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Atmospheric Mercury Modeling 101 Mark Cohen Air Resources Laboratory ARL 101 June 19, 2012. In many waterbodies – including the Great Lakes and Gulf of Mexico -- levels of mercury in some fish are too high for safe consumption by humans and wildlife. - PowerPoint PPT Presentation
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Air Resources Laboratory 1
Atmospheric Mercury Modeling 101
Mark CohenAir Resources Laboratory
ARL 101June 19, 2012
6/19/2012
6/19/2012 Air Resources Laboratory 2
In many waterbodies – including the Great Lakes and Gulf of Mexico -- levels of mercury in some fish are too high for safe consumption by humans and wildlife
Air Resources Laboratory 36/19/2012
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1.0
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1.4
1.6
Aver
age
Mer
cury
Con
cent
ratio
n (p
arts
per
mill
ion
by w
eigh
t)Mercury Concentrations in Gulf of Mexico Seafood Species
approximate concentrationin light tuna – can have 12 oz per week
6/19/2012 Air Resources Laboratory 4
In many waterbodies – including the Great Lakes and Gulf of Mexico -- levels of mercury in some fish are too high for safe consumption by humans and wildlife
For many waterbodies, atmospheric deposition is the largest loading pathway for mercury
For a given waterbody, where does the mercury come from that is deposited?
Atmospheric mercury emitted from other regional and more
distant sources
wet deposition: pollutants brought down to the earth’s surface in rain and snow
dry deposition: pollutants brought down to the earth’s surface in the absence of rain or snow
Gaseous pollutants can be absorbed by the surface
Particles with pollutants on them can “fall” to the surface
Large Point Sources of Mercury Emissions Based on the 2002
EPA NEI and2002 Envr Canada NPRI*
size/shape of symbol denotes amount of mercury emitted (kg/yr)
5 - 10 10 - 50 50 - 100 100 – 300 300 - 500
500 - 1000
color of symbol denotes type of mercury source
coal-fired power plants
other fuel combustion
waste incineration
metallurgical
manufacturing & other
1000 - 3000
* Note – some large Canadian point sources may not be included due to secrecy agreements between industry and the Canadian government.
2002 U.S. and Canadian Emissions of Total Mercury [Hg(0) + Hg(p) + RGM]
There are a lot of sources!
Air Resources Laboratory 76/19/2012
Anthropogenic Mercury Emissions (ca. 2005)
Dry and wet deposition of the pollutants in the puff are estimated at each time step.
The puff’s mass, size, and location are continuously tracked…
Phase partitioning and chemical transformations of pollutants within the puff are estimated at each time step
= mass of pollutant(changes due to chemical transformations and deposition that occur at each time step)
Centerline of puff motion determined by wind direction and velocity
Initial puff location is at source, with mass depending on emissions rate
TIME (hours)0 1 2
deposition 1 deposition 2 deposition to receptor
lake
Lagrangian Puff Atmospheric Fate and Transport ModelNOAA HYSPLITMODEL
one Hg emissions
source
Beltsville monitoring
site
Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007
100 - 1000 10 – 100 1 - 100.1 – 1
* hourly deposition converted to annual equivalent
deposition(ug/m2)*
Washington D.C.
NOAA Silver Spring
one Hg emissions
source
Beltsville monitoring
site
Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007
100 - 1000 10 – 100 1 - 100.1 – 1
* hourly deposition converted to annual equivalent
deposition(ug/m2)*
Washington D.C.
NOAA Silver Spring
one Hg emissions
source
Model-predicted hourly mercury deposition (wet + dry) in the vicinity of one example Hg source for a 3-day period in July 2007
100 - 1000 10 – 100 1 - 100.1 – 1
* hourly deposition converted to annual equivalent
deposition(ug/m2)*
Washington D.C.
Large, time-varying spatial gradients in deposition & source-receptor relationships
Beltsville monitoring
site
NOAA Silver Spring
Geographical Distribution of 2005 Atmospheric Mercury Emissions (Natural + Re-emit + Direct Anthropogenic)
Policy-Relevant Scenario Analysis
Here’s where the mercury is emitted from...
But what is the relative importance of different source regions to atmospheric deposition of mercury to the Great Lakes?
Does most of it come from China?
Presentation to IJC-IAQAB, Apr 25, 2012NOAA Air Resources Laboratory 13
Geographical Distribution of 2005 Atmospheric Mercury Deposition Contributions to Lake Erie
Policy-Relevant Scenario Analysis
Here’s where the mercury came from that was deposited to Lake Erie (~2005)
Presentation to IJC-IAQAB, Apr 25, 2012NOAA Air Resources Laboratory 14
-500
1,000 1,500 2,000 2,500 3,000 3,500 4,000
< 50
0 km
500
-1,0
00 k
m
1,00
0 -3
,000
km
3,00
0 -1
0,00
0 km
10,0
00 -
20,0
00 km
Mer
cury
Em
issio
ns (
Mg/
yr)
Distance of Emissions Source from the Center of Lake Erie
Emissions from Natural Sources
Emissions from Re-Emissions
Emissions from Anthropogenic Sources
A tiny fraction of 2005 global mercury emissions within 500 km of Lake Erie
-
50
100
150
200
250
< 50
0 km
500
-1,0
00 k
m
1,00
0 -3,
000
km
3,00
0 -10
,000
km
10,0
00 -2
0,00
0 km
Dep
ositi
on C
ontr
ibuti
on (
kg/y
r)
Distance of Emissions Source from the Center of Lake Erie
Contributions from Natural Sources
Contributions from Re-Emissions
Contributions from Anthropogenic Sources
Modeling results show that these “regional” emissions are responsible for a large fraction of the modeled 2005 atmospheric deposition
Important policy implications!
Presentation to IJC-IAQAB, Apr 25, 2012NOAA Air Resources Laboratory 15
0
500
1,000
1,500
2,000
2,500
3,000
3,500
4,000
Uni
ted
Stat
es
Chin
a
Cana
da
Indi
a
Russ
ia
Mex
ico
Indo
nesia
Sout
h Ko
rea
Japa
n
Colo
mbi
a
Tota
l Atm
osph
eric
Dep
ositi
on to
th
e G
reat
Lak
es B
asin
(kg/
yr)
anthropogenic re-emissions from land
direct anthropogenic emissions
Model-estimated 2005 deposition to the Great Lakes Basin from countries with the highest modeled contribution from direct and re-emitted anthropogenic sources
Presentation to IJC-IAQAB, Apr 25, 2012NOAA Air Resources Laboratory 16
Modeling needed to help interpret and extend measurements and to estimate source-receptor relationships
Monitoring needed to ground-truth models and provide solid deposition estimates at specific locations
To get the answers we need, we need to use both monitoring and modeling -- together
Air Resources Laboratory 186/19/2012
Extra Slides
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1.5
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2.5
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Mercury Concentration(parts per million)
Om
ega
III F
atty
Aci
ds
(gra
ms
per 3
oz
serv
ing)
TilefishShark
Swordfish
King MackerelRed Snapper
GrouperOrange Roughy
Tuna (fresh or frozen)
Lobster
Halibut
Herring
Salmon
Mahi Mahi
Oysters
Clams
Shrimp
Flounder or SolePollock
Graph based on data presented by the American Heart Association -- http://www.americanheart.org
* canned, light
Cod
Tuna*Crabs
CatfishScallops
Fish concentration data from NOAA and FDA. Downloaded Sept 2008 from the EPA-FDA fish-mercury website: http://www.cfsan.fda.gov/~frf/sea-mehg.html
Mercury Levels in Commercial Fish and Shellfish
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0TI
LEFI
SH (G
OM
)SH
AR
KSW
OR
DFI
SHM
AC
KER
EL K
ING
TUN
A -
BIG
EYE)
OR
AN
GE
RO
UG
HY
MA
RLI
NG
RO
UPE
RM
AC
KER
EL S
PAN
ISH
(GO
M)
TUN
A (s
peci
es u
nkno
wn)
BA
SS C
HIL
EAN
TUN
A (A
LL)
ALB
AC
OR
E TU
NA
ALB
AC
OR
E TU
NA
(can
)B
LUEF
ISH
YELL
OW
FIN
TU
NA
LOB
STER
(Nor
th A
mer
.)W
HIT
E C
RO
AK
ERSC
OR
PIO
NFI
SHSE
A T
RO
UT
HA
LIB
UT
SAB
LEFI
SHB
ASS
(sal
twat
er)
SKIP
JAC
K T
UN
AB
UFF
ALO
FISH
SNA
PPER
MA
CK
EREL
SPA
NIS
H (S
. Atla
ntic
)M
ON
KFI
SHLO
BST
ER (S
peci
es U
nkno
wn)
TILE
FISH
(Atla
ntic
)C
AR
PPE
RC
H (F
resh
wat
er)
SKA
TESH
EEPS
HEA
DTU
NA
(can
ned,
ligh
t)JA
CK
SMEL
TC
OD
LOB
STER
(Spi
ny)
MA
CK
EREL
CH
UB
(Pac
ific)
CR
OA
KER
ATL
AN
TIC
TRO
UT
(fres
hwat
er)
SQU
IDW
HIT
EFIS
HSH
AD
AM
ERIC
AN
CR
AB
BU
TTER
FISH
MA
CK
EREL
ATL
AN
TIC
SCA
LLO
PC
ATF
ISH
MU
LLET
FLA
TFIS
HH
ERR
ING
AN
CH
OVI
ESPO
LLO
CK
CR
AW
FISH
HA
DD
OC
K (A
tlant
ic)
SAR
DIN
EH
AK
ESA
LMO
NO
YSTE
RTI
LAPI
AC
LAM
PER
CH
OC
EAN
SALM
ON
(CA
NN
ED)
SHR
IMP
WH
ITIN
G
Hg
Con
cent
ratio
n (p
pm)
x
300 - 700100 - 30050 - 10010 - 50 1 - 10
Number of Samples“error bars” show range of mercury concentrations in data for a given species
What Influences Hg Levels in Fish?
Current / past atmospheric and other Hg inputs to the fish’s ecosystem
Food web structure of the waterbody and trophic level of species
Biogeochemical factors influencing the degree of mercury methylation in the ecosystem (sulfate, dissolved organic carbon, pH, etc)
Age (size) of fish – as fish age, they accumulate more and more mercury
History of that particular fish
Note – Hg in fish muscle tissue, so can’t easily avoid it (PCB’s, Dioxins and other hydrophobic contaminants concentrated in fat)
Knowledge gaps for Hg levels and reasons for levels:o freshwater (inland) fish -- LARGEo estuarine & marine fish -- VERY LARGE
0
0.2
0.4
0.6
0.8
1
1.2
Swordfis
hSha
rk
Lobs
ter-A
merica
n
Halibu
t
Sable
fish
Rockfi
sh
Tuna-c
anne
d
Crabs-D
unge
ness
Polloc
k
Crabs-S
now
Crabs-B
lue
Lobs
ter-S
piney Cod
Flatfis
h
Crabs-K
ing
Perch-O
cean
Shrimp
Salmon
Oyster
s
Crawfis
h
Catfish
Scallo
ps
Sardine
s
Clams
Met
hylm
ercu
ry C
once
ntra
tion
(ppm
)Mean Methylmercury Concentrations for "Top 24" Types of
Fish Consumed in U.S. Commercial Seafood Market
Source of data: Carrington and Bolger, 2002Based on slide from: Elsie Sunderland,
USEPA
Percent Contribution to per capita Methylmercury Intake by Fish Type for "Top 24" Types of Fish in U.S. Commercial Seafood Market
Source of data: Carrington and Bolger, 2002Based on slide from: Elsie Sunderland,
USEPA
0%
5%
10%
15%
20%
25%
30%
35%
40%
Fish Type
Perc
ent†
of T
otal
Met
hylm
ercu
ry in
U.S
. Mar
ket
†Estimate based on the product of per capita fish consumption rates and mean methylmercury concentrations of each type of fish (Carrington and Bolger, 2003)
Sunderland, E. (2007). Mercury exposure from domestic and imported estuarine and marine fish in the U.S. seafood market. Environ Health Perspect 115(2):235-42.
Seafood consumption estimated in this study
from NMFS fisheries supply data compared with available data for
marine and estuarine fish consumption from CSFII
dietary survey data [uncooked weights
(U.S. EPA 2002].
Percentage of total Hg intake (product of
seafood supply and Hg concentrations) for the
top 15 seafood categories; intake is
allocated by the source region for each of the
fisheries products [Atlantic, Pacific, imported (foreign
sources), and high seas landings].
U.S. Population-Wide Consumption & Hg Exposure for Marine and Estuarine Fish
Source: Gary Ginsberg, Connecticut Dept of Public Health (2007). “Risk-Benefit Synthesis for Fish Consumption Advisories,” presented at National Forum on Fish Contaminants, Portland, ME. http://www.epa.gov/waterscience/fish/forum/2007/pdf/section2f.pdf
0
2,000
4,000
6,000
8,000
10,000
12,000
14,000
Uni
ted
Stat
es
Chin
a
Cana
da
Indi
a
Russ
ia
Mex
ico
Indo
nesia
Sout
h Ko
rea
Japa
n
Colo
mbi
a
Tota
l Atm
osph
eric
Dep
ositi
on to
the
Gre
at L
akes
Bas
in (u
g/yr
-per
son)
anthropogenic re-emissions from land
direct anthropogenic emissions
Model-estimated per capita 2005 deposition to the Great Lakes Basin from countries with the highest modeled contribution from direct & re-emitted anthropogenic sources
Presentation to IJC-IAQAB, Apr 25, 2012NOAA Air Resources Laboratory 26
Modeling – ApproachesBack-trajectory analyses with HYSPLIT
Fate and transport modeling with HYSPLIT-Hg
6/19/2012 Air Resources Laboratory 27
…focus on source-receptor relationships
6/19/2012 Air Resources Laboratory 28
Back Trajectory Analysis – Episodes
07:
30 0
8:30
09:
30 1
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11:
30 1
2:30
13:
30 1
4:30
15:
30 1
6:30
(Eastern Standard Time)January 7, 2007
0
20
40
60
80
100
RG
M (p
g/m
3)
Reactive Gaseous Mercury episodeBeltsville, Maryland
mercury site
07:
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8:30
09:
30 1
0:30
11:
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(Eastern Standard Time)January 7, 2007
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M (p
g/m
3)
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(Eastern Standard Time)January 7, 2007
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M (p
g/m
3)
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RG
M (p
g/m
3)
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(Eastern Standard Time)January 7, 2007
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M (p
g/m
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M (p
g/m
3)
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M (p
g/m
3)
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(Eastern Standard Time)January 7, 2007
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M (p
g/m
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RG
M (p
g/m
3)
07:
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11:
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6:30
(Eastern Standard Time)January 7, 2007
0
20
40
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M (p
g/m
3)
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6:30
(Eastern Standard Time)January 7, 2007
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M (p
g/m
3)
6/19/2012 Air Resources Laboratory 29
Chesap
eake
BayBaltimore
Washington D.C.
North American mercury sources
mercury that doesn’t
deposit continues
its global circulation
*
regional and and global
sources contribute to atmospheric
mercury deposition
30
mercury from global
atmospheric pool entering
North America
Thousands of fish-advisories throughout North America due
to mercury contamination
Polar-specific air-chemistry can lead to enhanced
mercury deposition under some conditions
Atmospheric mercury deposition varies spatially and temporally, and is always a complex combination of impacts from local, regional, national, and global emissions sources.
Air Resources Laboratory6/19/2012
6/19/2012 Air Resources Laboratory 31
Different “forms” of mercury in the atmosphere
Elemental Mercury -- Hg(0)• most of total Hg in atmosphere• doesn’t easily dry or wet deposit• globally distributed
Reactive Gaseous Mercury -- RGM• a few % of total atmos. Hg• oxidized Hg (HgCl2, others)• very water soluble and “sticky”• bioavailable
Particulate Mercury -- Hg(p)• a few % of total atmos. Hg• Hg in/on atmos. particles• atmos. lifetime 1~ 2 weeks• bioavailability?
?
Elemental Mercury -- Hg(0)• most of total Hg in atmosphere• doesn’t easily dry or wet deposit• globally distributed
Reactive Gaseous Mercury -- RGM• a few % of total atmos. Hg• oxidized Hg (HgCl2, others)• very water soluble and “sticky”• bioavailable
Particulate Mercury -- Hg(p)• a few % of total atmos. Hg• Hg in/on atmos. particles• atmos. lifetime 1~ 2 weeks• bioavailability?
?
6/19/2012 Air Resources Laboratory 32
Modeling – Comprehensive Fate and Transport Simulations
Start with an emissions inventory
Use gridded meteorological data
Simulate the dispersion, chemical transformation, and wet and dry deposition of mercury emitted to the air
Source-attribution information needed at the end, so optimize modeling system and approach to allow source-receptor information to be captured
HYSPLIT-Hg developed over the last ~10 years with specialized algorithms for simulation of atmospheric mercury
Air Resources Laboratory 33
Provide sound scientific information on the emission, dispersion, transformation, and air-surface exchange of atmospheric mercury compounds
Measure and understand spatial and temporal trends in air concentrations and air-surface exchange
Provide robust source-attribution information for atmospheric mercury deposition to sensitive ecosystems, to inform policies to reduce loadings
6/19/2012
Mercury exposure via fish consumption is an important public health concern
NOAA has a primary stewardship responsibility for the nation’s fisheries
Atmospheric emissions and subsequent deposition is a significant pathway through which mercury contamination enters sensitive aquatic ecosystems
Context
Goals
Air Resources Laboratory 346/19/2012
Modeling used to aid in data interpretation and measurement planning
Measurements used for model evaluation and
improvement
Mercury: Measurements and Modeling
speciated atmospheric mercury
other air pollutants, e.g., SO2, O3, CO
wet deposition air-surface exchange
MEASUREMENTS
back trajectories
comprehensive fate and transport
MODELING
source-attribution for deposition
Mercury transformed by bacteria into methylmercury in sediments, soils & water, then bioaccumulates in fish
Humans and wildlife affected primarily byeating fish containing mercury
Best documented impacts are on the developing fetus: impaired motor and cognitive skills
atmospheric deposition to the watershed
atmospheric depositionto the water surface
adapted from slides prepared by USEPA and NOAA
Environmental Mercury Cycling -- Natural vs. Anthropogenic
This has always been going on, ... always has been Hg in fish
Mercury (Hg) is an element... there is the same amount of mercury on Earth today as there always has been
“natural” Hg cycle: o transported throughout the
environmento chemical transformations
interconvert different mercury species
Sunderland and Mason (2007). Global Biogeochemical Cycles 21, 4022
Pre-Industrial Global Mercury Cycling
-20
-10
0
10
20natural
extraction from deep reservoirs,
e.g., volcanoes
naturaldep to ocean
106
molesper
year natural dep to land
naturalevasion
fromocean
naturalevasion
fromland
pre-industrial: total mercury in atmosphere ~
8.0 x 106 moles
Based on data presented in Sunderland and Mason (2007) Global Biogeochemical Cycles 21: GB4022
(note -106 moles ~ 200 metric tons)GLOBAL MERCURY CYCLING
Environmental Mercury Cycling -- Natural vs. Anthropogenic
Most anthropogenic Hg is “released” as atmospheric emissions: Hg in coal is released to the air when coal is burned Hg in other fuels is released to the air when they are processed and burned Hg in ores is released to the air during metallurgical processes Hg in products is released to the air when burned or landfilled after being discarded
(e.g., batteries, switches)
This has always been going on, and there has always been Hg in fish
Mercury (Hg) is an element... there is the same amount of mercury on Earth today as there always has been
“natural” Hg cycle – Hg is transported throughout the environment, and chemical transformations interconvert different mercury species
But, we make some Hg unexpectedly “bioavailable”
Average, current atmospheric Hg deposition is ~3x pre-industrial levels
Evidence suggests that newly deposited Hg is more bioavailable
-20
-10
0
10
20natural
extraction from deep reservoirs,
e.g., volcanoes
naturaldep to ocean
106
molesper
year natural dep to land
naturalevasion
fromocean
naturalevasion
fromland
pre-industrial: total mercury in atmosphere ~
8.0 x 106 moles
-20
-10
0
10
20anthropdirect emit
anthropre-emit
fromocean
anthropdep to land anthrop
dep to ocean
anthropre-emit
fromland106
molesper
year
contemporary: total mercury in atmosphere ~
28.0 x 106 moles
Based on data presented in Sunderland and Mason (2007) Global Biogeochemical Cycles 21: GB4022
(note -106 moles ~ 200 metric tons)GLOBAL MERCURY CYCLING
Freemont Glacier, Wyoming
source: USGS, Shuster et al., 2002
Natural vs. anthropogenicmercury?
Studies show that anthropogenic activities have typically increased bioavailable Hg concentrations in ecosystems by afactor of 2 – 10
Hg from other sources: local, regional & more distant
Measurement of ambient air
concentrations
Measurement of wet
deposition