3 About GhanaGhana is Africa's second-largest gold producing country after South AfricaClose to 60 million ounces of gold have been mined in Ghana over the last centuryGold reserves and resources are estimated at well over 100 million ouncesMining industry contributes approximately 40% of Ghana's gross export earnings
5 History of Obuasi(Underock) Gold Mine Obuasi Gold MineHistory of Obuasi(Underock) Gold MineGold mining at Obuasi began in 1898 by private businessmen.Before Ghana was originally called Gold Coast or the Land of GoldGold has been part of the culture and history of the countryGold mining is the largest foreign exchange earner, contributing about 45% of the country’s total foreign currency.
6 Gold ore at site consists of pyrites(FeS) and Arsenopyrites(FeAsS) Obuasi Gold MineCompany has been purchased by Anglogold –a worldwide conglomerate company with over 2 million sharesIt can be considered as the single industrial hub of the Ghanaian economy.Gold ore at site consists of pyrites(FeS) and Arsenopyrites(FeAsS)
7 Basic Information Arsenic 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)
9 ArsenicTrail of destructionDue to roasting of Arsenopyrites and pyrites ores into the atmosphere.Golow, AA et alProcess water from plant discharge into nearby rivers and creeksTailings rich in Arsenic left to be rain washed into pristine areas and rivers
11 ArsenicBoth, the United States Environmental Protection Agency (US-EPA) 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.
12 Risks Associated with Arsenic 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 ChinaMost toxic was the Pompora Treatment –shut down a couple of years ago. Dodoo, DK et al
15 Objectives of the Proposal 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
16 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.
17 Species Selection Species 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 tolerantEasy to propagate- rhizomatousHighly tolerant and phytoaccumulator of Arsenic. Madejon, P. et al, Weaver, R W et al,
18 Vetiver Grass Species 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. 2002It’s leaf is cm long and cm wide- has a smooth and waxy leaf textureFast 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.
19 Vetiver Grass Phytoremediation Roots can grow a total length of 7meters in 36 months after planting. Lavania et al 2003Extensive 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 seedsHas stiff and erect stems up to 2m high Truong, 2002
20 Resistance to Herbicides PhytoremediationResistance to HerbicidesVetiver cells are 170-fold resistant to glugosinate compared to susceptible cellsThe glutamine synthethase activity of resistant cells was twice as high as susceptible cells
21 Physiological Characteristics PhytoremediationPhysiological CharacteristicsAdaptable to extreme environmental conditions. Truong, 1999a.Can tolerate a time of submergence (more than 120 days). Much higher than Bahiagrass days: Carpetgrass days: sour Paspalum days: St. Augustine grass days and Centipede grass- only 7-10 daysIt 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
22 Physiological Characteristics PhytoremediationPhysiological CharacteristicsAdaptable 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 d, and Centipede grass: 7-10 daysIt 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
23 Phytoremediation potential of Bermudagrass Native SpeciesBermudagrass has been used as a phytoextraction potential spp. for Cu in Zaire (Katanga Region) Shucta et al 2010Bermudagrass has also been used for Arsenic and Mercury hyperaccumulation research. Weaver et al 1984
25 Bermudagrass Species 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.
26 SpeciesBermudagrassIt 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.
31 Experimental Plan Plan 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 trialsClippings to mimic herbivory, and conduct bioassay.Results will be applied to the field.
33 Phytoremediation- Best alternative option Phytoremediation is the use of plant based system to remediate contaminated soilsCheap, affordable and environmental friendlyIn situ applicationLaboratory and Field research work on Arsenic in Minetailings Smits, Pilon et al, Moreno-Jimenez J et al.
34 ConclusionsCompanies 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.
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