Evidence for multiple potential drivers of increased phosphorus in high-elevation lakes

Area of Science:

• Environmental Science
• Ecology
• Limnology

Background:

• Remote mountain lakes in the Western US show rising total phosphorus (TP) concentrations.
• Increased frequency of algal blooms is observed in these systems.
• Traditional drivers like agricultural runoff are unlikely explanations for TP increases.

Purpose of the Study:

• Investigate atmospheric and terrestrial mechanisms for TP increases in mountain waterbodies.
• Test the hypothesis that warming soils elevate phosphorus (P) fluxes.
• Utilize northern Utah mountain ranges as a case study.

Main Methods:

• Measured total and bioavailable P inputs via dust deposition.
• Conducted soil leaching experiments simulating acidification and recovery.
• Analyzed decadal increases in soil temperatures and growing season length.

Main Results:

• Bioavailable dust-P loading in the Uinta Mountains ranged from 1.6 to 23.1 mg P m^-2 yr^-1.
• A 0.5-unit soil pH increase could elevate leached P by 4.7 to 65 mg P m^-2.
• Increased soil temperatures (historical +3 °C, future +2 °C) prospectively increased leached P by 2 to 264 mg SRP m^-2.

Conclusions:

• Warming soils and dust deposition are plausible drivers of increased P in Western US mountain lakes.
• While pH shifts can mobilize P, no pH changes were observed in the Uinta Mountains.
• Increased summer soil temperatures were observed, suggesting a significant role in P mobilization across various regions.