Germination and seedling growth of the water cress Rorippa sp. exposed to the chelant [S,S]-EDDS

With the implementation of the new EU environmental framework directives, high tier risk assessments of chemicals will be increasingly needed. For high production chemicals, additional tests will complement the standard battery for aquatic toxicity assessments (daphnids, algae, and fish). In the context of a new chemical notification at the European Union level, we have developed a seed germination and root elongation toxicity test with the freshwater aquatic plant Rorippa nasturtium-aquaticum (water cress) to confirm the low environmental risk of the chelant [S,S]-EDDS. A 14 day semi-static growth inhibition test was conducted with daily renewal of the test solution. No concentration related inhibition was found on the basis of any of the criteria investigated, i.e., time and extent of germination, biomass, number of leaves, stalk and root lengths. The no-observed effect concentration was considered to be >or=387 mg SS-EDDS/l. Although germination was selected as an appropriate endpoint to assess the effect of a chelant on an aquatic plant (other endpoints would have been dependant on essential metals that are chelated in standard culture tests), the absence of dose related effects requires further tests with higher exposure concentrations and/or other toxicant(s) to assess the validity of the test as a general tool for aquatic risk assessment.     

A framework for understanding ecological traps and an evaluation of existing evidence

When an animal settles preferentially in a habitat within which it does poorly relative to other available habitats, it is said to have been caught in an "ecological trap." Although the theoretical possibility that animals may be so trapped is widely recognized, the absence of a clear mechanistic understanding of what constitutes a trap means that much of the literature cited as support for the idea may be weak, at best. Here, we develop a conceptual model to explain how an ecological trap might work, outline the specific criteria that are necessary for demonstrating the existence of an ecological trap, and provide tools for researchers to use in detecting ecological traps. We then review the existing literature and summarize the state of empirical evidence for the existence of traps. Our conceptual model suggests that there are two basic kinds of ecological traps and three mechanisms by which traps may be created. To this point in time, there are still only a few solid empirical examples of ecological traps in the published literature (although those few examples suggest that both types of traps and all three of the predicted mechanisms do exist in nature). Therefore, ecological traps are either rare in nature, are difficult to detect, or both. An improved library of empirical studies will be essential if we are to develop a more synthetic understanding of the mechanisms that can trigger maladaptive behavior in general and the specific conditions under which ecological traps might occur.     

Evaluation of approaches for terrestrial hazard classification

Hazard assessment is an essential element in the evaluation of the potential effects of chemical substances on the environment. To date, most work has focused on hazard assessment schemes for the aquatic environment, but in recent years, a number of proposals have been developed for other environmental compartments. Due to limited datasets, the suitability of the toxicity cut-off values in these schemes has not been fully determined and the practicalities associated with using these approaches have not been fully established. This study, which focused on the soil compartment, was performed to examine cut-off values proposed by two terrestrial hazard assessment schemes and establish the availability of data. Data on earthworms indicated that current proposals for toxicity cut-off values are appropriate. However, analysis of IUCLID (International Uniform ChemicaL Information Database) indicates that even for commonly used high production volume chemicals, insufficient data are available to enable classification. Whilst the necessary data may already be available for selected groups of substances (e.g. pesticides and veterinary medicines), a significant experimental testing programme would therefore be required before a terrestrial classification system could be applied widely. Such data may become available in the future as a result of initiatives such as REACH.     

The analysis of flue gas treatment residues using non-destructive X-ray fluorescence as a regulatory compliance test

Current and proposed European Union (EU) regulations require the residual material from municipal solid waste incineration to be characterised prior to disposal. X-Ray fluorescence (XRF) provides a rapid and non-destructive technique for analysing such materials.     

Assessing the Potential Effects of Fungicides on Nontarget Gut Fungi (Trichomycetes) and Their Associated Larval Black Fly Hosts

Fungicides are moderately hydrophobic and have been detected in water and sediment, particularly in agricultural watersheds, but typically are not included in routine water quality monitoring efforts. This is despite their widespread use and frequent application to combat fungal pathogens. Although the efficacy of these compounds on fungal pathogens is well documented, little is known about their effects on nontarget fungi. This pilot study, a field survey in southwestern Idaho from April to December 2010 on four streams with varying pesticide inputs (two agricultural and two reference sites), was conducted to assess nontarget impact of fungicides on gut fungi, or trichomycetes. Tissues of larval black flies (Diptera: Simuliidae), hosts of gut fungi, were analyzed for pesticide accumulation. Fungicides were detected in hosts from streams within agricultural watersheds but were not detected in hosts from reference streams. Gut fungi from agricultural sites exhibited decreased percent infestation, density and sporulation within the gut, and black fly tissues had elevated pesticide concentrations. Differences observed between the sites demonstrate a potential effect on this symbiotic system. Future research is needed to parse out the details of the complex biotic and abiotic relationships; however, these preliminary results indicate that impacts to nontarget organisms could have far‐reaching consequences within aquatic ecosystems.     

Catalytic ozonation of 2,4-dichlorophenoxyacetic acid using alumina in the presence of a radical scavenger

Using a laboratory-scale mixed reactor, the performance of alumina in degrading 2,4-Dichlorophenoxyacetic acid with ozone in the presence of tert-butyl alcohol radical scavenger was studied. The operating variables investigated were the dose of alumina catalyst and solution pH. Results showed that using ozone and alumina leads to a significant increase in 2,4-D removal in comparison to non-catalytic ozonation and adsorption processes. The observed reaction rate constants (k(obs)) for 2,4-D during ozonation were found to increase linearly with increasing catalyst dose. At pH 5, the k(obs) value increased from 19.3 to 26 M(-1) s(-1) and 67 M(-1) s(-1) when varying the alumina dose from 1 to 2 and 4 g L(-1), respectively. As pH was increased, higher reaction rates were observed for both non-catalytic ozonation and catalytic ozonation processes. Thus, at pH 3 and using a catalyst dose of 8 g L(-1), the k(obs) values for non-catalytic ozonation and catalytic ozonation processes were 3.4 and 58.9 M(-1) s(-1), respectively, whereas at pH 5 reaction rate constants of 6.5 and 128.5 M(-1) s(-1) were observed, respectively. Analysis of total organic carbon suggested that catalytic ozonation with alumina achieved a considerable level of mineralization of 2,4-D. Adsorption of 2,4-D on alumina was found to play an important role in the catalytic ozonation process.     

Theoretical studies of the conformations and 19F NMR spectra of linear and a branched perfluorooctanesulfonamide (PFOSAmide)

Technical perfluorooctanesulfonate (PFOS) and its derivatives, such as perfluorooctanesulfonamide (PFOSA), are not clean compounds but, instead, complex mixtures of linear and branched isomers, and other compounds including sulfonate homologues. Questions have been raised as to whether the linear and the branched isomers behave differently in the environment. However, little is known about the physical properties or the finer details of the structures of the individual branched isomers. This study sought an effective computational method to model the preferred conformations of PFOS derivatives, and the energy differences between them and to determine if these results can be used to explain the temperature dependence of their NMR spectra. Good predictions of the 19F chemical shifts were obtained for some PFOSA-type molecules with a computational approach [B3LYP-GIAO/6-31++G(d,p)//B3LYP/6-31G(d,p)] that is relatively inexpensive. Large 5JFF couplings found in one of the branched isomers could be rationalized on the basis of the relevant F-F distances in the optimized structure. At low temperatures, the splitting observed in the NMR spectrum at C-1 for these sulfonamides can be explained by the existence of the two conformers predicted by the computations.     

The effects of 3,3′,4,4′-tetrabromobiphenyl on rats fed diets containing a constant level of copper and varying levels of molybdenum

Copper (Cu) metabolism is altered in rats fed diets high in molybdenum (Mo) and low in Cu. This 10-week study was carried out to examine the effects of supplemental Mo (7.5–240 μg/g diet) on male Sprague–Dawley rats fed diets adequate in Cu (5 μg/g diet) and to determine the susceptibility of Mo-treated animals to the environmental pollutant 3,3′,4,4′-tetrabromobiphenyl (TBB). After 7 weeks of dietary treatment, half of the rats in each group received a single IP injection of TBB (150 μM/kg bw), while the other half received the corn oil vehicle. Rats sacrificed at 10 weeks showed no effects of Mo on growth, feed efficiency, or selected organ or tissue weights. Dose-dependent effects on plasma Mo (0–5.1 μg/mL), plasma Cu (0.95–0.20 μg/mL), and bone Cu (3.4–10 μg/g) in control through the high dose were found. Cu sequestration in the bone of Mo-treated rats is a new finding. TBB treatment resulted in dramatic weight loss and loss of absolute organ mass. Relative organ weights were increased, except for the thymus. TBB altered the concentrations of certain amino acids. Compared to control rats, this polybrominated biphenyl congener significantly decreased plasma Cu and ceruloplasmin at higher concentrations of dietary Mo and promoted the process of plasma Cu decrease by Mo, suggesting a combined effect.