1. 3rd session of the INC on a Hg instrument
Contribution of contaminated sites to the global mercury budget
Milena Horvat1, David Kocman1, Nicola Pirrone2, Sergio Cinnirella 2
1Jožef Stefan Institute, Ljubljana, Slovenia
2CNR-Institute of Atmospheric Pollution Research, Rome and Rende, Italy
3rd session of the INC on a Hg instrument
Nairobi, 2nd November, 2011

2. Content
The extent and global distribution of Hg contaminated sites (by Hg source category; by continents)
Contribution of contaminated sites to the global mercury budget
Quantification of Hg emissions
Hg spreading through hydrological cycles 

3. (II) Soil and vegetation
Mercury Transformations in Atmosphere & at the air/water/snow/soil Interfaces
(I) Water/lakes/Ocean
(II) Soil and vegetation
Long-range
transport
Local deposition
Soil
Emission/
Biomass burning
Wet/Dry
Deposition
(III) Sea Ice/
snow
Hg(0)
Hg(II) hv
Hg(II)/
aerosols
Cl2/Br2
Hgp
Hg(II) Reduction
food web
XHgCH3
BrCl + hv  Br/Cl
Br2 + hv  2Br
Br/Cl + O3  BrO/ClO + O2
BrO/ClO + Hg0  Br/Cl + HgO
BrOH/ClOH + Hg0  HBr/HCl + HgO
2Br/2Cl + Hg0  HgBr2/HgCl2
Surface microbes
zooplankton
fish
Industry

4. What is a contaminated site?
"A site at which hazardous substances occur at concentrations above background levels and where assessment indicates it poses, or is likely to pose an immediate or long-term hazard to human health or the environment."
ANZECC (1992)

5. What is a hot spot?
“The definition of hot spots depends upon the medium that is contaminated. Generally, for water, a hot spot exists if contamination results in a significant adverse effect on the beneficial use of that resource and if restoration or protection of the beneficial use can occur within a reasonable amount of time.
For media other than water, a hot spot exists if the site presents an unacceptable risk and if the contamination is highly concentrated, highly mobile or cannot be reliably contained.”
DEQ, 1998

6. The extent of contaminated sites
CONCENTRATED “HOT SPOTS”
Active
Intentional (use of Hg in processes and products)
Non intentional (Hg as by-product)
Historical
(mining, industrial waste, sludge…)
DISPERSED
Catchments impacted by Hg
Coastal areas impacted by Hg

7. Inventory of contaminated sites by source category
Mercury mining and smelting
Chlor-alkali industry
Precious metal processing: large scale
Artisanal and small-scale gold mining
Non-ferrous metal production
Other industrial and urban sites
Acetaldehyde production
Vinyl chloride and vinyl acetate
Oil refineries
Urban landfilds

8. Mercury contaminated sites
GLOBAL PRESPECTIVE:
 70% of CS concentrated in industrial regions of Europe and N America
Asia, India: number of CS increasing due to rising use of Hg in various products and processes

9. CSs vs. meteorological and land cover conditions
New Almaden
Releases: 4-30 kg/yr*
Idrija
Production: t
Precipitation: 2000 mm
Releases: 1000 kg/yr
New Idria
Production: t
Precipitation: 330 mm
Releases: 1.5 kg/yr**
* Thomas et al., Geochem (2002), **Ganguli et al., ES&T (2000)

10. Quantification of Hg emissions from contaminated sites – data needs
Characterization and identification of CS:
Extent and spatial distribution of contamination (Hg content in soils, delineation of “hot spots”…)
Transport between compartments (erosion rates, surface/air exchange)
Differential absorption lidar technique, portable instruments (e. Lumex), flux chamber experiments…

11. Hg releases into the hydrosphere - data availability
Releases of Hg from CSs – literature overview:
Poorly documented
Short observation periods not adopted to meteorological conditions
Difficult to determine relative contribution of the contaminated part of the catchment
Coexistence of various types of Hg contaminated sites
Case studies - lessons learned:
Variability in releases (production, Hg content, control equipment, mitigation, process…)
Releases are significant: up to hundreds of kg/yr/site
Meteorological conditions the most important factor controlling releases – majority of transport occurs during flood events

12. Quantification of Hg emissions and releases – modeling approach
Hg release to aquatic systems
Erosion and runoff depend on land cover/use, geology, pedology, topography, precipitation…
Hg atmospheric emission
Emissions depend on substrate, Hg content, soil temperature, solar radiation, soil moisture

13. Mercury atmospheric and terrestrial flux from contaminated sites
Name
Flux in air
(kg yr-1)
Terrestrial*
Reference
New Idria (USA)
2.7 (from 0.6 km2) and
15 (from 229 km2)
1.5
Gustin et al., 2002
Ganguli et al., 2000
Sulphur Bank (USA)
17 (3.8 km2)
Gustin, 2003
Ivanoe District, Nevada (USA)
78 (586 km2)
Engle et al., 2001
Wanshan (China)
1-5
Wang et al., 2006
Lanmuchang (China)
3.5 (3 km2)
Wang et al., 2005
Almaden (Spain)
1750
Ferrara et al., 1998b
Idrija (Slovenia)
(from 640 km2)
900
Kocman (2008)
Mt. Amiata (Italy)
Ferrara et al.,1998a
New Almaden (USA)
4-30
Thomas et al., 2002
San Francisco Bay
50-600
David et al., 2006

14. Contaminated sites vs. meteorological and land cover conditions
Temperature
Precipitation
Vegetation cover

15. Total mercury emissions from contaminated sites
Atmosphere
(t yr-1)
Hydrosphere
(t yr-1)*
Mercury mining
5-20
10-50
Chlor-alkali industry
1-3
2-5
Non-ferrous metal processing
1-5 -
Precious metal processing (large scale)
2-10
5-10
Artisanal and small scale gold mining (ASGM) 50
50-100
Other industrial and urban sites
10-20
Total
70-110
70-165
Total (A+H)

16. Global Mercury Emissions
Natural
5207
Anthropogenic
2320
Volcanoes 90
Forest fires
675
Forest & agriculture
1664
Oceans
2778
Global Emission (2008):
7438 Mg yr-1
Source: Pirrone et al. ACP, 2010

17. Global Mercury Emissions in Mg yr-1
Anthropogenic
2320
Global Emission (2008):
7438 Mg yr-1
Natural
5207
(~ 4 %)
Rivers to estuaries
( )
( )
(~ 5 %)
Rivers to open waters
( ) (7-16)
Redistribution by currents
(5-10)
Historic accumulation
(5000 – )
Sources:
Pirrone et al. ACP, 2010
Sunderland and Mason, 2007

18. Conclusions (I)
Total Hg emissions and releases from contaminated sites are between tons per year.
Hg releases to the hydrosphere are in the same order of magnitude as the atmospheric emissions.
>40% of contaminated sites are located at the coast and have for decades introduced waste containing mercury directly into local estuaries (5000 to tons accumulated).

19. Conclusions (II)
Mercury emissions and releases from contaminated depend strongly on the climatic conditions and the topography of the site in question.
Comparability of data reported in different studies is also questionable due to different approaches used – standardization is needed.

20. What needs to done?
Standardized tools to identify and characterise contaminated sites and quantify Hg emissions and releases
Training and capacity building at a country level
Improved inventories of contaminated sites

21. To remember
Releases and emission from contaminated sites are less than 10 % of the total global anthropogenic Hg release. However, contaminated sites will release Hg for a very long time, if not managed properly and/or remediated.
Inappropriate management of contaminated sites may further increase Hg releases resulting in an increased risk for local populations and ecosystem.
Remediation of such sites can be expensive, and the decisions are difficult to take because the issue is complex.