Effect of cobalt sorption on metal fractionation in anaerobic granular sludge

A sequential extraction procedure was applied to two anaerobic methanogenic sludges (Eerbeek and Nedalco) to examine the speciation of micro- and macronutrients in the sludges after cobalt sorption by exposing the sludge to a 1 mM Co solution for 4 d at pH 7 and 30 degrees C. The effect of different physicochemical conditions on cobalt sorption was studied as well: effect of pH (6-8), effect of competition by a second trace element (Ni or Fe), modification of the granular matrix by glutaraldehyde or heat treatment, and EDTA (ethylenediaminetetraacetic acid) addition. Sorbed Co was found to distribute between the carbonates, organic matter + sulfides, and residual fractions. Cobalt adsorption resulted in an antagonistic interaction with other metals present in the granular matrix, evidenced by the solubilization of other trace elements (e.g., Ni, Cu, and Zn) as well as macronutrients (especially Ca and Fe). Modification of the sludge matrix by glutaraldehyde or heat treatment, or exposure to EDTA, led to serious modifications of the Co sorption capacity and strong interactions with multivalent cations (i.e., Ca(2+) and Fe(2+)).     

Overexpression of ATP sulfurylase in Indian mustard: effects on tolerance and accumulation of twelve metals

Indian mustard [Brassica juncea (L.) Czern.] transgenics overexpressing ATP sulfurylase (APS plants) were shown previously to have higher levels of total thiols, S, and Se. The present study explores the effect of ATP sulfurylase overexpression on tolerance and accumulation of other metals, both oxyanions and cations, reasoning that some anions may react directly with ATP sulfurylase, while other ions may be bound by its thiol end products. The APS transgenics were compared with wild-type plants with respect to tolerance and accumulation of As, Cd, Cr, Cu, Hg, Mn, Mo, Ni, Pb, V, W, and Zn, supplied individually in agar medium (seedlings) or in hydroponics (mature plants). At the seedling stage, APS transgenics were more tolerant than wild type to As(III), As(V), Cd, Cu, Hg, and Zn, but less tolerant to Mo and V. The APS seedlings had up to 2.5-fold higher shoot concentrations of As(III), As(V), Hg, Mo, Pb, and V, and somewhat lower Cr levels. Mature APS plants contained up to 2.5-fold higher shoot concentrations of Cd, Cr, Cu, Mo, V, and W than wild type. They also contained 1.5- to 2-fold higher levels of the essential elements Fe, Mo, and S in most of the treatments. Mature APS plants showed no differences in metal tolerance compared with the wild type. Overexpression of ATP sulfurylase may be a promising approach to create plants with enhanced phytoextraction capacity for mixtures of metals.     

Scope insensitivity in contingent valuation of complex environmental amenities

It has been argued that respondents in contingent valuation (CV) surveys, asked to value complex environmental amenities, will state willingness to pay (WTP) independently of the scope of the project. Such insensitivity to scope would be at odds with rational choice, and could therefore imply that CV is not a theoretically valid method for biodiversity valuation. The scope test in the present CV study was applied to endangered species preservation. Respondents were split in four sub-samples facing different scopes of endangered species preservation. The design allowed for both external and internal scope tests. Furthermore, the tests were split according to elicitation format. Of four external tests of insensitivity to scope, one was rejected, two gave mixed results, depending on either the type of test or elicitation format, and for the last one the null hypothesis could not be rejected. Of five internal tests, insensitivity to scope was rejected in three cases, one test gave mixed results, and one could not be rejected. Survey design features of the CV study, especially an unfamiliar sub-group of endangered species, could explain the apparent insensitivity to scope observed.     

New Zealand drivers study: developing a methodology for conducting a follow-up study of newly licensed drivers

PROBLEM: In recent years, there has been a significant reduction in traffic crash injury among young people, but they continue to be overrepresented in the traffic crash statistics. To improve this situation, sound scientific evidence is needed to develop effective policies and programs. METHOD: The aim of the proposed study is to provide this evidence by examining early driving and driving-related experiences of newly licensed drivers as they progress through the learner-, restricted-, and full-license stages of the graduated licensing system and to determine the impact of these experiences on subsequent negative traffic-related outcomes (risky driving behavior, injury traffic crashes, noninjury traffic crashes, infringements, convictions). Given the size and complexity of the proposed study, a comprehensive pilot study was undertaken to determine the feasibility of conducting a New Zealand-wide cohort study of newly licensed drivers. RESULTS: This article describes the pilot study process and the methodology that has been developed for the New Zealand-wide study.     

Tracking chlordane compositional and chiral profiles in soil and vegetation

The cycling of chlordane and other persistent organic pollutants through the environment must be comprehensively elucidated to assess adequately the human health risks posed from such contaminants. In this study the compositional and chiral profiles of weathered chlordane residues in the soil and vegetative compartments were investigated in order to provide details of the fate and transport of this persistent pesticide. Zucchini was planted in a greenhouse in three bays containing chlordane-contaminated soil. At harvest the vegetation and soil were extracted and analyzed for chlordane content using chiral gas chromatography/ion trap mass spectrometry. Both achiral and chiral chlordane components were quantified. The chlordane concentration in the rhizosphere (soil attached to roots) was significantly less than that in the bulk soil. However, the enantiomeric ratio of the chiral components and overall component ratios had changed little in the rhizosphere relative to the bulk soil. Significant levels of chlordane were detected in the vegetation, the amount varying in different plant tissues from a maximum in roots to a minimum in fruit. In addition to the chlordane concentration gradient in plant tissues, significant shifts in compositional profile, as indicated by the component ratios, and in chiral profile, as indicated by the enantiomeric ratio, of the contaminant were observed in the plant tissues. The data indicate that abiotic processes dominate the transport of the chlordane components through the soil to the plant. This is the first report of the effect of rapid biotic processes within the plant compartment on chlordane compositional and chiral profiles.     

Reindeer in the Swedish mountains: an assessment of grazing impacts

During the last decade, several well-publicized grazing-related incidents of vegetation degradation have helped to form an official opinion of overutilization of some mountain areas and a concern that Swedish reindeer husbandry may not be ecologically sustainable. We examine these examples in a temporal and management perspective to assess the scale of impact on summer grazing grounds in the Swedish mountains. Long-term data on population dynamics of reindeer show no trend with fluctuations around 225 000 animals for the last century. Data on grazing effects from L?ngfj?llet (Dalarna) and Mitt?kl?ppen (H?rjedalen) are discussed in detail. We compare these data to the situation in Finnmark, Norway, and in northern Finland where reindeer husbandry in recent decades does not seem to have been ecologically sustainable. We conclude that large-scale overexploitation by reindeer in the Swedish mountains is not evident. However, strong grazing and trampling effects may be found around enclosures and fences.     

Photolysis of atrazine and ametryne herbicides in Barbados sugar cane plantation soils and water

The photodegradation kinetics of atrazine (2-chloro-6-(ethylamino)-4-isopropylamino-1,3,5-triazine) and ametryne (2-methylthio-4-ethylamino-6-isopropylamino-s-triazine), in fresh and coastal salt water from Barbados, were measured under irradiation with artificial solar and UV254-radiation. The first-order rate constants were greater for ametryne than for atrazine, and the rates were reduced in seawater relative to fresh water, and in soil slurries relative to fresh water. However, rates were accelerated in the presence of iron(III) at pH 3 due to photo-Fenton type processes. This rate enhancement was reduced at ambient pH values (pH 7-7.5) representative of surface water in Barbados. These results have important implications for the relative persistence of these contaminants in aquatic environments in tropical areas.