Controls on the epilimnetic phosphorus concentration in small temperate lakes.

Area of Science:

• Environmental Science
• Limnology
• Water Quality Management

Background:

• Phosphorus (P) is a primary limiting nutrient for algal growth in freshwater lakes.
• Predicting P concentration is vital for water quality management and stakeholder decisions.
• Lake P dynamics are influenced by a complex interplay of physical, chemical, and watershed factors.

Purpose of the Study:

• To identify key drivers of summer total epilimnetic P concentrations in Maine lakes.
• To develop predictive models for lake P based on physicochemical, climate, and land-use attributes.
• To provide a quantitative tool for lake and watershed management.

Main Methods:

• Data collection from 126 lakes in Maine, USA.
• Development of regression-based predictive models incorporating lake and watershed variables.
• Analysis of lake physical attributes, sediment chemistry, water column chemistry, and watershed land use.

Main Results:

• Agricultural land use in the watershed was the most significant land-use driver of P concentration.
• Lake average depth was a critical physical driver; shallow lakes exhibited higher susceptibility to P accumulation.
• Sediment Al:P ratio and dissolved organic carbon (DOC) concentration were key chemical drivers influencing P levels.

Conclusions:

• Lake depth and sediment quality are critical, long-term factors influencing P dynamics.
• The developed model serves as a management tool to assess lake vulnerability to watershed development, especially agriculture.
• Findings support sustainable watershed development and targeted lake remediation strategies based on internal P release potential.