Legacy Phosphorus and Eutrophication in the Lake Erie Basin
Abstract
Excess phosphorus (P) loading from anthropogenic activity has contributed to algal blooms and eutrophication in freshwater systems across the world. Algal blooms in the Lake Erie Basin have been increasing in the last decade, and this has been attributed to a combination of factors from increasing storm intensity and frequency, to legacy P from decades of agricultural activity. Much work remains to understand how P usage in a watershed leads to the buildup of legacy stores and how these legacy stores contribute to stream P fluxes even when watershed P inputs have been reduced. To address this knowledge gap, we first developed temporal trajectories of P input and output across multiple watersheds in the Lake Erie Basin. We used a mass balance approach to quantify P surplus across these watersheds over 87 years (1930-2016). These decadal input trajectories were then compared with the total P and soluble P trajectories in the streams draining these watersheds to determine time lags in water quality response. We found response patterns to vary significantly across the Lake Erie basins, with watersheds dominated by point source inputs documenting shorter lag times than those dominated by non-point sources. As Lake Erie continues to be impacted by algal blooms, our work provides a path forward for designing more targeted approaches to water quality management and will help guide decision-makers to set realistic targets for reducing P loading.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFM.H25E1093M