Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China

Observations of the feeding behavior of Cirriformia filigera (Delle Chiaje, 1825) (Annelida: Polychaeta) from the intertidal zone of São Francisco and Engenho D'água beaches (São Sebastião, State of São Paulo) were made in the laboratory. This species, like other cirratulids, is a deposit feeder, feeding mainly on sediment surface with the aid of its grooved and ciliated palps, which are used to capture food particles. The worm lies just beneath the substrate surface in a J-shaped tube. When feeding, it extends up to 4 palps over the sediment surface, capturing food particles which pass down the groove of each palp directly to the mouth. Only fine sand grains are ingested. The worm frequently extends 4 branchial filaments into the overlying water for aeration. When it moves with the prostomium sideways, it collects and transports sand grains that pass backwards along its ventral region until reaching the middle part of its body. Next, the parapodia and palps move the sand grains to the dorsal posterior end of the animal, covering this area with sand. Some sand grains are also ingested as the worm moves.

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Mass transport in water waves over a thin layer of soft viscoelastic mud

Journal of Fluid Mechanics ◽

10.1017/s0022112006003508 ◽

2007 ◽

Vol 573 ◽

pp. 105-130 ◽

Cited By ~ 30

Author(s):

CHIU-ON NG ◽

XUEYAN ZHANG

Keyword(s):

Mass Transport ◽

Thin Layer ◽

Water Waves ◽

Stokes Equations ◽

Steady Motion ◽

Single Layer ◽

Viscoelastic Layer ◽

Layer System ◽

Overlying Water ◽

Viscoelastic Parameter

A theory is presented for the mass transport induced by a small-amplitude progressive wave propagating in water over a thin layer of viscoelastic mud modelled as a Voigt medium. Based on a sharp contrast in length scales near the bed, the boundary-layer approximation is applied to the Navier–Stokes equations in Lagrangian form, which are then solved for the first-order oscillatory motions in the mud and the near-bed water layers. On extending the analysis to second order for the mass transport, it is pointed out that it is inappropriate, as was done in previous studies, to apply the complex viscoelastic parameter to a higher-order analysis, and also to suppose that a Voigt body can undergo continuous steady motion. In fact, the time-mean motion of a Voigt body is only transient, and will stop after a time scale given by the ratio of the viscosity to the shear modulus. Once the mud has attained its steady deformation, the mass transport in the overlying water column can be found as if it were a single-layer system. It is found that the near-bed mass transport has non-trivial dependence on the mud depth and elasticity, which control the occurrence of resonance. Even when the resonance is considerably damped by viscosity, the mass transport in water over a viscoelastic layer can be dramatically different, in terms of magnitude and direction, from that over a rigid bed.

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Identification of suspected paleotsunami deposits study from Karapyak Beach, Pangandaran area, West Jawa, Indonesia

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.36.2.2021.727 ◽

2021 ◽

Vol 36 (2) ◽

Author(s):

Aswan Aswan ◽

Yan Rizal

Keyword(s):

Thin Layer ◽

Energy Flow ◽

Fine Sand ◽

High Energy ◽

Grain Size Analysis ◽

Size Analysis ◽

Tsunami Deposit ◽

Tsunami Deposits ◽

Rock Fragments ◽

Coarse Grains

Identifying and constraining palaeotsunami deposits can be a vital tool for establishing the periodicity of earthquakes and their associated tsunami events beyond the historical records. However, the deposits can be difficult to establish and date. In this study we used the characteristics of the 2006 Pangandaran tsunami deposit as a reference for identification of paleotsunami deposits in Karapyak Beach, Pangandaran area, West Java, Indonesia. Similar to the 2006 Pangandaran tsunami deposit, the Karapyak Beach paleotsunami deposit is characterized by light brown loose sand materials overlying a dark brown paleosoil layer with erosional contact. A thin layer that varies in thickness is locally found right above the erosional contact, with non-laminated coarser grain in the lower part that gradually change into medium to fine sand-sized in upper part. The base of the lower part is rich with broken mollusc shells and corals, and the mid-top of the lower part may contain several intact molusc shells and corals, rock fragments and anthropogenic products (rooftile). Those types of fragments are absent in the upper part of the thin layer. Grain size analysis shows a mixture of fine and coarse grains in the lower part of 2006 tsunami deposits as well as in the suspected paleotsunami deposits, suggesting uprush high energy flow during sedimentation. Fining upward sequence above mixed grain layers reflects waning flow or pre-backwash deposition. Foraminifera analysis also shows a mixture of shallow and deep marine foraminifera in the two deposits. Based on the characteristics of the 2006 tsunami deposits, there are at least four identified paleotsunami deposits at Karapyak Beach, Pangandaran area.

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Preparation and application of an innovative integrated agent product for phosphorus control and oxygen release

Water Science & Technology Water Supply ◽

10.2166/ws.2021.264 ◽

2021 ◽

Author(s):

Zhikang Zhou ◽

Yulong Liu ◽

Xiaogang Gu ◽

Chaoxiang Yang ◽

Shuguang Lyu

Keyword(s):

Citric Acid ◽

Calcium Phosphate ◽

Stearic Acid ◽

River Water ◽

Fine Sand ◽

Aluminum Phosphate ◽

Phosphorus Release ◽

Oxygen Release ◽

Overlying Water ◽

Dissolved Phosphorus

Abstract In this study, an oxygen-releasing and phosphorus-controlling agent (ORPC) consisting of calcium peroxide (CaO2), bentonite, cement, stearic acid (SA), citric acid (CA) and fine sand was synthesized successfully and used to purify rich-phosphorus river water. The removal of phosphorus using ORPC was studied in actual river water and the results found that over 75.0% phosphorus was removed by adding ORPC at 30 mL h−1 flow rate in the initial phosphorus concentrations of 0.76 mg L−1. The ORPC was further used to evaluate the changes of aluminum phosphate (Al-P), ferric phosphate (Fe-P) and calcium phosphate (Ca-P) in sediment. Fe-P, Al-P, and Ca-P in the sediment increased from 0.14, 0.196, and 1.63 mg g−1 to 0.159, 0.372, and 2.74 mg g−1 respectively within 28 days, indicating that the total dissolved phosphorus in the overlying water could be adsorbed by ORPC and further transformed into Al-P, Ca-P, and Fe-P in the sediment, thus inhibiting the release of endogenous phosphorus in sediment to water. Besides, the performance of ORPC with various contents of SA and CaO2 was investigated. In summary, ORPC can be employed to adsorb phosphorus in water and prevent phosphorus release from sediment, therefore achieving the purpose of controlling phosphorus and maintaining DO at a reasonable level.

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Phosphorus Release Processes in Nearshore Southern Lake Michigan

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f86-149 ◽

1986 ◽

Vol 43 (6) ◽

pp. 1201-1207 ◽

Cited By ~ 17

Author(s):

Michael A. Quigley ◽

John A. Robbins

Keyword(s):

Pore Water ◽

Lake Michigan ◽

Sampling Site ◽

Soluble Reactive Phosphorus ◽

Fine Sand ◽

Phosphorus Release ◽

Fickian Diffusion ◽

Phosphorus Cycle ◽

Release Rates ◽

Overlying Water

We determined soluble reactive phosphorus (SRP) release rates from intact, medium-fine sand cores obtained from an 11-m-deep sampling site in nearshore Lake Michigan during July–October 1980. Mean SRP release ranged from 0.17 ± 0.03 (SE) to 0.57 ± 0.04 mg PO4-P∙m−2∙d−1. Pore water analysis indicated that, despite high dissolved oxygen concentrations in the uppermost 6 cm of sediment, SRP concentrations increased rapidly with depth throughout this zone. Moreover, a Fickian diffusion equation based on the SRP pore water gradient and physical sediment features predicted a release rate (1.12 mg PO4-P∙m−1∙d−1) that was 2–7 times higher than release rates measured from intact cores. Results suggest that nearshore sediments provide a ready pathway for the return of SRP to overlying water, and this process warrants inclusion in future conceptual models of Lake Michigan's phosphorus cycle.

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Aqueous Mercury Removal with Carbonaceous and Iron Sulfide Sorbents and Their Applicability as Thin-Layer Caps in Mercury-Contaminated Estuary Sediment

Water ◽

10.3390/w12071991 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1991 ◽

Cited By ~ 1

Author(s):

Boon-Lek Ch’ng ◽

Che-Jung Hsu ◽

Yu Ting ◽

Ying-Lin Wang ◽

Chi Chen ◽

...

Keyword(s):

Activated Carbon ◽

Thin Layer ◽

Removal Efficiency ◽

Iron Sulfide ◽

Aqueous System ◽

Batch Adsorption ◽

Overlying Water ◽

Salinity Levels ◽

Microcosm Studies ◽

Aqueous Mercury

This study aimed to investigate the Hg removal efficiency of iron sulfide (FeS), sulfurized activated carbon (SAC), and raw activated carbon (AC) sorbents influenced by salinity and dissolved organic matter (DOM), and the effectiveness of these sorbents as thin layer caps on Hg-contaminated sediment remediation via microcosm experiments to decrease the risk of release. In the batch adsorption experiments, FeS showed the greatest Hg2+ removal efficiencies, followed by SAC and AC. The effect of salinity levels on FeS was insignificant. In contrast, the Hg2+ removal efficiency of AC and SAC increased as increasing the salinity levels. The presence of DOM tended to decrease Hg removal efficiency of sorbents. Microcosm studies also showed that FeS had the greatest Hg sorption in both freshwater and estuary water; furthermore, the methylmercury (MeHg) removal ability of sorbents was greater in the freshwater than that in the estuary water. Notably, for the microcosms without capping, the overlying water MeHg in the estuary microcosm (0.14−1.01 ng/L) was far lesser than that in the freshwater microcosms (2.26−11.35 ng/L). Therefore, Hg compounds in the freshwater may be more bioavailable to microorganisms in methylated phase as compared to those in the estuary water. Overall, FeS showed the best Hg removal efficiency, resistance to salinity, and only slightly affected by DOM in aqueous adsorption experiments. Additionally, in the microcosms, AC showed as the best MeHg adsorber that help inhibiting the release of MeHg into overlying and decreasing the risk to the aqueous system.

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Underprints of vertebrate and invertebrate trackways in the Coconino Sandstone (Permian) in northern Arizona

The Paleontological Society Special Publications ◽

10.1017/s2475262200005931 ◽

1992 ◽

Vol 6 ◽

pp. 33-33

Author(s):

Leonard R. Brand ◽

Jon Kramer

Keyword(s):

Thin Layer ◽

Fine Sand ◽

Front Edge ◽

Separate Paper ◽

Northern Arizona ◽

Behavioral Aspects ◽

Show Evidence ◽

Permian Deposit ◽

Made In

The Coconino Sandstone is a Permian deposit of cross-bedded sandstone which is distributed over much of northern Arizona. Vertebrate fossil trackways are abundant in the Coconino Sandstone, and invertebrate trackways are present but less abundant. No other fossils have been found in this formation.A number of papers dealing with the systematics and paleoecology of these tracks have been published, but underprints have not previously been reported from the Coconino Sandstone. A slab from north of Seligman, Arizona bears intersecting trackways of an invertebrate and two tetrapods. A portion of the slab contains the surface on which the animals were walking. On the remainder of the slab a thin layer bearing that upper surface has broken away to reveal another surface with well preserved underprints of both invertebrates and tetrapods (systematic and behavioral aspects of these trackways will be described in a separate paper).The underprints are very distinct, deep depressions with uniformly rounded edges, while the original tracks are shallower and much less distinct because some sand slumped into them. It appears that as the animal lifted its foot out of a track the sand partly filled in the depression, but in underlying laminae the contour of the underprint was protected by the sand pushed down from above by the animal's foot.Comparison of this slab with other fossil trackways from the Coconino Sandstone suggests that a number of these trackways may be underprints. Evidence favoring that interpretation are the clarity and depth of the footprints and their uniformly rounded edges. This interpretation also suggests an explanation for some footprints that are so deep that the sand on the front edge of the track overhangs the footprint impression. The Coconino Sandstone is composed of fine sand and does not show evidence of clays or other material that could provide the cohesion to retain such steep, even overhanging, surfaces. If these footprints are underprints, the deep, undercut impressions may have been preserved by the continuity of the overlying laminae while the surface depressions were partly filled by slumping sand.It might be expected that underprints would be less distinct and detailed than the actual print. That may be true for tracks made in a substrate with an ideal consistency for preserving the tracks, but in pure, fine sand slumping of sand at the surface can apparently obliterate footprint details that are preserved in the underprints.

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Applications of Photoelectron Microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092499 ◽

1976 ◽

Vol 34 ◽

pp. 506-507

Author(s):

William J. Baxter

Keyword(s):

Electron Microscopy ◽

Thermal Decomposition ◽

Chemical Composition ◽

Ultraviolet Radiation ◽

Thin Layer ◽

Edge Effects ◽

Electron Optics ◽

Surface Layers ◽

Crystalline Orientation ◽

Fluorescent Screen

In this form of electron microscopy, photoelectrons emitted from a metal by ultraviolet radiation are accelerated and imaged onto a fluorescent screen by conventional electron optics. image contrast is determined by spatial variations in the intensity of the photoemission. The dominant source of contrast is due to changes in the photoelectric work function, between surfaces of different crystalline orientation, or different chemical composition. Topographical variations produce a relatively weak contrast due to shadowing and edge effects.Since the photoelectrons originate from the surface layers (e.g. ∼5-10 nm for metals), photoelectron microscopy is surface sensitive. Thus to see the microstructure of a metal the thin layer (∼3 nm) of surface oxide must be removed, either by ion bombardment or by thermal decomposition in the vacuum of the microscope.

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