Environmental impacts of small-scale gold mining in Suriname

Mercury pollution in the aquatic
environment of Suriname
Paul Ouboter
National Zoological Collection(NZCS)/
Environmental Research Center (CMO)
Anton de Kom University of Suriname
Small-scale gold mining
in Suriname
• First gold rush 1880-1910
• Present gold rush 1980-present
• 25,000 to 35,000 gold miners (est. GMD
2000)
• Production 10,000-20,000 kg gold/year (est.
Veiga, 1997)
• Many gold miners are mining illegally
• Most miners are Maroons and Brazilians
• Mining concentrated in Greenstone Belt
Small-scale gold mining
in Suriname
• Small-scale operations have recently
changed into medium-scale operations
• Mercury used for amalgamation, usually in
combination with sluice boxes or dredges
• Usually no tailing ponds used
• Mercury lost to environment 10,00020,000 kg (est Veiga, 1997)
• 55% of mercury lost to atmosphere, 45%
to streams
Method used in smaller streams
Environmental impacts
•
•
•
•
•
•
•
•
Deforestation
Destruction of hydrology
Increase of insolation due to deforestation
Increase of turbidity, metals and nutrients in
stream
Change in aquatic vegetation
Change in fish community
Mercury pollution
Mercury accumulation in food chain
Mercury bioaccumulates
Mercury is
volatile
What is the problem with mercury?
Fish and wildlife in
remote areas have
elevated levels
Mercury levels
globally rising
Mercuryis is
Mercury
neurotoxic
neurotoxic
Regular consumption
of fish with elevated
levels poses health
risk
Piscivorous wildlife
impacted
Mercury bound to
fine sediments
Mercury remains in
ecosystems for ages
MERCURY RESEARCH IN
SURINAME
Mercury research other organizations/authors
• OAS project on introduction of retorts (incl. some
measurements) (Pollack, de Kom, Quik & Zuilen, 1998)
• Mercury levels in gold-miners (de Kom, van der Voet &
de Wolff, 1998)
• Mercury in communities at the Lawa River (Cordier,
Grasmick, Paquier-Passelaigue, Mandereau, Weber &
Jouan, 1998)
• Mercury in fish (Mol, Ramlal, Lietar & Verloo, 2001)
• Mercury in gold-mining sites (Arets, v.d. Meer, v.d. Brink,
Tjon, Atmopawiro & Ouboter, 2006)
Mercury research other organizations/authors
(cont.)
• Mercury in pregnant women and new-borns (Mohan,
Tiller, van der Voet & Kanhai, 2005)
• Mercury in communities in the interior (Peplow &
Augustine, 2007)
• Mercury in the coastal and urban atmosphere (Müller,
Wip, Warneke, Holmes, Dastoor & Notholt, 2012)
• Mercury in communities (Min. public health; to start?)
Projects NZCS/CMO
• Mercury pollution in the Commewijne River
(Quik & Ouboter, 2000; WWF-Guianas)
• Mercury pollution in the gold mining areas
(Ouboter, Landburg, White, Mol, v.d. Lugt &
Quik, 2007; WWF-Guianas)
• Atmospheric transportation of mercury (Ouboter,
Mol & Quik, 2003; Schure-Beijerinck-Popping
Fund)
• Mercury source in the Fallawatra Formation
(Landburg, 2005; NZCS/CMO)
Projects NZCS/CMO (cont.)
• Mercury poisoning of Brownsweg villagers (Ouboter &
Landburg, 2010; WWF-Guianas)
• Mercury levels in Western Suriname (NZCS/CMO)
• Environmental and community levels of mercury in
Kwakoegron and Pikin Saron (e.g. Hawkins, Lichtveld &
Ouboter, 2011; Tulane University)
• Mercury levels in sediment cores of floodplain rivers
(NZCS/CMO)
• Mercury levels in mud flats before the coast of Suriname
(NZCS/CMO & Tulane University)
Publication incl. most of these projects: Ouboter, Landburg,
Quik, Mol & v.d. Lugt, 2012
Methods
• Data based on 9 different projects carried out between 19982013, including 60 localities:
–
–
–
–
–
14 localities in Greenstone Belt
18 localities downstream Greenstone Belt
7 control localities upstream of gold mining
17 localities in central and western Suriname
4 localities at the coast of Suriname
• 5 communities, 3 in Greenstone Belt, 1 downstream of
Greenstone Belt and 1 upstream of Greenstone Belt for fish
consumption study and mercury in hair
• Measurement of water quality in the field (pH, conductivity,
dissolved oxygen, temperature, turbidity)
• Sampling of water, sediment and fish tissue according to
sampling protocol
• Fish caught using gill nets or bought from local fishermen
• Samples transported to laboratory on ice
• Mercury analyzed with mercury analyzer using cold-vapor
atomic absorption
• Quality check for all analytic sessions
Hoplias aimara (anjoemara)
Piranha
(Serrasalmus
rhombeus)
Serrasalmus rhombeus (piranha)
Why investigate mercury in aquatic
ecosystems ?
• Air and water are transportation
mechanisms; provide one-moment in time
data
• Terrestrial soil data spatially very variable
• Mercury bound to sediment in aquatic
environment
• Mercury bio-accumulated in fish
Mercury in water
Mercury in bottom sediment
Mercury in predatory fish
Serrasalmus rhombeus
3.5
3
Hg (mg/kg)
2.5
Gold mining areas
2
Brokopondo Reservoir
Piki Pada
Upstream gold mining
1.5
Western Suriname
1
0.5
0
0
5
10
15
20
25
Standard length (cm )
30
35
40
45
Hoplias aimara
1.6
1.4
1.2
Hg (mg/kg)
1
Gold mining areas
0.8
Upstream gold mining
Western Suriname
0.6
0.4
0.2
0
0
10
20
30
40
50
Standard length (cm )
60
70
80
90
WHAT IS THE SOURCE OF
THE MERCURY
Natural mercury emission sources
•
•
•
•
Geologic weathering
Volcanism
Evaporation from waters
Plant transpiration and decomposition
Anthropogenic mercury emission
sources
•
•
•
•
•
Producers of mercury and its compounds
Consumers of mercury and its compounds
Burning of fossil fuels
Pyrometallurgical processes
Forest fires
Estimated annual anthropogenic Hg
emissions ( in 103 kg Hg yr-1)
Gold
mining
Brazil
1. Lacerda & Marins,
1997
2. Meech et al., 1995
Suriname
1. Mol et al., 2001
2. UNEP, 2008
Biomass Industry
burning
77.91
8.71
28.91
70 - 1702 88 - 1042
201
0.31
0.15-0.62
Where does the mercury come
from in Suriname??
• Gold mining ?
• Naturally in base rock, sediment and soil ?
Roulet et al.(1998): “… the natural burden of the soils is much
more important than potential new inputs of anthropic Hg from
goldmining or biomass burning, representing more than 97%
of the Hg accumulated in soils. Consequently, the deposition
and incorporation of anthropic Hg is negligible and soils could
be considered as a major reservoir of natural Hg”.
Mercury in core samples from
floodplains
Mercury in core samples from floodplains
Nickerie 3
0-5
Nickerie 2
5-10
Nickerie 1
10-15
Coppename 4
15-20
Coppename 3
20-25
Coppename 2
25-30
Coppename 1
30-35
Saramacca 4
35-40
Saramacca 3
Saramacca 2
40-45
Saramacca 1
45-50
0
0.05
0.1
0.15
0.2
0.25
0.3
0.35
0.4
Results show:
• Relatively high mercury levels in
undisturbed Western Suriname
• No correlation between mercury levels and
distance from Greenstone Belt
• No mercury source in Fallawatra formation
• Mercury in core samples indicate an
anthropogenic origin
• Mercury in floodplain of Coppename River
(undisturbed) on average higher than in
Saramacca River (gold mining)
WHY HIGH MERCURY LEVELS
IN UNDISTURBED AREAS?
Mechanism 1:
Mercury
evaporated
and
transpirated
in gold
mining areas
Mercury
vapor
transported
to SW by NE
tradewind
Wet and dry
depositing of
mercury in
central and
SW
Suriname
• Most depositing occurs in areas with high
precipitation (windward side of mountain
ranges)
Mechanism 2:
In polluted
rivers much
of the
mercury is
bound to the
high load of
suspended
sediments
In pristine
rivers the
load of
suspended
sediments is
less
Mercurysediment
complex will
not easily
pass
biological
membranes
Mercury is
less
biological
available
Mercury is
more
biological
available
Higher
mercury
levels in biota
Predicted mercury levels
IMPACT ON PUBLIC HEALTH
Pikin Saron
Kwakugron
Brownsweg
Njun Jacobkondre
Pusugrunu
Mercury in hair
14
12
HG (UG/G)
10
8
6
Women
Men
Adults
4
2
0
Children (5-12 y)
Fish consumption surveys Brownsweg
Conclusions on mercury levels in
aquatic ecosystems in Suriname
• Levels in predatory fish often above norm for human
consumption in most of Suriname
• Levels in bottom sediments often high
• Highest levels in Brokopondo Reservoir
• Increased levels in human population
• Also high levels in shallow sea and “pristine” areas
in Central and Western Suriname
• Small-scale gold mining is the main cause of
increased mercury levels, also in pristine areas
• Pristine areas are polluted by atmospheric
transportation of mercury, precipitation and
biological availability.
Impacts of mercury on local
communities
• Drinking water usually below norm
(suspended sediments biggest problem)
• Predatory fish often above norm for
human consumption
• Mercury may remain in system for long
time
• Mercury may interfere with public health
and, in worst case scenario also with
development of communities in interior
WHAT CAN WE DO ABOUT
THE PROBLEM?
Phase 1:
• Additional research
• Increase awareness of population, esp.
local communities
• Advocate restricted consumption of large
predatory fish
Phase 2:
• Regulate and control gold mining
operations
• Train gold miners in methods without
mercury (and other environmental
measures)
• Prohibit the import and use of mercury
Phase 3:
• Rehabilitate mined-out areas
Present and future research on
mercury levels:
• Extension of human related projects to other
communities in the interior
• Investigate correlation between mercury in fish
and humans and water chemistry (turbidity, pH
and DOC)
• Investigate mercury levels in mud flats at the
coast
Acknowledgements
• All persons assisting in the field and
laboratory
Financial support:
• WWF-Guianas
• Schure-Beijerinck-Popping Fund
• Tulane University
• Tropenbos
• Stinasu
Thank you!