Transcript Nitrogen cycle

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