Chemical pollution poses a threat to biodiversity on a global scale. This has been acknowledged in the Post-2020 Biological Diversity Framework which proposes to regulate the release of chemicals to the environment and names specific indicators focusing on pesticides, nutrients and plastic waste. We fully endorse the inclusion of these substances but argue that in order to protect biodiversity from hazardous chemicals, the scope of Target 7 should feature other groups of pollutants with potential to contribute to biodiversity loss. We propose the inclusion of non-agricultural biocides, per- and polyfluoroalkyl substances (PFASs), toxic metal(loid)s, and endocrine disrupting chemcials (EDCs). Furthermore, data on emerging pollutants (e.g., rare earth elements, industrial chemicals, liquid crystal monomers, pharmaceuticals, personal care products) need to be regularly scanned and these pollutants added to Target 7 in case of biodiversity risk. We suggest to amend Target 7 to postulate the aim for the overall reduction of chemical production and emissions, as well as the addition of the described substance groups of high concern to biodiversity for discussion and implementation in the Post-2020 Biodiversity Framework. We further elaborate on different strategies for the reduction of emissions of hazardous chemicals through chemical simplification and grouping, reduction of chemicals with non-essential use, and innovative synthesis strategies (“benign by design”). In this context the full life cycle of chemicals, i.e., production, use, end of life needs to be considered. Lastly, we propose to set up data inventories that transparently inform about production, transport and emissions of chemicals in cooperation with industry, that can serve as basis for indicators related to monitoring the effectiveness of the goals set under Target 7.

Aquatic fate models and risk assessment require experimental information on the potential of contaminants to interact with riverine suspended particulate matter (SPM). While for dissolved contaminants partition or sorption coefficients are used, the underlying assumption of chemical equilibrium is invalid for particulate contaminants, such as engineered nanomaterials, incidental nanoparticles, micro- or nanoplastics. Their interactions with SPM are governed by physicochemical forces between contaminant-particle and SPM surfaces. The availability of a standard SPM material is thus highly relevant for the development of reproducible test systems to evaluate the fate of particulate contaminants in aquatic systems. Finding suitable SPM analogues, however, is challenging considering the complex composition of natural SPM, which features floc-like structures comprising minerals and organic components from the molecular to the microorganism level. Complex composition comes with a heterogeneity in physicochemical surface properties, that cannot be neglected. We developed a procedure to generate SPM analogue flocs from components selected to represent the most abundant and crucial constituents of natural riverine SPM, and the process-relevant SPM surface characteristics regarding interactions with particulate contaminants. Four components, i.e., illite, hematite, quartz and tryptophan, combined at environmentally realistic mass-ratios, were associated to complex flocs. Flocculation was reproducible regarding floc size and fractal dimension, and multiple tests on floc resilience towards physical impacts (agitation, sedimentation-storage-resuspension, dilution) and hydrochemical changes (pH, electrolytes, dissolved organic matter concentration) confirmed their robustness. These reproducible, ready-to-use SPM analogue flocs will strongly support future research on emerging particulate contaminants.

The release of fragments from plastic products, that is, secondary microplastics, is a major concern in the context of the global plastic pollution. Currently available (thermoplastic) polyurethanes [(T)PU] are not biodegradable and therefore should be recycled. However, the ester bond in (T)PUs might be sufficiently hydrolysable to enable at least partial biodegradation of polyurethane particles. Here, we investigated biodegradation in compost of different types of (T)PU to gain insights into their fragmentation and biodegradation mechanisms. The studied (T)PUs varied regarding the chemistry of their polymer backbone (aromatic/aliphatic), hard phase content, cross-linking degree, and presence of a hydrolysis-stabilizing additive. We developed and validated an efficient and non-destructive polymer particle extraction process for partially biodegraded (T)PUs based on ultrasonication and density separation. Our results showed that biodegradation rates and extents decreased with increasing cross-linking density and hard-segment content. We found that the presence of a hydrolysis stabilizer reduced (T)PU fragmentation while not affecting the conversion of (T)PU carbon into CO2. We propose a biodegradation mechanism for (T)PUs that includes both mother particle shrinkage by surface erosion and fragmentation. The presented results help to understand structure–degradation relationships of (T)PUs and support recycling strategies.