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Titolo:
Influence of particle shape and sorting upon sample size estimates for a coarse-grained upland stream
Autore:
Milan, DJ; Heritage, GL; Large, ARG; Brunsdon, CF;
Indirizzi:
Univ Newcastle Upon Tyne, Dept Geog, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England Univ Newcastle Upon Tyne Newcastle Upon Tyne Tyne & Wear England NE1 7RU Univ Salford, Dept Geog, Salford M5 4WP, Lancs, England Univ Salford Salford Lancs England M5 4WP Salford M5 4WP, Lancs, England
Titolo Testata:
SEDIMENTARY GEOLOGY
fascicolo: 1-2, volume: 129, anno: 1999,
pagine: 85 - 100
SICI:
0037-0738(199911)129:1-2<85:IOPSAS>2.0.ZU;2-R
Fonte:
ISI
Lingua:
ENG
Soggetto:
FLUVIAL GRAVELS; PRECISION; SEDIMENTS;
Keywords:
sediments; sample size; shape; sorting; truncation; fluvial gravel; freeze-cores;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
25
Recensione:
Indirizzi per estratti:
Indirizzo: Milan, DJ Univ Newcastle Upon Tyne, Dept Geog, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England Univ Newcastle Upon Tyne Newcastle Upon Tyne Tyne &Wear England NE1 7RU
Citazione:
D.J. Milan et al., "Influence of particle shape and sorting upon sample size estimates for a coarse-grained upland stream", SEDIMENT GE, 129(1-2), 1999, pp. 85-100

Abstract

Present bulk-sampling recommendations for the characterisation of fluvial sediments based upon ellipsoids of revolution do not take into account variations in particle shape and sorting. Disc-shaped particles with equivalentb-axes to spheres have lower relative masses and require more relaxed sampling criteria compared to existing recommendations, whereas heavier cube- and rod-shaped particles require more stringent criteria. Empirical data from the River Reds, Northumberland, UK, an upland gravel-bed channel, indicate that samples are dominated by discs. However, particle shape was not constant in every grain-size fraction; blocky material (cubes and rods) was more frequent in the >63 mm fraction in comparison to the other finer fractions. Data based on the weight of the D-99.9 particle indicate that a larger sample weight is required when the coarsest size category of that sample is dominated by blocky material. Sorting also affects the size of the sample required to characterise a deposit; the more poorly sorted the deposit, the larger the sample has to be or the finer should be the truncation,sr ain size. This is particularly evident in samples with a high matrix concentration. Two sample reference Lines, developed from these data using the 0.1% by mass criteria, recommend larger minimum sample sizes (or finer truncation) in comparison to other published standards. Data from a second site supportthese results, indicating that they may be applicable to other poorly sorted upland gravel-bed streams. Analysis of the size category variance demonstrates that the new guidelines returned the lowest variance levels, suggesting that they should be used where particularly accurate sampling procedures are required. (C) 1999 Elsevier Science B.V. All rights reserved.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 20/09/20 alle ore 23:36:30