Research snapshot: Legacy of phosphorus bioavailability from cumulative watershed disturbance pressures, especially wildfire

Researchers from the forWater Network have recently published insights from four years of field research. They have released a series of research snapshots, the most recent featuring the first of its kind study showing legacy effects of wildfire on water quality over long distances.

The findings come from an international collaboration leveraging expertise from different disciplines, Geography and Engineering, at the University of Waterloo as well as forest hydrology from the University of Alberta and expertise in water resources and land management from Rothamsted Research in the UK.

Authored by Water Institute members Mike Stone and Monica Emelko and, MSc Graduate, Caitlin Watt, Uldis Silins (Alberta), Adrian Collins (Rothamsted), this research describes the impact of landscape disturbances on the transport and fate of particulate phosphorus (PP) in rivers.

This study examined changes in major element chemistry and PP forms in riverbed sediments along 50 km of an oligotrophic river at low flow. This section of river represents a gradient of increasing cumulative landscape disturbance (forest harvesting, wildfire, municipal wastewater discharge) pressures on water quality. The work showed that after landscape disturbances, sediments stored in riverbeds are present far downstream (i.e., tens of kilometers) and remain enriched with PP (i.e., legacy P). These sediments serve as an important internal source of bioavailable P that can promote algal blooms, challenge water treatment, and degrade ecosystem health for decades.