The formation of apatite from crab faecal pellets

1994 ◽  
Vol 74 (2) ◽  
pp. 459-462 ◽  
Author(s):  
K. Simkiss ◽  
M.G. Taylor
Keyword(s):  
Digestive Gland ◽  
Marine Environment ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Shore Crab ◽  
X Ray Diffraction ◽  
X Ray ◽  
Faecal Pellets ◽  
Saline Solutions

Intracellular granules have been isolated from the digestive gland of the shore crab Carcinus maenas (L.). These granules are normally shed from this tissue during the digestive cycle and are shown to occur in considerable numbers in the faecal strands. The granules are amorphous to x-ray diffraction and remain in this state in sea-water for several weeks, although they will transform into crystalline apatite in simpler saline solutions. The fate of these deposits in the marine environment is discussed in relation to their contribution to sediments and phosphorites.

Zinc Regulation in the Lobster Homarus Gammarus: Importance of Different Pathways of Absorption and Excretion

1986 ◽  
Vol 66 (1) ◽  
pp. 175-199 ◽  
Author(s):  
G. W. Bryan ◽  
L. G. Hummerstone ◽  
Eileen Ward
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
The Body ◽  
Shore Crab ◽  
Freshwater Crayfish ◽  
Uptake Mechanism ◽  
Major Pathway ◽  
Homarus Gammarus ◽  
Wide Range ◽  
Body Concentration

Zinc is one of the most important of the essential trace metals and more than 90 zinc-containing enymes and proteins have been discovered: furthermore, zinc increases the activity of many other enzymes (Vallee, 1978). It is not surprising, therefore, that in some groups of animals the body concentration is regulated against fluctuations in intake. Decapod crustaceans comprise one such group, although the ways in which regulation is achieved vary from species to species. In the freshwater crayfish, Austropotamobius pallipes, excretion in the faeces is a major pathway for removing zinc (Bryan, 1967a) whereas in the shore crab Carcinus maenas losses over the body surface also assume considerable importance (Bryan, 1966). On the other hand, preliminary work on the lobster Homarus gammarus (formerly H. vulgaris) suggests that in this species urinary excretion plays a major role in regulation (Bryan, 1964). The present work continues the study of zinc regulation in lobsters and its main aims are: (1) to measure rates of absorption from sea water over a wide range of concentrations and study the uptake mechanism; (2) to examine absorption from the stomach under different conditions; (3) to determine the relative importance of different pathways for the removal of zinc in response to various levels of intake.

The hydrocerussite-related phase, NaPb5(CO3)4(OH)3, from the ancient slags of Lavrion, Greece

2018 ◽  
Vol 82 (4) ◽  
pp. 809-819 ◽  
Author(s):  
Oleg I. Siidra ◽  
Diana O. Nekrasova ◽  
Nikita V. Chukanov ◽  
Igor V. Pekov ◽  
Vasiliy O. Yapaskurt ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Infrared Spectroscopy ◽  
Sea Water ◽  
Mining District ◽  
X Ray Diffraction ◽  
Electron Pairs ◽  
X Ray ◽  
Lead Hydroxide ◽  
Lamellar Crystals ◽  
Related Phase

ABSTRACTThe hydrocerussite-related phase, NaPb5(CO3)4(OH)3, has been found as colourless lamellar crystals in cavities within a pebble of the ancient marine slag collected in the Pacha Limani area of the Lavrion mining district, Attiki, Greece. This phase of anthropogenic origin was characterized by electron microprobe, infrared spectroscopy, powder and single-crystal X-ray diffraction. The unique crystal structure (P63/mmc,a= 5.2533(11),c= 29.425(6) Å,V= 703.3(3) Å3andR1= 0.047) is based upon structurally and chemically different electroneutral blocks. Each of the blocks can be split into separate sheets. The outer sheets in each block are topologically identical and have the composition [PbCO3]0. The [Pb(OH)2]0lead hydroxide sheet is sandwiched between the two [PbCO3]0sheets resulting in the formation of the first block [Pb3(OH)2(CO3)2]0structurally and compositionally identical to that one in hydrocerussite Pb3(OH)2(CO3)2. Similarly the [Na(OH)]0sheet is sandwiched between another two [PbCO3]0sheets thus forming the [NaPb2(OH)(CO3)2]0block described previously in the structure of abellaite NaPb2(OH)(CO3)2. Stereochemically active lone electron pairs on Pb2+cations are located between the blocks. There are two blocks of each type per unit cell, which corresponds to the following formula: [Pb3(OH)2(CO3)2][NaPb2(OH)(CO3)2] or NaPb5(CO3)4(OH)3in the simplified representation. The formation of NaPb5(CO3)4(OH)3in Lavrion slags is by the contact of lead-rich slags with the sea water over the last two thousand years.

scholarly journals Characterization of Slag Reprocessing Tailings-Based Geopolymers in Marine Environment

Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 832 ◽  
Author(s):  
Jie Wu ◽  
Jing Li ◽  
Feng Rao ◽  
Wanzhong Yin
Keyword(s):  
Compressive Strength ◽  
Marine Environment ◽  
Copper Slag ◽  
X Ray Diffraction ◽  
Strength Measurement ◽  
X Ray ◽  
Sodium Aluminosilicate ◽  
Marine Concrete ◽  
Sodium Aluminosilicate Hydrate

In this study, copper slag reprocessing tailings (CSRT) were synthesized into geopolymers with 40%, 50% and 60% metakaolin. The evolution of compressive strength and microstructures of CSRT-based geopolymers in a marine environment was investigated. Except for compressive strength measurement, the characterizations of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM) were included. It was found that marine conditions changed the Si/Al ratio in the sodium-aluminosilicate-hydrate (N-A-S-H) gel backbone, promoted the geopolymerization process, led to more Q4(3Al), Q4(2Al) and Q4(1Al) gel formation and a higher compressive strength of the geopolymers. This provided a basis for the preparation of CSRT-based geopolymers into marine concrete.

scholarly journals Chloride Distribution and Steel Corrosion in a Concrete Bridge after Long-Term Exposure to Natural Marine Environment

Materials ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 3900 ◽  
Author(s):  
Jun Liu ◽  
Zhilu Jiang ◽  
Yulong Zhao ◽  
Hao Zhou ◽  
Xiaodong Wang ◽  
...  
Keyword(s):  
Reinforced Concrete ◽  
Marine Environment ◽  
Chloride Transport ◽  
Steel Corrosion ◽  
Concrete Bridge ◽  
Reinforced Concrete Structure ◽  
X Ray Diffraction ◽  
Tidal Zone ◽  
X Ray

Chloride-induced steel corrosion is the most concerning issue for the durability of concrete structures. Concrete and steel samples were obtained from a 30-year-old reinforced concrete bridge. The chloride content was measured by a potentiometric titration method and the microstructure of concrete was obtained by scanning electron microscopy and mercury intrusion porosimetry. The rust phases of the steel were detected by X-ray diffraction and Raman analysis. It was found that the convection depth for chloride transport in cracked concrete was significantly larger than that in uncracked concrete. The concrete in a pier column facing upstream had greater porosity due to the water impact and calcium leaching. The coefficients of variability of chloride diffusivity of concrete for the bridge deck and the pier column were significantly different. Rust phases including lepidocrocite, goethite, akaganeite, magnetite, and maghemite were detected using Raman spectroscopy and X-ray diffraction. The major phases of steel rust in the atmospheric zone were lepidocrocite and goethite, while they were lepidocrocite and maghemite in the tidal zone. The results of this study would provide information concerning the chloride-induced steel corrosion under a marine environment in order to predict long-term behaviors of a reinforced concrete structure.

Reducing Activity and the Formation of Base in the Shore Crab, Carcinus Maenas

1985 ◽  
Vol 65 (2) ◽  
pp. 505-530 ◽  
Author(s):  
Peter S. B. Digby
Keyword(s):  
Outer Surface ◽  
Biological Material ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Water Salinity ◽  
Shore Crab ◽  
Calcareous Deposits ◽  
Reducing Activity ◽  
Diffusion Potentials ◽  
Active Processes

Crustacean cuticle consists essentially of chitin impregnated and coated with protein which is tanned with quinone (Dennell, 1947a). The outer surface is most heavily tanned, and the cuticle is further strengthened by calcification. The various theories as to the mechanism of calcification in crustacean and other biological material have been reviewed briefly by Digby (1967). Most appear unsatisfactory for various reasons, and evidence was outlined that calcification might arise from the formation of base by processes which are essentially electrochemical in origin. The quinone-tanned protein of the cuticle is electrically semiconducting and supports electrode action in suitable gradients of potential (Digby, 1965), and small potential differences may arise by diffusion or by active processes. Thus the deposition of calcareous salts might arise partly at least by action comparable to that which takes place at a metallic cathode. In support of this, the position of the initial calcareous deposits in Carcinus maenas (L.) was found to change with the gradient of sea-water salinity in the manner expected if some control were exercised by diffusion potentials, acting across a thin semiconducting layer to generate small changes of pH (Digby, 1968).

Suspension feeding in larval crabs (Carcinus maenas)

1993 ◽  
Vol 73 (1) ◽  
pp. 207-211 ◽  
Author(s):  
Jan Robert Factor ◽  
Barbara L. Dexter
Keyword(s):  
Size Range ◽  
Sea Water ◽  
Carcinus Maenas ◽  
Epifluorescence Microscopy ◽  
Shore Crab ◽  
Suspension Feeding ◽  
Natural Diet ◽  
Crab Larvae ◽  
Water Suspensions ◽  
Detrital Particles

First-stage zoeal larvae of the green (shore) crab, Carcinus maenas (Crustacea: Brachyura: Portunidae), ingested three types of particles offered in sea-water suspensions. In experiments using two types of fluorescent particles (1–2 µm and 1–7 µm ) and living Dunaliella tertiolecta cells (5–7 µm), particles were ingested in at least 40% of the zoeae examined with brightfield, darkfield, and epifluorescence microscopy. These results suggest that green crab larvae may be capable of utilizing planktonic particles in the size range of bacteria, small algal cells, and organically-enriched detrital particles in their natural diet.

Bio‐fouling and corrosion characteristics of 60/40 brass in Mandapam waters

2002 ◽  
Vol 49 (3) ◽  
pp. 194-198 ◽  
Author(s):  
S. Palraj ◽  
G. Venkatachari ◽  
G. Subramanian
Keyword(s):  
Corrosion Rate ◽  
Sea Water ◽  
Xrd Analysis ◽  
Weight Loss Measurement ◽  
X Ray Diffraction ◽  
Fouling Community ◽  
X Ray ◽  
Water Characteristics ◽  
Measurement And Analysis ◽  
Fouling Characteristics

The bio‐fouling and corrosion characteristics of 60/40 brass were investigated in the Palk Bay waters of the Mandapam Coast, India, over a period of a year. The experimental methods included corrosion rate by weight loss measurement and analysis of the corrosion product by X‐ray diffraction. The bio‐fouling characteristics of 60/40 brass were studied in terms of seasonality of recruitment of organisms and quantification of the fouling community development pattern. The XRD analysis of the products on brass threw more light on the protective nature of the compounds formed and their impact on the overall corrosion rate of the material. The organisms found in fouling deposits on brass included algae, bryozoans and hydroids. The results of the study are discussed in the light of the sea‐water characteristics and monsoonal effects.

Respiratory and Circulatory Adjustments during Aquatic Treadmill Exercise in the European Shore Crab Carcinus Maenas

1992 ◽  
Vol 162 (1) ◽  
pp. 37-54 ◽  
Author(s):  
N. M. HAMILTON ◽  
D. F. HOULIHAN
Keyword(s):  
Sea Water ◽  
Carcinus Maenas ◽  
Fold Increase ◽  
Co2 Exchange ◽  
Total Carbon ◽  
Shore Crab ◽  
Rate Of Oxygen Consumption ◽  
Novel Design ◽  
Cardiac Stroke Volume ◽  
Aquatic Treadmill

Carcinus maenas (L.) were exercised using a novel design of aquatic treadmill respirometer. Tethered exercise was performed in sea water at 5.8 m min−1 for 5min. The rate of oxygen consumption and the heart and scaphognathite beat rates increased at the onset of exercise, reaching a steady state within 180 s. The estimated haemolymph flow rate rose 2.6-fold during exercise, achieved by a 1.8-fold increase in heart rate and a 1.5-fold increase in the estimated cardiac stroke volume. The haemolymph total oxygen content difference increased significantly during exercise. Haemolymph total carbon dioxide content did not change significantly during exerise, but haemolymph pH deceased as a result of an L-lactate-induced metabolic acidosis. The acidosis may also have led to a reduced Bohr shift. It is concluded that O2 and CO2 exchange were not impaired during exercise and that C. maenas relied primarily upon O2 to fuel underwater running at 5.8 m min−1.

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