Abstract
Cadmium (Cd) is known to be toxic to plants and animals and can be transported to both ground and surface water through specific physical mechanisms. The chemical dynamics of Cd and other similar (heavy) metals in the soil environment is controlled by its interactions with both solid and aqueous phases of soil. The concentration of Cd and other metals in soil solution is highly influenced and regulated by processes such as adsorption-desorption, ion exchange, precipitation-dissolution, and soil and solution phase composition. Such processes, in turn, are function of soil properties such as pH, charge density and distribution, thickness of diffuse double layer and the activity of Cd present in solution. This report intends to provide a comprehensive and critical review to the effect of such properties on Cd transport.
1. Introduction
Historically, the discover of Cadmium (Cd) goes back to the eighteenth century (1817) by the German scantiest Friedrich Stromeyer who found it as an impurity in zinc carbonate. In the modern world, Cd is used in many industrial, urban, and agricultural applications ([1], [2]) and is often found together at sites contaminated with heavy metals. As Cd is a toxic metal to humans [3] and animals alike, the environmental and soil contamination with Cd is becoming of great concern in the last few decades. Therefore, it is important for chemists, environmental scientists and engineers to understand the chemistry of Cd interactions in soils to understand its bioavailability.
Millions of tonnes of hazardous waste containing CD are generated in the world on yearly basis. Because of the inefficient waste handling techniques and hazardous waste leakage in the past, thousands of sites, es...
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...in terms of two basic mechanisms: specific adsorption, which is characterized by more selective and less reversible reactions including chemisorbed inner-sphere complexes, and nonspecific adsorption (or ion exchange), which involves rather weak and less selective outer-sphere complexes [14]. It is established that specific adsorption brings about strong and irreversible binding of heavy metal ions with organic matter and variable charge minerals while nonspecific adsorption is an electrostatic phenomenon in which cations from the pore water are exchanged for cations near the surface. Cation exchange is a type of outer-sphere complexation with only weak covalent bonding between metals and charged soil surfaces. The process is naturally reversible and occurs rather quickly as it is typical for reactions which are diffusion-controlled and of electrostatic nature [14].
The copper ions are transferred from the water where they are of a high concentr... ... middle of paper ... ... is likely to be placed and a thorough environmental impact assessment carried out to ensure that the processes do not cause undue environmental damageι. Finally governmental permission must be obtained before commercial activity can take placeι. References α - Article 1 from examination pack: Mining with microbes, John Merson. β - How hydrometallurgy and the SX/EW process made copper the "green" metal, William Dresher. γ - Article 2 from examination pack: Extracting copper from leaching solutions.
Society of Environmental Toxicology and Chemistry. (2013). SETAC/Rachel Carson Award - Society of environmental toxicology and chemistry. Retrieved from Society of Environmental Toxicology and Chemistry: http://www.setac.org/?SETACAwardSRachel
The Hazardous Waste (England and Wales) Regulations 2005 No.894. ENVIRONMENTAL PROTECTION, ENGLAND AND WALES http://www.legislation.gov.uk/uksi/2005/894/contents/made
U.S. Chemical Safety and Hazard Investigation Board. (March 20, 2007). Final Investigation Report. Retrieved July 26, 2010, from U.S. Chemical and Safety Board: http://www.csb.gov/assets/document/CSBFinalReportBP.pdf
Arsenic is the 20th most common element in the earth’s crust and can be found naturally in our environment. There is around 0.006 to 0.03 ppm or arsenic distributed in seawater, and 20 ppm of arsenic in soil (before pesticides). Every human will ingest about 0.5 to 1 mg of arsenic in a day from food and water, because arsenic is present in higher quantities in se...
Arsenic (As) is a lethal metalloid found in rocks, sediments, water, soil and air. It enters into the terrestrial and aquatic ecosystems through a combination of natural processes such as volcanism, process of weathering and biological activity, as well as a result of anthropogenic (Human made) activities. Excessive utilization of As-based pesticides, fertilizers or herbicides, wood preservatives, arsenic additives in domestic animals feeds, pharmaceutical works, electronics industries, ammunition and galvanizing factories, and coal or petroleum incineration (Simith et al., 1998:Matschullat, 2000), and indiscriminate disposal of industrial wastes and domestic (sewage) , as well as mining activities, have resulted in extensive contamination of Arsenic in soil / terrestrial ecosystems attracts worldwide attention principally because of its undesirable impact on human health(Lee et al., 2008; Duker et al., 2005; Liao et al., 2005; Liu et al., 2005; Ongley et al., 2007).
The purpose of this experiment is to become familiar with metal and nonmetal ions and with tests to determine the presence or absence of these important ions as well as to estimate approximate amounts. This experiment is divided into three sections: cations (six tests), anions (four tests), and identification of an unknown salt. For Fe+3 (Iron) test, place about 2 mL of 5% iron(III) chloride (FeCl3) solution in a test tube and add 10% ammonium thiocyanate (NH4SCN) solution until a deep red color appears. Mix the two solutions gently and record the observations on the data sheet. Next is a flame test for Na+1 (Sodium).
China is becoming one of the increasingly crucial environmental concerns of heavy metal contamination on agricultural land. Heavy metal contamination happens when water resources are short and wastewater is then applied to plants causing major health risks to environmental quality and food production. Many scientists have been exploring solutions of this environmental problem and some research say that mycorrhizae have made a positive outcome in fighting the heavy metals and toxins in the soil. Heggo,A. (1990) studied the mechanism of mycorrhizae and heavy metals and resulted that mycorrhizae fungi may filter excessive metals in the soil. Another study showed that mycorrhizae enhanced tolerance of plants infected with toxic soils. Scientists are still studying to find out ways how mycorrhizae fungi improve these plants and resistance from heavy metals. However, metal and toxin uptake might be also impacted from the soils condition. Mycorrhizae symbiosis are well familiar for their enhancement of phosphorus uptake. This nutritional benefit is questioned to account for the plants tolerance of heavy metals and toxins in the soil. The way that heavy metals and toxins affect the ecosystem is the life of organisms such as plants don’t grow in a healthy manner causing toxic plants where animals and humans can
There are many ways to be exposed to dioxins by eating beef, pork, chicken, milk, cheese, shell fish and fish; this is more than 90% of the intake of CDDs for the general population. Also, breathing low levels in the air and drinking water. Skin contact with pesticides and herbicides, living near an uncontrolled hazardous waste site containing CDDs or incinerators releasing CDDs. People working in industries that are producing pesticides, working at paper and pulp mills are being exposed to CDDs. They are produced primarily during the incineration or burning of waste; many materials contain chlorine, plastics, wood treated with (PCP), pesticide-treated wastes and even bleached paper can produce CDDs. CDDs are released during combustion of fossil fuels; coal, oil, natural gas and wood. CDDs have been detec...
When the water comes into contact with the pyrite, the chemical reactions that take place causes the water to increase in pH which will dissolve heavy metals which stay in solution. However, when the pH levels reach a certain stage, the iron can then precipitate out, coating sediments with the characteristic yellow, red or orange colourings (D.E.P. 2, 2002; U.S.G.S.; U.S.E.P.A., 2002). The rate that A.M.D. advances is also influenced by the presence of certain bacteria (Doyle; U.S.G.S). A.M.D that has dissolved heavy metals such as copper, lead and mercury can contaminate ground and surface water. Especially at risk are mines that are located above the water table (Keller, 2000; D.E.P. 2, 2002). The sources of water that get polluted can be surface water that permeates into the mine, shallow ground water flowing through the mine or any water that comes into contact with the waste tailings produced by mines.
Hazardous materials are in almost every community placing everyone at some level of contact with various chemicals almost daily as they exist throughout the community and in our households. Chemicals are used for a variety of purposes such as in the water purification process, by farmers to produce a higher crop yield and are used in households and almost every business. Not all chemicals are hazardous but most pose some level of risk to people...
Zinc is an essential trace element for many living organisms. While this can be said about other essential metals, zinc is unique in its physiochemical properties that give it the ability to interact with donor groups of different ligands, resulting in a broad range of stability constants and diversity of the biological functions and processes that zinc is involved in. It was discovered and recognized as a new metal in the eightieth century, While its biological essentiality was found by Raulin for the growth of Aspergillus niger In 1869 [1]. In 1933 Zinc was found essential for the growth of animals while studying its effect on rats. [2]
Phytoremediation is a novel, efficient, environmentally friendly, low-cost technology, which uses plants and trees to clean up soil and water contaminated with heavy metals and/or organic contaminants such as solvents, crude oil, polyaromatic hydrocarbons and other toxic compounds from contaminated environments. This technology is useful for soil and water remediation.
Soil is a standout amongst the most vital layers of earth which is required for the continuation of life. It is of incredible significance to ranchers who invest the vast majority of their energy planting products and giving nourishment to humanity. One of the real issues undermining this common asset is soil disintegration..
As a result of this process, the mine sites "do not develop normal soil structure or support the establishment of a plant cover". Many mine sites have...