Sorption mechanisms of cephapirin, a veterinary antibiotic, onto quartz and feldspar minerals as detected by Raman spectroscopy

Raman spectroscopy was used to investigate sorption mechanisms of cephapirin (CHP), a veterinary antibiotic, onto quartz (SiO₂) and feldspar (KAlSi₃O₈) at different pH. Sorption occurs by electrostatic attraction, monodentate and bidentate complexation. The zwitterion (CHP^o) adsorbs to a quartz⁽⁺⁾ surface by electrostatic attraction of the carboxylate anion group (-COO⁻) at low pH, but adsorbs to a quartz⁽⁻⁾ surface through electrostatic attraction of the pyridinium cation, and possibly COO⁻ bridge complexes, at higher pH. CHP⁻ bonds to quartz⁽⁻⁾ surfaces by bidentate complexation between one oxygen of -COO⁻ and oxygen from carbonyl of an acetoxymethyl group. On a feldspar^(+/−) surface, CHP^o forms monodentate complexes between CO, and possible -COO⁻ bridges and/or electrostatic attachments to localized edge (hydr)oxy-Al surfaces. CHP⁻ adsorbs to feldspar⁽⁻⁾ through monodentate CO complexation. Similar mechanisms may operate for other cephalosporins. Results demonstrate, for the first time, that Raman techniques can be effective for evaluating sorption mechanisms of antibiotics.     

Bioaccessibility of metals in soils and dusts contaminated by marine antifouling paint particles

Fragments of antifouling paint and environmental geosolids have been sampled from the island of Malta and analysed for total and bioaccessible metals. Total concentrations of Ba, Cd, Cu, Pb, Sn and Zn were two to three orders of magnitude higher in spent antifouling composites relative to respective values in background soils and road dusts. Paint fragments were visible in geosolids taken from the immediate vicinity of boat maintenance facilities and mass balance calculations, based on Ba as a paint tracer, suggested that the most contaminated soils, road dusts and boatyard dusts contained about 1%, 7% and 9%, respectively, of antifouling particles. Human bioaccessibilities of metals were evaluated in selected samples using a physiologically based extraction technique. Accessibilities of Cd, Cu, Pb and Zn in the most contaminated solids were sufficient to be cause for concern for individuals working in the boat repair industry and to the wider, local community.     

The digital workshop: exploring the use of interactive and immersive visualisation tools in participatory planning

This paper examines the emerging role of digital tools in a collaborative planning process for British Columbia's Bowen Island. The goal of this research was to evaluate the effectiveness of a 'digital workshop', combining the interactive CommunityViz tool with the immersive lab facilities at the Collaborative for Advanced Landscape Planning (CALP). In support of the larger community planning process, two 3-h workshops were held at CALP's Landscape Immersion Lab. To facilitate collaborative exploration, the interactive landscape visualisation and real-time data analysis capabilities of CommunityViz were employed to illustrate the possible outcomes of residential density policies for Bowen Island's Snug Cove community. The community planning workshops were structured to provide the 14 semi-expert participants with the opportunity to explore and discuss the contentious residential density components of the draft Snug Cove Village Plan. The abilities to dynamically explore the visualisations of the planning proposals, and to see real-time changes in indicator metrics were considered particularly informative, and appeared to increase participants' understanding of the plan. Written and verbal responses indicated, however, that there was insufficient time to examine and interact with the information during the workshop, suggesting a need to examine in greater depth how and when these tools might best be employed in collaborative settings. Current and future research relating to this project is discussed.     

Influence of Mowing <Emphasis Type="Italic">Artemisia tridentata</Emphasis> ssp. <Emphasis Type="Italic">wyomingensis</Emphasis> on Winter Habitat for Wildlife

Mowing is commonly implemented to Artemisia tridentata ssp. wyomingensis (Beetle & A. Young) S.L. Welsh (Wyoming big sagebrush) plant communities to improve wildlife habitat, increase forage production for livestock, and create fuel breaks for fire suppression. However, information detailing the influence of mowing on winter habitat for wildlife is lacking. This information is crucial because many wildlife species depended on A. tridentata spp. wyomingensis plant communities for winter habitat and consume significant quantities of Artemisia during this time. Furthermore, information is generally limited describing the recovery of A. tridentata spp. wyomingensis to mowing and the impacts of mowing on stand structure. Stand characteristics and Artemisia leaf tissue crude protein (CP), acid detergent fiber (ADF), and neutral detergent fiber (NDF) concentrations were measured in midwinter on 0-, 2-, 4-, and 6-year-old fall-applied mechanical (mowed at 20 cm height) treatments and compared to adjacent untreated (control) areas. Mowing compared to the control decreased Artemisia cover, density, canopy volume, canopy elliptical area, and height (P < 0.05), but all characteristics were recovering (P < 0.05). Mowing A. tridentata spp. wyomingensis plant communities slightly increases the nutritional quality of Artemisia leaves (P < 0.05), but it simultaneously results in up to 20 years of decrease in Artemisia structural characteristics. Because of the large reduction in A. tridentata spp. wyomingensis for potentially 20 years following mowing, mowing should not be applied in Artemisia facultative and obligate wildlife winter habitat. Considering the decline in A. tridentata spp. wyomingensis-dominated landscapes, we caution against mowing these communities.     

Single-well, gas-sparging tests for evaluating the in situ aerobic cometabolism of cis-1,2-dichloroethene and trichloroethene

This study developed single-well, gas-sparging tests for assessing the feasibility of in situ aerobic cometabolism of trichloroethene (TCE) and cis-1,2-dichloroethene (cis-DCE) using propane and methane as growth substrates. Tests were performed in groundwater contaminated with TCE (100-400 microg l(-1)) and cis-DCE (20-60 microg l(-1)). A series of gas-sparging tests was performed by first sparging ("bubbling") gas mixtures in a well fitted with a "straddle" packer and then periodically sampling groundwater from the same well to develop concentration profiles and to estimate transformation rate coefficients. Evidence that gas-sparging of propane (or methane) and oxygen had stimulated organisms expressing a propane (or methane) monooxygenase enzyme system and the capability to transform TCE and cis-DCE included: (1) the transformation of sparged ethylene and propylene to their corresponding cometabolic by-products, ethylene oxide and propylene oxide, (2) the transformation of both cis-DCE and TCE in the propane-sparged well, (3) the transformation of cis-DCE in the methane-sparged well, and (4) the inhibition of ethylene and propylene transformations in the presence of acetylene, a known monooxygenase inactivator. At a well sparged with propane, first-order rate coefficients for propane utilization and ethylene and propylene transformation were similar, ranging from 0.007 to 0.010 h(-1). At the well sparged with methane, the propylene first-order transformation rate coefficient was 0.028 h(-1), a factor of 1.8 and 1.6 greater than methane and ethylene, respectively. The results demonstrated that gas-sparging tests are a rapid, low-cost means of assessing the potential for the in situ aerobic cometabolism of cis-DCE and TCE.     

The effect of winter stress on Ilex aquifolium L.previously fumigated with ozone

European Holly (Ilex aquifolium) received either charcoal-filtered air (CFA) or CFA with 70 nl l(-1) ozone added for 7 h day(-1) over a 28 day period. Plants were then transferred into cooling incubators for hardening (4 degrees C day/2 degrees C night; day length 12 h) for 7 days and then to the frosting stage (2 degrees C day and -5, -10 or -15 degrees C night) for 4 days. The plants were then placed in ambient conditions. Treatment produced significant differences in chlorophyll fluorescence data. Stomatal conductance was significantly higher for the ozone treatments though both showed a general decline over all temperature regimes. Ozone also significantly increased electrolyte leakage and reduced winter survival. These results show that ambient concentrations of ozone can reduce the tolerance of I. aquifolium to freezing stress, which may have serious implications for its establishment and survival.     

Degradation of inhibitory substances by heterotrophic microorganisms during bioleaching of heavy metals from anaerobically digested sewage sludge

The presence of organic acids was found to be inhibitory to the bioleaching of sewage sludge and the objective of the present study was to elucidate the roles of heterotrophic microorganisms in removing organic acids during the bioleaching of heavy metals from anaerobically digested sewage sludge. Microbiological analysis showed that acetic and propionic acids posed a severe inhibitory effect on iron-oxidizing bacteria as reflected by a sharp decrease in their viable counts in the first 4d and it only started to increase 2d after the depletion of both acids. Biodegradation of these inhibitory organic acids was revealed by sharp increases in total fungi and acidophiles between day 3 and day 5 which coincided with degradation of organic acids. This was further confirmed by the increases in total counts of both acetate and propionate degraders in the same period. Two yeast strains Y4 and Y5 with strong ability to degrade acetate and/or propionate were isolated and identified as Pichia sp. and Blastoschizomycetes capitatus, respectively. B. capitatus Y5 was an more important player in removing the inhibitory organic acids during the bioleaching process since it could utilize both acetate and propionate as sole carbon source while Pichia sp. Y4 was an strict acetate degrader. Results from the present study not only provided the evidence for biodegradation of organic acids by heterotrophs, but also disclosed a biological mechanism for the initiation of bioleaching of organic acid-laden sewage sludge.     

Prenatal screening for Down syndrome in twin pregnancies: Estimates of screening performance based on 61 affected and 7302 unaffected twin pregnancies

The aims of this study were to determine whether assumptions used in prenatal screening for Down syndrome in twin pregnancies are valid and derive estimates of risk and screening performance in twin pregnancies using observed data. Data were collected on nuchal translucency, chorionicity, pregnancy associated plasma protein-A (PAPP-A), and free ß human chorionic gonadotrophin (free ß-hCG) from 61 twin pregnancies with Down syndrome and 7302 unaffected twin pregnancies. Distribution parameters were determined and used to estimate screening performance. The assumption that proportional differences in serum marker levels in affected and unaffected singleton pregnancies apply to twin pregnancies was not confirmed. Median free β-hCG value in monochorionic affected twin pregnancies (2.63 multiples of the median [MoM]; 95% CI, 1.79-3.22 MoM) was lower than that assuming proportionality (3.76 MoM), and the median PAPP-A value in dichorionic affected twin pregnancies (1.88 MoM; 95% CI, 1.60-2.17 MoM) was higher than that based on proportionality (1.33 MoM). The detection rate was 87% for a 3% false-positive rate in monochorionic twin pregnancies and 74% in dichorionic twin pregnancies compared with 86% in singleton pregnancies. Estimates of screening performance in Down syndrome twin pregnancies do not need to rely on assumptions and can take account of chorionicity and gestational age.     

Performance assessments for the geological storage of carbon dioxide: Learning from the radioactive waste disposal experience

The geological storage of carbon dioxide is currently being considered as a possible technology for reducing emissions to atmosphere. Although there are several operational sites where carbon dioxide is stored in this way, methods for assessing the long-term performance and safety of geological storage are at an early stage of development. In this paper the similarities and differences between this field and the geological disposal of radioactive wastes are considered. Priorities are suggested for the development of performance assessment methods for carbon dioxide storage based on areas where experience from radioactive waste disposal can be usefully applied. These include, inter alia, dealing with the various types of uncertainty, using systematic methodologies to ensure an auditable and transparent assessment process, developing whole system models and gaining confidence to model the long-term system evolution by considering information from natural systems. An important area of data shortage remains the potential impacts on humans and ecosystems.