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Nitrogen cycle Biogeochemistry October 17, 2005 Maria Moskalenko, Gretchen Miles, Emily Paduano, Jaconette Mirck Outline Background Information on N Papers: Kaiser, 2001. The Other Global Pollutant Agriculture: fertilizer & food Mitsch, 2001. Reducing N loading to Gulf Mississippi River-hypoxia Solutions to N-pollution Driscoll, 2003. N Pollution in Northeast US Atmospheric Inputs Estuaries Models Discussion Nitrogen Forms, Phases and Oxidation States * * NOx, greenhouse gases * Nitrogen the other global pollutant (Kaiser, 2001) Essential element for growth/primary production Surplus nitrogen = pollutant Sources: Fertilizer Fossil fuels Results in various problems: Algal bloom Greenhouse gas Ozone Solutions Increase requirements for fossil fuels Smaller cars Hybrids Eat less meat to reduce food of live stock Less manure Food control, precise amino acid ratio Reduce runoff Increase price of fertilizer Reducing Nitrogen Loading to the Gulf of Mexico from the Mississippi River Basin: Strategies to Counter a Persistent Ecological Problem -Mitsch, et al. 2001 Problems Anthropogenic Additions of N to aquatic systems cause Increased Productivity Eutrophication Hypoxia Fish Kills Sources Agriculture Waste Water Draining Wetlands Drained wetlands converted to agricultural land Solutions: Controlling N in Miss. River Basin Modifying Agricultural Practice - use less fertilizer - apply fertilizer in spring - account for N sources present Riparian and Wetland Buffers - effective nitrogen sinks due to high levels of denitrification Example of Riparian Buffer Solutions cont. Urban & Suburban Non-point Source Control Point Source Control Controls on Atmospheric NOx Mississippi River Diversions Creation of Wetlands Benefits of Reducing Nitrogen Levels in the Mississippi River Basin Predicted 40% reduction of nitrogen loading to the Gulf through implementation of these practices In addition to reduced hypoxia - reduced river pollution reduced wetland loss improved river ecosystems improved control of floods Northeast U.S. Brief History Population Changes Land Use Changes Capacity of 2nd Growth Forests for N-retention N-pollution Sources in Northeast U.S. (Driscoll et al. 2003) Atmospheric N Sources Food Imports Fertilizer & Farming Practices Feed Imports Wastewater Effluent Mycorrhizae & Legumes Problems Acidic Deposition Ground Level Ozone Formation Coastal Eutrophication Acidification & Overfertilization N-enrichment Forest (N-saturation) Freshwater (high flow) Smog in LA & Chicago Wet Deposition and Emissions a: nitrate, sulfate, b: nitrate & ammonium, c: sulfate, nitrate, chloride Ozone Formation For Formation: NOx & VOC’s (volitile organic compounds) Or NO from soil + Oxygen VOC’s were thought to be limiting factor Automobile VOC’s are regulated VOC’s are also produced naturally (isoprene) In Northeast U.S. we now believe that NOx regulates O3 formation Ground Level O3 in many U.S. cities exceeds National Ambient Air Quality Standards Solution: Reductions in N Management Options: Coastal Watersheds Wastewater Treatment Plants Agriculture Atmosphere Fossil fuel electric utilities Transportation Agriculture Purpose of Modeling Models were run to test proposed management options and determine their effectiveness Atmospheric Model: PnET-BGC Estuary Loading: WATERSN Conclusions Estuary: Major N-source Wastewater effluent: Add biotic N-removal to wastewater treatment practices Atmosphere: Source Specific Control (due to numerous sources) Discussion Topics Ecotechnology Phytoremediation Willow Project Theoretical Models vs. Real Life Problems? Lifestyle Changes No Meat = No Nitrogen SUV’s, Hybrids,Public Transportation, Walk, Bike Other Effects of N Purely Atmospheric take on N- Aerosols Willow Applications Set-aside arable land Bio-remediation of contaminated soils, like brownfields (phytoremediation) Nutrient and waste management systems Windbreaks/snow fences Buffer zones for clean water Incorporating willow biomass crops into riparian buffers produces clean water and renewable energy (Salix Maskiner 2000) Soil Conservation • Very little soil erosion • One year old coppcie growth once the crop is established Negligible N leaching from established willow plantings, even with large applications nitrogen (Adegbidi 1999, Aronsson et al. 2000). Nitrogen Movement Pots with willow growth Pots without willow growth p-value NO3-N (kg/ha) NH4-N (kg/ha) 4.3 + 2.6 1.3 + 0.2 140.8 +12.9 1.3 + 0.2 <0.01 0.75 Trial with organic amendments with nitrogen loads ranging from 200 – 1,880 TKN kg/ha (Adeigbidi 1999) Aerosols What??? Aerosols absorb or scatter light Ecological Effect Photosynthesis GCEP 2004 Orientation Presentation by Jeff Gaffney The End