Inventory and Impactsof Reactive Nitrogen in the
Environment
Thomas L. TheisInstitute for Environmental Science and Policy
University of Illinois at Chicago
RET 15 July 2008
What is Reactive Nitrogen (Nr)?
All chemical forms of nitrogen, except N2, that have an impact on the environment
Examples: NH3‐NH4+, N2O, NO, NO2, NO2‐, NO3‐
Organic‐N
Two faces of nitrogenTwo faces of nitrogen
Nitrogen problems
NNDYING DYING REEFSREEFS
FISH KILLSFISH KILLS
ALGAL BLOOMSALGAL BLOOMS
ACID RAIN & ACID RAIN & BIODIVERSITBIODIVERSIT
YY
GLOBAL GLOBAL WARMINGWARMING
GROUNDWATERGROUNDWATER
OZONE/PM OZONE/PM 2.52.5
RED TIDES & RED TIDES & DEAD ZONESDEAD ZONES
Why we need reactive nitrogen
• Human Nr requirement = 4.3 kg/cap/yr • US = 1.4 Tg/yr• World = 28 Tg/yr
The Nitrogen Cascade
Atmospheric
Terrestrial
Agricultural
animalscrops
soils
Vegetated
grasslandsforests
soils
Groundwater
Aquatic Surface Water & Wetlands
Coastal Bays & Estuaries
Oceans
NOy, NHx, Norg
NOx NH3, Norg
NOy, NHx, Norg
N2O
Populated
landscapepeople
soils
ecosystem acidification
greenhouse gases
eutrophication
ecosystem productivity
denitrification potential
N2O
troposphere
stratosphere
NOy , NHxNorg
ozone
Food Production& creation of synthetic fertilizers
Energy Production& combustion of fossil fuels
“new” nitrogen
NHx
NOx
ozone depletion
particulate matter
acidification
Reactive Nitrogen Inputs, US (2002)
4.8surface and subsurface water N flux Nr to Aquatic
0.2industrial point sources 1.3human waste 6.0manure production 10.9synthetic fertilizer use 7.7fixation in cultivated croplands 5.9atmospheric deposition
Nr to Terrestrial0.7other3.9combustion-transportation1.4combustion-power4.0agricultureTg/yrNr to Atmosphere
The Nitrogen Cascade
Atmospheric
Terrestrial
Agricultural
animalscrops
soils
Vegetated
grasslandsforests
soils
Groundwater
Aquatic Surface Water & Wetlands
Coastal Bays & Estuaries
Oceans
NOy, NHx, Norg
NOx NH3, Norg
NOy, NHx, Norg
N2O
Populated
landscapepeople
soils
ecosystems acidification
greenhouse gases
eutrophication
ecosystem productivity
denitrification potential
N2O
troposphere
stratosphere
ozone
Food Production& creation of synthetic fertilizers
Energy Production& combustion of fossil fuels
“new” nitrogen
NHx
NOx
ozone depletion
particulate matter
acidification
5.7
18.6
4.8
4.8
3.11.1
Storage 1.6
Source: USEPA SAB
U.S. NOX Emissions in 2005
On-Road Vehicles
43%
NonroadVehicles
12%
Stationary Fuel Combustion
38%
Industrial processes, waste disposal & other
7%
Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990-2005
U.S. N2O Emissions in 2005
On-Road Vehicles 7%Non-Road Mobile 0.8%
Agricultural and Soil Management
78%
Other Sources 14%
Source: Inventory of U.S. Greenhouse Gas Emissions and Sinks, 1990-2005
US ammonia emissions
Nitrification and Denitrification Reactions
Nitrification
NH4+ NH2OH [HNO]
NO
[X]
NO2-
NO
N2O
NO3-
N2 N2O NO NO2- NO3
-
Denitrification
NO
Main ControlsSubstrate, O2, H2O, T
Facultative Anaerobic BacteriaMain ControlsSubstrate, available C, O2 , H2O, T
NitrosomonasNitrosospiraNitrosococcus
Nitrobacter
0.00
1000.00
2000.00
3000.00
4000.00
5000.00
6000.00
7000.00
8000.00
9000.00
AL
AZ
AR
CA CO CT DE FL GA ID IL IN IA KS
KY LA ME
MD
MA MI
MN
MS
MO
MT NE
NV
NH NJ
NM NY
NC
ND OH
OK
OR PA RI SC SD TN TX UT
VT
VA
WA
WV WI
WY
Wet Ndep, kg/km2/yr
N manure, kg/km2/yr
Synthethic Nfert, kg/km2/yr
Human Waste, kg/km2/yr
State subtotals surface balance
-1000
0
1000
2000
3000
4000
5000
6000
Nitr
ogen
, kg/
km2 /y
r
PEN
KEN
AN
DSA
CM
ERC
HA
BLA
CO
NH
UD
MO
HD
ELSC
HSU
SPO
TR
AP
JAM
Net import in feedNet import in foodFertilizer useAgricultural N2 fixationNet atmospheric depositionForest N2 fixation
Sources of N to watersheds
Alexander et al. 2002
SPARROW simulated N fluxes in stream reaches
TN Flux (metric tons/yr)< 100100 to 250250 to 1,000> 1,000
StatesKEY
TN Flux (metric tons/yr)< 100100 to 250250 to 1,000> 1,000
Total Fertilizer Consumption, US
0
2
4
6
8
10
12
14
1955 1965 1975 1985 1995 2005
ferti
lizer
con
sum
ptio
n, M
mt N
/yr
30354045505560657075
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Kg g
rain
per
kg
N .
Corn grain produced in the U.S. per Corn grain produced in the U.S. per unit of fertilizer N used, 1964 to 2005.unit of fertilizer N used, 1964 to 2005.
4343
6464*
*Application rate for 2004 estimated as avg of 2003 & 2005.
Data sources: USDA Ag Chem Use Survey & Annual Crop Production.
51% increase in N efficiency12% increase in N fertilizer useSince 1975:
Grain N recovery efficiency usually remains < 50% …room for improvement.
y = 1.829x - 3522r2 = 0.84
0
20
40
60
80
100
120
140
160
180
1960 1965 1970 1975 1980 1985 1990 1995 2000 2005
Corn
yie
ld, b
u/A
U.S. corn yields, 1964 to 2006.U.S. corn yields, 1964 to 2006.
43 years of 1.8 43 years of 1.8 bubu/A/yr/A/yr
Concept by Cassman, 2006
Genetic Genetic
improvement improvement
Expansion ofExpansion of
irrigation irrigation
Increase inIncrease in
N fertilization N fertilization
Soil testing & balanced
Soil testing & balanced
NPK fertilization
NPK fertilization
IPM IPM TransgenicTransgenic
traits traits Cons.Cons.
tillagetillage
US NOx emission trends 1970-2006
0
1000
2000
3000
4000
5000
6000
7000
8000
1970
1975
1980
1985
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
Year
Thou
sand
Met
ric T
ons
of N
itrog
en(c
onve
rted
from
sho
rt to
ns o
f NO
x, a
s N
O2) Misc
Highway vehiclesOff Highway vehiclesIndustrial Manufacturing and ProcessesIndustrial and Other CombustionElectric Utility
Percent reductions in NOx emissions by source, 1990-2002
-40 -30 -20 -10 0 10 20 30
Percent change from 1990 to 2002
Highway VehiclesOff Highway VehiclesIndustrial and Other CombustionElectric Utility
Changes in N wet deposition, 1994-2006
4546474849505152535455
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007A
tmos
pher
ic w
et N
dep
ositi
on in
USA
oxidized N in precipitation, %reduced N in precipitation, %
US Meat Production, 1970-2006
US Milk Production, 1970-2006
Change in U.S. Vehicle Movement, 1990-2005
% 0 10% 20% 30% 40% 50% 60% 70%
CommercialAircraft
FreightTrucks
Light-Duty Vehicles Vehicle Miles Traveled +39%
Ton-Miles +58%
Passenger Miles Traveled +68.8%
Sources: Highway Statistics 2006 Table VM-1, National Transportation Statistics 2005 Table 4-21
Population +19%
GDP +55%
Change in U.S. Vehicle Movement, 1990-2005
0% 10% 20% 30% 40% 50% 60% 70%
CommercialAircraft
FreightTrucks
Light-Duty Vehicles Vehicle Miles Traveled +39%
Ton-Miles +58%
Passenger Miles Traveled +68.8%
Sources: Highway Statistics 2006 Table VM-1, National Transportation Statistics 2005 Table 4-21
-47% NOx
-20.5% N2O
-24% NOx
N2O +1%
NOx +62%
N2O +35.2%
Factors Affecting Mobile N2O and NOX tailpipe emissions
• Fuel characteristics• Air‐Fuel mixes• Combustion temperatures• Use of pollution control equipment• N2O in particular can be formed by catalytic processes used to control NOx, CO, and hydrocarbon emissions
Freight Trucks• GHGs increased 69.4 percent (3.6 percent
annualized)• Medium- and heavy-duty trucks have become
less energy efficient since the mid-1990s – Fuel economy of medium trucks (10,000 to
26,000 lbs) decreased from 8.6 MPG in 1997 to 8.0 mpg in 2002
– FE of heavy trucks (over 26,00G0 lbs) decreased from 6.1 MPG in 1997 to 5.8 MPG in 2002
– Possible explanations for decreased fuel economy
• Demand for more powerful engines• Impact of congestion• Elimination of mandatory speed limits
Tropospheric NO2 Column, East Asia
Boersma et al. (2006) Atmos. Chem. Phys. Discuss., 6, 12301–12345
USEPA
Share of Nitrogen Sources in the Chesapeake Bay Watershed According to Different Metrics
0%
20%
40%
60%
80%
100%
Tonnes N Million $Damage
Mortality Mitigation$/Tonne
Freshwater Emissions
Terrestrial Emissions
Atmospheric Emissions
Ethanol Explosion
Source: Renewable Fuels Association and preliminary CARD projections
0
3
6
9
12
15
1980
1983
1986
1989
1992
1995
1998
2001
2004
2007
Bill
ion
Gal
lons
Expansions/New Construction
Currently in Production
Ethanol Plants
U.S. corn exports at record high in 2007 U.S. corn exports at record high in 2007 with 25% of crop used for ethanolwith 25% of crop used for ethanol
USDA-FAS, 12/2007.
Continuation of this accomplishment will be challenging.
Iowa the Saudi Arabia of Biomass
Source: U.S. DOE
Energy Independence and Security Act (2007) Section 204
EPA Report to Congress
SEC. 204. Not later than 3 years after the enactment of this section and every 3 years thereafter, the Administrator of the Environmental Protection Agency, in consultation with the Secretary of Agriculture and the Secretary of Energy, shall assess and report to Congress on the impacts to date and likely future impacts of the requirements of section 211(o) of the Clean Air Act on the following:
(1) Environmental issues, including air quality, effects on hypoxia, pesticides, sediment, nutrient and pathogen levels in waters, acreage and function of waters, and soil environmental quality.
(2) Resource conservation issues, including soil conservation, water availability, and ecosystem health and biodiversity, including impacts on forests, grasslands, and wetlands.
(3) The growth and use of cultivated invasive or noxious plants and their impacts on the environment and agriculture.
In advance of preparing the report required by this subsection, the Administrator may seek the views of the National Academy of Sciences or another appropriate independent research institute.
Energy and Independence Security Act (EISA)
• Requires EPA to develop new Renewable Fuel Standard to achieve goal of expanding biofuels to 36 billion gallons by 2022
• Requires lifecycle assessments of different fuel types and blends compared to petroleum fuel
• Requires that biofuel production does not adversely impact the environment or natural resources– EPA to assess and Report to Congress on environmental impacts of biofuel system
– Particular recognition of impacts to water quality, EISA amends the Clean Air Act to integrate water quality into a fuel assessment analysis
Renewable Fuel Standard Based on Lifecycle Assessment
• Lifecycle assessment required to determine which fuels meet mandated GHG performance thresholds compared to petroleum fuel replaced– 20% reduction for new facility renewable fuel– 50% reduction for biomass‐based diesel– 60% reduction for cellulosic biofuel
• Lifecycle assessment must include impacts on domestic and foreign land use
• Corn based ethanol capped at 15 billion/gallons by 2015
How do we assess sustainability?
• Scoping–define goals and system boundaries
• Inventory–document material & energy flows
• Impact Assessment– characterize & assess env. effects using data obtained from inventory
Life Cycle Approach
Carbon and Nitrogen Global Cycles
Relative C/N Profiles