Long Term Anthropogenic Phosphorus Sinks and Sources Across the Continental US
Abstract
The overuse of phosphorus (P) from fertilizers and detergents and the intensification of livestock production have led to an increase in the incidence of eutrophication events and harmful algal blooms. Excess P can accumulate across the landscape, becoming long-term sources of P in surface waters. The lack of understanding of the sources, sinks, and storage of P across US watersheds precludes the development of meaningful policies to improve water quality. Thus, it is crucial to develop comprehensive datasets to quantify the trajectory of different sources of P across spatial scales.
Here, we construct a comprehensive, 88-year (1930 to 2017) dataset of county-scale P surplus trajectories across the continental US. P surplus is the difference between P inputs (inorganic fertilizer, manure, human waste, atmospheric deposition, detergents) and non-hydrological output (crop uptake). We find regions that are accumulating and depleting in P stores and changes in the dominant sources of P over the past 88 years. We also find that the national P use efficiency (PUE), the ratio of P removed from crop uptake to the P supplied through fertilizers, varies in space during the past decades. At the national scale, we observed a downward trend in PUE after 1930 until the 1970s, at which point PUE began to increase. Insights from P surplus and usage trajectories can improve our understanding of long-term nutrient dynamics and can work as a powerful tool for modelling the impacts of nutrients on past, present, and future environmental outcomes.- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMGC22J0700B