Impacts of the Nitrogen Cascade on Ecosystems Presentation to - - PowerPoint PPT Presentation
Impacts of the Nitrogen Cascade on Ecosystems Presentation to NYSERDA October 8, 2003 William Moomaw Fletcher School, Tufts University Reactive N and Unreactive N 2 Unreactive N is N 2 (78% of earths atmosphere) Reactive N (Nr)
and Unreactive N2
Unreactive N is N2 (78% of earth’s atmosphere) Reactive N (Nr) includes all biologically, chemically and physically
active N compounds in the atmosphere and biosphere of the Earth
N controls productivity of most natural ecosystems N2 is converted to Nr by biological nitrogen fixation (BNF) N2 is converted to Nr by humans fossil fuel combustion, the Haber
Bosch process, and cultivation-induced BNF.
and Unreactive N2
Unreactive N is N2 (78% of earth’s atmosphere) Reactive N (Nr) includes all biologically, chemically and physically
active N compounds in the atmosphere and biosphere of the Earth
N controls productivity of most natural ecosystems N2 is converted to Nr by biological nitrogen fixation (BNF) N2 is converted to Nr by humans fossil fuel combustion, the Haber
Bosch process, and cultivation-induced BNF.
Bottom Lines
– Humans create more Nr than do natural terrestrial processes. – Nr is accumulating in the environment. – Nr accumulation contributes to most environment issues of the day. – Challenge is to reduce anthropogenic Nr creation.
and Unreactive N2
Unreactive N is N2 (78% of earth’s atmosphere) Reactive N (Nr) includes all biologically, chemically and physically
active N compounds in the atmosphere and biosphere of the Earth
N controls productivity of most natural ecosystems N2 is converted to Nr by biological nitrogen fixation (BNF) N2 is converted to Nr by humans fossil fuel combustion, the Haber
Bosch process, and cultivation-induced BNF.
Bottom Lines
– Humans create more Nr than do natural terrestrial processes. – Nr is accumulating in the environment. – Nr accumulation contributes to most environment issues of the day. – Challenge is to reduce anthropogenic Nr creation.
But, this is complicated by fact that Nr creation sustains most of
the world’s food needs.
– The real challenge is how can we provide food (and energy) while also reducing Nr creation rates and arresting the nitrogen cascade?
Regional air quality (LRTAP) Climate change (UNFCCC & Kyoto Prot.) Ozone Depletion (Montreal Protocol) Biodiversity loss (CBD) Transboundary water quality (Non-navigational
Estuary damage (Regional Seas) Fisheries loss (Law of the Sea?)
1750 1800 1850 1900 1950 2000 2050
Humans, millions
1,000 2,000 3,000 4,000 5,000 6,000 7,000
N-Discovered
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
1750 1800 1850 1900 1950 2000 2050
Humans, millions
1,000 2,000 3,000 4,000 5,000 6,000 7,000
N-Discovered N-Nutrient BNF
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
1750 1800 1850 1900 1950 2000 2050
Humans, millions Legumes/Rice, Tg N
1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Discovered N-Nutrient BNF
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
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1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Discovered N-Nutrient BNF N2 + O2
1750 1800 1850 1900 1950 2000 2050
Humans, millions Legumes/Rice, Tg N NOx emissions, Tg N
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
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1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Discovered N-Nutrient BNF N2 + O2
World is running out of N*
1750 1800 1850 1900 1950 2000 2050
Humans, millions Legumes/Rice, Tg N NOx emissions, Tg N
*1898, Sir William Crookes, president of the British Association for the Advancement of Science
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
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1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Discovered N-Nutrient BNF N2 + O2
N2 + 3H2
1750 1800 1850 1900 1950 2000 2050
Humans, millions Legumes/Rice, Tg N NOx emissions, Tg N
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
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1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Discovered N-Nutrient BNF N2 + O2
N2 + 3H2
H-B
1750 1800 1850 1900 1950 2000 2050
Humans, millions Haber Bosch Legumes/Rice, Tg N NOx emissions, Tg N
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
1750 1800 1850 1900 1950 2000 2050
Humans, millions Energy Production Food Production
1,000 2,000 3,000 4,000 5,000 6,000 7,000 50 100 150 200
N-Nutrient N-Discovered BNF H-B
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
1,000 2,000 3,000 4,000 5,000 6,000 7,000 1750 1800 1850 1900 1950 2000 2050 50 100 150 200
Humans, millions Total N Fixed, Tg
Galloway JN and Cowling EB. 2002; Galloway et al., 2002a
N-Nutrient N-Discovered BNF Nr, natural
H-B
y
2
x
5 5
120 120
Galloway et al., 2002b
0.3 0.3 15 15
y
2
x
5 5
120 120
Galloway et al., 2002b
6 6 7 7 8 8 0.3 0.3 6 6 9 9 11 11 8 8 15 15 27 27
y
2
x
5 5 6 6
120 120
Galloway et al., 2002b
y
2
x
5 5
110 110
Galloway et al., 2002b
6 6 7 7 8 8 0.3 0.3 6 6 9 9 11 11 8 8 15 15 27 27
y
2
x
5 5 6 6 120 120
y
2
x
25 25 5 5 33 33 100 100
N2 + 3H2 2NH3
110 110
Galloway et al., 2002b
6 6 7 7 8 8 0.3 0.3 6 6 9 9 11 11 8 8 15 15 27 27
y
2
x
5 5 6 6 120 120
6 6 7 7 8 8 0.3 0.3 6 6 9 9 11 11 8 8 15 15 27 27
y
2
x
5 5 6 6
y
2
x
21 21 25 25 16 16 25 25 5 5 33 33 23 23 26 26 6 6 39 39 48 48 18 18 100 100
N2 + 3H2 2NH3
110 110 120 120
Galloway et al., 2002b
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TgN/yr
8.3 21.8
2 2.1 5 9.1 4.4 7.8 7.4 9.7 7.7 8.5
Galloway et al, 2002b; Boyer et al., in preparation
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mg N/m2/yr
5000 2000 1000 750 500 250 100 50 25 5
Galloway and Cowling, 2002; Galloway et al., 2002b
Humans mobilize ~50%
– Food production accounts for 75%
Nr is widely dispersed
– Atmospheric Nr emissions have increased 3-fold since 1860; NH3 twice as important as NOx
Nr is accumulating in
What are the consequences
What is projected for future? How can science and policy
Haber-Bosch has facilitated
agricultural intensification
40% of world’s population is
alive because of it
An additional 3 billion people
by 2050 will be sustained by it
Most N that enters
agroecosystems is released to the environment.
NOx emissions contribute to
OH, which defines the
atmosphere
NOx emissions are responsible
for tens of thousands of excess- deaths per year in the United States
O3 and N2O contribute to
atmospheric warming
N2O emissions contribute to
stratospheric O3 depletion
N is the limiting nutrient in
most temperate and polar ecosystems
Nr deposition increases and
then decreases forest and grassland productivity
Nr additions probably decrease
biodiversity across the entire range of deposition
Surface water
– Tens of thousands of lakes and streams – Significant biodiversity losses – Negative feedbacks to forested ecosystems
Nr inputs intoco
coastalreg regionsresu result i in neut eutr ro
phicat cati ion,
bi bio
di iv ver ersi sit ty y lo losse sses, s,e em missio ission ns sof
N2
2O
Oto to th the e at atm mo
spher phere e. . Mos Most tco coas ast ta al reg l regi ions
are imp e impacted. acted. Nr inputs into astal ions lt
Riverine and atmospheric deposition
are significant Nr sources to coastal systems
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Galloway et al., 2002a
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Energy Production
Ozone Effects NOx
Galloway et al., 2002a
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Energy Production
PM & Visibility Effects Ozone Effects NOx
Galloway et al., 2002a
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Energy Production
PM & Visibility Effects Ozone Effects NOx
Forests & Grassland Soil
Galloway et al., 2002a
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Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects
Energy Production
PM & Visibility Effects Ozone Effects NOx
Forests & Grassland Soil
Galloway et al., 2002a
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Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects Coastal Effects
Energy Production
PM & Visibility Effects Ozone Effects NOx
Forests & Grassland Soil
Galloway et al., 2002a
zyxwvutsrqponmlkjihgfedcbaWUTSRPONMLKJIHGFEDCBA
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects Coastal Effects
Energy Production
PM & Visibility Effects Ozone Effects NOx
Forests & Grassland Soil Ocean Effects
Galloway et al., 2002a
zyxwvutsrqponmlkjihgfedcbaWUTSRPONMLKJIHGFEDCBA
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects Coastal Effects
Energy Production
PM & Visibility Effects Ozone Effects Agroecosystem Effects NHx
Food Production
NOx Crop Animal
People (Food; Fiber)
Soil
Norg Forests & Grassland Soil Ocean Effects
Galloway et al., 2002a
zyxwvutsrqponmlkjihgfedcbaWUTSRPONMLKJIHGFEDCBA
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects Coastal Effects
Energy Production
PM & Visibility Effects Ozone Effects Agroecosystem Effects NHx
Food Production
NOx NOx Crop Animal
People (Food; Fiber)
Soil NO3
NH3 Norg Forests & Grassland Soil Ocean Effects
Galloway et al., 2002a
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects
Energy Production
PM & Visibility Effects Ozone Effects Agroecosystem Effects NHx
Food Production
NOx NOx Crop Animal
People (Food; Fiber)
Soil NO3
NH3
Norg Forests & Grassland Soil Coastal Effects Ocean Effects
Atmosphere
Terrestrial Ecosystems Aquatic Ecosystems
Human Activities
Groundwater Effects Surface water Effects Coastal Effects Stratospheric Effects
Energy Production
PM & Visibility Effects Ozone Effects Agroecosystem Effects NHx
Food Production
NOx NOx Crop Animal
People (Food; Fiber)
Soil NO3
NH3
Norg Forests & Grassland Soil Ocean Effects
N2O
GH Effects
N2O
Food and energy production results in creation of ~160 Tg
We know where some of it goes and we generally know
We do not know:
– How much is stored in ecosystems vs. how much is denitrified to N2. – How to feed and fuel the global population without releasing excess N to environmental reservoirs.
We know another thing--Nr creation will increase in
12 10 8 6 4 2
today 2050
1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100
Year
TgN/yr
60 5 32 10 32 2
after Galloway and Cowling, 2002
TgN/yr
60 92 5 13 32 27 10 17 32 42 2 3
2050 rates scaled by:
after Galloway and Cowling, 2002
TgN/yr
60 568 5 190 32 67 10 87 32 42 2 5
2050 rates scaled by:
after Galloway and Cowling, 2002
10,000 8,000 6,000 4,000 2,000 1750
1000 800 600 400 200 1800 1850 1900 1950 2000 2050 2100
Humans, millions Total Nr Fixed, Tg N
Possible trajectories of future Nr creation
after Galloway and Cowling, 2002
♦ We need food; we need energy.
♦ How do we get it without Nr accumulation?
♦ Create less Nr by:
♦ increasing N use efficiency in food production, ♦ Reducing NOx emissions from fossil fuel combustion.
Convert Nr to N2 before environmental release.
The Clean Air Act favors existing plants in three
Half of coal plant capacity was built before 1975,
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 1996 NOX Emission Rate (lb/MMBtu)
1930 1940 1950 1960 1970 1980 1990 2000 Unit Vintage
Cost of new gas plant Coal plant operating costs
Cost ($/MWh)
100
90 80 70 60 50 40 30 20 10 10 20 30 40 50 60 70 80 90 100 Capacity Factor (%)
Cost of new gas plant Coal plant operating costs
Cost ($/MWh)
100
90 80 70 60 50 40 30 20 10 10 20 30 40 50 60 70 80 90 100 Capacity Factor (%)
Cost of new gas plant Coal plant operating costs
Cost ($/MWh)
100
90 80 70 60 50 40 30 20 10 10 20 30 40 50 60 70 80 90 100 Capacity Factor (%)
No one wants to build a new coal plant -- and no
The key cost comparison: how do operating costs
Three versions of this comparison:
N Fertilizer Produced N Fertilizer Consumed N in Crop N Harvested N in Food N Consumed
N Fertilizer Produced N Fertilizer Applied N in Crop N In Feed N in Store N Consumed