STREAM SYNCHRONY: UNDERSTANDING THE SYNCHRONY OF NUTRIENTS, POLLUTION, AND WATER IN RIVER ECOSYSTEMS

Rivers convey and transform the water, nutrients and pollutants they receive fromthe landscape. High concentrations of nutrients such as nitrogen and phosphorus may act as pollutants, damaging freshwater and estuary ecosystems through processes such as eutrophication. Anthropogenic activities, including agriculture and fertiliser application, are the main causes of polluting levels of nitrogen and phosphorus in many river systems, leading to overall poor river health across many regions of the UK (The Rivers Trust, 2021). Dissolved organic carbon (DOC) is an important component of landscape carbon cycling, and at the same time another potential pollutant of river water quality. The carbon available to river networks, and how it is cycled, has also been altered by land use and climate change. The main source of DOC to stream water in the UK are from soils and peatlands (e.g., Ritson et al., 2019), but human activity like sewage treatment plant inputs is known to also play an important role (Worrall et al., 2019).
Interestingly, the input of these nutrients and pollutants is not constant over time but varies with changes in peak supply from sources and removal by natural reaction processes. Furthermore, the potential impact of nutrients and pollutants on river systems fundamentally depends on how much water river systems are conveying, which can vary seasonally due to the seasonality of precipitation and evapotranspiration. Moreover, under changing climates and anthropogenic stress, the frequency, magnitude, and timing of all these inputs are shifting, leading to changing nutrient and pollution dynamics that both ecosystems themselves and water managers have to adapt to.
A fundamental and large-scale knowledge gap for both understanding the processes involved and how they could be better managed revolves around the question of how synchronous all these inputs (water, nutrients, pollutants) are with one another (Abbott et al., 2017). This project will be the first to use existing large datasets to estimate how synchronous (or asynchronous) the inputs of water, carbon, nitrogen, and phosphorus are across the UK and Europe, and how and why this synchrony might be changing in both time and space. Helping to answer this question of synchrony will provide deeper insights into the functioning of river ecosystems, and a template for priorities in pollution and water management