2 Projects, page 1 of 1
Source streams, or headwaters, are often provided with the least protection from forestry and other land uses. However, the impact on ecological status of small streams from increasing water temperature, mobilising sediment, nutrients and contaminants may overwhelm the resilience of these stream ecosystems. Moreover, such changes initiate the downstream transport of these altered conditions. Protection of source streams by providing sufficient buffers is considered to be costly, but that is primarily as opportunity costs for industry. When the values of ecosystem services to downstream users is included, there is a potentially different solution. This is critical to fulfilling the Water Framework Directive 7 (and similar goals for protection of water in Canada and other countries) to ensure that anthropogenic alterations do not impair the ecological status of streams, or their inputs to downstream rivers and lakes. Source streams with small catchment areas are also prone to extreme events, both droughts and floods, relevant to the Floods Directive. Moreover, climate-proofing our stream networks through riparian area protection to reduce uncertainty about water supplies and downstream impacts may provide additional values to aid in sorting out the trade-offs among benefits (relevant to Horizon 2020). This project aims to estimate the ecological, hydrological, water quality, and economic consequences of different management scenarios (e.g., buffers), by comparing the economic and social trade-offs for different value sets and management practices, and to reduce uncertainty of how these possible impacts integrate across scales. We have three objectives. First, we will develop a model platform to explore the consequences of various forms of streamside management around source (headwater) streams. This model will use existing and new data on nutrient flows, sediment fluxes, temperature increases, and loss of productive capacity under different forest management treatments and across many landscapes. The opportunity costs of foregone timber extraction will be compared against the trade-offs to other ecosystem values (clean water, flood protection, productivity). We will generate scenarios of different management configurations to be explored by policy-makers. This will enable a discussion of the value of better protecting source streams and perhaps giving up some protection to larger streams to meet Water Framework Directive objectives. Our second objective is to augment the available data for small stream responses to forest management across our varied landscapes, using comparisons of harvested versus unharvested (no recent harvests) with and without riparian reserves, and to compare headwater versus larger streams. This will be coupled with mesocosm-scale experiments to determine mechanisms of responses by small streams to forestry impacts. Our third objective is to prepare a design and white paper for the large, distributed, landscape-scale experiment that should be done to determine the ecosystem values gained by protection of headwater streams.
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.