We estimate the microplastic (MP) input to agricultural lands from wastewater and sewage sludge reuse in Europe and North America to be comprehensively between 107,000 and 730,000 tonnes/year making the farm environment one of the major receptors and, possibly, environmental reservoirs of MPs. While it is widely acknowledged that microplastics in the ocean are a serious environmental problem, the alarming threats posed by MPs and associated contaminants accumulating in agricultural soils are almost entirely unknown. According to recent reports a large fraction of the MPs generated and used in industrialized countries may end up in municipal wastewater and sewage sludge. A sizeable fraction of wastewater and sewage sludge is reused in these countries in agricultural lands with no technology in place to remove MPs. This is especially alarming given the high concentrations of toxic compounds and endocrine disrupting substances that can be found in plastics. Effectively, wastewater reuse and sewage sludge application may be causing persistent, pernicious and so far unacknowledged contamination of agricultural land. In IMPASSE, we propose to develop and communicate the new understanding of MP behaviour, toxicology and impacts in agrosystems. Highlights from the project are: • Development of monitoring schemes to track the fluxes and impacts of MP in agrosystems from reuse of wastewater and sewage sludge, including: i) assessment of MPs inputs, loads and fate in 3 catchment case studies, and ii) ecotoxicology of MPs in agrosystems (i.e. accumulation in soil and freshwater organisms, implication for bioaccumulation of substances contained in MPs). • Analysis of risks posed to human health from the reuse of wastewater and sewage sludge in agriculture. Specifically, the implications for enrichment of MP-derived contaminants and metabolites in crop and milk from farmlands treated with sludge and wastewater. • Interactive stakeholder engagement (including risk communication and participatory definition of management and modelling scenarios) • Development of decision support tools (including catchment modelling of MP transport and analysis of economic and environmental implications of various mitigation scenarios). This part will focus on analysis of economic and environmental co-benefits and trade-offs associated with, e.g., introduction of new technology for wastewater/sludge processing, irrigation and drainage management, and soil amendment practices that minimize exposure to MPs. • Dissemination of scenario assessment results to farmers, stakeholder groups, scientists and regulators. IMPASSE will develop awareness about a new and potentially serious threat for farms and natural ecosystems. Alarmingly, this threat has passed, so far, unobserved. Our ultimate goal is to find solutions that safeguard agricultural sustainability, human and animal health, and circular economy goals.

The arctic environment is changing at an alarming rate and it is essential to understand the consequences of such changes on arctic biodiversity. Longterm monitoring programmes of key arctic species are the backbone of scientific research aiming at studying these ecological consequences. The Circumpolar Biodiversity Monitoring Program of the Arctic Council recommends that such monitoring should be conducted and coordinated at a pan-arctic scale, and should involve indigenous participants. However, these monitoring programmes are still mainly operated by national research institutions, with a very uneven distribution of study sites across the Arctic and little involvement of local communities. In this context our project will handle the following key questions: What is the best, most efficient survey design for pan-arctic monitoring? Are current monitoring plans adequate, and how can they be improved? How can participatory citizen science best contribute to pan-Arctic long-term monitoring? What are the current participatory initiatives, and how can they be improved? We will focus on land vertebrates and seabirds which are acknowledged indicator species of arctic change and emblematic species for local communities. Using interviews of representatives of institutions funding arctic research and of representatives of arctic communities, we will assess their perceptions and expectations of pan-arctic, long-term participatory research activities on land vertebrates and seabirds. Further, we will use pan-arctic data on existing monitoring programmes of land vertebrates and seabirds, to test the hypothesis that this network of monitoring sites is unevenly distributed relative to environmental gradients. These analyses will allow us to propose a revised, ecologically sound network of key monitoring sites for land vertebrates and seabirds, that allows the most efficient study of these key species on a pan-arctic scale while fully involving local communities in participatory citizen science programmes.