitial fauna from the channel to the near-floodplain, then maintained similar relative abundance levels with increasing distance from the river. Stygobionts attained maximum values at near- and central-floodplain habitats where copepods and ostracods dropped to the lowest levels. Distribution and abundance patterns of Crustacea at the floodplain scale are structured by hydrogeologic and geomorphic processes reflected only in part by distance from the river channel. The flood plain appears to contain a latticework of alluvial-filled paleochannels of high hydraulic conductivity that induce spatial discontinuities within the aquifer and that may play an important role in determining crustacean distribution patterns.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00006892

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Synthesis and properties of polydiacetylene-containing polyesters (1994)

Lovell, P. A. ; Stanford, J. L. ; Wang, Y-F. ; [et al.]

New York, NY [u.a.] : Wiley-Blackwell

Polymer International 34 (1994), S. 23-33

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ISSN: 0959-8103

Keywords: polyesters ; diacetylenes ; cross-polymerisation ; DSC ; Raman spectroscopy ; tensile deformation ; Raman shift factors ; Chemistry ; Polymer and Materials Science

Source: Wiley InterScience Backfile Collection 1832-2000

Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics

Notes: A series of diacetylene-containing polyesters with number-average molar masses (GPC) in the range 900-4200 g mol-1 were prepared from terephthaloyl chloride and hexa-2,4-diyne-1,6-diol using benzoyl chloride as a monofunctional reactant for control of molar mass. Degrees of crystallinity were estimated from WAXD to be up to 29%. Correlations between molar mass, melting behaviour, degree of crystallinity and thermal cross-polymerisation of diacetylene-containing polyesters have been established using hot-stage microscopy, DSC and resonance Raman spectroscopy. The polyester with M̄n of 1264 g mol-1 gave the best balance between processability and the ability to cross-polymerise efficiently. Its degree of crystallinity before cross-polymerisation was estimated from WAXD measurments to be 24%, a value coincident with the percentage conversion of diacetylene units to polydiacetylene chains measured by 13C solid-state NMR. The optimum conditions for compression moulding the polyester to produce a material with a strong Raman spectrum involved heating under vacuum at 120°C for 6h after an initial 3 h heat-up period. The material thus produced gave an intense Raman C=C stretching band, which upon tensile deformation shifted linearly with strain to lower wavenumber by 12.0 cm-1 %-1. The potential use of the diacetylene-containing polyesters in the preparation of model blends for use in quantitative micromechanics studies of stress transfer between phases is briefly discussed.

Additional Material: 9 Ill.