Gold has become one of the most studied nanomaterials due its rarity and unique properties in the development of electronics. For instance, the COVID-19 antigen and antibody tests, which are among the millions of fast medical diagnostic test kits made each year, use gold nanoparticles[1]. As the demand for electronic devices such as phones -which had over 6.648 billion users as of June 2022 [2] - grows, it necessitates the bulk provision of this essential raw material.
Although gold is obtained through different types of mining, the mining process itself commences after a series of multifaceted stages. For example, before any gold can be extracted, some exploratory activities are first designed to discover new gold deposits that will ultimately lead to the development of new mines[3].
However, despite the advancements made by utilizing geochemical and geophysical methods, finding new Au resources is technically difficult in recent years. The primary reason is that deposits that have clear geophysical and geochemical fingerprints have already been found [4]. Other approaches such as seismic refraction, borehole geophysics and magnet-related techniques are not practical for artisanal miners in Ghana owing to their expensive nature.
One of the top two producers of gold in Africa is Ghana[5]. However, the fact that artisanal and small-scale miners produce more than 35% of Ghana's total gold output has received little attention. An estimated 4.5 million Ghanaians, or around 12% of the population, depend on artisanal and small-scale mining for their livelihood [6]. They make up more than 60% of the workforce employed in the nation's mining industry [7]. Artisanal and small-scale mining is often low-tech, indigenous and often informal. Over 80 mineral-rich developing countries experience this type of mining and up to 100 million people globally work in the sector [8].
Prospecting is the process of exploring areas of lands for selected mineral elements. For gold. approaches to prospecting have been well-researched and documented by a previous iGEM team from the University of Toronto[9]. That said, based on our interviews with governmental mining agencies, we highlight the most predominant ones in the Ghanaian context below:
This is analogous to seismic reflection in that energy is produced by an acoustic source. Seismic refraction requires technology to measure the change in direction of the energy as it flows between media, which distinguishes it from the other two methods. Prior to the energy returning to the surface, where additional detectors are positioned, times of arrival are recorded as it is refracted along a second layer boundary. The new angle and time are then recorded. The subsurface strata are once again mapped using this data.
In this method, samples are taken from streams or soils near potential deposits with a proven success record. These samples are then brought to labs for analysis using various chemical techniques. Normally, this method is used in combination with Geophysical Survey methods including - but not limited to- Induced Polarization Survey, Magnetics, and Gravity Survey. Further prospecting involves pitting and trenching.
Geophysics of a borehole entails recording formations, depths, and events while a hole is being drilled. While drilling is taking place, multiple instruments are dropped into the well to record different variables vs depth. It might be anything from radioactivity to porosity or even resistance. Well logging is therefore a very adaptable tool that may be utilized for various geological investigation techniques.
Naturally, Ghanaian artisanal small-scale miners, who usually live below the poverty line and resort to a USD 10 daily wage from mining as a means of sustenance [10], cannot afford these resource-intensive methods and therefore rely on a trial and error approach. Thus, they usually employ surface mining techniques using rudimentary practices. These pollute water bodies, create several open trenches that breed diseases such as malaria and also affect the general health of miners through direct exposure to toxic pollutants
In other words, even though Ghana's mining sector contributes significantly to the country, several government agencies and demonstrators, including national and international environmentalists and agriculturalists, have advocated for a ban on unlawful mining. Other specific concerns include the loss of biodiversity, chemical contamination, inadequate safety design of mines, air and water pollution, land degradation, and child labor. We highlight some of the important implications below:
In their study, Ahern and Stephens claim that mining is still one of the riskiest jobs in the world, both in terms of immediate danger and fatalities as well as long-term effects like cancer and respiratory diseases including silicosis, asbestosis, and pneumoconiosis [11]. Skin diseases have been reported in some mining communities[12]. As a matter of fact, according to medical experts, the surge in kidney disease in the country can be attributed, in part, to the mass usage of mercury by miners. Artisanal small-scale miners are also at a perpetual risk of experiencing some fatal misfortune. A typical example is a mining pit that caved in close to the Offin River, taking the lives of over 100 miners in Dunkwa-on-Offin, in the central region of Ghana [13].
Acid mine drainage, heavy metal contamination and leaching, processing chemical pollution, erosion and sedimentation are the four basic ways that mining affects water quality [14]. The major streams and rivers (Kwabrafo, Pompo, Nyam, Jimi, Akapori, Wheaseammo, and Kunka) have all been contaminated by mining and other human activities, according to the Obuasi city development report [15]. In addition most streams, rivers and other water bodies are either polluted with chemicals or dried up.
Land degradation has been identified as a major effect of surface mining, which is one primary method adopted by artisanal miners. First, the removal of topsoil, trees, and vegetation with heavy machinery depletes the land of nutrients, rendering it infertile and unproductive for agricultural purposes[16].There are areas in Ghana where the presence of rocks and other debris from mining activities have hampered plant growth and made farming activities impossible[17].
The use of mercury and cyanide in artisanal small-scale mining activities contaminates water bodies and destroys the quality of drinking water in communities and aquatic life.
The heavy use of water in washing ore pollutes water bodies and makes them unsafe for consumption.
Artisanal small-scale miners work in conditions and engage in activities that lead to unsafe open trenches.These trenches have been shown to correlate with malaria incidents in the country. This endangers the communities.
Artisanal small-scale mining exposes Ghanaians to several harmful chemicals through drinking from polluted water bodies and inhaling gaseous mercury, which damages the central nervous system
Workers in the ASM sector are at a standstill due to the danger from hazardous chemicals and the obvious physical job hazard linked with mining. However, to the 4.5 million locals, mining is a lucrative venture that secures their escape from unemployment and poverty. Thus, their livelihoods as artisanal miners are often chosen over their well-being. This is true as the impression of safety, which is defined as may be skewed if their livelihood depends on it. Despite the risks involved in gold mining being clear, miners nonetheless put themselves in perilous positions. The theory of cognitive dissonance, which describes the tension one has when their action conflicts with their views and beliefs, may help to explain this. Risks may be exaggerated and consequently viewed as less damaging as a means of accepting the decisions one makes. Reduced apparent danger takes away the motivation to stop engaging in these unhealthy behaviors, forcing miners to put their health at risk to support their livelihood.
Leveraging the insights above, we quickly realize that mining, whether small-scale, large-scale, regulated or unregulated is not going anytime soon. However, while it persists, artisanal small-scale miners who resort to mining as the only means to survival will employ damaging and rudimentary techniques that impact both them and their environments. As such, we sought to develop a biological exploratory approach with locals in mind. This is meant to be cheap and expedient. In a matter of days, one can tell the likelihood of discovering a gold deposit in an area. We are doing so by engineering several E. coli cultures that either detect the presence of gold or some of the selected pathfinder elements (Arsenic and Iron). These bacteria will be co-cultured to create a multifunctional biosensor which produces an indicator color spectrum. In addition, since these bacteria can be safely removed from the environment, it eliminates the problem of environmental destruction due to the unsuccessful selection of mining areas.
Ghana was formerly known as the Gold Coast because of its large supply of gold. Today, Ghana is the leading producer of gold in Africa and the sixth leading producer globally[4]. Sadly, extensive environmental damage results from the gold exploration phase. In the long run, the negative impact outweighs the benefits. The team’s passion for sustainable development in Ghana and beyond drove us to tackle this problem. Our biosensor as a gold exploration tool will serve three main stakeholders in this space: the local mining communities, large-scale miners, and artisanal miners. We project a cut on resource wastage: time and capital, boost the income of local miners and reduce damage to the environment.
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