Comparing Drivers of Spatial Variability in U.S. Lake and Stream Phosphorus Concentrations.
Robert D Sabo, Brian Pickard, Jiajia Lin, Ben Washington, Christopher M Clark, Jana E Compton, Michael Pennino, Britta Bierwagen, Stephen D LeDuc, James N Carleton, Marc Weber, Meridith Fry, Ryan Hill, Steve Paulsen, Alan Herlihy, John L Stoddard
Author Information
Robert D Sabo: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA. ORCID
Brian Pickard: Tetratech, Research Triangle Park, NC, USA.
Jiajia Lin: US Oak Ridge Institute for Science and Education, Corvallis, OR, USA. ORCID
Ben Washington: Verisk Analytics, Information Systems and Technology, Washington, DC, USA. ORCID
Christopher M Clark: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA. ORCID
Jana E Compton: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
Michael Pennino: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA.
Britta Bierwagen: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA.
Stephen D LeDuc: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Research Triangle Park, NC, USA. ORCID
James N Carleton: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA. ORCID
Marc Weber: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
Meridith Fry: Center for Public Health and Environmental Assessment, Health and Environmental Effects Division, US EPA, Office of Research and Development, Washington, DC, USA. ORCID
Ryan Hill: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
Steve Paulsen: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
Alan Herlihy: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
John L Stoddard: Pacific Ecological Systems Division, Center for Public Health and Environmental Assessment, US EPA, Office of Research and Development, Corvallis, OR, USA. ORCID
Decision makers need to know the drivers of surface water phosphorus (P) concentrations, the environmental factors that mediate P loading in freshwater systems, and where pollution sources and mediating factors are co-located to inform water quality restoration efforts. To provide this information, publicly available spatial data sets of P pollution sources and relevant environmental variables, like temperature, precipitation, and agricultural soil erodibility, were matched with >7,000 stream and lake total P observations throughout the conterminous United States. Using three statistical approaches, consisting of (a) correlation, (b) regression, and (c) machine learning techniques, we identified likely drivers of P concentrations. Surface water concentrations in streams were more strongly correlated and effectively predicted by annual fertilizer and manure input rates and agricultural legacy sources compared to that of lakes. This observation suggests that streams may be more immediately responsive to improvements in agricultural nutrient management. In contrast, lake concentrations, though still positively associated with agricultural input and surplus variables, may be more influenced by historic erosional inputs, internal lake recycling, and other environmental factors. Thus, lake TP concentrations may not be as immediately responsive as streams to improvements in phosphorus management. Both stream and lake P concentrations will potentially increase because of warming temperatures and forest recovering from past acidification, putting even further pressure on existing water quality restoration efforts to meet nutrient loading reduction targets. The identified spatial data sets and relationships elucidated in this effort can inform the placement and development of watershed restoration strategies to reduce excess P in aquatic systems.
