A modelling approach to evaluate the present and future effectiveness of hypolimnetic withdrawal for the restoration of eutrophic Lake Varese (Northern Italy).

Hypolimnetic withdrawal has been applied as a restoration measure in lakes subject to eutrophication together with external load reduction, to decrease internal load by removing limiting nutrient phosphorus (P) from anoxic deep waters and contributing to the unloading of bottom sediments from previously deposited nutrients and organic matter. The aim of this study is to evaluate the effect of hypolimnetic withdrawal on Lake Varese, a 24 m-deep and 14.8 km2-large subalpine lake in North-Western Italy. The lake suffered from extended eutrophication in the second half of the 20th century due to uncontrolled delivery of untreated urban sewage. Several restoration measures have been implemented during the years, including hypolimnetic withdrawal. In 2019, a cooperative programme for the protection and management of the lake and its surroundings was launched, establishing a systematic annual hypolimnetic withdrawal in the stratified season since 2020. In this research, we calibrated a one-dimensional (1D) coupled ecological-hydrodynamic model (General Lake Model/Aquatic EcoDynamics - GLM/AED2) of Lake Varese with data surveyed in the lake in 2019-2021. Model simulations of the period 2020-2021 with and without the performed withdrawal proved the effectiveness of this measure on hypolimnetic P concentration reduction. Then, future simulations of 2023-2085 were carried out to predict the future efficiency of hypolimnetic withdrawal and of reductions in external nutrient loads under climate change scenarios. Results show that the prescribed withdrawal increases hypolimnetic temperatures. This effect, coupled with thermocline deepening due to global warming, will possibly lead to decreasing water mass stability in autumn and shorter stratification in the moderately deep Lake Varese, with an eventual decrease of P concentrations in the water column. The future effectiveness of hypolimnetic withdrawal is further discussed considering the possible role of dry periods.

Safe(r)-by-design principles in the thermoplastics industry: guidance on release assessment during manufacture of nano-enabled products.

Background: The application of nanomaterials (NMs) and nano-enabled products (NEPs) across many industries has been extensive and is still expanding decades after first being identified as an emerging technology. Additive manufacturing has been greatly impacted and has seen the benefits of integrating NMs within products. With the expansion of nanotechnology, there has been a need to develop more adaptive and responsive methods to ascertain risks and ensure technology is developed safely. The Safe(r)-by-Design (SbD) concept can be used to establish safe parameters and minimise risks during the materials' lifecycle, including the early stages of the supply chain. Exposure monitoring has advanced in recent years with the creation of standardised protocols for occupational exposure assessment of nano-objects and their aggregates and agglomerates (NOAA). Methods: To aid in the development of an online SbD-supporting platform by the EU-funded project SAbyNA, we adopt a Europe Standard for monitoring release of NOAA to identify if a greater release of NOAA is associated with incorporation of NMs within NEPs compared to a polymer matrix alone. Case studies included filaments of polypropylene (PP) with nano-Ag or polycarbonate (PC) with single-walled carbon nanotubes (SWCNTs). NMs were received in masterbatch, and therefore previously modified to align with SbD interventions. Results were collected in line with European Standard recommendations: monitoring particle concentrations using direct reading instruments (DRI), sampling for offline chemical and morphological analysis, and collecting contextual information. Results and discussion: Based on the criteria described in the European standard (BS EN 17058), data from both case studies identified that inhalation exposure relating to NM was "unlikely". Despite this, during the production of the SWCNT-PC filaments, some noteworthy observations were made, including several DRI activity measurements shown to be higher than background levels, and material morphologically similar to the reference SWCNT/polymeric masterbatch observed in offline analysis. The data collected during this campaign were used to discuss choices available for data interpretation and decision-making in the European Standard for monitoring release of NOAA and also to facilitate the development of SAbyNA's user-friendly industry platform for the SbD of NMs and NEPs.

Comparison between Communicated and Calculated Exposure Estimates Obtained through Three Modeling Tools.

This study aims to evaluate the risk assessment approach of the REACH legislation in industrial chemical departments with a focus on the use of three models to calculate exposures, and discuss those factors that can determine a bias between the estimated exposure (and therefore the expected risk) in the extended safety data sheets (e-SDS) and the expected exposure for the actual scenario. To purse this goal, the exposure estimates and risk characterization ratios (RCRs) of registered exposure scenarios (ES; "communicated exposure" and "communicated RCR") were compared with the exposure estimates and the corresponding RCRs calculated for the actual, observed ES, using recommended tools for the evaluation of exposure assessment and in particular the following tools: (i) the European Centre for Ecotoxicology and Toxicology of Chemicals Targeted Risk Assessment v.3.1 (ECETOC TRA), (ii) STOFFENMANAGER® v.8.0 and (iii) the Advanced REACH Tool (ART). We evaluated 49 scenarios in three companies handling chemicals. Risk characterization ratios (RCRs) were calculated by dividing estimated exposures by derived no-effect levels (DNELs). Although the calculated exposure and RCRs generally were lower than communicated, the correlation between communicated and calculated exposures and RCRs was generally poor, indicating that the generic registered scenarios do not reflect actual working, exposure and risk conditions. Further, some observed scenarios resulted in calculated exposure values and RCR higher than those communicated through chemicals' e-SDSs; thus 'false safe' scenarios (calculated RCRs > 1) were also observed. Overall, the obtained evidences contribute to doubt about whether the risk assessment should be performed using generic (communicated by suppliers) ES with insufficient detail of the specific scenario at all companies. Contrariwise, evidences suggested that it would be safer for downstream users to perform scenario-specific evaluations, by means of proper scaling approach, to achieve more representative estimates of chemical risk.