Food, Fodder and Phosphorus: A Quantification of Nutrient Legacies in Human-Impacted Watersheds
Kimberly Van Meter, University of Waterloo, [email protected]
Philippe Van Cappellen, University of Waterloo, [email protected]
Nandita Basu, University of Waterloo, [email protected]
Abstract
Phosphorus (P) inputs to human-impacted watersheds have more than doubled over the last century in response to the use of fertilizers, detergents, and P additives in a range of products, from animal feed to motor oil. Although mass balance studies consistently show P inputs exceeding outputs in human-impacted areas, the forms and relative magnitudes of legacy P accumulation are still not well understood. In the present work, we have developed a parsimonious, process-based model, ELEMeNT-P, that pairs soil P dynamics with both erosion processes for simulation of surface P transport and a travel time-based approach for simulation of transport and retention along subsurface pathways. Using a more than 100-year trajectory of watershed P inputs to the Grand River Watershed, we have not only reconstructed total phosphorus yields at the watershed outlet, but also estimate the magnitudes of P accumulation along surface and subsurface pathways. As Lake Erie and other inland lakes continue to be impacted by eutrophication events, even after significant improvements in nutrient management practices, such estimates of legacy P accumulation will be crucial to setting realistic targets for reducing P loading and for better understanding the contribution of P legacies to current and future lake nutrient dynamics.
1. Keyword
phosphorus
2. Keyword
nutrients
3. Keyword
modeling
4. Additional Keyword
Lake Erie
5. Additional Keyword
legacy