mercury - overview of global emissions, transport and effects john munthe ivl swedish environmental...
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Mercury - overview of global emissions, transport and effects
John Munthe
IVL Swedish Environmental Research Institute
www.ivl.se
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Presentation topics
Introduction
Emissions
Main transport pathways - modelling
Contribution of global cycling on deposition in Europe and the USA
Monitoring
The Arctic
Research with hemispherical and/or global focus
Main uncertainties in quantifying the global mercury cycle
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Mercury basics
Natural component of earth´s crust in the form of Cinnabar (HgS)
Global burden increased from natural background by about a factor 3 (air, soils, sediments, fish)
Sources include both intentional use and fuel contamination
UNEP Global Assessment Report and UNEP Governing Council have stated " Mercury is a pollutant of global concern"
Main human impact is via consumption of fish contaminated with methylmercury
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Atmospheric mercury speciation Main form in air is elemental mercury vapour (Hg0)
Is relatively stable towards oxidation and has an atmospheric lifetime of around 1 year
Deposition (dry and wet) is controlled by presence of oxidised gaseous mercury (e.g. HgCl2) and particulate mercury forms.
Oxidised mercury is emitted from some point sources and is also formed in the atmosphere via oxidation (OH, halogens, O3)
Operationally defined mercury species:- RGM = Reactive Gaseous Mercury = Oxidised gaseous mercury, Hg(II)- TPM = Total Particulate Mercury, HgP - GEM = Gaseous Elemental Mercury- TGM = Total Gaseous Mercury = GEM + RGM
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Methylmercury
The most toxic form of mercury in the environment
Present in air, water, soils, sediments as a small fraction of the total mercury (0.1 to 5 %)
Bioaccumulates and biomagnifies in aquatic food chains
Methylmercury 90-100% of total mercury in fish
Biotic formation e.g. via methylation of mercury by sulphate reducing bacteria
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Air 26 Mmole +17Hgp 98% Hgº Hgº
2% Hgp
Hgº CH3Hg+
Hg2+ Hgp
Wet & DryDeposition
NaturalEmissions
AnthropogenicEmissions
ParticleRemoval
100m
Mixed Layer +2654 Mmole
10.210.6
512.6
8.6
G.R.I.M.M.
OceanicEvasion
3.5
Air 8.6 MmoleHgp 98% Hgº Hgº
2% Hgp
Deposition Hg2+
Hgº CH3Hg+
Hg2+ Hgp
Wet & DryDeposition
NaturalEmissions
ParticleRemoval
100m
Mixed Layer28.5 Mmole
3.4
4.6
3.5
All Fluxes in Mmole/y
OceanicEvasion
1.9
5
Current Pre-Industrial
Burial 1.7
Upwelling
2.7
Burial 1.5
Upwelling
3.1
Deposition Hg2+
Thermocline +1781080 Mmole1000m 1000m Thermocline
902 MmoleFigure Style Adapted fromMason et al., 1994 Deep Ocean Seds. +9
Terr. Seds.+318 (58%)
LAMBORG et al., Geochim. Cosmochim. Acta, 66, 1105–1118, 2002
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Geographical distribution
Continents - Total emission: 2269 tonnes
18%
52%
6%
11%
4%
9%
AFRICA
ASIA
AUSTRALIA
EUROP E
SOUTH AMERICA
NORTH AMERICA
Slide courtesy of Jozef Pacyna, NILU
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Emission categories
Categories - Total emission: 2269 tonnes
67%5%
7%
1%3%1%
10%5%1%
Stationary Combustion
Cement Production
Non-ferrous Metal Production
Pig Iron & Steel Production
Caustic Soda Production
Mercury Production
Gold Production
Waste Disposal
Other
Slide courtesy of Jozef Pacyna, NILU
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10Speciation of emitted mercury
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
Power plants Residential heat Cement Production Lead Zinc Pig & iron Waste Disposal
Hg (partic.)
HgII
Hg0 (gas)
Hg0
RGM
HgP
Slide courtesy of Jozef Pacyna, NILU
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Point source emissions - speciation
Combustion processes emit Hg0, oxidised mercury (RGM) and small fractions of HgP
RGM and HgP will deposit on local to regional scales whereas Hg0 will add to the global background
Measurement methods for speciation exist but are not frequently applied - inventories rely on estimates
Uncertainties in available data on speciation are large
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Natural sources and re-emissions
Natural sources believed to be of same order of magnitude as anthropogenic
Main source areas associated with cinnober deposits and other Hg-containing minerals, volcanos
Re-emissions occur from water bodies as well as soils and vegetation
For water surfaces, re-emissions may be of same magnitude as deposition
Uncertainties very large for both natural emissions and re-emissions
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Atmospheric chemistry of mercury - schematic description
Gas phase Hg(0) Hg(II) Hg(p)oxidation
Hg(0) Hg(II)
Hg(p)
Hg(p)
oxidation
reduction
Aqueous phase
adsorption to soot
Slide courtesy of Christian Seigneur, AER
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Global transport modelling
GRAHM (Global/Regional Atmospheric Heavy Metals Model) simulation – Ashu Dastoor, Meteorological Service of Canada,Environment Canada
Average elemental mercury surface concentrations for Jan 2001 (ng/m3)
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Global transport modelling
Average elemental mercury surface concentrations for July 2001 (ng/m3)
GRAHM (Global/Regional Atmospheric Heavy Metals Model) simulation – Ashu Dastoor, Meteorological Service of Canada,Environment Canada
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16Contribution of sources other than U.S. anthropogenic
sources to Hg deposition
AER/EPRI Modeling System for Atmospheric MercuryChristian Seigneur
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Experimental modelling results courtesy of Russell Bullock, US EPA
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18MSC-East Hemispherical model. Spatial distribution of mean annual concentration of elemental mercury in the surface air of the Northern Hemisphere
Travnikov and Ryaboshapko, MSC-E Technical Report 6/2002
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Annual deposition field of mercury fromEuropean anthropogenic sources. The red rectangle depicts the EMEP domain
Travnikov and Ryaboshapko, MSC-E Technical Report 6/2002
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Spatial distribution of annual mercury deposition to the EMEP domain
From European anthropogenic sources From external anthropogenic andglobal natural sources
Travnikov and Ryaboshapko, MSC-E Technical Report 6/2002
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Relative contributions of differentregions to the entire mercury deposition to Europe.
Travnikov and Ryaboshapko, MSC-E Technical Report 6/2002
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Contribution of Natural, global and re-emission sources to wet deposition of Hg, 2001
Data from: http://www.msceast.org/hms/results_relation.html2005-05-31
0
10
20
30
40
50
60
70
80
90
100
Country
Pe
rce
nt
of
de
po
sit
ion
fro
m R
NG
Median 56% from re-emissions, natural and global sources
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Monitoring
Atmospheric mercury is not included in existing global or hemispheric monitoring networks
Mercury monitored at < 10 EMEP stations located in Northern Europe
More extensive networks exist in USA and Canada
Methods have existed for >2 decades, modern automated methods > 5 years
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Total Gaseous Mercury at Swedish West Coast 1979 to 2002
0
2
4
6
8
10
12
14
1979 1980 1981 1982 1983 1984 1985 1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002
Date
TG
M n
g/m
3
Large influence from European emissionsand regional transport
Mainly global background
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TGM from Mace Head 1991 to 1997
y = -0,000008x + 1,76 : Trend = - 0,15 % y-1
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
aug
-91
okt
-91
dec
-91
feb
-92
apr-
92
jun
-92
aug
-92
okt
-92
dec
-92
feb
-93
apr-
93
jun
-93
aug
-93
okt
-93
dec
-93
feb
-94
apr-
94
jun
-94
aug
-94
okt
-94
dec
-94
feb
-95
apr-
95
jun
-95
aug
-95
okt
-95
dec
-95
feb
-96
apr-
96
jun
-96
aug
-96
okt
-96
dec
-96
TG
M (
ng
Hg
/m3 )
Slide courtesy of Dr Ralf Ebinghaus, GKSS Research Centre ([email protected])
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Hg in blood of mothers and women of reproductive age
Biomagnification and human exposure
Slide courtesy of the Arctic Monitoring and Assessment Programme - AMAP
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Mercury Depletion Events - example from Ny Aalesund
0
0.5
1
1.5
2
2.5
3
3.5
01.01.00 01.01.01 01.01.02 01.01.03
GE
M (
ng
/m3)
Slide courtesy of Torunn Berg, NILU ([email protected])
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Mercury Depletion Events - mechanisms
Slide courtesy of the Arctic Monitoring and Assessment Programme - AMAP
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Mercury Depletion Events
Large research efforts have been made on mechanisms and occurrence including re-emission from snow pack
Model calculations to estimate net input to Arctic ecosystems - twice expected amount without depletion events
Source of mercury is "Global background"
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Mauna Loa, Hawaii Monitoring Site
Slide courtesy of Dr Matthew Landis, US EPA ([email protected])
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Aug
05
Aug
11
Aug
18
Aug
24
Sep
t 07
Sep
t 14
Sep
t 21
Sep
t 27
Oct
04
Oct
12
Oct
19
Oct
27
Hg0 n
g m
-3
0
2
4
6
8
10
12
14
16
RG
M p
g m
-3
0
100
200
300
400
Hg(
p) p
g m
-3
0
50
100
150
200
Hg0 RGM Hgp
Mauna Loa Hg Time Series2001 “Downslope”
Slide courtesy of Dr Matthew Landis, US EPA ([email protected])
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32Spring 2004 Experiment: Simultaneous Hg Observations at Mt.Bachelor and Okinawa
Okinawa
MBO
Slide courtesy of Eric Prestbo Ph.D. ([email protected]) and Professor Dan Jaffe ([email protected]).
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Slide courtesy of Eric Prestbo Ph.D. ([email protected]) and Professor Dan Jaffe ([email protected]). From: Jaffe D.A, E. Prestbo, P. Swartzendruber, P. Weiss-Penzias, S.Kato,A.Takami, S.Hatakeyama and Y.Kajii. Export of Atmospheric Mercury from Asia. Atmospheric Environment 39, 3029-3038, 2005.
Hg0 vs CO at Okinawa
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34Pollutant transport to US west coast from Asia April 25, 2004
Slide courtesy of Eric Prestbo Ph.D. ([email protected]) and Professor Dan Jaffe ([email protected])
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Current knowledge
Global emission inventory for mercury species
Modelling tools to calculate atmospheric transport and deposition on hemispherical and global scales
Basic understanding of some main chemical processes of atmospheric mercury
Observational evidence of global background mercury levels and influence of regional emissions
Observational evidence of Mercury Depletion Events in the Arctic (and Antarctic)
Observations of transport from Asia to North America
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Main uncertainties in quantifying the global mercury cycle
Emission inventories for anthropogenic sources: Needs continuous updating and better information on speciation
Natural emissions: High level of uncertainty. Mainly in the form of Hg0 which mainly influences global background.
Re-emissions: Very high level of uncertainty. Data available only from a few specific sites. Need estimates of e.g. oceanic emissions.
Atmospheric chemistry: Basic facts are known but there are indications of major gaps in e.g. rapid processes in free troposphere
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Main uncertainties in quantifying the global mercury cycle Atmospheric models need continuous updating and testing.
Models need to take into account both a) direct transport - trajectories from source to receptor over shorter time period e.g. from Asia to NA b) additions to/contributions from "global background" which will influence deposition at remote sites and for long time periods
Many current regional models have tendency (or are forced to due to lack of data) to lump or completely ignore natural emissions and re-emissions. This may be acceptable for regional applications but for hemispherical/global applications over longer time periods, better descriptions are needed.