Use of high-performance liquid chromatography to investigate the production of paralytic shellfish toxins by Protogonyaulax spp. in culture

Procedures have been developed for the extraction and high-performance liquid chromatography (HPLC) analysis of paralytic shellfish poisoning (PSP) toxins from Protogonyaulax spp. grown in batch culture. Using these procedures, the toxin content of two isolates of P. tamarensis (NEPCC 183 and 255) and one isolate of P. catenella (NEPCC 355) were examined. Total toxin and individual toxin concentrations were measured for each isolate during the exponential and stationary phases of growth in batch culture. The total toxicity of each isolate as measured by HPLC analysis was found to agree with toxicity as determined by the standard mouse bioassay. Two of the isolates (255 and 355) were found to be toxic and the third (183) was non-toxic. The toxic isolates (255 and 355) both showed higher average total PSP toxin content during the exponential phase (35 and 23 fmol toxin cell^-1, respectively) than during the stationary phase (21 and 8 fmol toxin cell^-1, respectively). These cultures differed dramatically in their toxin composition. P. tamarensis (255) contained a large proportion of the N(21) sulfo toxins (B₁, B₂, C₁, C₂) while P. catenella (355) contained primarily Gonyautoxins 1 through 4. The percent composition of individual toxins was found to be constant throughout the growth cycle for both toxic isolates, even though the total toxin concentration varied. Our results suggest that PSP toxin profiles might be useful as chemotaxonomic indicators.     

Increasing industrial safety practices and conditions through posted feedback

This study examined the effects of posted feedback for improving safety in a paper mill. Data were taken once a week on 24 practices and 7 conditions. In addition, data on injuries with and without lost time were collected monthly. After posting feedback on safe and unsafe conditions for 6 months, more than half of the 17 divisions of the mill showed improvement. Similarly, safe practices increased after feedback was provided for them for 2 months. Most importantly, injuries were cut in half.     

Partnerships for sustainability: Effective practice?

This paper presents as case studies some New Zealand local government sustainable development initiatives in cleaner production and civic building design. From a series of structured interviews with key players, it describes key motivators and demotivators and puts these in the context of behaviour change theory. These enable a set of actions for local government to be developed that, if applied, could result in an advancement of the sustainable development agenda. However, other critical factors are given that are external to these actions and on which their overall success is dependent. In reviewing these factors as a group we conclude that far greater understanding of the partnership formation process and its dynamic in engendering successful sustainable development decision-making processes is crucial to move beyond the rhetoric of partnerships and enter the more complex and difficult world of truly participatory approaches.     

Control of Tamarix in the Western United States: Implications for Water Salvage, Wildlife Use, and Riparian Restoration

Non-native shrub species in the genus Tamarix (saltcedar, tamarisk) have colonized hundreds of thousands of hectares of floodplains, reservoir margins, and other wetlands in western North America. Many resource managers seek to reduce saltcedar abundance and control its spread to increase the flow of water in streams that might otherwise be lost to evapotranspiration, to restore native riparian (streamside) vegetation, and to improve wildlife habitat. However, increased water yield might not always occur and has been substantially lower than expected in water salvage experiments, the potential for successful revegetation is variable, and not all wildlife taxa clearly prefer native plant habitats over saltcedar. As a result, there is considerable debate surrounding saltcedar control efforts. We review the literature on saltcedar control, water use, wildlife use, and riparian restoration to provide resource managers, researchers, and policy-makers with a balanced summary of the state of the science. To best ensure that the desired outcomes of removal programs are met, scientists and resource managers should use existing information and methodologies to carefully select and prioritize sites for removal, apply the most appropriate and cost-effective control methods, and then rigorously monitor control efficacy, revegetation success, water yield changes, and wildlife use.     

Environmental cadmium levels increase phytochelatin and glutathione in lettuce grown in a chelator-buffered nutrient solution

Phytochelatins are enzymatically synthesized peptides involved in metal detoxification and have been measured in plants grown at very high Cd concentrations, but few studies have examined the response of plants at lower environmentally relevant Cd concentrations. Using an ethylenediaminetetraacetic acid (EDTA)-buffered nutrient medium, we have varied Cd exposure and measured phytochelatin and glutathione concentrations in romaine lettuce (Lactuca sativa L. var. longifolia Lam. var. Parris Island) grown in a flow-through hydroponic (FTH) system. Very low free ionic Cd (10(-9.6) M) increased average phytochelatin concentrations above those of controls, and increasing Cd resulted in increased phytochelatin production, though increases were tissue dependent. Glutathione concentrations also increased with increasing Cd. In other standard hydroponic experiments, the media were manipulated to vary total Cd concentration while the ionic Cd was fixed. We found that the total amount of Cd (primarily EDTA bound) in the medium altered thiol production in roots, whereas thiols in leaves remained constant. The Cd uptake into roots and translocation to old leaves was also influenced by the total concentration in the medium. Cadmium in all tissues was lower and in some tissues thiol concentrations were higher than in FTH-grown plants grown in identical medium, suggesting that nutrient delivery technique is also an important variable. Though phytochelatin and glutathione production can be sensitive to changes in bioavailable Cd, thiol concentrations will not necessarily reflect the Cd content of the plant tissues.     

Characterization and phosphate stabilization of dusts from the vitrification of MSW combustion residues

The use of soluble PO₄³⁻ as a heavy metal chemical stabilization agent was evaluated for a dust generated from melting or vitrification of municipal solid waste combustion residues. Vitrification dusts contain high concentrations of volatile elements such as Cl, Na, K, S, Pb, and Zn. These elements are present in the dusts largely as simple salts (e.g. PbCl₂, ZnSO₄) which are highly leachable. At an experimental dose of 0.4 moles of soluble PO₄³⁻ per kg of residue, the pH-dependent leaching (pH 5,7,9) showed that the treatment was able to reduce equilibrium concentrations by factors of 3 to 100 for many metals; particularly Cd, Cu, Pb and Zn. Bulk and surface spectroscopies showed that the insoluble reaction products are tertiary metal phosphate [e.g. Zn₃(PO₄)₂] and apatite [e.g. Pb₅(PO₄)₃Cl] family minerals. Geochemical thermodynamic equilibrium modeling showed that apatite family and tertiary metal phosphate phases act as controlling solids for the equilibrium concentrations of Ca²⁺, Zn²⁺, Pb²⁺, Cu²⁺, and Cd²⁺ in the leachates during pH-dependent leaching. Both end members and ideal solid solutions were seen to be controlling solids. Soluble phosphate effectively converted soluble metal salts into insoluble metal phosphate phases despite the relatively low doses and dry mixing conditions that were used. Soluble phosphate is an effective stabilization agent for divalent heavy metals in melting dusts where leachable metals are present in high concentrations.     

Analysis of volatile fatty acids by ion-exclusion chromatography,with special reference to marine pore water

A method for measuring volatile fatty acids using ion-exclusion chromatography is presented. The system was found to be applicable to samples with high salt concentrations (e.g. seawater and marine pore water) when coupled with a vacuum distillation procedure. The method is straightforward, with no sample preconcentration and no introduction of external contamination. Calibration was found to be linear, with good reproducibility (coefficient of variation normally less than 5%) and the system was sufficiently sensitive to operate at the sub-ppm level (minimum detection limit for acetate and propionate was approximately 0.02 and 0.05 ppm, respectively). This technique was used to investigate the distribution of volatile fatty acids with sediment depth at Station E70 in Loch Eil, Scotland (sample was collected in March, 1983) and the results were in good agreement with recent publications. Although the system, at present, is limited in marine pore water to acetate and propionate, it has certain advantages over alternative systems and these are described.     

Interaction between peat, humic acid and aqueous metal ions

Analysis of peat samples from four regions of the British Isles indicates that the concentrations of Al, Pb and common transition metals tend, as expected, to be higher in regions subject to industrial pollution, but that the concentrations of the nontransition metals Na, K, Mg, Ca and Zn tend to be higher in regions remote from industrial pollution. Humic acids were extracted from the most polluted and least polluted of the peat samples and some characteristics of these acids were compared with those of two commercial acids. Values for stability constants of complexes formed between humic acids extracted from peat and Cu²⁺, Zn²⁺ or Pb²⁺ have been obtained by an ionexchange equilibrium method. Of the three metal ions examined, Pb²⁺ was found to form the most stable humic acid complexes, followed by Cu²⁺: this order agrees with the findings of Irving and Williams and of Bunzl. Implications to the binding of actinide and other heavy metal ions in aqueous humic acid are discussed.