Nadim Saadi

Microplastic ingestion by marine zooplankton can alter faecal pellet properties and potentially affect the biological carbon pump. However, there is a paucity of dose-dependent response data across environmentally relevant concentration gradients. This study investigated the effects of polyethylene microplastics on uptake, faecal pellet characteristics and sinking velocity in the copepod Calanus helgolandicus. Adult females were exposed for 24 h to polyethylene microspheres (27–32 µm) across at concentrations of 1 x 10⁻⁵–10⁰ g L⁻¹. Microplastic abundance within faecal pellets, pellet volume and sinking velocity were quantified. Polyethylene incorporation into faecal pellets increased sigmoidally with exposure concentration. Microplastic abundance ranged from 0-2 particles pellet⁻¹ at 10⁻⁵ g L⁻¹ to ≥20 particles pellet⁻¹ at concentrations ≥10⁻² g L⁻¹. Sinking velocity declined sigmoidally with increasing polyethylene concentration, with an estimated EC50 of 5.39 × 10⁻³ g L⁻¹ (95% CI: 1.52 × 10⁻³-9.27 × 10⁻³ g L⁻¹). Microplastic abundance was strongly negatively related to sinking velocity (adjusted R² = 0.405), whereas faecal pellet volume explained little variation in sinking rates (adjusted R² = 0.017) and did not significantly improve predictive models. No significant reductions in sinking velocity were observed at the lowest exposure concentrations (10⁻⁵-10⁻⁴ g L⁻¹). This study provides the first dose-response relationships describing polyethylene effects on copepod faecal pellet sinking rates across a broad concentration gradient. The results improve understanding of the role zooplankton play in the biologically mediated transport of microplastics and provide empirical parameters for modelling studies investigating microplastic export and effects on the marine biological pump.

Highlights● Fate factors in terrestrial, freshwater and marine compartments are calculated● The marine fate integrates the TrackMPD ocean tracking model● The fate factors are region, material, size, shape, and compartment-specific

Textile clothing is a significant contributor to microfiber pollution in aquatic ecosystems. A large portion of these emissions are cellulosic-based, either natural (e.g., cotton, linen) or semisynthetic (e.g., viscose, lyocell), which can be ingested by aquatic organisms, posing harmful effects even at environmentally relevant concentrations. Studies comparing the effects of cellulosic and synthetic fibers report conflicting results: some suggest synthetic fibers are more harmful, others the opposite. However, despite their high environmental abundance, the lack of a species sensitivity distribution (SSD) for cellulosic microfibers (CMFs) has prevented comparison of their effects with synthetic microfibers (SMFs). Further, although SMFs have been integrated into life cycle assessment (LCA) through characterization factors (CFs), equivalent CFs for CMFs are missing due to a lack of an exposure and effect factor (EEF) specific to these fibers. We derived CFs for six CMFs (cotton, linen, viscose, lyocell, rayon, and modal) by combining modeled fate factors in marine water and sediments with an EEF calculated from a hazardous concentration for 20% of species (HC20), using an SSD of EC10eq values. Taxonomically split SSDs were also obtained for further analysis of the mode of action of CMFs and microplastics. The HC20 for CMFs was not significantly different from that of microplastics, suggesting similar physical effect mechanisms. Fate modeling indicated lower persistence for CMFs, resulting in CFs one to two orders of magnitude lower than those for SMFs. Computed CFs were applied in an LCA comparing the ecosystem quality impacts of a cotton and a polyester tee shirt while accounting for microfiber emissions. Results show that polyester emissions caused significant impacts compared with other life cycle impacts, whereas cotton emissions did not. This work therefore provides the first comparative LCA of a cellulosic and a synthetic textile that considers impacts of microfiber emissions, and computes CFs compatible with different life cycle impact assessment methods.

Textile clothing is a significant contributor to microfiber pollution in aquatic ecosystems. A large portion of these emissions are cellulosic-based, either natural (e.g., cotton, linen) or semi-synthetic (e.g., viscose, lyocell), which can be ingested by aquatic organisms, posing harmful effects even at environmentally relevant concentrations. Studies comparing the effects of cellulosic and synthetic fibers report conflicting results: some suggest synthetic fibers are more harmful, others the opposite. However, despite their high environmental abundance, the lack of a species sensitivity distribution (SSD) for cellulosic microfibers (CMFs) has prevented comparison of their effects with synthetic microfibers (SMFs). Further, while SMFs have been integrated into Life Cycle Assessment (LCA) through characterization factors (CFs), equivalent CFs for CMFs are missing, due to a lack of an exposure and effect factor (EEF) specific to these fibers. We derived CFs for six CMFs (cotton, linen, viscose, lyocell, rayon, and modal) by combining modelled fate factors in marine water and sediments with an EEF calculated from a hazardous concentration for 20% of species (HC20), using an SSD of EC10eq values. Taxonomically split SSDs were also obtained for further analysis of the mode of action of CMFs and microplastics. The HC20 for CMFs was not significantly different from that of MPs, suggesting similar physical effect mechanisms. Fate modelling indicated lower persistence for CMFs, resulting in CFs one to two orders of magnitude lower than those for SMFs. Computed CFs were applied in an LCA comparing the ecosystem quality impacts of a cotton and a polyester T-shirt while accounting for microfiber emissions. Results show that polyester emissions caused significant impacts compared to other lifecycle impacts, while cotton emissions did not. This work therefore provides the first comparative LCA of a cellulosic and a synthetic textile that considers impacts of microfiber emissions, and computes CFs compatible with different LCIA methods.

Many dimensions of urban sustainability are intricately intertwined; however, systematic assessment of those linkages is often missing. To explore the details of these interdisciplinary linkages, we employ an in-depth literature review technique coupled with a multidimensional assessment of sustainability for 1300+ cities and regions in Europe. The wealth of indicators affecting economic, smart, social and environmental dimensions are linked within a coherent framework illustrating systemic links in urban sustainability. The performance of cities is illustrated using the multidimensional framework highlighting the contributions of various factors. The spectacular performance of Stockholm, Paris, London, Gothenburg, Malmö, Munich and Hamburg are illustrated with examples. Policy recommendations are offered to make cities and regions around the world more sustainable.