Sensitivities of US lake and stream phosphorus concentrations to climatic and anthropogenic impacts
Abstract
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 datasets 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 1) correlation, 2) regression, and 3) machine learning techniques, we identified likely drivers of P concentrations. Surface water concentrations in streams may be more immediately responsive to improvements in agricultural nutrient management (e.g., leveraging legacy sources and efficient use of fertilizer and manure nutrients), whereas lake concentrations may be more influenced by historic erosional inputs and other environmental factors. Thus, lake TP concentrations may not be as immediately responsive as streams to improvements in phosphorus management in the agricultural and urban sectors. Further research should explore likely factors that determine lake response times to changes in loading inputs. 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 datasets and relationships elucidated in this effort can inform the placement and development of watershed restoration strategies to reduce excess P in aquatic systems.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFMGC12C..08S