Effect of different soil types on the enchytraeids Enchytraeus albidus and Enchytraeus luxuriosus using the herbicide Phenmedipham

Soil ecotoxicology studies are usually performed in standard soils, such as the OECD (Organization for Economic Cooperation and Development) artificial soil or the LUFA St. 2.2, a natural soil. When assessing the toxic effects in the environment, soil properties are often different from those in standard soils, which might lead to a different exposure situation for the test species and, therefore, to a different evaluation of the risk of the test substance. Selected to cover a broad range of properties and based on the Euro-Soils concept, 18 different soils were studied regarding their suitability to two test species: Enchytraeus albidus and Enchytraeus luxuriosus (Enchytraeidae). In reproduction tests, the test species reacted differently to the tested soils, but both enchytraeids did not survive in acid soils (i.e. pH相似文献   

Inter- and intra-species variation in acute zinc tolerance of field-collected cladoceran populations

Acute zinc toxicity was assessed for 10 freshwater cladoceran species collected in six different ecosystems across Europe and for two standard laboratory-reared species (Daphnia magna and Ceriodaphnia dubia). The collected organisms belonged to five different genera: Daphnia (subgenus Daphnia and Ctenodaphnia), Ceriodaphnia, Simocephalus, Acroperus and Chydorus. The 48-h EC50 of the field-collected organisms tested in standard laboratory water ranged from 375+/-141 to 4314+/-1513 microg Znl(-1). The laboratory clone of D. magna was less sensitive than the majority of the field-collected species, while our laboratory Ceriodaphnia dubia was the second most sensitive. Considerable inter-species variation was found within the genus of Ceriodaphnia (factor 6) and within the genus Daphnia (factor 8). Among the different (sub)genera tested, Chydorus and Ctenodaphnia were significantly more tolerant than the others (up to a factor 3 difference). A significant positive relationship (r2=0.67, p<0.05) between the mean cladoceran 48-h EC50 and the ambient zinc concentration of the different aquatic systems was demonstrated, suggesting a role of acclimation and/or adaptation. No significant correlation between the acute zinc tolerance and the length of the organisms was found.     

Laboratory evaluation of thermophilic-anaerobic digestion to produce Class A biosolids. 2. Inactivation of pathogens and indicator organisms in a continuous-flow reactor followed by batch treatment.

Thermophilic-anaerobic digestion in a single-stage, mixed, continuous-flow reactor is not approved in the United States as a process capable of producing Class A biosolids for land application. This study was designed to evaluate the inactivation of pathogens and indicator organisms in such a reactor followed by batch treatment in a smaller reactor. The combined process was evaluated at 53 degrees C with sludges from three different sources and at 51 and 55 degrees C with sludge from one of the sources. Feed sludge to the continuous-flow reactor was spiked with the pathogen surrogates Ascaris suum and vaccine-strain poliovirus. Feed and effluent were analyzed for these organisms and for indigenous Salmonella spp., fecal coliforms, Clostridium perfringens spores, and somatic and male-specific coliphages. No viable Ascaris eggs were observed in the effluent from the continuous reactor at 53 or 55 degrees C, with greater than 2-log removals across the digester in all cases. Approximately 2-log removal was observed at 51 degrees C, but all samples of effluent biosolids contained at least one viable Ascaris egg at 51 degrees C. No viable poliovirus was found in the digester effluent at any of the operating conditions, and viable Salmonella spp. were measured in the digester effluent in only one sample throughout the study. The ability of the continuous reactor to remove fecal coliforms to below the Class A monitoring limit depended on the concentration in the feed sludge. There was no significant removal of Clostridium perfringens across the continuous reactor under any condition, and there also was limited removal of somatic coliphages. The removal of male-specific coliphages across the continuous reactor appeared to be related to temperature. Overall, at least one of the Class A pathogen criteria or the fecal coliform limit was exceeded in at least one sample in the continuous-reactor effluent at each temperature. Over the range of temperatures evaluated, the maximum time required to meet the Class A criteria by batch treatment of the continuous-reactor effluent was 1 hour for Ascaris suum and Salmonella spp. and 2 hours for fecal coliforms.     

Modelling of the life cycle of Chironomus species using an energy-based model

Little is known about the differences between the species of the genus Chironomus relatively to their life cycle strategies. This knowledge is however crucial to fully understand the response of the Chironomus community to field perturbations. Here, we proposed to study four Chironomus species by using an energy-based model to describe growth, emergence and reproduction. We used data from the literature for two species (Chironomus plumosus and Chironomus tentans) and data from our experiments for two other species (Chironomus prasinus and Chironomus riparius). We showed that our model is able to accurately describe the life-history attributes for all the species tested, which suggests that Chironomus species have the same fundamental characteristics (low maintenance energetic costs, isomorphism), which makes possible the building of a common modelling framework to assess effects of toxicants at individual and population level. The species showed a few differences relatively to the parameters of the models with possible consequences when assessing effects of chemicals on Chironomus community. For instance, due to differences in growth parameters, C. riparius population dynamics should be more sensitive to effects on individual growth than C. prasinus or C. plumosus ones.     

The fate and removal of triclosan during wastewater treatment.

This work examines the variation in removal efficiency of triclosan in wastewater treatment works in the United Kingdom between November 2003 and April 2004. Concentrations of triclosan were measured at set points within three different types of wastewater treatment works: rotating biological contactors, trickling filters, and activated sludge. Overall removal of triclosan through these plants ranged from 58 to 96% (rotating biological contactors), 86 to 97% (trickling filter), and 95 to 98% (activated sludge).     

Avoidance behaviour of Enchytraeus albidus: effects of benomyl, carbendazim, phenmedipham and different soil types

Enchytraeids are typical inhabitants of many soils, contributing to vital processes of this environmental compartment. Indirectly they are involved in regulating the degradation of organic matter, as well as improving the pore structure of the soil. Due to their behaviour, they are able to avoid unfavourable environmental conditions. Avoidance tests with enchytraeids, initially developed with earthworms by several authors, are quick and easy to perform. With these tests a first assessment of the toxicity of a (contaminated or spiked) soil is possible in just 48 h by using the reaction of the enchytraeids as measurement endpoint. In this period of time the organisms can choose between the control soil and the other soil (a contaminated or spiked or another soil with different physico-chemical properties). In the tests reported here, the enchytraeids were exposed to control soils spiked with the fungicides Benomyl and Carbendazim and the herbicide Phenmedipham. Several chemical concentrations were tested in order to evaluate the avoidance behaviour to toxic substances. In fact, often these short-term screening tests gave results showing avoidance at concentrations in a range similar to the acute test results but, higher than in chronic tests. Further tests are needed to decide whether the results gained in this study can be extrapolated to other chemicals. It is proposed to standardize the Enchytraeid Avoidance Test as it is currently done for the Earthworm Avoidance Test by the International Standard Organization (ISO).     

Influence of sediment on the fate and toxicity of a polyethoxylated tallowamine surfactant system (MON 0818) in aquatic microcosms

The fate and toxicity of a polyethoxylated tallowamine (POEA) surfactant system, MON 0818, was evaluated in water-sediment microcosms during a 4-d laboratory study. A surfactant solution of 8 mg l(-1) nominal concentration was added to each of nine 72-l aquaria with or without a 3-cm layer of one of two natural sediments (total organic carbon (TOC) 1.5% or 3.0%). Control well water was added to each of nine additional 72-l aquaria with or without sediment. Water samples were collected from the microcosms after 2, 6, 24, 48, 72, and 96 h of aging to conduct 48-h toxicity tests with Daphnia magna and to determine surfactant concentrations. Elevated mortality of D. magna (43-83%) was observed in overlying water sampled from water-only microcosms throughout the 96-h aging period, whereas elevated mortality (23-97%) was only observed in overlying water sampled from water-sediment microcosms during the first 24h of aging. Measured concentrations of MON 0818 in water-only microcosms remained relatively constant (4-6 mg l(-1)) during the 96-h period, whereas the concentrations in overlying water from microcosms containing either of the two types of sediment dissipated rapidly, with half-lives of 13 h in the 3.0% TOC sediment and 18 h in the 1.5% TOC sediment. Both toxicity and the concentration of MON 0818 in overlying water decreased more rapidly in microcosms containing sediment with the higher percent TOC and clay and with a higher microbial biomass. Mortality of D. magna was significantly correlated with surfactant concentrations in the overlying water. These results indicate that the toxicity of the POEA surfactant in water rapidly declines in the presence of sediment due to a reduction in the surfactant concentration in the overlying water above the sediment.     

Copper regulation and homeostasis of Daphnia magna and Pseudokirchneriella subcapitata: influence of acclimation

This study aimed to evaluate (1) the capacity of the green alga Pseudokirchneriella subcapitata and the waterflea Daphnia magna to regulate copper when exposed to environmentally realistic copper concentrations and (2) the influence of multi-generation acclimation to these copper concentrations on copper bioaccumulation and homeostasis. Based on bioconcentration factors, active copper regulation was observed in algae up to 5 microg Cu L(-1) and in daphnids up to 35 mug Cu L(-1). Constant body copper concentrations (13+/-4 microg Cu g DW(-1)) were observed in algae exposed to 1 through 5 microg Cu L(-1) and in daphnids exposed to 1 through 12 microg Cu L(-1). At higher exposure concentrations, there was an increase in internal body copper concentration, while no increase was observed in bioconcentration factors, suggesting the presence of a storage mechanism. At copper concentrations of 100 microg Cu L(-1) (P. subcapitata) and 150 microg Cu L(-1) (D. magna), the significant increases observed in body copper concentrations and in bioconcentration factors may be related to a failure of this regulation mechanism. For both organisms, internal body copper concentrations lower than 13 microg Cu g DW(-1) may result in copper deficiency. For P. subcapitata acclimated to 0.5 and 100 microg Cu L(-1), body copper concentrations ranged (mean+/-standard deviation) between 5+/-2 microg Cu g DW(-1) and 1300+/-197 microg Cu g DW(-1), respectively. For D. magna, this value ranged between 9+/-2 microg Cu g DW(-1) and 175+/-17 microg Cu g DW(-1) for daphnids acclimated to 0.5 and 150 microg Cu L(-1). Multi-generation acclimation to copper concentrations >or =12 microg Cu L(-1) resulted in a decrease (up to 40%) in body copper concentrations for both organisms compared to the body copper concentration of the first generation. It can be concluded that there is an indication that P. subcapitata and D. magna can regulate their whole body copper concentration to maintain copper homeostasis within their optimal copper range and acclimation enhances these mechanisms.     

The evaluation of electrical energy per order (E(Eo)) for photooxidative decolorization of four textile dye solutions by the kinetic model

Photooxidative decolorization of four textile dyestuffs, C.I. Acid Orange 7 (AO7), C.I. Acid Orange 8 (AO8), C.I. Acid Orange 52 (AO52) and C.I. Acid Blue 74 (AB74), by UV/H2O2 was investigated in a laboratory scale photoreactor equipped with a 15 W low pressure mercury vapour lamp. The decolorization of the dyes was found to follow pseudo-first-order kinetics, and hence the figure-of-merit electrical energy per order (E(Eo)) is appropriate for estimating the electrical energy efficiency. The E(Eo) values were found to depend on the concentration of H2O2, concentration and basic structure of the dye. This study shows that these textile dyes can be treated easily and effectively with the UV/H2O2 process with E(Eo) values between 0.4 and 5 kW h m-3 order-1, depending on the initial concentrations of dyes and H2O2. The kinetic model, based on the initial rates of degradation, provided good prediction of the E(Eo) values for a variety of conditions.     

A net loss: policy instruments for commercial cod fishing in Sweden

This paper describes the overfishing of the seas, in particular for cod in Sweden. It discusses policy instruments such as individual quotas, labelling and marine reserves. A tentative conclusion is that something needs to be done to the very structure of the policy instruments used. Information on stock depletion is available but goes unheeded and is counteracted by fishermen who want to fish more and who are routinely supported by "the political establishment" who appear to be most concerned about (short-term) employment. The whole debate is taking place before the eyes of a general public that does not care sufficiently and difficult international bureaucracy. In this situation, the most important changes may be to strengthen both the rights and the duties of the fishermen. The integrity of fish stocks must be given absolute priority, but it is also important to motivate the fishermen with a greater stake and interest in the stock by giving them quotas that have, as far as possible, the characteristics of property.