Transcript Graduate Proposal - Colorado State University

Phytoremediation Potential
of Bermudagrass and
Vetivergrass on
Arsenic Pollutants at Obuasi
Minetailings
in Ghana
-Koduah Owusu Ansah
-Ana Gonzalez
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Geographic Location
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Ghana is Africa's secondlargest gold producing
country after South Africa
Close to 60 million ounces
of gold have been mined
in Ghana over the last
century
Gold reserves and
resources are estimated
at well over 100 million
ounces
Mining industry
contributes
approximately 40% of
Ghana's gross export
earnings
About Ghana
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Gold and Culture
Gold and Culture Ashanti King
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Obuasi Gold Mine
History of Obuasi(Underock) Gold Mine
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Gold mining at Obuasi began in 1898 by private
businessmen.
Before 1957 -Ghana was originally called Gold
Coast or the Land of Gold
Gold has been part of the culture and history of
the country
Gold mining is the largest foreign exchange
earner, contributing about 45% of the country’s
total foreign currency.
Obuasi Gold Mine
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Company has been
purchased by Anglogold –
a worldwide
conglomerate company
with over 2 million shares
 It can be considered as
the single industrial hub of
the Ghanaian economy.
 Gold ore at site consists of
pyrites(FeS) and
Arsenopyrites(FeAsS)
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Arsenic
Basic Information
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Arsenic (As) can be present in soils, air and
water as a metalloid and as a chemical
compound in both organic and inorganic
forms.
Arsenic ranks 20th in abundance of elements
in the earth’s crust, 14th in seawater and is the
12th most abundant element in the human
body.
Despite its abundance, it is one of the most
toxic
elements
encountered
in
the
environment. (Arsenite and Arsenate)
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Arsenic
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Arsenic
Trail of destruction
 Due
to roasting of Arsenopyrites and
pyrites ores into the atmosphere.
Golow, AA et al
 Process water from plant discharge into
nearby rivers and creeks
 Tailings rich in Arsenic left to be rain
washed into pristine areas and rivers
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Levels of pollution
Arsenic
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Arsenic
Both, the United States Environmental Protection Agency (USEPA) and the World Health Organization (WHO) have
established the As level for drinking water at 10 μg/ L
Unfortunately, some developing countries still use the old
standard of 50 μg/ L, primarily because of economical factors
that prevent access to new technologies.
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Risks Associated with Arsenic
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Several types of cancer
(skin, stomach, lung) skin
pigmentation,
respiratory
infections, causes high infant
mortality rate etc. Hearing
and
vision
impairment,
keratosis, edema, gangrene,
liver damage, etc.
Arsenic pollution has been a
problem in Ghana, Zambia,
Tanzania,
Taiwan,
Bangladesh, Latin America
and China
Most toxic was the Pompora
Treatment –shut down a
couple
of
years
ago.
Dodoo, DK et al
Arsenic
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Arsenic Pollution
Arsenic
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Arsenic
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Objectives
Objectives of the Proposal
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Test the selected species, Vetiver Grass and
Bermuda Grass, using greenhouse study and later
on site.
Determine if any amendments are needed and
consider the possibility of genetically enhancing
the plants.
Remove arsenic pollution with the use of the
selected species down to a level which is
considered safe for humans.
Monitor the concentration of arsenic periodically
to make sure mining activities don’t cause a
recurrent
problem
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Why consider this research?
 Most
research work carried out on rock
formations, effect of Arsenic pollution and
risk assessments - Smedley et al, Golow et
al, Amonoo-Niezar et al.
 United Nations curative health initiative.
 No research work on Environmental
restoration using Phytoremediation known
so far- which is cheaper and affordable.
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Species
Species Selection
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Bermudagrass( Cynodon dactylon)- a C₄ Warm season
grass spp.
Very adaptable to Warm not very humid conditions in
that part of the world. (Native to area)- Drought tolerant
Easy to propagate- rhizomatous
Highly tolerant and phytoaccumulator of Arsenic.
Madejon, P. et al, Weaver, R W et al,
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Vetiver Grass
Vetivera Zizanioides
MORPHOLOGY OF VETIVER
•Vetiver belongs to the Poaceae family,
originated from Indian sub continent, but can
be found throughout tropical and subtropical
regions of Africa, Asia, South and North
Americas and Mediterranean Europe. Maffei,
et al. 2002
•It’s leaf is 45-100cm long and 0.6-1.2cm widehas a smooth and waxy leaf texture
•Fast growing perennial grass, a long (3-4m) fast
massive and complex root system and can
penetrate to deeper layers of soil.
•1yr old Vetiver grass can produce 1meter long
roots.
Species
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Phytoremediation
Vetiver Grass
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•
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Roots can grow a total length
of 7meters in 36 months after
planting. Lavania et al 2003
Extensive root system support
plant under severe drought and
withstand high velocity
subterranean flow.
Extensive root system can
scavenge for pollutants and
sterile under growing
conditions. Produces not seeds
Has stiff and erect stems up to
2m high Truong, 2002
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Phytoremediation
Resistance to Herbicides
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Vetiver cells are 170-fold resistant to
glugosinate compared to susceptible
cells
The glutamine synthethase activity of
resistant cells was twice as high as
susceptible cells
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Phytoremediation
Physiological Characteristics
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Adaptable to extreme environmental conditions. Truong, 1999a.
Can tolerate a time of submergence (more than 120 days).
Much higher than Bahiagrass-60-70 days: Carpetgrass-32-40
days: sour Paspalum-25-32 days: St. Augustine grass- 18-32 days
and Centipede grass- only 7-10 days
It can survive more than 3 mts under muddy water.
Has an average net biomass of more than 100 tons of dry
matter per year. Truong 2003
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Phytoremediation
Physiological Characteristics
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Adaptable to extreme environmental conditions.
Truong, 1999a.
Can tolerate a time of submergence (more than
120 days). higher than Bahiagrass:60-70d,
Carpetgrass: 32-40d, sour Paspalum: 25-32d, St.
Augustine grass- 18-32d, and Centipede grass: 710 days
It can survive more than 3 mths under muddy
water.
Has an average net biomass of more than 100
tons of dry matter per year. Truong 2003
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Phytoremediation
Phytoremediation potential of
Bermudagrass
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Native Species
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Bermudagrass has been
used as a phytoextraction
potential spp. for Cu in
Zaire (Katanga Region)
Shucta et al 2010
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Bermudagrass has also
been used for Arsenic and
Mercury
hyperaccumulation
research. Weaver et al
1984
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Bermudagrass
Phytoremediation
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Bermudagrass
Cynodon dactylon
MORPHOLOGY
•Native to north and east Africa,
Asia,
Australia
and
southern
Europe.
•The name "Bermuda Grass" derives
from its abundance as an invasive
species on Bermuda.
Species
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Bermudagrass
•It has a deep root system; in
drought situations with penetrable
soil, the root system can grow to
over 2 m deep.
•It is fast growing and tough.
•The blades are a grey-green colour
and are short, usually 2–15
centimetres (0.79–5.9 in) long with
rough edges. The erect stems can
grow 1–30 centimetres (0.39–12 in)
tall.
Species
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Goldmine
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Goldmine
Contrasts
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Goldmine
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Contrasts
Goldmine
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Plan
Experimental Plan
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3 replications: 1-3 concentrations of As
(10mg/kg 15mg/kg and 20mg/kg for each sp.
3 replications of arsenic(10/15/20mg/kg plus
20mmol NTA chelating agent for each
replication.
Six controls – We shall use conetainer
containers for the trials
Clippings to mimic herbivory, and conduct
bioassay.
Results will be applied to the field.
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Phytoremediation
Phytoremediation- Best alternative option
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Phytoremediation is the
use of plant based
system to remediate
contaminated soils
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Cheap, affordable and
environmental friendly
In situ application
Laboratory and Field
research work on Arsenic
in Minetailings Smits, Pilon
et al, Moreno-Jimenez J
et al.
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Conclusions
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Companies need to take responsibility for the
repercussions caused by their activities. Prepare risk
assessment plans and contingency measures for cases
such as this one.
Phytoremediation is the best solution for pollution control
in developing countries, considering government
regulations, technology limitations and poverty.
The selected species are great options because of their
fast growth, deep roots, pollutant tolerance and
economic value.
NGOs can be considered as a good option for funding
and managing a project such as this one.
References
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Smedley PL (1996) Arsenic in rural groundwater in Ghana. J Afr Earth Sci 22:459-470
Ma, L.Q.; Tu, M.S.; Fayiga, A.O.; Stamps, R.H.; Zillioux, E.J. (2004) Phytoremediation of ArsenicContaminated Groundwater by the Arsenic Hyperaccumulating Fern Pteris vittata L. Int. J. of
Phytoremediation 6(1): 35-47.
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