Document ID: EPA-HQ-OAR-2003-0053-0463
Agency: epa
Document Type: Supporting & Related Material
Title: 
Posted Date: 2004-03-17T05:00Z

Nitrogen
Deposition
Can
Harm
Forests
and
Coastal
Ecosystems
Sensitive
Forests
°
High
nitrogen
deposition
can
cause
"
nitrogen
saturation,"
which
occurs
when
too
much
nitrogen
enters
sensitive
forest
soils
and
begins
to
leach
out,
stripping
soil
nutrients
and
affecting
water
quality.

°
Sensitive
forests
showing
signs
of
nitrogen
saturation
are
found
in
the
eastern
and
western
U.
S.
and
include
the
Great
Smoky
Mountains,

Adironack/
Catskill
Mountains,
the
Colorado
Front
Range
and
southern
California.
Wet
Nitrate
Deposition
(
Kg/
ha)

1
>
24
Annual
Wet
Nitrate
Deposition
to
Sensitive
Resources
Nitrogen
Saturated
Forest
Coastal
Estuary
Area
Deposition
measured
by
CASTNET
and
NADP,
1997­
1999
°
Nitrogen
deposition
occurs
when
nitrogen
in
deposited
to
the
Earth's
surface.

°
Power
plant
NOx
emissions
are
a
significant
source
of
the
nitrogen
that
reaches
our
coastal
ecosystems
and
sensitive
forests.
When
nitrogen
levels
in
these
ecosystems
are
too
high,
problems
develop.

°
Coastal
ecosystems:
10
to
40
percent
of
the
nitrogen
reaching
many
East
and
Gulf
coast
estuaries
comes
from
the
air.

°
Too
much
nitrogen
in
these
waters
leads
to
a
condition
known
as
"
eutrophication."

°
Two­
thirds
of
U.
S.
estuaries
(
more
than
80
estuaries)
show
symptoms
of
moderate
to
high
eutrophication.

°
Eutrophication
can
result
in:

°
Fish
and
shellfish
"
kills"
due
to
low
levels
of
dissolved
oxygen
°
Algal
blooms,
including
toxic
red
and
brown
tides;

°
Loss
of
important
habitat,
such
as
seagrass
beds
and
coral
reefs;

°
Changes
in
marine
biodiversity
and
species
distribution;
and
°
Economic
and
social
impacts
resulting
from
a
loss
of
fisheries
and
tourism
The
Proposed
Interstate
Air
Quality
Rule
Will
Reduce
Nitrogen
Deposition
in
the
Eastern
U.
S.

Projected
Improvements
in
2010
and
2015
resulting
from
the
Interstate
Air
Quality
Rule
*
Base
case
assumes
implementation
of
existing
Clean
Air
Act
programs
and
the
proposed
nonroad
diesel
rule.

Projected
nitrogen
deposition
changes
in
2010,
compared
to
the
base
case*
Projected
nitrogen
deposition
changes
in
2015,

compared
to
the
base
case*

Legend
100th
Parallel
Percent
Reduction
0
to
5
6
­
10
11
­
15
16
­
20
21
­
25
26
­
32
Estimates
for
2015
show
additional
and
larger
reductions
across
a
broader
region
in
the
East.

By
2010,
nitrogen
deposition
would
be
lower
 
up
to
15
percent
in
many
areas
of
the
eastern
U.
S.
Acid
Rain
Damages
Lakes,
Streams,

Forests
and
Buildings
°
Acid
deposition
occurs
when
emissions
of
SO
2
and
NOx
react
in
the
atmosphere
to
create
acidic
gases
and
particles
that
reach
the
ground
in
wet
and
dry
forms.

°
The
greatest
sulfur
and
nitrogen
deposition
occurs
in
areas
of
the
Midwest
and
northeastern
United
States
which
are
downwind
of
the
highest
SO
2
and
NOx
emission
areas.

°
Impacts
occur
both
in
the
East
and
mountainous
areas
of
the
West.

°
Effects
of
acid
deposition
include:

 
Acidification
of
lakes
and
streams,
making
them
unable
to
support
fish
and
other
aquatic
life;

 
Damage
to
forests
through
acidification
of
soil,
depletion
of
soil
nutrients,
and
direct
injury
to
sensitive
tree
leaves
and
needles;

 
Harm
to
buildings,
statues
and
monuments.
°
Despite
substantial
emissions
reductions
over
the
last
20
years,
significant
amounts
of
sulfur
and
nitrogen
still
deposit
to
acid­
sensitive
lakes
and
streams,
leading
to
high
levels
of
acidity.

°
Southeastern
streams
will
continue
to
grow
more
acidic
without
significant
further
reductions
in
sulfate
and
nitrogen
deposition.

°
Many
scientists
believe
that
significant
further
reductions
in
SO
2
and
NOx
emissions
are
necessary
to
fully
protect
acidsensitive
ecosystems.
Wet
Sulfate
Deposition
(
Kg/
ha)

1
35
Acid
sensitive
surface
waters
Source:
CASTNet/
NADP;
National
Surface
Water
Survey
Projected
changes
in
sulfur
deposition,

compared
to
the
base
case
in
2010
IAQR
Sulfur
Deposition
Improvements
in
2010
and
2015
Projected
changes
in
sulfur
deposition,

compared
to
the
base
case
in
2015
Legend
100th
Parallel
Percent
Reduction
0
­
5
6
­
10
11
­
15
16
­
20
21
­
25
26
­
30
31
­
35
36
­
40
41
­
45
46
­
50
51
­
55
56
­
61
*
Base
case
assumes
implementation
of
existing
Clean
Air
Act
programs
and
the
proposed
nonroad
diesel
rule.
portions
of
Pennsylvania,
Virginia,
Maryland
and
West
Virginia
will
see
reductions
of
up
to
45
percent.
Estimates
for
2015
show
additional
reductions,
especially
in
the
Southeast.

By
2010,
the
proposed
Interstate
Air
Quality
Rule
would
reduce
sulfur
deposition
beyond
reductions
expected
without
implementation
of
this
rule.
The
majority
of
the
East
will
see
sulfur
deposition
reductions
of
up
to
20
percent
in
2010,
while
some