Legacy phosphorus accumulation and management in the global context: insights from long-term analysis of major river basins

Thursday, 18 December 2014: 9:15 AM
Stephen M Powers1, Timothy Peter Burt2, Neng Iong Chan3, James J Elser3, Philip M Haygarth4, Nicholas J K Howden5, Helen P Jarvie6, Heidi Marie Peterson7, Jianbo Shen8, Fred Worrall9 and Andrew N Sharpley10, (1)Univ of Notre Dame, South Bend, IN, United States, (2)Durham University, Durham, United Kingdom, (3)Arizona State University, Tempe, AZ, United States, (4)Lancaster University, Lancaster, United Kingdom, (5)University of Bristol, Bristol, BS8, United Kingdom, (6)Centre for Ecology and Hydrology, Wallingford, Oxfordshire, United Kingdom, (7)Minnesota Department of Agriculture, St. Paul, MN, United States, (8)CAU China Agricultural University, Beijing, China, (9)University of Durham, Durham, DH1, United Kingdom, (10)University of Arkansas, Fayetteville, AR, United States
Phosphorus (P) is closely linked to major societal concerns including food security and water quality, and human activities strongly control the modern global P cycle. Current knowledge of the P cycle includes many insights about relatively short-term processes, but a long-term and landscape-level view may be needed to understand P status and optimize P management towards P sustainability. We reconstructed long-term (>40 years) P mass balances and rates of P accumulation in three major river basins where excess P pollution is demanding improvements in P management at local, national, and international levels. We focus on: Maumee River Basin, a major source of agricultural P to Lake Erie, the southernmost and shallowest of the Laurentian Great Lakes; Thames River Basin, where fluxes of effluent P from the London, England metropolitan area have declined following improvements in wastewater treatment; Yangtze (Changjiang) River Basin, the largest in China, which is undergoing rapid economic development. The Maumee and Thames are intensively monitored, and show long-term declines in basin P inputs that represent a step towards P sustainability. However, river P outputs have been slower to decline, consistent with the hypothesis that legacy P is mobilizing from soils or from within the river network. Published data on the Yangtze indicate the P flux from land to water has clearly increased with industrialization and population growth. Historical trajectories of P accumulation and depletion in major river basins are providing new understanding about the long-term impacts of P management, including watershed P legacies and response times, that may inform future policy towards local, national, and global P sustainability.