ESM 202

Eutrophication

US East Coast

Source: Issues in Ecology #2 (1998)

Gulf of Mexico Dead Zone

Source: NOAA

Effects of Eutrophication

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Source: Issues in Ecology #2 (1998)

Effects of Eutrophication

Source: Issues in Ecology #2 (1998)

Source: Issues in Ecology #2 (1998)

Source: Issues in Ecology #2 (1998)

Lake Ageing

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Classification of Lakes

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Probable, not certain…

Eutrophic

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Total P vs. Chlorophyll a

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Classification of Lakes

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Lake Stratification

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Lake Stratification

Source: Principles Env. Sci. & Eng. (Davis & Masten)

Diagnostics…

Source: Biogeochemistry, Schlesinger, 1997

Diagnostics…

Flux in g/m2 yr

Source: Biogeochemistry, Schlesinger, 1997

Diagnostics…

Source: Biogeochemistry, Schlesinger, 1997

Analysis of Cause and Effect

Low Nutrient Supply

Low N & P conc. in lake

Low algae productivity

Low chlorophyll a

Lake more transparent

Greater Secchi disc depth

High Nutrient Supply

High N & P conc. in lake

High algae productivity

High chlorophyll a

Lake less transparent

Smaller Secchi disc depth

Gradient of Conditions

Toxicinflow

HighSediment

HighFlowrate

Solutions… Source Reduction

Eliminate excess fertilizationWastewater treatment plantsBMPs

In Lake Control:Mechanical harvesting of aquatic plantsChemical control (algaecides)Biological control (increase grazing)Flow augmentationDeep water aerationSelective removal of deep waterSediment removal

Modern wastewater treatment

Process Diagram

Modern wastewater treatment

Packaged wastewater treatment

Performance & Policies

Pathogen removal

Lagoon Treatment Systems

Constructed Wetland

Septic Systems

Key Points Eutrophication is a natural process

Can be greatly accelerated by human activitySerious ecological effectsMust use diagnostics to get at the root of the problem

Point vs non-point source, magnitude and timing of load, N or P?

Range of solutions depending on sources and socioeconomic choices