1. Model assessment of heavy metal pollution from global to local scales
Thematic session 10(c)
Model assessment of heavy metal pollution from global to local scales
Oleg Travnikov 1

2. Atmospheric dispersion of heavy metals
Properties of heavy metals
Property
Pb, Cd Hg
Atmospheric forms
Pbpart, Cdpart
Hg0gas, HgIIgas, HgIIpart
Atmospheric chemistry
not important
important
Lifetime vs. deposition
weeks
days-months
Geographical scope of pollution
regional
global-local
Accumulation in media
significant
Secondary emissions
(probably)
Heavy metal atmospheric transport
Pbpart
Cdpart
Pbpart
Cdpart

3. Atmospheric dispersion of heavy metals
Properties of heavy metals
Property
Pb, Cd Hg
Atmospheric forms
Pbpart, Cdpart
Hg0gas, HgIIgas, HgIIpart
Atmospheric chemistry
not important
important
Lifetime vs. deposition
weeks
days-months
Geographical scope of pollution
regional
global-local
Accumulation in media
significant
Secondary emissions
(probably)
Heavy metal atmospheric transport
HgII
gas
part
Hg0
Hg0 Hg

4. Multi-model assessment of Hg pollution on a global scale
What is known: Spatial patterns
Multi-model assessment of Hg pollution on a global scale
Air concentration of Hg0 (2015)
Hg wet deposition (2015)
Model, g/km2/y 1 10 40
Observed, g/km2/y
0.6 2 3
Model, ng/m3
Observed, ng/m3
UN Environment Global Mercury Assessment 2018

5. Operational model assessment of Hg, Pb, and Cd pollution within EMEP
Spatial patterns: Regional scale
Operational model assessment of Hg, Pb, and Cd pollution within EMEP
Pb in air
Hg0 concentration in air
Cd in air
Output information:
Concentration and deposition pattern
Source apportionment of deposition
Ecosystem-specific deposition

6. Ecosystem-specific deposition of HMs for evaluation of adverse effects
Spatial patterns: Regional scale
Ecosystem-specific deposition of HMs for evaluation of adverse effects
Hg deposition to forests (2016)
Hg deposition inland waters (2016)
Harmonization of the land cover data is required within the Convention to avoid inconsistencies in data products

7. Importance of fine resolution
Deposition of Cd within region
2010
Exceedance of critical loads of Cd in 2010
Cd deposition in Central Europe
Czech
Republic
Poland
Germany
Austria
Slovakia
Deposition flux
Distance
Grid cell
Detailed and reliable input data are critical for improvement of modelling results with fine spatial resolution
Critical loads
Deposition

8. Model assessment of long-term changes of HM pollution
What is known: Temporal trends
Model assessment of long-term changes of HM pollution
Long-term changes of HM deposition
Reduction of HM deposition
-20 20 40 60 80
100 Pb Cd Hg
Overall redcution ( ), %
EMEP
EU28
EECCA 10 20 30 40
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
Pb deposition, kg/km2/y
0.6
1.2
1.8
2.4
Cd and Hg deposition, g/km2/y Cd Hg Pb

9. Evaluation of modelling results vs. measurements in mosses
What is known: Temporal trends
Evaluation of modelling results vs. measurements in mosses
Measurement of HM in mosses
0.0
0.1
0.2
0.3
1990
1995
2000
2005
2010
Conc. in mosses, mg/kg 15 30 45
Total deposition, g/km 2 /y
Conc. in moss
Deposition flux Cd 3 6 9 12
0.6
1.2
1.8
2.4
Total deposition, kg/km Pb

10. Mercury oxidation and reduction chemistry in the atmosphere
Gaps in knowledge
: Hg chemistry
Mercury oxidation and reduction chemistry in the atmosphere
Measurements
ECHMERIT
GLEMOS
GEM-MACH-Hg
GEOS-Chem 20 40 60 80
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Wet deposition, ng/m2/day
Hg0 + Br
Hg0 + O3
Hg0 + OH
Hg wet deposition in Europe
Travnikov et al. (2017)
Hg atmospheric chemistry Br O3 OH
NO2
HO2
BrO Cl
ClO
Br2
HgII
gas
part
Hg0
gas
hn (?)

11. Mercury emissions from legacy and natural sources
Gaps in knowledge: Secondary emissions
Mercury emissions from legacy and natural sources
Source apportionment of Hg deposition (2015)
Hg deposition to Europe
Direct anthrop. sources (33%)
Legacy & natural sources (67%)
g/km2/y 5 10 15 20 25 30 35
- legacy and natural sources
Available estimates of Hg emission from secondary (re-emission) and natural sources are still very uncertain
UN Environment Global Mercury Assessment 2018

12. Wind re-suspension of particulate heavy metals (Pb, Cd)
Gaps in knowledge: Secondary sources
Wind re-suspension of particulate heavy metals (Pb, Cd)
Wind erosion and dust suspension from arable soils
Anthrop. emission and re-suspension of Pb in Europe ( )
Relative contribution of wind re-suspension to total emissions could increase significantly due to strong reduction of direct emissions

13. Heavy metal accumulation in soil
Gaps in knowledge: Accumulation
Heavy metal accumulation in soil
Pb air concentration
Aneboda
Gårdsjön
Gammtratten
Kindla
ICP IM sites:
mg/kg dw
1980
1990
2000
2010 40 60 80
100 FH
0-5 cm
5-20 cm
Pb in soil (Sweden)
1990
1995
2000
2005
2010 3 6 9 12
Conc. in mosses, mg/kg
Pb concentration in moss

14. Mercury bioaccumulation in aquatic environment
Gaps in knowledge: Accumulation
Mercury bioaccumulation in aquatic environment
Hg general cycle in aquatic ecosystems
© USGS
(ICP Waters report 132/2017)
Hg concentration in fish
>0.5 mg/kg in 40% of lakes

15. Evaluation of adverse effects of Hg on ecosystems and human health
Gaps in knowledge: Exposure assessment
Evaluation of adverse effects of Hg on ecosystems and human health
Exceedance of critical loads of Hg (2010)
Human exposure via fish consumption
© USGS
How to establish the proper link between atmospheric deposition and human/ecosystem exposure?

16. Summary Current status:
Monitoring and modelling tools provide acceptable estimates of HM dispersion in the atmosphere, spatial patterns and temporal trends of pollution levels
Scientific gaps:
Uncertainties in Hg atmospheric chemistry
Poorly known process of HM accumulation in soil, water etc.
Uncertain estimates of secondary emissions (re-emission, re-suspension)
The link between atmospheric deposition and human/ecosystem exposure

17. Summary Scientific needs:
Complex monitoring of HMs in different media (atmosphere, soil, water) to study accumulation and long-term changes
Development of multi-media modelling approach for assessment of HM dispersion and cycling (Hg)
Development of methods for assessment of HM exposure and adverse effects (critical loads, dynamical modelling etc.)