Eutrophication in Water bodies By Kelly Toy Overview

Eutrophication in Water bodies By: Kelly Toy

Overview ① ② ③ ④ ⑤ What is Eutrophication management Experiments Nitrogen or Phosphorus control Debate Case Study: Baltic Sea Recommendations

1. What is Eutrophication? • • Definition Sources Process Importance

Definition - Eutrophication �Degradation of water bodies from overfertilization of nitrogen (N) and phosphorus (P), resulting in excess plant biomass and consequently oxygen and habitat depletion. Seagrasses covered with attached algae in a Danish estuary. Removing microalgal blooms at the Olympic Sailing Venue, China.

Excess N and P from Human Activities �N and P enters water through �Runoff �Wastewater treatment and industrial discharges �Agriculture �Excess fertilizers, manure �Combustion of fossil fuels �N in air acid rain water

Eutrophication Process Excess N +P Bacteria consume oxygen to degrade dead biomass Denitrification (no N) occurs in anaerobic conditions Growth of Plant biomass Anoxia (no O 2) in deep waters N-fixing cyanobacteria dominate Blooms die and sink to sediment Fish and wildlife die Internal loading of P, system is N-deficient

Why does Eutrophication matter? �Global expansion of dead zones �oxygen depleted areas where fish and wildlife are extinct �Decreased biodiversity �New species invasion �Toxic algal blooms (some cyanobacteria) �Aesthetically unpleasing �Severe impacts on fisheries �Economic detriment industries relying on water quality/ aquatic ecosystems (tourism)

2. Eutrophication Management Experiments • 1970’s Schindler Experiment • Response • Effects on Lakes and Estuaries

1970’s experimentation 37 -years long with entire-ecosystem lakes D. W. Schindler found: �P controls phytoplankton �Reducing N increased cyanobacteria Response: �U. S. and Europe ban P in detergents �Ramp up P removal in wastewater treatment plants Only N inputs N + P inputs Experimental Lake 226 Ontario, Canada

Effect on Lakes and Estuaries �Water quality in lakes improved dramatically �Eutrophication in estuaries increased �N pollution grew tremendously since the 1970’s �N contributes to eutrophication in estuaries � (no N-fixing cyanobacteria, N can limit growth) Definitons Lake- Freshwater surrounded by land Estuary- Freshwater inlet connects to ocean outlet • Salinity varies throughout water body

Dead Zones in Estuaries � 146 coastal regions affected by anoxia �Eliminating fish and bottom-feeding life forms �Size of dead zones growing �Gulf of Mexico dead zone- state of New Jersey

3. N or P Control Debate Evidence for each side

Debate: N or P control? �Reducing P increased eutrophication in estuaries �Reducing N increased N-fixing cyanobacteria �Expert Liminologists are still debating which nutrient controls eutrophication �cannot perform Schindler experiments in estuaries �Each water body is condition specific �Region and environment/ecosystem

4. Case Study: Baltic Sea Description High Societal Stakes Recommendations

Case Study: Baltic Sea � 9 countries bordering �Low salinity estuary �N-fixers abundant �Spatial extent and intensity of Hypoxia (low O 2) growing

Dual Nutrient reduction strategy �Abatement plan was signed by all Baltic Sea countries in 2007 cost $4 billion/year �Upgrade P urban sewage treatment �decrease eutrophication to levels in 1900 -1920

High Societal Stakes $$ �Swedish Department of Agriculture calculates N reductions in the plan cannot be fulfilled unless a large part of Swedish agriculture is shut down �Damaging aquatic ecosystem �Economic detriment to fishing and water industries �Many Countries input �Many Countries affected

5. Recommendations Results should be well tested Expensive Other ways to mitigate Eutrophication

Recommendation �All beneficial effects of dual N and P control must be robustly predicted before implementing high cost of nutrient reductions �N abatement is a very expensive pilot study �May favor cyanobacteria instead of water quality �Do not install N removal technologies at ww treatment plant yet �Continue P reductions to reduce sedimentation �Reduce both N + P at the source

In the meantime We can reduce N and P inputs without expensive treatment Control Measures for Runoff of both N and P: �Decreased use of fertilizers �Containment and treatment of manure �Tillage practices that conserve soil �Vegetative buffers along shoreline �Maintenance and restoration of wetlands �Convert croplands sensitive to erosion to other uses that do not pollute waterways �Eating less meat – fewer fertilizers needed to grow grain for livestock and less manure

Conclusion Eutrophication is destroying aquatic ecosystems Experiments and Observations How do we manage N and P? Expensive Societal effects on Countries

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