Colonization and Selection of Fly-Ash Substrates by Marine Invertebrates

Fly-ash dumped on the sea bed causes a local impoverishment of the benthos. Experiments on ash in sea water have shown bacterial colonization to occur, at a slower rate than on natural silt, limited meiofaunal colonization after 18 months, selection by meroplanktonic larvae for the ash, though inhibition of development after settlement, and selection against ash by mobile benthic adults. the major inhibition to colonization is the lack of organic content in the ash.     

Pozzolanic aggregates of fly ash in the sea

Pulverized fuel ash (pfa) readily forms pozzolanic aggregates when wetted, and these are common at sites of ash dumping at sea, where they can be up to 2 m across. Field observations on the structure and fauna of aggregates from an ash dumping ground off the Northumberland (UK) coast were undertaken in 1975, together with experimental studies of aggregation, to determine the influence of ash aggregates on the benthic substrate and the faunistic colonisation of aggregates in situ. The aggregates are of a soft sandstone consistency, but are persistent at the sea bed. Particle analysis of aggregates showed negligible contribution by inorganic particles other than the ash, and an overrepresentation of larger diameter particles (3.5 to 4 Φ) compared to pure ash. There was an exponential relationship between aggregation and ash content of experimental sediments. It is suggested that only 15 to 17% of the ash reaching the sea bed will be involved in aggregation. The naturally occurring aggregate fauna consisted of a sparse but diverse sessile epifauna, which depended on encrusting bryozoans for initial colonisation, and a few boring species (Zirfaea crispata, Hiatella arctica, Polydora flava). The presence of 7 yr-old Z. crispata in aggregates confirms their persistence at the sea bed, and indicates that the ash is not toxic.     

Chemical Behaviour of Calcium in Stabilized Oil Ash Reef Blocks After Five Years in the Ocean

Abstract

Reef blocks made from stabilized oil ash were taken from the sea after five years in the ocean to examine the chemical behaviour of calcium. Experiments included (1) determination of the calcium leaching rate and a comparison with the rate for unexposed blocks to test the validity of a diffusion model for predicting long term (5 years) leaching rates, (2) determination of the effect of biological cover (shell) on the leaching rate, (3) determination of the leaching rate of the core of exposed reef blocks, (4) determination of the calcium content in ‘ring areas’ - regions of discoloration observed in sectioned exposed reef blocks, and (5) determination of the leachable fraction of the total calcium in exposed reef blocks. Results showed the presence of a pronounced calcium discontinuity zone located 3–7 cm from the outside surface of the reef blocks. Cumulated calcium release rates ranged from 2.81–3.14 μmol cm^?2 day^?1 for original unexposed reef blocks and the core of exposed (in the ocean for five years) blocks, respectively, to 0.47–0.50 μmol cm^?2 day^?1 for outside (facing sea water) surfaces of exposed reef blocks. Tank leaching studies also showed that the presence or absence of hard biological cover (shells) had little or no effect on the calcium release rate. the diffusion model normally used in modelling the chemical behaviour of calcium cannot be used to predict the long term (five years) leaching of calcium. the core of the exposed blocks released calcium at a rate similar to new, unexposed reef block material. Overall, it appears that the calcium discontinuity zone is probably responsible for restricting the release of calcium and hence the failure of the diffusion model.     

Application of High-Volume Fly Ash Concrete to Marine Structures

A new material with high content of fly ash named ‘Ashcrete’ has been developed. to examine the applicability of Ashcrete to marine structures, strength characteristics, resistance to sea water attack, and safety in the marine environment have been studied. the following results have been obtained:

1) the strength characteristics of high-volume fly ash concrete depend upon the type and proportions of chemical activators as well as curing conditions.

2) Ashcrete using sodium chloride (NaCI) as a chemical activator shows high initial strength and good strength development with age.

3) Ashcrete containing NaCI activator shows good resistance to sea water from the viewpoint of its strength characteristics, volume changes and microstructurcs.

4) Since 1980 many types of large-scale artificial reefs made of Ashcrete have been installed in the sea. As a result of long-term studies and underwater observations, the Japanese Government has demonstrated the durability of the material, safety in the marine environment and attractiveness to fish.

5) It is therefore proposed that Ashcrete might be used in constructing large-scale sea mounts in deep water for the purpose of generating upwelling.     

Possible Use of Ash Residues for the Construction of Artificial Reefs at Sea

Utilization of ash residues, including coal ash, oil ash, and municipal solid waste combustion ash, for the construction of artificial reefs at sea has been investigated by many researchers throughout the world for nearly 20 years. Both laboratory and field studies have shown that an artificial reef made of stabillized ash-concrete (SAC) has had no adverse effect on the marine environment. Indeed, published studies have shown that fish counts increase around SAC reefs owing to an abundance of colonizing organisms and to protection provided by cavities within the reef structures. However, public and regulatory resistance to the use of SAC for artificial reef construction at sea is still very strong in certain countries due to concern for possible negative environmental impacts, primarily in the area of bioaccumulation of elements or compounds originating from the ash component of SAC.

In this paper, technological feasibility of using ash residues for artificial reef construction is presented, based on the available 20 years of scientific data, including engineering workability, physical integrity, chemical leaching potential and biological effects. More important, we also identify conceptual barriers for the acceptance of using SAC for the construction of ocean reefs and suggest approaches to overcome these barriers.     

Leaching Characteristics of Lead and Cadmium From Waste-To-Energy Residues in Sea Water

Laboratory studies were conducted to determine leaching characteristics of waste-to-energy (WTE) residues in sea water to provide initial evaluation on the potential impact of WTE residues on the marine environment. Both loose and stabilized WTE residues were investigated for the leachability of lead (Pb) and cadmium (Cd) in sea water. Results of the study showed that loose WTE fly ash was very reactive in sea water; release of Pb and Cd occurred immediately (<0.5 hr) after the ash came in contact with sea water. Stabilization (treated with Portland cement and other additives), however, significantly reduced leaching of Cd and Pb. While ocean disposal of untreated WTE residues would not be advisable, utilization of stabilized WTE residues for beneficial uses should be investigated.     

Utilization of fly ash in adsorption of heavy metals from wastewater

The aim of this study was to assess the toxicity reduction of wastewaster after treatment with fly ash. Fly ash is a waste material which is formed as a result of coal burning in power plants, but has the potential to adsorb heavy metal ions. The present study examined the adsorption capacity of fly ash to adsorb Pb²⁺, Cu²⁺, and Zn²⁺ from waste water under different conditions of contact time, pH, and temperature. Uptake of metal ions by fly ash generally rose with increasing pH. At lower temperatures the uptake of heavy metal adsorption were enhanced. Significant reduction in Pb²⁺ (79%), Cu²⁺ (53%), and Zn²⁺ (80%) content was found after treatment with fly ash of waste water treatment. Using the microtox test toxicity of the effluent was reduced by 75% due to removal of Pb²⁺ ion by the fly ash. Data indicated that fly ash generated by power plants may be used beneficially to remove metals from waste water.     

Nitrification model with an inhibitory effect of sea water

A dynamic model of nitrification including bacterial growth equations was developed for the understanding of nitrification in estuaries. Sensitivity analysis based on the model revealed that not only maximum specific growth rates of nitrifiers but also yield constants and initial bacterial concentrations have great effect on the nitrification process.Batch experiments were carried out in order to investigate nitrification rates and an inhibitory effect on nitrification by sea water. The maximum specific growth rate of ammonia oxidizing bacteria in fresh water was estimated as 0.04 (h^?1) using a nonlinear regression method. The sea water content of 10%, 25%, 50% and 100% reduced the maximum specific growth rate of ammonia oxidizing bacteria to 0.027, 0.016, 0.0085 and 0.0028 (h^?1) respectively. The effect of sea water on nitrification was interpreted as noncompetitive inhibition. The computed results of inhibition of nitrification based on the noncompetitive inhibition model are presented.     

The nature of the migration route shapes physiological traits and aerodynamic properties in a migratory songbird

Migration distance is supposed to represent an important selection pressure shaping physiological and morphological properties. Previous work has focussed on this effect, while the importance of ecological barriers in this context has been rarely considered. We studied two subspecies of a migratory songbird, the northern wheatear (Oenanthe oenanthe oenanthe and O. o. leucorhoa L.), on an island in the North Sea. The former subspecies reaches their Scandinavian breeding areas after a short sea crossing, whereas leucorhoa northern wheatears cross the North Atlantic towards Iceland, Greenland or Canada. Physiological traits (fuel deposition rate) and wings’ aerodynamic properties (wing pointedness independent of body size), both affecting migration speed, were hypothesized to be more pronounced in leucorhoa than in oenanthe northern wheatears. Within subspecies, the physiological and aerodynamic properties were hypothesized to explain arrival date at the stopover site with “fast migrants” arriving early. Physiological and aerodynamic properties in leucorhoa northern wheatears lead to a faster and less costly migration, favouring a sea crossing, but in trade-off lower flight manoeuvrability than in oenanthe birds. Wings’ aerodynamic properties affected the seasonal occurrence of leucorhoa females, whereas the physiological traits significantly influenced arrival date in oenanthe individuals. The less risky migration route in oenanthe birds with few short sea crossings may have favoured higher flight manoeuvrability for foraging (less pointed wings), in trade-off an energetically more costly flight. Hence, not the migration distance itself, but the presence/absence of a sea barrier presents an important selection pressure in migratory land birds favouring low flight costs.     

The genetic mating system of a sea spider with male-biased sexual size dimorphism: evidence for paternity skew despite random mating success

Male-biased size dimorphism is usually expected to evolve in taxa with intense male–male competition for mates, and it is hence associated with high variances in male mating success. Most species of pycnogonid sea spiders exhibit female-biased size dimorphism, and are notable among arthropods for having exclusive male parental care of embryos. Relatively little, however, is known about their natural history, breeding ecology, and mating systems. Here we first show that Ammothella biunguiculata, a small intertidal sea spider, exhibits male-biased size dimorphism. Moreover, we combine genetic parentage analysis with quantitative measures of sexual selection to show that male body size does not appear to be under directional selection. Simulations of random mating revealed that mate acquisition in this species is largely driven by chance factors, although actual paternity success is likely non-randomly distributed. Finally, the opportunity for sexual selection (I _s), an indirect metric for the potential strength of sexual selection, in A. biunguiculata males was less than half of that estimated in a sea spider with female-biased size dimorphism, suggesting the direction of size dimorphism may not be a reliable predictor of the intensity of sexual selection in this group. We highlight the suitability of pycnogonids as model systems for addressing questions relating parental investment and sexual selection, as well as the current lack of basic information on their natural history and breeding ecology.     

Experiences of Coal Ash Artificial Reefs in Taiwan

A feasibility study for using fly-ash from Taiwan coal-fired power stations for artificial reef production was started in 1983. Various mixtures of fly ash stabilized with lime, cement, or industrial wastes and formed into blocks were tested in the laboratory. the results showed that the development of compressive strength of those blocks immersed in the sea water was much better than those exposed in the air. Heavy metal (Cd, Cr, Cu, Ni, Pb, Zn) content of the blocks has been monitored routinely to determine the leaching rates. the result indicates that solidification of fly-ash could indeed immobilize heavy metals better than the original fly ash. From March 1984 to February 1987, 3,682 coal ash stabilized blocks with total weight of 300 tons were designed, fabricated and installed at both Hsin-ta, south western coast, and Kuei-hou, northern coast of Taiwan, for field trials. After four years' underwater observations on 100 cubic blocks at Wan-Li, northern Taiwan, it was shown that the physical integrity of the ash reef blocks had been maintained. the compressive strength and durability was better than the concrete artificial reefs nearby. the ash reefs could also attract fishes and the colonization by benthic organisms was similar to that on concrete reefs. Eighty-eight species of fishes were observed, of which 27 were commercially important, comprising more than 80% of the total biomass. These results demonstrate a potential use for stabilized coal ash as artificial reefs to replace traditionally used concrete reefs to protect and enhance the coastal fishery resources in Taiwan in the future.     

Postingestive selection in the sea scallop (Placopecten magellanicus) on the basis of chemical properties of particles

Suspension-feeding bivalves are adapted to use a highly variable mixture of particles by sorting them before and after ingestion. Postingestive sorting in bivalves has been confirmed for several bivalve species, but few studies have attempted to isolate the factors influencing postingestive selection among different particles presented simultaneously. The ability of the sea scallop, Placopecten magellanicus (Gmelin), to sort a mixture of organic (¹⁴C-labeled dinoflagellates, Prorocentrum minimum) and inorganic (⁵¹Cr-labeled beads, diameter 16-18 µm) particles of similar size and shape within the stomach was examined. The study was carried out in August 1997 using scallops collected near Deer Island, New Brunswick, Canada. Sorting of the two particle types was measured by dissecting the scallops at intervals after feeding and comparing the ¹⁴C:⁵¹Cr ratios within the stomach, digestive gland, and feces. The ¹⁴C:⁵¹Cr ratio in the stomach decreased over time, indicating that sea scallops were sorting organic from inorganic particles. The ability of P. magellanicus to sort particles solely on the basis of chemical properties was tested in a second study by presenting them with a mixture of protein-coated and uncoated beads of two different colors. This study was carried out in February 2000 using scallops collected near Maces Bay, New Brunswick, Canada. Gut retention times of the two types of beads were measured using flow cytometry. Scallops retained protein-coated beads in the gut longer than uncoated beads, indicating postingestive selection by chemical properties. This study provides the first evidence for simultaneous postingestive sorting by bivalves of particles based solely on chemical properties. This would potentially enable P. magellanicus to preferentially retain particles of higher food quality longer than those of poor quality, thereby enhancing digestive efficiency.     

Long-term change of the marine environment and plankton in the Xiamen Sea under the influence of climate change and human sewage

ABSTRACT

Long-term observations of the Xiamen Sea in Fujian Province were used to analyze variations in sea temperature, salinity, inorganic nitrogen (N), activated phosphate (P), and phytoplankton, as well as the features of red tides. Results showed that in recent decades, sea temperature and concentrations of N and P nutrients increased while salinity decreased attributed to climate warming, rainfall, and human sewage. In addition, reduction in the number of phytoplankton species and rising abundance of phytoplankton indicated that the structure of phytoplankton community presented a simplified and minimized trend which magnified the dominance of dominant phytoplankton species. Since 2000, red tides have occurred more frequently, and the eutrophic-type diatom species, Skeletonema costatum appears to be the predominant species. Data suggested that variations of N and P nutrients exert a potent and rapid influence on phytoplankton than sea temperature and ocean salinity.     

Interactions Among the Copper Species and Forms in Sea Water/Sediments and Copper Bioaccumulation in Oysters

Abstract

Earlier papers indicated that the first incident of green discoloration in oysters (Crassostrea gigas) and the mass mortality observed in 1986 along the Taiwan Erhjin Chi coastal area were caused by the higher contents of total copper and copper species (mainly bioavailable and free ion) in sea water. the copper in sea water would be sorbed by suspended matter and transferred to sediments, and the copper in the sediments would also be desorbed to sea water. Processes of copper adsorption and desorption are the major factors influencing the contents of total copper and copper species in sea water and sediments. in this study, the Erhjin Chi sediments were mixed with sea water by a shaker technique. When the mixture was shaken for one hour, analogous to tidal mixing in estuaries, only copper desorption from sediments was observed. If the shaking time is increased for more than 3 hours, the copper released from the sediments was resorbed to the remaining solid phases. the higher the contents of mud (91.71%) and total copper (701 mg kg^?1) in sediments, the higher the copper desorption rate (1.86 ppm hr^?1) and copper adsorption rate (0.50 ppm hr^?1) were observed. in sediments containing lower mud (0.80%) and lower copper (43.5 mg kg^?1), the copper desorption and adsorption rates were 0.83 ppm hr^?1 and 0.22 ppm hr^?1, respectively. the interactions among the total copper and copper species in sea water and sediments, chemical and ecological parameters, and copper bioaccumulation in oysters in the Erhjin Chi estuarine and coastal area are also discussed.     

Dietary preferences of the opisthobranch mollusc Stylocheilus longicauda for secondary metabolites produced by the tropical cyanobacterium Lyngbya majuscula

Pure compounds isolated from the cyanobacterium Lyngbya majuscula Gomont were evaluated in an artificial diet for their influence on the feeding preferences of the sea hare Stylocheilus longicauda (Quoy and Gaimard, 1824), which lives in and feeds on this filamentous cyanobacterium (blue-green alga). Microcolin B, ypaoamide, malyngolide and other natural products acted as feeding deterrents at natural concentrations. At lower concentrations, sea hares were indifferent to ypaoamide and malyngolide in their diets. In contrast, barbamide stimulated sea hare feeding at the concentrations normally found in L. majuscula. Malyngamides and majusculamides, the most common natural products found in samples of L. majuscula from Guam, increased sea hare feeding at low concentrations and inhibited feeding at the higher concentrations that occurred in some collections of L. majuscula. Dietary selection of cyanobacteria by S. longicauda may be regulated by the concentration of specific chemical cues produced by L. majuscula. Received: 28 January 1997 / Accepted: 24 April 1998     

Behaviour of Dioxins,Furans and Metals Associated with Stabilized Msw Combustor Ash in Sea Water

This report presents the results of a research programme designed to examine the engineering and environmental acceptability of stabilizing municipal solid waste (MSW) combustor ash for artificial reef construction. Municipal solid waste combustor ash was combined with Portland cement to form solid blocks using conventional construction block making technology. the resultant stabilized combustor ash (SCA) blocks were used to construct an artificial habitat in Conscience Bay, Long Island Sound, New York and compared to identical concrete blocks, fabricated using natural aggregates. Over a 4.5 year period divers periodically returned to the site to monitor the interaction of SCA blocks with the marine environment and compare the performance of these blocks with the concrete control blocks. Results show that the SCA blocks retain their strength after prolonged sea water exposure. Contaminants of environmental concern, including metals, dioxins and furans, were retained within the cementitious matrix of the SCA blocks after prolonged sea water submersion. in addition, organisms growing on the surfaces of the SCA blocks did not accumulate contaminants from the blocks.     

A field colonization experiment with meiofauna and seagrass mimics: effect of time,distance and leaf surface area

From a conservation point of view, it is essential to know how fast an ecosystem can recover after physical disturbance. Meiofauna and especially harpacticoid copepods are abundant in seagrass beds and are therefore useful to study ecosystem recovery after disturbance. In the western Caribbean coast, a fragmented Thalassia testudinum seagrass bed was selected to conduct a colonization field experiment by means of plastic seagrass mimics. Meiofauna colonization, with special emphasis on harpacticoid copepods, was followed in relation to: (1) colonization time (2, 4, 6, 10, 14 and 21 days); (2) distance to source of colonizers (close and far series) and (3) leaf surface area to colonize (small, medium, large). Colonization was recorded after 2 days with average meiofauna densities of 480 ind/100 cm² (close) and 1350 ind/100 cm² (far) of leaf surface area, while on average 400 ind/100 cm² were collected from the natural seagrass plants. In this early phase, the meiofauna diversity was high, with on average 8 taxa. A longer period of colonization (21 days) showed an increased meiofaunal density and diversity (average density: 3220 ind/100 cm², 13 taxa). Increasing meiofauna colonization with time is probably related to the development of a biofilm making the leaf more attractive for meiofauna. The effect of distance was not so pronounced as that of time. Total absolute densities were highest in the far series (5 m away from natural seagrass patch), mainly because of nematode densities. Meiofauna diversity was lower in the far series than in the close series (at the border of the natural seagrass patch). A larger individual leaf surface area did not affect the overall meiofauna densities but had a significant positive effect on copepod densities. Larger surface areas promoted the presence of epiphytic copepod families such as Tegastidae and Dactylopusiidae. Overall, we found a rapid recovery of meiofauna in fragmented seagrass beds with primary colonizers (both nematodes and benthic opportunistic copepods) originating from the sediment and later colonizers as epiphytic copepods and their nauplii from the local seagrass regeneration pool.     

Behaviour of Dioxins, Furans and Metals Associated with Stabilized Msw Combustor Ash in Sea Water

This report presents the results of a research programme designed to examine the engineering and environmental acceptability of stabilizing municipal solid waste (MSW) combustor ash for artificial reef construction. Municipal solid waste combustor ash was combined with Portland cement to form solid blocks using conventional construction block making technology. the resultant stabilized combustor ash (SCA) blocks were used to construct an artificial habitat in Conscience Bay, Long Island Sound, New York and compared to identical concrete blocks, fabricated using natural aggregates. Over a 4.5 year period divers periodically returned to the site to monitor the interaction of SCA blocks with the marine environment and compare the performance of these blocks with the concrete control blocks. Results show that the SCA blocks retain their strength after prolonged sea water exposure. Contaminants of environmental concern, including metals, dioxins and furans, were retained within the cementitious matrix of the SCA blocks after prolonged sea water submersion. in addition, organisms growing on the surfaces of the SCA blocks did not accumulate contaminants from the blocks.     

Epithelial immunity in a marine invertebrate: a cytolytic activity from a cuticular secretion of the American horseshoe crab, <Emphasis Type="Italic">Limulus polyphemus</Emphasis>

The cuticle of the American horseshoe crab, Limulus polyphemus, is largely free of the macroscopic epibionts that rapidly colonize most solid surfaces exposed to sea water. Here, we describe a viscous surface secretion that coats the carapace of the horseshoe crab. We report methods for stimulating production of the substance, identify hemolytic and liposome-permeabilizing activities and provide a partial biochemical characterization. We propose that this secretion functions as an anti-fouling agent protecting the chitinized epithelium of the cuticle from colonization by deleterious epibionts.     

Studies on mycorrhizal inoculation on dry matter yield and root colonization of some medicinal plants grown in stress and forest soils

Five medicinal plants viz. Abelmoschatus moschatus Linn., Clitoria tematea L., Plumbagozeylanica L., Psorolea corylifolia L. and Withania sominifera L. were grown in a polypot experiment in five soils representing coal mine soil, coppermine soil, fly ash, skeletal soil and forest soil with and without mycorrhizal inoculations in a completely randomized block design. Dry matter yield and mycorrhizal root colonization of plants varied both in uninoculated and inoculated conditions. The forest soil rendered highest dry matter due to higher yield of A. moschatus, P. zeylanica and P corylifolia while fly ash showed lowest dry matter without any inoculants. P. cematea were best in coalmine soil and W. sominifera in copper mine soil without mycorrhizal inoculation. The mycorrhiza was found to enhance the dry matter yield. This contributed minimum 0.19% to maximum up to 422.0% in different soils as compared to uninoculated plants. The mycorrhizal dependency was noticed maximum in plants grown in fly ash followed by coal mine soil, copper mine soil, skeletal soil and forest soil. The mycorrhizal response was increased maximum in W. sominifera due to survival in fly ash after inoculation followed by P corylifolia and P cematea. Percent root colonization in inoculated plant was increased minimum of 1.10 fold to maximum of 12.0 folds in comparison to un-inoculated plants . The native mycorrhiza fungi were also observed to colonize 4.0 to 32.0% roots in plants understudy. This study suggests that mycorrhizal inoculation increased the dry matter yield of medicinal plants in all soils under study. It also helps in survival of W. sominifera in fly ash.