Modeling of acoustic penetration into sandy sediments: Physical and geometrical aspects

2009 ◽  
Vol 126 (5) ◽  
pp. 2206-2214 ◽  
Author(s):  
V. Aleshin ◽  
L. Guillon
Keyword(s):  
Acoustic Penetration ◽  
Sandy Sediments

Approaching daily life at Late Palaeolithic camps: The case of Lubrza 10, Western Poland

2020 ◽  
Vol 95 (2) ◽  
pp. 311-333
Author(s):  
Iwona Sobkowiak-Tabaka ◽  
Aleksandr Diachenko
Keyword(s):  
Daily Life ◽  
Site Formation ◽  
Site Formation Processes ◽  
The North ◽  
Locational Analysis ◽  
Research Procedure ◽  
Sandy Sediments ◽  
Integrative Social ◽  
Late Palaeolithic

AbstractThe aim of this paper is to develop a systematic approach to understanding daily life at Late Palaeolithic camps and identifying its impact on broader site formation processes. Late Palaeolithic contexts are often poorly preserved, especially those found in the sandy sediments of the North European Plain. However, taphonomic obstacles may be overcome through the introduction of spatial statistics into research procedures. We illustrate our approach using a case study of Federmesser and Swiderian campsites at the site of Lubrza 10, Western Poland. The locational analysis of hearths, features that constitute the most important integrative social foci of Palaeolithic camps, provides information on activity areas, seasonality and occupational duration. Additionally, we examine the function of spatially distinct artefact concentrations and their methods of aggregation. The presented research procedure enables us to trace the contribution of individuals to group behaviour, as well as specific individual activities at both camps.

Size spectra, body width and morphotypes of intertidal nematodes: an ecological interpretation

1999 ◽  
Vol 79 (6) ◽  
pp. 1007-1015 ◽  
Author(s):  
G. Tita ◽  
M. Vincx ◽  
G. Desrosiers
Keyword(s):  
Nematode Species ◽  
The Body ◽  
Influential Factor ◽  
Tidal Level ◽  
Body Width ◽  
Size Spectra ◽  
Lawrence Estuary ◽  
Quality Food ◽  
The Mean ◽  
Sandy Sediments

Nematode species from three intertidal assemblages (St Lawrence Estuary, Quebec, Canada) were studied in order to form an ecological interpretation of three allometric attributes: body width, size spectra, and morphotypes. The three assemblages were characterized by a very similar sediment grain median (Md) but different silt–clay proportions: A1 (upper-tidal level; Md=122 μm; silt=34.8%), A3 (mid-tidal level; Md=182 μm; silt=12.8%), and A5 (lower-tidal level; Md=122 μm; silt=6.8%). Silt–clay proportions were an influential factor in determining the mean nematode body width, used as a morphological discriminant between burrowing and interstitial organisms. A plot of the number of species vs the body width-classes showed two peaks: between 19.3 and 22.6 μm (interstitial), and between 32.0 and 45.5 μm (burrowers). As for the size spectra, in sandy sediments the mean nematode individual biomass was smaller than in muddy sediments. As a consequence, the estimated mean individual respiration rate was greater in muddy (A1=2.26 nl O2 h−1) than sandy sediments (A3=1.25 nl O2 h−1; A5=1.12 nl O2 h−1). In contrast, estimated metabolic ratios were lower in A1 (2.78 nl O2 h−1 μg−1 dry weight, DW) than in A3 (2.95 nl O2 h−1 μg−1 DW) and A5 (3.01 nl O2 h−1 μg−1 DW) suggesting different productivity and/or physiological adaptations to different lifestyles (burrowing vs interstitial) between species inhabiting muddy or sandy sediments. Morphotypes (body width/body length ratio=w/l ratio) were found to be associated with feeding groups. Small w/l ratios were typical of microvores, while greater ratios were typical of epigrowth feeders and predators. Ciliate-feeders, deposit-feeders and facultative predators had intermediate ratios. A morphotype food-related hypothesis is proposed: the species morphotype reflects the quality of exploited food; a small w/l ratio (i.e. long gut) would favour digestive efficiency and would be an adaptation to low quality food (microvores); inversely, a greater w/l ratio (i.e. short gut) would be an adaptation to high quality food (epigrowth-feeders and predators).

scholarly journals Remote sensing of underwater vegetation using single-beam acoustics

2009 ◽  
Vol 67 (3) ◽  
pp. 594-605 ◽  
Author(s):  
Victor Quintino ◽  
Rosa Freitas ◽  
Renato Mamede ◽  
Fernando Ricardo ◽  
Ana Maria Rodrigues ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Grain Size ◽  
Algal Biomass ◽  
Sediment Grain Size ◽  
Coastal System ◽  
Single Beam ◽  
Acoustic Data ◽  
Sediment Types ◽  
Caulerpa Prolifera ◽  
Sandy Sediments

Abstract Quintino, V., Freitas, R., Mamede, R., Ricardo, F., Rodrigues, A. M., Mota, J., Pérez-Ruzafa, Á., and Marcos, C. 2010. Remote sensing of underwater vegetation using single-beam acoustics. – ICES Journal of Marine Science, 67: 594–605. A single-beam, acoustic, ground-discrimination system (QTC VIEW, Series V) was used to study the distribution of underwater macrophytes in a shallow-water coastal system, employing frequencies of 50 and 200 kHz. The study was conducted in Mar Menor, SE Spain, where the expansion of Caulerpa prolifera has contributed to the silting up of the superficial sediments. A direct relationship was identified between algal biomass and sediment-fines content. Acoustic information on sediment grain size and data on algal biomass were obtained in muddy and sandy sediments, including vegetated and non-vegetated seabed. Non-vegetated muddy areas were created by diving and handpicking the algae. The multivariate acoustic data were analysed under the null hypotheses that there were no acoustic differences between bare seabeds with contrasting superficial sediment types or among low, medium, and high algal-biomass areas, having in mind that grain size can act as a confounding factor. Both null hypotheses were rejected, and the results showed that 200 kHz was better than 50 kHz in distinguishing cover levels of algal biomass. The relationship between the 200-kHz acoustic data and algal biomass suggests utility in modelling the latter using the former.

A high-resolution pore water sampler for sandy sediments

2001 ◽  
Vol 46 (1) ◽  
pp. 203-210 ◽  
Author(s):  
Peter Berg ◽  
Karen J. McGlathery
Keyword(s):  
High Resolution ◽  
Pore Water ◽  
Water Sampler ◽  
Sandy Sediments ◽  
Pore Water Sampler

scholarly journals Microphytobenthic primary production on exposed coastal sandy sediments of the Southern Baltic Sea using ex situ sediment cores and oxygen optodes

Oceanologia ◽  
2021 ◽  
Vol 63 (2) ◽  
pp. 247-260
Author(s):  
Kana Kuriyama ◽  
Sigrid Gründling-Pfaff ◽  
Nora Diehl ◽  
Jana Woelfel ◽  
Ulf Karsten
Keyword(s):  
Primary Production ◽  
Baltic Sea ◽  
Sediment Cores ◽  
Ex Situ ◽  
Southern Baltic Sea ◽  
Southern Baltic ◽  
Sandy Sediments

AE monitoring-based CO2 hydrate formation and its influences to hydrate-bearing sandy sediments

2021 ◽  
pp. 104292
Author(s):  
Xiaodong Zhao ◽  
Tingting Luo ◽  
Shengye Zhuang ◽  
Zejin Lai ◽  
Ruilin Li
Keyword(s):  
Hydrate Formation ◽  
Sandy Sediments

scholarly journals Common environmental descriptors of two benthic amphi-atlantic mollusc assemblages

2006 ◽  
Vol 54 (1) ◽  
pp. 65-73 ◽  
Author(s):  
Ricardo S. Absalão ◽  
J. Moreira ◽  
Jesus S. Troncoso
Keyword(s):  
Rio De Janeiro ◽  
Environmental Data ◽  
Multiple Discriminant Analysis ◽  
Medium Sand ◽  
Sediment Grain Size ◽  
Environmental Space ◽  
Macro Scale ◽  
Molluscan Fauna ◽  
Mollusc Assemblages ◽  
Sandy Sediments

Two benthic mollusc assemblages of the continental shelf on both sides of the Atlantic Ocean, a tropical one in Rio de Janeiro, Brazil, and another, temperate, in Galicia, Spain were investigated, with a view to finding common environmental descriptors which would explain, on a macro-scale, why these assemblages are there. Both of the assemblages concerned show approximately the same species richness, about 150 taxa each. The molluscan fauna of both regions live on sandy sediments. The Galician assemblages are at about 2-12 m depth, while those in Rio de Janeiro are at about 10-40 m depth. Malacological assemblages were defined through Cluster Analysis and Multiple Discriminant Analysis of the environmental data showed that each assemblage has its own environmental space. These assemblages have no species in common, but show the same phenological characters associated with each sedimentological facies. The same set of environmental variables (median sediment grain size, skewness, kurtosis, sorting, fine and medium sand fractions and depth) were selected as controlling these assemblages, suggesting that they play their role as general environmental descriptors.

Mantis shrimps Rissoides desmaresti in Tremadog Bay, North Wales

2001 ◽  
Vol 81 (4) ◽  
pp. 695-696 ◽  
Author(s):  
Kirsten Ramsay ◽  
Rohan H.F. Holt
Keyword(s):  
Average Length ◽  
Average Diameter ◽  
Survey Area ◽  
Horizontal Section ◽  
Mantis Shrimp ◽  
North Wales ◽  
Burrow Entrance ◽  
Sand And Gravel ◽  
Sandy Sediments ◽  
Burrow Morphology

In 1999 divers discovered a population of the burrowing mantis shrimp Rissoides (Meiosquilla) desmaresti (Crustacea: Stomatopoda) east of the St Tudwal's Islands, North Wales. This species has only sporadically been recorded in UK waters and commonly occurs in the Mediterranean. In summer 2000 the burrow morphology and distribution of these shrimps in the area east of the St Tudwal's Islands was investigated. Burrows were found at ten of the 15 sites investigated in a survey area measuring ∼18 km2. Burrow density varied from one to 11 burrows per 100 m2. The burrows were always recorded in sediments consisting of a mixture of mud, sand and gravel but were not present at sites with a high proportion of mud (>70%) or sandy sediments with very little mud ([les ]2%). Resin casts of six burrows revealed that these have a simple elongated U-shape, with an average length of ∼450 mm and depth of ∼160 mm. The average diameter of the burrow entrance was 19±2 mm and the diameter of the burrow along the horizontal section varied between 18 and 38 mm with a distinct constriction part way along.

scholarly journals Crevasse splays within a lignite seam at the Tomisławice opencast mine near Konin, central Poland: architecture, sedimentology and depositional model

Geologos ◽  
2020 ◽  
Vol 26 (1) ◽  
pp. 25-37 ◽  
Author(s):  
Lilianna Chomiak
Keyword(s):  
Middle Miocene ◽  
Structural Features ◽  
Fine Grained ◽  
Opencast Mine ◽  
Main River ◽  
Main River Channel ◽  
Lignite Mine ◽  
Flooding Event ◽  
Crevasse Splay ◽  
Sandy Sediments

AbstractThe present article focuses predominantly on sandy deposits that occur within the Middle Miocene lignite seam at the Tomisławice opencast mine, owned by the Konin Lignite Mine. As a result of mining activity, these siliciclastics were available for direct observation in 2015–2016. They are situated between two lignite benches over a distance of ~500 m in the lower part and ~200 m in the higher part of the exploitation levels. The maximum thickness of these sandy sediments, of a lenticular structure in a S–N cross section, is up to 1.8 m. With the exception of a thin lignite intercalation, these siliciclastics comprise mainly by fine-grained and well-sorted sands, and only their basal and top layers are enriched with silt particles and organic matter. Based on a detailed analysis of the sediments studied (i.e., their architecture and textural-structural features), I present a discussion of their genesis and then propose a model of their formation. These siliciclastics most likely formed during at least two flood events in the overbank area of a Middle Miocene meandering or anastomosing river. Following breaching of the natural river levee, the sandy particles (derived mainly from the main river channel and levees) were deposited on the mire (backswamp) surface in the form of crevasse splays. After each flooding event, vegetation developed on the top of these siliciclastics; hence, two crevasse-splay bodies (here referred to as the older and younger) came into existence. As a result, the first Mid-Polish lignite seam at the Tomisławice opencast mine is currently divided in two by relatively thick siliciclastics, which prevents a significant portion of this seam from being used for industrial purposes.

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