Phytomining, sometimes called agromining, [1] is the concept of extracting heavy metals from the soil using plants. [2] Specifically, phytomining is for the purpose of economic gain. [3] The approach exploits the existence of hyperaccumulators, proteins or compounds secreted by plants to bind certain metal ions. These extracted ores are called bio-ores. [4] The approach has little practical value ("its commercial viability is limited" [1] ) because it is slow and inefficient.
Phytomining was first proposed in 1983 by Rufus Chaney, a USDA agronomist. [5] He and Alan Baker, a University of Melbourne professor, first tested it in 1996. [5] They, as well as Jay Scott Angle and Yin-Ming Li, filed a patent on the process in 1995 which expired in 2015. [6]
Phytomining would in principle cause minimal environmental effects compared to mining. [2] Phytomining could also remove low-grade heavy metals from mine waste. [4]
Ore is natural rock or sediment that contains one or more valuable minerals concentrated above background levels, typically containing metals, that can be mined, treated and sold at a profit. The grade of ore refers to the concentration of the desired material it contains. The value of the metals or minerals a rock contains must be weighed against the cost of extraction to determine whether it is of sufficiently high grade to be worth mining and is therefore considered an ore. A complex ore is one containing more than one valuable mineral.
Open-pit mining, also known as open-cast or open-cut mining and in larger contexts mega-mining, is a surface mining technique that extracts rock or minerals from the earth using a pit, sometimes known as a borrow pit.
Bioremediation broadly refers to any process wherein a biological system, living or dead, is employed for removing environmental pollutants from air, water, soil, flue gasses, industrial effluents etc., in natural or artificial settings. The natural ability of organisms to adsorb, accumulate, and degrade common and emerging pollutants has attracted the use of biological resources in treatment of contaminated environment. In comparison to conventional physicochemical treatment methods bioremediation may offer considerable advantages as it aims to be sustainable, eco-friendly, cheap, and scalable.
Phytoremediation technologies use living plants to clean up soil, air and water contaminated with hazardous contaminants. It is defined as "the use of green plants and the associated microorganisms, along with proper soil amendments and agronomic techniques to either contain, remove or render toxic environmental contaminants harmless". The term is an amalgam of the Greek phyto (plant) and Latin remedium. Although attractive for its cost, phytoremediation has not been demonstrated to redress any significant environmental challenge to the extent that contaminated space has been reclaimed.
A hyperaccumulator is a plant capable of growing in soil or water with high concentrations of metals, absorbing these metals through their roots, and concentrating extremely high levels of metals in their tissues. The metals are concentrated at levels that are toxic to closely related species not adapted to growing on the metalliferous soils. Compared to non-hyperaccumulating species, hyperaccumulator roots extract the metal from the soil at a higher rate, transfer it more quickly to their shoots, and store large amounts in leaves and roots. The ability to hyperaccumulate toxic metals compared to related species has been shown to be due to differential gene expression and regulation of the same genes in both plants.
Soil contamination, soil pollution, or land pollution as a part of land degradation is caused by the presence of xenobiotic (human-made) chemicals or other alteration in the natural soil environment. It is typically caused by industrial activity, agricultural chemicals or improper disposal of waste. The most common chemicals involved are petroleum hydrocarbons, polynuclear aromatic hydrocarbons, solvents, pesticides, lead, and other heavy metals. Contamination is correlated with the degree of industrialization and intensity of chemical substance. The concern over soil contamination stems primarily from health risks, from direct contact with the contaminated soil, vapour from the contaminants, or from secondary contamination of water supplies within and underlying the soil. Mapping of contaminated soil sites and the resulting clean ups are time-consuming and expensive tasks, and require expertise in geology, hydrology, chemistry, computer modelling, and GIS in Environmental Contamination, as well as an appreciation of the history of industrial chemistry.
Geobotanical prospecting refers to prospecting based on the composition and health of surrounding botanical life to identify potential resource deposits. Using a variety of techniques, including indicator plant identification, remote sensing and determining the physical and chemical condition of the botanical life in the area, geobotanical prospecting can be used to discover different minerals. This process has clear advantages and benefits, such as being relatively non-invasive and cost efficient. However, the efficacy of this method is not without question. There is evidence that this form of prospecting is a valid scientific method, especially when used in conjunction with other prospecting methods. But as identification of commercial mines are invariably guided by geological principles and confirmed by chemical assays, it is unclear as to whether this prospecting method is a valid standalone scientific method or an outdated method of the past.
This list covers hyperaccumulators, plant species which accumulate, or are tolerant of radionuclides, hydrocarbons and organic solvents, and inorganic solvents.
Evaporation ponds are artificial ponds with very large surface areas that are designed to efficiently evaporate water by sunlight and expose water to the ambient temperatures. Evaporation ponds are inexpensive to design making it ideal for multiple purposes such as wastewater treatment processes, storage, and extraction of minerals. Evaporation ponds differ in usage and result in a wide range of environmental and health effects.
Biomining refers to any process that uses living organisms to extract metals from ores and other solid materials. Typically these processes involve prokaryotes, however fungi and plants may also be used. Biomining is one of several applications within biohydrometallurgy with applications in ore refinement, precious metal recovery, and bioremediation. The largest application currently being used is the treatment of mining waste containing iron, copper, zinc, and gold allowing for salvation of any discarded minerals. It may also be useful in maximizing the yields of increasingly low grade ore deposits. Biomining has been proposed as a relatively environmentally friendly alternative and/or supplementation to traditional mining. Current methods of biomining are modified leach mining processes. These aptly named bioleaching processes most commonly includes the inoculation of extracted rock with bacteria and acidic solution, with the leachate salvaged and processed for the metals of value. Biomining has many applications outside of metal recovery, most notably is bioremediation which has already been used to clean up coastlines after oil spills. There are also many promising future applications, like space biomining, fungal bioleaching and biomining with hybrid biomaterials.
Bioretention is the process in which contaminants and sedimentation are removed from stormwater runoff. The main objective of the bioretention cell is to attenuate peak runoff as well as to remove stormwater runoff pollutants.
Leaching is the process of a solute becoming detached or extracted from its carrier substance by way of a solvent.
Environmental effects of mining can occur at local, regional, and global scales through direct and indirect mining practices. Mining can cause erosion, sinkholes, loss of biodiversity, or the contamination of soil, groundwater, and surface water by chemicals emitted from mining processes. These processes also affect the atmosphere through carbon emissions which contributes to climate change. Some mining methods may have such significant environmental and public health effects that mining companies in some countries are required to follow strict environmental and rehabilitation codes to ensure that the mined area returns to its original state. Mining can provide various advantages to societies, yet it can also spark conflicts, particularly regarding land use both above and below the surface.
Zinc mining is the process by which mineral forms of the metal zinc are extracted from the earth through mining. A zinc mine is a mine that produces zinc minerals in ore as its primary product. Common co-products in zinc ores include minerals of lead and silver. Other mines may produce zinc minerals as a by-product of the production of ores containing more valuable minerals or metals, such as gold, silver or copper. Mined ore is processed, usually on site, to produce one or more metal-rich concentrates, then transported to a zinc smelter for production of zinc metal.
Reuse of human excreta is the safe, beneficial use of treated human excreta after applying suitable treatment steps and risk management approaches that are customized for the intended reuse application. Beneficial uses of the treated excreta may focus on using the plant-available nutrients that are contained in the treated excreta. They may also make use of the organic matter and energy contained in the excreta. To a lesser extent, reuse of the excreta's water content might also take place, although this is better known as water reclamation from municipal wastewater. The intended reuse applications for the nutrient content may include: soil conditioner or fertilizer in agriculture or horticultural activities. Other reuse applications, which focus more on the organic matter content of the excreta, include use as a fuel source or as an energy source in the form of biogas.
Pycnandra acuminata is a species of plant in the family of Sapotaceae. It is a rainforest shrub, endemic to New Caledonia, and is adapted to the nickel-rich ultramafic soils found there. Pycnandra acuminata is notable as one of the most prolific hyperaccumulators of trace metals known, actively absorbing nickel from the soil and concentrating it within the plant to a concentration of up to 25% nickel citrate as dry weight of the sap, which is turquoise-green in colour due to the nickel content. the only known plant with turquoise sap. An excellent photo can be seen at. The vernacular name in French is sève bleue.
Bioremediation of petroleum contaminated environments is a process in which the biological pathways within microorganisms or plants are used to degrade or sequester toxic hydrocarbons, heavy metals, and other volatile organic compounds found within fossil fuels. Oil spills happen frequently at varying degrees along with all aspects of the petroleum supply chain, presenting a complex array of issues for both environmental and public health. While traditional cleanup methods such as chemical or manual containment and removal often result in rapid results, bioremediation is less labor-intensive, expensive, and averts chemical or mechanical damage. The efficiency and effectiveness of bioremediation efforts are based on maintaining ideal conditions, such as pH, RED-OX potential, temperature, moisture, oxygen abundance, nutrient availability, soil composition, and pollutant structure, for the desired organism or biological pathway to facilitate reactions. Three main types of bioremediation used for petroleum spills include microbial remediation, phytoremediation, and mycoremediation. Bioremediation has been implemented in various notable oil spills including the 1989 Exxon Valdez incident where the application of fertilizer on affected shoreline increased rates of biodegradation.
Mycorrhizal amelioration of heavy metals or pollutants is a process by which mycorrhizal fungi in a mutualistic relationship with plants can sequester toxic compounds from the environment, as a form of bioremediation.
Legacy pollution or legacy pollutants are persistent materials in the environment that were created through a polluting industry or process that have polluting effects after the process has finished. Frequently these include persistent organic pollutants, heavy metals or other chemicals residual in the environment long after the industrial or extraction processes that produced them. Often these are chemicals produced by industry and polluted before there was widespread awareness of the toxic effects of the pollutants, and subsequently regulated or banned. Notable legacy pollutants include mercury, PCBs, Dioxins and other chemicals that are widespread health and environmental effects. Sites for legacy pollutants include mining sites, industrial parks, waterways contaminated by industry, and other dump sites.
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