Eutrophication in Water bodies

1. Eutrophication in Water bodies By: Kelly Toy

2. Overview • What is Eutrophication • Eutrophication management Experiments • Nitrogen or Phosphorus control Debate • Case Study: Baltic Sea • Recommendations

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

4. 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. Removing microalgal blooms at the Olympic Sailing Venue, China. Seagrasses covered with attached algae in a Danish estuary.

5. 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

6. Eutrophication Process

7. 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)

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

9. 1970’s experimentation37-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

10. 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

11. 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

12. 3. N or P Control Debate Evidence for each side

13. 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

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

15. Case Study: Baltic Sea • 9 countries bordering • Low salinity estuary • N-fixers abundant • Spatial extent and intensity of Hypoxia (low O2) growing

16. 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

17. 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

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

19. 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

20. 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

21. 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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