The Multi-Scale Response of Water Quality, Biodiversity and C Sequestration to Coupled Macronutrient Cycling from Source to Sea

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Catchment research has traditionally been focussed on the science and management of water flow and quality. In recent years, achieving good ecological status and compliance with the Water Framework Directive has been a priority. This has been challenging not least because the majority of rivers in the UK are heavily polluted with nitrogen, phosphorus, and a range of contaminants including pathogens and transfers of dissolved organic C from upland areas are increasing. These can be detrimental to the ecology of rivers and coastal waters, be a risk for human health and increases costs of the water industry. Following the publication of the National Ecosystem Assessment (2011) and the Government's White Paper on the Natural Environment (2011), catchment managers face an even greater challenge trying to ensure water resource objectives do not compromise delivery of other functions which deliver a range of regulating, provisioning or cultural services which we all benefit from. Underpinning delivery of these ecosystem services are basic ecosystem processes such as carbon fixation by plants and the return of carbon back to the atmosphere through decomposition (the carbon cycle), the cycling of nutrients such as nitrogen and phosphorus through plants, soil, water and the atmosphere and detoxification of a range of contaminants including pathogens. Much is known concerning the individual carbon, nitrogen and phosphorus (C, N and P) and contaminant cycles, however the coupling of these cycles through the landscape and the subsequent impacts on the natural environment and the services provided are rarely studied. To respond to this gap in our current understanding we will address two research questions. The first is when, where and how do coupled macronutrient cycles (of C, N and P) affect the the functioning of the natural environment within and between landscape units at the catchment scale? The second is how will these coupled cycles alter under land use, air pollution, and climate-change and what will be the effect on water quality, carbon sequestration and biodiversity (three important ecosyststem services) at both catchment and national scale? To achieve this, we will quantify the fluxes, transformations and coupling of the C, N, and P cycles through key processes (net primary productivity, decomposition, nutrient cycling) and quantify the links to pathogen transfer and viability using a combination of targeted field-based monitoring and field- and laboratory-based experimentation in the Conwy catchment supplemented by measurements in intensively farmed areas of the Ribble. The following outcomes are expected:1. Quantification and improved process-understanding of coupled C, N and P processes, transformations and fluxes across soil functional types and within processing hotspots. 2. Quantification of the effects of instream ecosystem function and co-limitation of N/P on eutrophication development in freshwaters.3. Testing of hypotheses that terrestrial and freshwater biodiversity can be explained at the catchment- and national-scales as function of macronutrient flux and primary productivity.4. Source to sea flux quantification and process-understanding of the fate of pathogens and the controls exerted by macronutrients within very fine sediments (flocs). 5. An integrated, parsimonious coupled macronutrient (C, N, P) air-land-water modelling platform, configured for a 1 km grid across the Conwy (i.e. an enhanced JULES model).6. Sensitivity analysis of carbon sequestration, water quality and biodiversity to past and future climate, nutrient and land (forest) cover change to determine the key controls on past and future changes in carbon sequestration, water quality and biodiversity.7. Quantification of trade offs in delivery of carbon sequestration, water quality and biodiversity at the catchment scale and the relationship to land cover type and climate regime.