Greening the Mines: Can Bamboo Help Rehabilitate Mining Sites?
Mining is a significant industry, but the harsh and destructive processes generally have negative impacts on the environment and local communities. Many mining sites pollute waterways, damage ecosystems, and even cause health problems for people living nearby. Some mining companies are rehabilitating closed mines and in Australia there is a requirement to contribute into a pool of money to rehabilitate future abandoned sites.
While this provides hope for rehabilitation, with the cost of rehabilitation vastly underestimated, in many cases, is it enough? How do you prevent erosion and stabilise slopes, provide shade and help to retain moisture in the soil and provide food and shelter for wildlife and an income for locals? In this blog post, we will discuss some of the environmental impacts of mining and how bamboo can be used to counter these negative effects.
The environmental impact of mining
The environmental impacts of mining can have long-term effects on the biodiversity and health of ecosystems, destroying natural habitats and displacing wildlife.
“Between 1972 and 1989, the Panguna mine, developed and majority-owned by Anglo-Australian mining giant Rio Tinto, was one of the world’s largest copper and gold mines. During this period, the company’s subsidiary, Bougainville Copper Limited (BCL) discharged over a billion tonnes of mine waste into local river systems, devastating the environment and the health and livelihoods of local communities” (Report by The Human Rights Law Centre).
Half the mountainside was obliterated during blasting to develop the pit and around 220 hectares of surrounding tropical rainforest was poisoned with Agent Orange and then burnt, with around 18 million cubic metres of waste washed into the Kawerong River. The waste rock and tailings from the mining operation choked the river system and altered the natural flow, with tailing overflow killing agricultural land and rainforest on either side of the river. Chemical pollution (copper, zinc, cadmium and mercury) wiped out the fish populations in rivers and tributaries destroying traditional sources of water, food and building supplies and local landowning clans were displaced by outside workers.
The Omai Gold Mine is a former open-pit gold mine located in Guyana. It was one of the largest gold mines in South America and was operated by Cambior, a Canadian mining company, from 1993 until 2005.
The mine was controversial as it was located in an area of high biodiversity, taking in the country’s largest river, the Essequibo, and the Omai Reservoir – an important source of water for the local population.
In 1995, a tailings dam at the mine failed, releasing approximately four billion litres of cyanide and heavy metal laden tailings into the Essequibo River and nearby creeks, causing significant environmental damage and affecting the livelihoods of thousands of people living between Omai and the Atlantic Ocean.
After the mine closed in 2005, the company was responsible for cleaning up the site and restoring the affected areas. However, the government of Guyana and local communities have reported that much of the environmental damage caused by the mine has not been fully addressed and that the clean-up efforts have been inadequate.
Dust and emissions
Dust and emissions from mining operations can also have a significant negative impact air quality and harm human health. Mining can lead to soil erosion, compaction and nutrient depletion making it difficult for plants and animals to survive in the area.
In 1883 Charles Rasp, a boundary rider, identified a significant ore body laden with silver, lead and zinc. Broken Hill became the birthplace of some of the world’s largest mining conglomerates, including Broken Hill Proprietary Limited (later BHP) in 1885 and Zinc Corporate Limited (later Rio Tinto Group) in 1905. A rapid influx of prospectors and subsequent mining operations drastically altered the natural contours and fluvial processes; hard-hooved animals such as sheep, goats and cattle decimated the soil structure while rabbits stipped the earth bare and ate the seeds and seedlings that would have allowed revegetation in this semi-arid region. What was once a mosaic of trees, shrubs and groundcovers adapted to the nutrient poor and often dry conditions was devastated as timber was cleared for use by the mines, pumping station and local shopkeepers.
Lead and zinc is mined through underground mining methods, and the mineral is then processed at on-site smelters. Along with lead and zinc, small amounts of silver, copper, and other minerals have also been mined in the area. The mining and smelting process releases pollutants into the air, which can cause respiratory problems and damage vegetation and wildlife.
Acid Mine Drainage is a common environmental problem associated with mining and the most widespread and persistent form of water pollution. When sulfur-bearing minerals are exposed to water and air, they undergo a chemical reaction that produces sulfuric acid. As it leaches through the mine waste, the acid liberates various metals from the rock, for example arsenic, cadmium, mercury, lead and zinc. These are highly toxic, with arsenic causing skin cancer and tumours, cadmium liver disease, mercury nerve damage and growth retardation in children. The acids and toxic metals can leach out of the mine waste and contaminate nearby water sources, killing virtually all aquatic life and badly degrading downstream environments.
In Broken Hill, the mining of lead and zinc has led to the generation of large amounts of waste rock and tailings that contain sulfur-bearing minerals.
Coal mining in Australia is a major industry, with the country being one of the world’s largest exporters of coal. The majority of coal mined in Australia is used for power generation and steel production.
The main coal-producing states in Australia are Queensland and New South Wales, where the majority of the coal mines are located. The Bowen Basin, located in Central Queensland, is one of the largest coal-producing regions in Australia, with mines that extract both thermal and coking coal. New South Wales’s Hunter Valley is another major coal-producing region, known for its high-quality thermal coal.
Coal mining can have a range of negative environmental impacts, including those associated with the storage and management of coal mine tailings and coal stockpiles. While tailings are often contained in dams and treated to remove pollutants, stockpiles are subject to wind and rain erosion. The protection and coverage of stockpiles can be limited owing to extreme heights and structure of stockpiles which creates problems with efficacy of dust control. Dislodgement of fines as a result of wind can transport dust particles long distances, triggering health and environmental hazards for communities within the vicinity of the source.
The aftermath of large-scale mining operation is generally a landscape of devastation: thousands of hectares of poisoned, rubble strewn land drained by acidified streams that will likely remain too polluted to support their full complement of life for thousands of years to come.
In many developing countries the companies that have enriched themselves through this destruction are under no binding obligation to attempt to mitigate it. While wealthier countries attempt to avoid being liable for the eventual clean-up by ensuring the mining companies set aside a certain amount of money up front to cover expenses necessary to meet environmental standards – money for water treatment, tailings pond lines etc – thus far the closing of operations has been underestimated by over $12 billion dollars, according to a 2003 estimate.
In 1992 the Canadian owner of the Summitville gold min in Colorado, Galactic Resources, declared bankruptcy and walked away, sticking the US taxpayer with a $200 million reclamation bill. The 3,300 hectare mine had been leaking cyanide into the Alamosa River since its first week of operation and had destroyed 25 km of river, having mined $130 million worth of metals.
In January 2000, at the Baia Mare mine in Romania, a tailings dam failed, releasing more than 100,000 tons of wastewater laden with cyanide and heavy metals into the Tisza River, making its way into the Danube, killing 1,240 tons of fish and contaminating the drinking water of 2.5 million people. Esmeralda Exploratio, the Australian company holding a principal interest, went into a form of bankruptcy to protect its shareholders – but the citizens of the countries affected received no such protection.
Rehabilitation and how bamboo can play a part
There are a variety of stakeholders who are pushing for the rehabilitation of closed mines, including:
- Many environmental organizations, such as Greenpeace, the Sierra Club, and the World Wildlife Fund, are concerned about the environmental and social impacts of mining activities and are pushing for the rehabilitation of closed mines as a way to mitigate these impacts.
- Local communities and indigenous groups who live near closed mines are often directly affected by the environmental and social impacts of mining activities and are pushing for the rehabilitation of closed mines as a way to protect their health and well-being, and to restore the land and resources on which they depend.
- Governments have a responsibility to protect the health and well-being of their citizens, and many governments are pushing for the rehabilitation of closed mines as a way to mitigate the environmental and social impacts of mining activities and to ensure that mining companies are held accountable for the environmental and social impacts of their operations.
- Organizations such as the United Nations, the World Bank, and the International Council on Mining and Metals (ICMM) are also pushing for the rehabilitation of closed mines as a way to promote sustainable development and to ensure that mining activities are conducted in a responsible and accountable manner.
Bamboo can help with a variety of rehabilitation activities
Stabilizing, restoring and improving soil quality
Bamboo’s strong root structure and fast growth rate can help to stabilize slopes on mine sites, preventing erosion and landslides.
Bamboo is a subfamily of grasses that can grow exponentially on degraded land, be managed without pesticides or fertiliser and sequester significant amounts of carbon over short periods of time.
The qualities of bamboo that incite opposition are its rapid growth and dense root matrix, yet these are exactly those characteristics that are essential for effective soil protection and conditioning. A rapid accumulation of biomass, evergreen canopy, ample ground litter, vigorous surface root extension and general hardiness are mandatory for successful regeneration.
In Yunnan and Fujian provinces of south east China, capital intensive, professionally engineered river bank protection schemes proved less successful during a period of extreme weather conditions than did adjacent natural bamboo groves prompting authorities there to speed up and extend their re-afforestation programs in water catchment and river systems. Similar experience in Japan has shown that even heavy flooding and the damage caused by floating debris will not deter the rapid regrowth of bamboo. Indeed, flood damaged areas responded with an above average growth in the following two seasons.
Phytoremediation is a low cost technique with minimal environmental side effects which utilises plants to remove heavy metals from the environment to render them harmless. Copper and other heavy metals are highly toxic for normal plants, however bamboo has been confirmed to have a high tolerance to heavy metal concentration in hydroponics. Species with quick growth and high biomass production have a strong ability to adapt to different environments. Open clumping bamboo species have been recognised as a potential phytoremediation material for heavy metal contaminated soils.
According to research funded by the European Commission, bamboo is effective in phytoremediating water. Phytoremediation processes use natural materials to eat up pollutants, making them distinct from processes that capture contaminants and dispose of them elsewhere. Bamboo has a high water and nutrient usage and seesthe effluent as liquid fertiliser, producing a fantastic growth rate. As water passes through the plants, the bamboo roots act as a filter, drawing out toxins and impurities, thereby cleaning the water.
Bamboo could be regarded as an ideal plant for phytoremediation as it possesses an extensive root system and maximum production of biomass in the presence of a high concentration of heavy materials. Additionally, the application of bamboo biochar in mine-polluted soil has the potential to reduce the toxicity of heavy metals in the soil and enhance the growth of vegetation.
Bamboo can also help to restore ecosystems on mine sites by providing food and shelter for a wide range of wildlife such as birds, mammals, insects and reptiles. This can help to create a diverse and thriving ecosystem on denuded mine sites.
Bamboo sequsters carbon by absorbing carbon dioxide from the atmosphere and storing it in its biomass, such as leaves, stems and roots. Bamboo is know to have a high rate of photosynthesis, which locks away carbon in the plant and doesn’t release it back into the atmosphere, thus sequestering carbon and improving the quality of the air.
Bamboo’s large leaves can help to retain soil moisture by providing shade and reducing evaporation. When the leaves of bamboo plants are fully expanded, they can cover up to 90% of the ground surface, which helps to reduce the amount of sunlight that reaches the soil surface. This can help to reduce evaporation, meaning that more water is available to be taken up by the roots of the plant and other plants nearby.
The leaves are also known for their waxy surface, which can help to reduce water loss through transpiration, meaning more water is retained in the soil. When they fall to the ground the litter helps to improve the overall health of the soil by providing organic matter, making the soil more porous and better able to retain moisture.
Dust and Emissions
At the coal loading facility near Blackwater and Acland mines in Queensland, bamboo has been planted specifically for the purpose of dust mitigation. Yarrabee Coal’s environmental co-ordinator, Julian Power, approached Durnford Dart (partner in The Bamboo Choice) to evaluate the practicality of utilising bamboo to minimise coal dust drift from the Boonal coal loading facility located adjacent to the Capricorn Highway near Blackwater.
Bamboo was planted and reached high density within three years. It not only minimises dust drift but:
- filters debris;
- provides visual amenity;
- provides livestock fodder and mulch
- receives carbon credits
Bamboo can also be harvested and used for construction, paper production, and other commercial purposes, which can help to create economic opportunities for local communities.
Bamboo is the fastest growing land plant in the world and is a viable replacement for wood. It can be harvested in 3-5 years, out yields pine 6 to 1 in biomass production, and there is a growing movement worldwide for organic and engineered bamboo products.
Bamboo can contribute to household income and rural livelihoods, through carefully managed propagation and forestry techniques. Young shoots are a source of food, while more mature plants can be utilised as fiber for clothing, in concrete reinforcement, to provide livestock feed or machined into numerous forms of lumber. It is also a clean source of charcoal for cooking stoves and due to its lightweight helps women participate in the village economy giving them access to a potentially lucrative source of income.
So why should we be using bamboo to regenerate mining sites?
Bamboo is a highly sustainable crop that is well-suited for regenerating mining sites because it is a fast-growing, hardy plant that can tolerate a wide range of environmental conditions. Bamboo can quickly establish itself on a mining site, providing a form of erosion control and helping to stabilize the soil. Bamboo can be used for a variety of purposes, including construction, paper production, and biofuel production, providing multiple benefits to the local economy. Bamboo can also act as a carbon sink and provide habitat for wildlife, helping to mitigate the impacts of mining activities on the environment. Additionally, bamboo can help in reforestation and soil conservation, improve water quality and increase the local water table, and be used for phytoremediation. It can be harvested after a relatively short period of time, allowing for multiple rotations of crops on the same land, and providing a consistent source of income for local communities.
The advantage of bamboo is that it does not spread by uncontrollable seed dispersal, it cannot invade or block water channels and is not poisonous to either native or domestic animals. Moreover, mature stands can be successfully and regularly cropped for economically valuable timber and for edible vegetable shoots without the slightest interruption of the solid binding role.
Bamboo is a hardy and resilient plant that requires minimal maintenance once established and there are native species on every continuent in the world. It can be used in a variety of different mine regeneration projects, from slope stabilisation to erosion control and phytoremediation and can be grown in monoculture or mixed with other plants, depending on the specific needs of the site and the local ecosystem.
It is crucial that greening of existing mines and rehabilitation of closed mines is done in a way that benefits local communities and the environment. Not only does the landscape and habitat need to be considered but also the needs and aspirations of local communities.
We already have a success story here in Australia which demonstrates its potential as a cost-effective and sustainable solution for mine site greening. As the global demand for sustainable mining practices increases, bamboo should become an increasingly popular choice for mine operators looking to rehabilitate and restore mined areas.