The pH of freshwater ecosystems affects bioavailability of various metals to various organisms, including daphnids. Although it is well known that daphnid species show interclonal variation of metal sensitivity, knowledge about interclonal variation of bioavailability effects, such as the pH effect, is scarce. Here, we compared the effect of pH on chronic copper toxicity between two clones of Ceriodaphnia dubia, within its natural pH niche, which we determined to be approximately pH 6.5-8.5 based on existing experimental and biological monitoring data. Using a Bayesian modeling approach, we found that the effect of pH was not statistically significantly different between the two clones (with a credibility > 95%). Overall, we found an approximately threefold decrease in chronic Cu toxicity with increasing pH between pH 6.5 and 8.5, with 7-day 20% effect concentration (EC20) values ranging between 11.0 and 30.9 µg/L dissolved Cu. We then calibrated a preliminary generalized bioavailability model (gBAM) using these data and found a pH-effect slope parameter SpH = -0.247, which is within the range of previously reported values for Daphnia magna (-0.056 to -0.361) and similar to the SpH value of -0.220 used in the "invertebrate gBAM" for bioavailability-based Cu risk assessment under the Registration, Evaluation, Authorisation and Restriction of Chemicals. The preliminary C. dubia gBAM captured the magnitude of the observed pH effect well (mean of 1.3-fold EC20 prediction error, n = 9). It was also able to accurately predict chronic Cu toxicity in natural waters reported in an independent dataset (mean of 1.4-fold prediction error, n = 6). Also, two D. magna gBAMs (for two clones) and the invertebrate gBAM showed comparable predictive capabilities. Collectively, our work highlights the importance of studying relations between pH and metal bioavailability within the species' natural niche. It also confirms earlier findings that biological variation of pH-bioavailability relations typically does not have a large impact on predictive capacity of bioavailability models, which is important for regulatory applications.
The primary objective of the present study was to examine the influence of early systemic toxicity resulting from copper (Cu) exposure on metamorphic processes in Xenopus laevis. A 28-day exposure study with copper, initiated at developmental stage 10, was performed using test concentrations of 3.0, 9.0, 27.2, 82.5, and 250 mu g Cu/L. The primary endpoints included mortality, developmental stage, embryo-larval malformation, behavioral effects, hindlimb length (HLL), growth (snout-vent length [SVL] and wet body weight), and histopathology. The 28-day LC50 value with 95% confidence intervals was 61.2 (51.4-72.9) mu g Cu/L with 250 mu g Cu/L resulting in complete lethality. Developmental arrest in the 82.5 and delay in the 27.2 mu g Cu/L treatments was observed as early as study day 10 continuing throughout the remainder of exposure. SVL-normalized HLL, body weight, and SVL in the 27.2 and 82.5 mu g Cu/L treatments were significantly decreased relative to control. At 82.5 mu g Cu/L, and thyroid gland size was markedly reduced when compared with controls consistent with the stage of developmental and growth arrest. Concentration-dependent findings in the intestine, liver, gills, eyes, and pharyngeal mucosa were consistent with non-endocrine systemic toxicity. These were prevalent in the 9.0 and 27.2 mu g Cu/L treatment groups but were minimally evident or absent in the 82.5 mu g/L group, which was attributed to developmental arrest. In conclusion, developmental delay in larvae exposed to 27.2 and 82.5 mu g Cu/L was the result of systemic toxicity occurring in early development prior hypothalomo-pituitary-thyroid axis (HPT)-driven metamorphosis and was not indicative of endocrine disruption.
Due to the limited loading capacity of mineral oil-filled transformers, grid operators must choose a transformer size that can handle the peak demand, resulting in a higher nominal rating than needed for typical usage. Some types of innovative transformers can withstand higher internal temperatures, and consequently higher peak demand, without compromising unit reliability or lifetime. They are sometimes called “dual nameplate” or “sustainable peak load” transformers, but the authors of this paper prefer to address them as “enhanced capacity transformers” for reasons of simplicity. The concept allows utilities to upgrade their networks while keeping the same unit dimensions. This could be of great help to absorb the expected power surges from PV production, EV charging and heat pumps. But what exactly is the potential of this concept in terms of cost, material use and energy losses? The authors conducted a modelling exercise to assess the impact of selecting enhanced capacity units for all transformer replacements in EU distribution networks.
Calorimetric studies and safety tests on lithion-ion cells and post-lithium cells Open Access Government interviews Dr Carlos Ziebert, of the Karlsruhe Institute of Technology (KIT), who explores the thermal and safety properties of batteries across calorimetric studies. The group batteries – calorimetry and safety – focus on calorimetric studies and safety tests on lithium-ion cells and post-lithium cells. Depending on the cell size and application, different types of calorimeters are used in Europe's largest Battery Calorimeter Laboratory, established in 2011. It provides seven Accelerating Rate Calorimeters (ARCs) from Thermal Hazard Technology allowing the evaluation of thermodynamic, thermal and safety data for Lithium-ion and post-Li cells on material, cell, and pack levels for both normal and abuse conditions (thermal, electrical, mechanical). The lab also includes glove boxes for cell assembly and disassembly, many temperature chambers, a thermal camera, and cyclers with several hundred channels. It contains extremely sensitive 3D Calvet calorimeters, providing thermodynamic parameters and gas chromatography-mass spectrometry systems from Perkin-Elmer for venting gas analysis.
Chemical contamination from point source discharges in developed (resource-rich) countries has been widely regulated and studied for decades; however, diffuse sources are largely unregulated and widespread. In the European Union (EU), large dischargers report releases of some chemicals, yet little is known of total emissions (point and diffuse) and their relative significance. We estimated copper loadings from all significant sources including industry, sewage treatment plants, surface runoff (from traffic, architecture, and atmospheric deposition), septic tanks, agriculture, mariculture, marine transport (antifoulant leaching), and natural processes. A combination of European datasets, literature, and industry data were used to generate export coefficients. These were then multiplied by activity rates to derive loads. A total of approximately 8 kt of copper per annum (ktpa) is estimated to enter freshwaters in the EU, and another 3.5 ktpa enters transitional and coastal waters. The main inputs to freshwater are natural processes (3.7 ktpa), agriculture (1.8 ktpa), and runoff (1.8 ktpa). Agricultural emissions are dominated by copper-based plant protection products and farmyard manure. Urban runoff is influenced by copper use in architecture and by vehicle brake linings. Antifoulant leaching from boats (3.2 ktpa) dominates saline water loads of copper. It is noteworthy that most of the emissions originate in a limited number of copper uses where environmental exposure and pathways exist, compared with the bulk of copper use within electrical and electronic equipment and infrastructure that has no environmental pathway during its use. A sensitivity analysis indicated significant uncertainty in data from abandoned mines and urban runoff load estimates. This study provided for the first time a methodology and comprehensive metal load apportionment to European aquatic systems, identifying data gaps and uncertainties, which may be refined over time. Source apportionments using this methodology can inform more cost-effective environmental risk assessment and management. Integr Environ Assess Manag 2023;19:1031-1047. © 2022 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).
