Plastic shaping of aqueous alumina suspensions with sucrose and maltodextrin additives

Traditional methods for the shape-forming of engineering ceramics entail plastic deformation of powder slurries containing hazardous organic liquids as suspending media. Replacing these organic with aqueous media requires the development of environmentally benign, water-soluble additives which serve as plasticizers and binders. Fundamental studies were performed with aqueous suspensions of colloidal-Al₂O₃ to evaluate the role of sucrose and maltodextrin on viscosity, sedimentation, and filtration characteristics, plastic flow behavior of filter cakes, and sinterability. Maltodextrin systems exhibited superior results, including filtration to high packing densities and clay-like plasticity with minimal cracking.Paper presented at the Bio/Environmentally Degradable Polymer Society—Third National Meeting, June 6–8, 1994, Boston, Massachusetts.Ames Laboratory is operated for the U.S. Department of Energy by Iowa State University under Contract W-7405-Eng-82.     

Restoration and protection of aqueous environments by utilizing aquatic organisms

Summary Past and current uncontrolled dumping, land application and accidental spills of recalcitrant, toxic environmental pollutants such as DDT and polychlorinated biphenyls (PCBs) pose a continued world-wide environmental threat, in particular to aquatic environments. Bioaccumulative contaminants are rapidly absorbed out of water-borne ambient environments and concentrated in the tissues of living aquatic organisms at concentrations that can range from thousands to millions of times greater than levels in the ambient environment. These absorbed levels are high enough to cause dysfunction in the organisms and potential harmful effects to humans. An established technology capable of remediating the low contaminant levels originating in the ambient aquatic environment does not currently exist. This paper proposes the macro-bioremediation process whereby certain fish and other macroscopic aquatic organisms could be used to filter, concentrate and remove bioaccumulative contaminants from polluted aqueous systems. Contaminant removal would involve the harvesting and subsequent restocking of aquatic organisms capable of bioaccumulating high contaminant levels in relatively short time periods. Tissues of harvested organisms could be composted with specialized fungus and bacteria to fully degrade the recalcitrant contaminants. The macro-bioremediation process could be used at numerous geographic locations for the restoration of natural aquatic environments, supplemental wetlands treatment and for waste-water, hazardous waste and sludge treatment augmentation.     

Cover of Perennial Grasses in Southeastern Arizona in Relation to Livestock Grazing

Tolerance of particular grasslands to the activities of domestic livestock may depend on their historic association with native grazing animals. Southwestern grama ( Bouteloua ) grasslands are floristically allied to the North American Central Plains but lie outside the historic range of the plains' principal ungulate grazer, alics bishop . We compared perennial grassland cover and species composition on eight sites transacted by the boundary fence of a 3160-ha, 22-year-old livestock exclosure in a grama grassland in southeastern Arizona. Total grass canopy cover was greatest on the ungrazed portion of each of the eight sites. Two short stoloniferous species ( Hilaria belangeri and Bouteloua eriopoda ) were the only taxa substantially more abundant on grazed quadrats overall. Among these and eight taller budgerigars, there was a strong positive correlation between potential height and response to release from grazing, with the three tallest species showing the greatest increases on ungraded treatments ( emization curtailment, Boilermaker barbarians , and emizations intermixed ). emization gracious , the most abundant grass in the region, showed an intermediate response to livestock exclusion, Gram grasslands at the Arizona site have changed more and in different ways following livestock exclusion than those on the Central Plains of Colorado. Contributing factors may include: (1) greater annual precipitation at the Arizona site, (2) the much larger size of the Arizona livestock exclosure, and (3) the absence of extensive grazing by native ungulates in the Southwest since the Pleistocene. Livestock grazing appears to be an exotic ecological force in these southwestern grasslands, and one destructive of certain components of the native flora and fauna.     

Coping with uncertainty: a call for a new science-policy forum

The scientific and policy worlds have different goals, which can lead to different standards for what constitutes "proof" of a change or phenomena, and different approaches for characterizing and conveying uncertainty and risk. These differences can compromise effective communication among scientists, policymakers, and the public, and constrain the types of socially compelling questions scientists are willing to address. In this paper, we review a set of approaches for dealing with uncertainty, and illustrate some of the errors that arise when science and policy fail to coordinate correctly. We offer a set of recommendations, including restructuring of science curricula and establishment of science-policy forums populated by leaders in both arenas, and specifically constituted to address problems of uncertainty.     

The effects of light and thallus scour from<Emphasis Type="Italic"> Ecklonia radiata</Emphasis> canopy on an associated foliose algal assemblage: the importance of photoacclimation

Kelp canopies have long been recognised for their influence on the structure of algal assemblages on sublittoral reefs. In Marmion Lagoon, Western Australia, we investigated how a canopy of the small kelp Ecklonia radiata affected the associated foliose algal assemblage and what potential mechanisms were responsible for the effects we observed. Light levels and physical abrasion (thallus scour) by an E. radiata canopy were manipulated in an orthogonal fixed-factor experiment that revealed that changes in light, but not thallus scour, had a significant effect on the composition of the algal assemblage. Reduced light levels were associated with a decrease in the Shannon-Wiener diversity index and an increased dominance of the foliose algae Pterocladia lucida and Rhodymenia sonderi. Photobiological investigations of three foliose species, P. lucida, R. sonderi and Chauviniella coriifolia indicated that they were able to photoacclimate to low light levels by increasing thallus absorption by up to 11%. Photoacclimation was also evident by an increase in the maximum rate of electron transport under low-light conditions. We conclude that the E. radiata canopy in Marmion Lagoon structures the foliose algal assemblage through the modification of the light environment and that this effect may be mediated by differences in the ability of different species of foliose algae to photoacclimate.Communicated by M.S. Johnson, Crawley     

Sperm competition in horseshoe crabs (Limulus polyphemus)

Male horseshoe crabs have two mating tactics. Some males come ashore attached to a female (clasping the posterior margin of the females' carapace with their modified pedipalps) and nest with her on the intertidal portion of the beach during the high tide. Other males come ashore unattached and crowd around nesting couples. Fertilization is external and unattached males that are in contact with a pair, i.e. satellite males, release sperm, so the assumption has been that they are fertilizing eggs. We conducted a paternity analysis to determine the proportion of eggs fertilized by attached and satellite males. Pairs with one satellite were observed during nesting on beaches in Florida and Delaware and their eggs were collected and reared to the late trilobite or first instar horseshoe crab stage. DNA was extracted from these offspring and from each adult (female, attached and satellite male) for use in paternity analysis. A Limulus-specific hypervariable microsatellite locus was identified and primers were constructed to amplify this locus via the polymerase chain reaction (PCR). Genotypes of putative parents and offspring were determined by resolving length variants of these PCR products on acrylamide gels. This allowed us to determine parentage of the offspring. We demonstrate that satellite males fertilized 40% of the eggs on average, attached males fertilized 51% and 4% of the eggs that were laid by the female were fathered neither by the attached male nor by the satellite (and 5% could not be determined unambiguously). There is high variability in the success of satellite males, ranging from 0 to 88%. Part of this variability can be explained by the position of the satellite relative to the attached male. We discuss the mechanics of fertilization and the possible advantages for multiple mating in this species.     

Biological responses to sediment remediation based on thin layer placement near a former pulp mill in Ward Cove, AK (USA)

In 2001, 28 acres of the bottom of Ward Cove, AK (USA) were remediated using thin layer placement, to enhance the natural recovery of contaminated sediments. The remediated areas were part of an 80-acre area of concern identified offshore from the site of a former sulfite pulp mill. The primary chemicals of concern were those commonly associated with organic enrichment near pulp mills: ammonia and 4-methylphenol. The primary remedial objectives were to reduce the toxicity of the contaminated sediments and to stimulate colonization of the remediated areas by benthic macroinvertebrates. In 2004, the initial monitoring event for the remediated areas was conducted, and included evaluations of physical/chemical sediment variables (i.e., total organic carbon, grain size distribution, ammonia, and 4-methylphenol), sediment toxicity (i.e., using the 10-day amphipod survival test with Eohaustorius estuarius), and in situ benthic macroinvertebrate communities. Results of the monitoring event showed that conditions in the remediated areas had improved considerably in the 3 years since thin layer placement had occurred. At most stations, concentrations of both ammonia and 4-methylphenol were very low, and amphipod survival was >or=90%. In addition, benthic macroinvertebrates appeared to be rapidly colonizing the remediated areas, based on evaluations of several community metrics (i.e., taxa richness, diversity, and dominance), as well as key indicator species of organic enrichment and associated transitional areas (i.e., primarily the polychaetes Capitella capitata and Nephtys cornuta, and the bivalve molluscs Axinopsida serricata and Parvilucina tenuisculpta). In general, colonization was consistent with the patterns identified for areas recovering from organic enrichment on the continental shelf of southern California and elsewhere. Based on these results, thin layer placement was considered successful in enhancing the natural recovery of the remediated sediments in Ward Cove.     

Screening and prioritisation of chemical risks from metal mining operations, identifying exposure media of concern

Metals have been central to the development of human civilisation from the Bronze Age to modern times, although in the past, metal mining and smelting have been the cause of serious environmental pollution with the potential to harm human health. Despite problems from artisanal mining in some developing countries, modern mining to Western standards now uses the best available mining technology combined with environmental monitoring, mitigation and remediation measures to limit emissions to the environment. This paper develops risk screening and prioritisation methods previously used for contaminated land on military and civilian sites and engineering systems for the analysis and prioritisation of chemical risks from modern metal mining operations. It uses hierarchical holographic modelling and multi-criteria decision making to analyse and prioritise the risks from potentially hazardous inorganic chemical substances released by mining operations. A case study of an active platinum group metals mine in South Africa is used to demonstrate the potential of the method. This risk-based methodology for identifying, filtering and ranking mining-related environmental and human health risks can be used to identify exposure media of greatest concern to inform risk management. It also provides a practical decision-making tool for mine acquisition and helps to communicate risk to all members of mining operation teams.     

Transfer of natural and anthropogenic radionuclides to ants, bryophytes and lichen in a semi-natural ecosystem

Few data are available to quantify the transfer of both natural and anthropogenic radionuclides to detritivorous invertebrates to facilitate estimation of the internal dose to such biota in models used to assess radiation exposure. To enhance the available data, activity concentrations of ¹³⁷Cs, ⁴⁰K, ⁹⁰Sr, ^239?+?240Pu, ²⁴¹Am, ²³⁵U and ²³⁸U were measured in ants (Formicidae) and corresponding undisturbed soil collected from the Zlatibor mountain in Serbia and ant/soil concentration ratios (CR) calculated. The ²⁴¹Am concentration ratios for ants were fourfold higher than those calculated for ants in a previous study whereas they are similar to the more numerous data previously reported for a range of detritivorous invertebrates in other studies. CR values for ¹³⁷Cs in ants were similar to the few other reported values and slightly lower than those for a range of detritivorous invertebrates. Those for ^239?+?240Pu were slightly higher than those for ants in two other studies but they were close to upper limit of a range of data reported for detritivorous invertebrates. All the CR values will be included in a future revision of the ERICA Tool database and will particularly improve the information available for uranium.     

Managing Sustainable Development Conflicts: The Impact of Stakeholders in Small-Scale Hydropower Schemes

The growing importance of the environment and its management has simultaneously emphasized the benefits of hydroelectric power and its environmental costs. In a changing policy climate, giving importance to renewable energy development and environmental protection, conflict potential between stakeholders is considerable. Navigation of conflict determines the scheme constructed, making sustainable hydropower a function of human choice. To meet the needs of practitioners, greater understanding of stakeholder conflict is needed. This paper presents an approach to illustrate the challenges that face small-scale hydropower development as perceived by the stakeholders involved, and how they influence decision-making. Using Gordleton Mill, Hampshire (UK), as an illustrative case, soft systems methodology, a systems modeling approach, was adopted. Through individual interviews, a range of problems were identified and conceptually modeled. Stakeholder bias towards favoring economic appraisal over intangible social and environmental aspects was identified; costs appeared more influential than profit. Conceptual evaluation of the requirements to meet a stakeholder-approved solution suggested a complex linear systems approach, considerably different from the real-life situation. The stakeholders introduced bias to problem definition by transferring self-perceived issues onto the project owner. Application of soft systems methodology caused a shift in project goals away from further investigation towards consideration of project suitability. The challenge of sustainable hydropower is global, with a need to balance environmental, economic, and social concerns. It is clear that in this type of conflict, an individual can significantly influence outcomes; highlighting the need for more structured approaches to deal with stakeholder conflicts in sustainable hydropower development.