Introduction Cadmium (Cd) toxicity is one of the most harmful heavy metal contaminations which could severely affect the environment in a number of ways and in turn affect the living population within that environment. This however can be due to a variety of issues such as environmental disruption or human activity. Cadmium is classed as a Class D heavy metal, meaning, “It does not have a known biological function and can be toxic even when in low amounts”. This very toxic water-soluble heavy metal is a by-product during mining, extraction or removing impurities from ores with Copper, Lead and Zinc. One of the well-known disasters in history is Thailand’s cadmium contamination due to zinc mining by humans.
An increase in industrial, agricultural practices and several anthropogenic activities adds a significant amount of heavy metals in soil and water. Presence of these metals beyond the threshold limit is toxic for the flora and fauna of the surroundings. So, there is a need for removing the harmful heavy metals from the environment. Conventional methods such as precipitation, evaporation, electroplating, ion exchange, membrane processes, etc. have been ineffective because of technical and economic issues.
It can pose a threat to human health and environment due to its hazardous effect.Heavy metals existence in water can damage many of human part even in low concentration. Therefore removing heavy metals in water are very important.The United States Environmental Protection Agency (USEPA) has set up the maximum contamination levels (MCLs) of heavy metals for surface or groundw... ... middle of paper ... ...ructural polysaccharides,amido, amino, sulphydryl carboxyl groups, alcohols and ester.These functional groups substitute hydrogen ions for metal ionsin solution or donation of an electron pair to form complexes with the metal ions in solutions. Due to abundant binding groups, AWBs could be an enormous potential source of adsorbent materials for decontaminating heavy metals from wastewater (T.A.H. Nguyen a, et al,2013). The hydroxyl and carboxyl groups present in these biopolymers are the responsible of Cr(VI) reduction and subsequent Cr(III) adsorption (Marta López-García a, 2013) (Lin andWang, 2012; Wang and Lee, 2011).
As Cd is a toxic metal to humans  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... ... middle of paper ... ...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 . 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.
Through industrial and consumer waste, heavy metals can enter a water supply or even from acidic rain breaking down soils and discharging heavy metals into streams, lakes, waterways, and groundwater. Some overwhelming metals incorporate: • Lead (Pb) • Mercury (Hg) • Chromium (Cr) (in spite of the fact that just the structure Cr(vi) is dangerous) • Zinc (Zn) • Copper (Cu) • Arsenic (As) • Nickel (Ni) • Cadmium (Cd) A few of these components are necessary for human health, and are useful when taken into the form in nourishments or as supplements at suitable, low levels. Alternately, cadmium, lead and mercury have no known living capacity and are lethal to people. Dis... ... middle of paper ... ...(mercurous chloride, Hg2cl2) is utilized as a standard as a part of electrochemical estimations and in medication as a laxative. Mercuric chloride (destructive sublimate, Hgcl2) is utilized as an insect spray, in rodent poison, and as a disinfectant.
Some of the chemicals in the fracking fluid and wastewater have been identified as carcinogens. Many of the other chemicals have been found to be harmful to humans (Environmental). According to Griswold, author of the article “The Fracturing of Pennsylvania,” wastewater is a combination of different chemicals that come from the process of fracking. Not only does this wastewater contain chemicals that were originally used in the drilling, but it also contains harmful substances that come from the earth like salts and other compounds (Griswold). Hundreds of chemicals are used during Marcellus Shale drilling; therefore, the process can cause contamination and pollution.
History and Case Studies of Mining and the Effects on the Environment Mines pose a threat to the environment. They can degrade soil and water quality if left untreated. The United States Environmental protection Agency (USEPA)'s Region 9 assessment of state data states that there are approximately 420,000 abandoned mines in the states of California, Arizona, and Nevada with 13,242 of them being considered "abandoned mines with potential environmental hazard" (arizona.edu, 2008). Left behind are tailings, which are large piles of crushed rock left over when minerals have been extracted from rocks that once contained them. These tailings are then left prone to wind dispersion and water erosion.
Priya Bajwa Mrs. Skelton English 4* March 15, 2014 Hazardous Landfills: A Growing Problem A landfill is a facility of disposal, storage, and treatment for waste products. Landfills can often excrete hazardous toxins, which may put the surrounding environment and people’s health in danger. These waste sites are positioned all across the United States and the world. The dreadful health and environmental effects of hazardous landfills can be deflated by the reduction of exposure to the population and by the selection of appropriate locations. The environment can be threatened by nearby hazardous landfills.
The increase in industrial, agricultural practices and several anthropogenic activities adds a significant amount of heavy metals in soil and water. Presence of these metals beyond threshold limit is toxic for the flora and fauna of the surroundings. So, there is a need for removing the harmful heavy metals from the environment. Several methods such as precipitation, evaporation, electroplating, ion exchange, membrane processes etc. have been developed for the decontamination of heavy metals from environment.
Another problem is the use and disposal of the cyanide solutions which are used to extract and dissolve the gold. Cyanide is a well known poison and is very toxic for humans. Cyanide is also very dangerous to plants and animals as even small amounts of cyanide can be dangerous to them. To produce just one single fine ounce (about 31,104 g) they need about 3.3 tons of ore, 5440 litres of water, 572 kilowatt ... ... middle of paper ... ...nes. The indirect impact of the mining industry has been huge in terms of funding for things like skill development through education and training, there is also provision made for social services in the mines (e.g.