This study aimed to quantify the environmental fate of antimicrobials applied in
Fenneropenaeus chinensis
aquaculture production in China and to assess their potential risks for surrounding aquatic ...ecosystems, for the promotion of antimicrobial resistance in target and non-target bacteria and for consumers eating shrimp products that contain antimicrobial residues. For this, we first used the results of an environmental monitoring study performed with the antimicrobial sulfamethazine to parameterize and calibrate the ERA-AQUA model, a mass balance model suited to perform risk assessments of veterinary medicines applied in aquaculture ponds. Next, a scenario representing
F. chinensis
production in China was built and used to perform risk assessments for 21 antimicrobials which are regulated for aquaculture in China. Results of the model calibration showed a good correspondence between the predicted and the measured sulfamethazine concentrations, with differences within an order of magnitude. Results of the ecological risk assessment showed that four antimicrobials (levofloxacin, sarafloxacin, ampicillin, sulfadiazine) are expected to have adverse effects on primary producers, while no short-term risks were predicted for invertebrates and fish exposed to farm wastewater effluents containing antimicrobial residues. Half of the evaluated antimicrobials showed potential to contribute to antimicrobial resistance in bacteria exposed to pond water and farm effluents. A withdrawal period of three weeks is recommended for antimicrobials applied via oral administration to
F. chinensis
in order to comply with the current national and international toxicological food safety standards. The results of this study indicate the need to improve the current regulatory framework for the registration of aquaculture antimicrobials in China and suggest compounds that should be targeted in future aquaculture risk assessments and environmental monitoring studies.
The biodiversity of food webs is composed of horizontal (i.e. within trophic levels) and vertical diversity (i.e. the number of trophic levels). Understanding their joint effect on stability is a key ...challenge. Theory mostly considers their individual effects and focuses on small perturbations near equilibrium in hypothetical food webs. Here, we study the joint effects of horizontal and vertical diversity on the stability of hypothetical (modelled) and empirical food webs. In modelled food webs, horizontal and vertical diversity increased and decreased stability, respectively, with a stronger positive effect of producer diversity on stability at higher consumer diversity. Experiments with an empirical plankton food web, where we manipulated horizontal and vertical diversity and measured stability from species interactions and from resilience against large perturbations, confirmed these predictions. Taken together, our findings highlight the need to conserve horizontal biodiversity at different trophic levels to ensure stability.
A key challenge for the ecological risk assessment of chemicals has been to evaluate the relative contribution of chemical pollution to the variability observed in biological communities, as well as ...to identify multiple stressor groups. In this study we evaluated the toxic pressure exerted by >200 contaminants to benthic macroinvertebrates in the Danube River using the Toxic Unit approach. Furthermore, we evaluated correlations between several stressors (chemical and non-chemical) and biological indices commonly used for the ecological status assessment of aquatic ecosystems. We also performed several variation partitioning analyses to evaluate the relative contribution of contaminants and other abiotic parameters (i.e. habitat characteristics, hydromorphological alterations, water quality parameters) to the structural and biological trait variation of the invertebrate community. The results of this study show that most biological indices significantly correlate to parameters related to habitat and physico-chemical conditions, but showed limited correlation with the calculated toxic pressure. The calculated toxic pressure, however, showed little variation between sampling sites, which complicates the identification of pollution-induced effects. The results of this study show that the variation in the structure and trait composition of the invertebrate community are mainly explained by habitat and water quality parameters, whereas hydromorphological alterations play a less important role. Among the water quality parameters, physico-chemical parameters such as suspended solids, nutrients or dissolved oxygen explained a larger part of the variation in the invertebrate community as compared to metals or organic contaminants. Significant correlations exist between some physico-chemical measurements (e.g. nutrients) and some chemical classes (i.e. pharmaceuticals, chemicals related to human presence) which constitute important multiple stressor groups. This study demonstrates that, in large rivers like the Danube, the variation in the invertebrate community seems to be more related to varying habitat and physico-chemical conditions than to chemical pollution.
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•An extensive monitoring dataset from the Danube River was evaluated.•The influence of chemical and non-chemical stressors on invertebrates was studied.•Habitat and water quality parameters explained the largest part of the variation.•Variation explained by physico-chemical parameters was larger than by organic pollutants.•Multiple stressor groups for invertebrates were identified.
Exposure patterns in ecotoxicological experiments often do not match the exposure profiles for which a risk assessment needs to be performed. This limitation can be overcome by using ...toxicokinetic-toxicodynamic (TKTD) models for the prediction of effects under time-variable exposure. For the use of TKTD models in the environmental risk assessment of chemicals, it is required to calibrate and validate the model for specific compound–species combinations. In this study, the survival of macroinvertebrates after exposure to the neonicotinoid insecticide was modelled using TKTD models from the General Unified Threshold models of Survival (GUTS) framework. The models were calibrated on existing survival data from acute or chronic tests under static exposure regime. Validation experiments were performed for two sets of species-compound combinations: one set focussed on multiple species sensitivity to a single compound: imidacloprid, and the other set on the effects of multiple compounds for a single species, i.e., the three neonicotinoid compounds imidacloprid, thiacloprid and thiamethoxam, on the survival of the mayfly
Cloeon dipterum
. The calibrated models were used to predict survival over time, including uncertainty ranges, for the different time-variable exposure profiles used in the validation experiments. From the comparison between observed and predicted survival, it appeared that the accuracy of the model predictions was acceptable for four of five tested species in the multiple species data set. For compounds such as neonicotinoids, which are known to have the potential to show increased toxicity under prolonged exposure, the calibration and validation of TKTD models for survival needs to be performed ideally by considering calibration data from both acute and chronic tests.
Single‐species acute toxicity data and (micro)mesocosm data were collated for 16 insecticides. These data were used to investigate the importance of test‐species selection in constructing species ...sensitivity distributions (SSDs) and the ability of estimated hazardous concentrations (HCs) to protect freshwater aquatic ecosystems. A log‐normal model was fitted to a minimum of six data points, and the resulting distribution was used to estimate lower (95% confidence), median (50% confidence), and upper (5% confidence) 5% HC (HC5) values. Species sensitivity distributions for specific taxonomic groups (vertebrates, arthropods, nonarthropod invertebrates), habitats (saltwater, freshwater, lentic, lotic), and geographical regions (Palaearctic, Nearctic, temperate, tropical) were compared. The taxonomic composition of the species assemblage used to construct the SSD does have a significant influence on the assessment of hazard, but the habitat and geographical distribution of the species do not. Moreover, SSDs constructed using species recommended in test guidelines did not differ significantly from those constructed using nonrecommended species. Hazardous concentrations estimated using laboratory‐derived acute toxicity data for freshwater arthropods (i.e., the most sensitive taxonomic group) were compared to the response of freshwater ecosystems exposed to insecticides. The sensitivity distributions of freshwater arthropods were similar for both field and laboratory exposure, and the lower HC5 (95% protection with 95% confidence) estimate was protective of adverse ecological effects in freshwater ecosystems. The corresponding median HC5 (95% protection level with 50% confidence) was generally protective of single applications of insecticide but not of continuous or multiple applications. In the latter cases, a safety factor of at least five should be applied to the median HC5.
Freshwater ecosystems are strongly influenced by weather extremes such as heatwaves (HWs), which are predicted to increase in frequency and magnitude in the future. In addition to these climate ...extremes, the freshwater realm is impacted by the exposure to various classes of chemicals emitted by anthropogenic activities. Currently, there is limited knowledge on how the combined exposure to HWs and chemicals affects the structure and functioning of freshwater ecosystems. Here, we review the available literature describing the single and combined effects of HWs and chemicals on different levels of biological organization, to obtain a holistic view of their potential interactive effects. We only found a few studies (13 out of the 61 studies included in this review) that investigated the biological effects of HWs in combination with chemical pollution. The reported interactive effects of HWs and chemicals varied largely not only within the different trophic levels but also depending on the studied endpoints for populations or individuals. Hence, owing also to the little number of studies available, no consistent interactive effects could be highlighted at any level of biological organization. Moreover, we found an imbalance towards single species and population experiments, with only five studies using a multitrophic approach. This results in a knowledge gap for relevant community and ecosystem level endpoints, which prevents the exploration of important indirect effects that can compromise food web stability. Moreover, this knowledge gap impairs the validity of chemical risk assessments and our ability to protect ecosystems. Finally, we highlight the urgency of integrating extreme events into multiple stressors studies and provide specific recommendations to guide further experimental research in this regard.
We reviewed the available literature describing the single and combined effects of heatwaves and chemicals on different levels of biological organization. We found that only few studies addressed these stressors in combination. Moreover, we highlight the imbalance towards single species and population experiments. This results in a knowledge gap for relevant community‐ and ecosystem‐level endpoints, which prevents the exploration of important indirect effects that can compromise food web stability. Finally, we highlight the urgency of integrating extreme events into multiple stressors studies and provide recommendations to guide further experimental research in this regard.
Summary Background The available data on antimicrobial stewardship programmes in Africa are scarce. The aims of this study were to assess the implementation of an antimicrobial stewardship programme ...in a setting with limited infectious disease resources. Methods We implemented a pharmacist-driven, prospective audit and feedback strategy for antimicrobial stewardship on the basis of a range of improvement science and behavioural principles across a diverse group of urban and rural private hospitals in South Africa. The study had a pre-implementation phase, during which a survey of baseline stewardship activities was done. Thereafter, a stepwise implementation phase was initiated directed towards auditing process measures to reduce consumption of antibiotics (prolonged duration, multiple antibiotics, and redundant antibiotic coverage), followed by a post-implementation phase once the model was embedded in each hospital. The effect on consumption was assessed with the WHO index of defined daily doses per 100 patient–days, and the primary outcome (change in antibiotic consumption between phases) was assessed with a linear mixed-effects regression model. Findings We implemented and assessed the antimicrobial stewardship programme between Oct 1, 2009, and Sept 30, 2014. 116 662 patients receiving antibiotics at 47 hospitals during 104 weeks of standardised measurement and feedback, were reviewed, with 7934 interventions by pharmacists recorded for the five targeted measures, suggesting that almost one in 15 prescriptions required intervention. 3116 (39%) of 7934 pharmacist interventions were of an excessive duration. The antimicrobial stewardship programme led to a reduction in mean antibiotic defined daily doses per 100 patient–days from 101·38 (95% CI 93·05–109·72) in the pre-implementation phase to 83·04 (74·87–91·22) in the post-implementation phase (p<0·0001). Interpretation Health-care facilities with limited infectious diseases expertise can achieve substantial returns through pharmacist-led antimicrobial stewardship programmes and by focusing on basic interventions. Funding None.
The area around Lake Ziway in Ethiopia is going through a major agricultural transformation with both small-scale farmers and large horticultural companies using pesticides and fertilisers at an ...increased rate. To be able to understand how this influences the water quality of Lake Ziway, water quality data was gathered to study the dynamics of pesticide concentrations and physicochemical parameters for the years from 2009 to 2015. Results indicate that for some physicochemical parameters, including pH, potassium and iron, over 50 % of the values were above the maximum permissible limit of the Ethiopian standard for drinking water. The fungicide spiroxamine poses a high chronic risk when the water is used for drinking water, while the estimated intake of diazinon was approximately 50 % of the acceptable daily intake. Higher-tier risk assessment indicated that the fungicide spiroxamine poses a high acute risk to aquatic organisms, while possible acute risks were indicated for the insecticides deltamethrin and endosulfan. Longer-term monitoring needs to be established to show the water quality changes across time and space, and the current study can be used as a baseline measurement for further research in the area as well as an example for other surface water systems in Ethiopia and Africa.
At the end of a rush lasting over half a century, in which CMOS technology has been experiencing a constant and breathtaking increase of device speed and density, Moore's law is approaching the ...insurmountable barrier given by the ultimate atomic nature of matter. A major challenge for 21st century scientists is finding novel strategies, concepts and materials for replacing silicon-based CMOS semiconductor technologies and guaranteeing a continued and steady technological progress in next decades. Among the materials classes candidate to contribute to this momentous challenge, oxide films and heterostructures are a particularly appealing hunting ground. The vastity, intended in pure chemical terms, of this class of compounds, the complexity of their correlated behaviour, and the wealth of functional properties they display, has already made these systems the subject of choice, worldwide, of a strongly networked, dynamic and interdisciplinary research community.
Oxide science and technology has been the target of a wide four-year project, named Towards Oxide-Based Electronics (TO-BE), that has been recently running in Europe and has involved as participants several hundred scientists from 29 EU countries. In this review and perspective paper, published as a final deliverable of the TO-BE Action, the opportunities of oxides as future electronic materials for Information and Communication Technologies ICT and Energy are discussed. The paper is organized as a set of contributions, all selected and ordered as individual building blocks of a wider general scheme. After a brief preface by the editors and an introductory contribution, two sections follow. The first is mainly devoted to providing a perspective on the latest theoretical and experimental methods that are employed to investigate oxides and to produce oxide-based films, heterostructures and devices. In the second, all contributions are dedicated to different specific fields of applications of oxide thin films and heterostructures, in sectors as data storage and computing, optics and plasmonics, magnonics, energy conversion and harvesting, and power electronics.
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