Complete the following with concise answers:
Volatility:
Mercury poisoning can result from vapor inhalation, ingestion,
injection, or absorption through the skin. Elemental mercury (Hg0)
is found as a liquid with a vapor pressure of 0.00185 mm at 25°C.
This means that ele- mental mercury is extremely volatile.
Hydrocyanic acid, also known as hydrogen cyanide, or HCN, is a highly volatile liquid that is produced on a large scale industrially. ... For example, in acetonitrile, the cyanide group is bonded to methyl (CH3). Because they do not release cyanide ions, nitriles are generally far less toxic than cyanide salts.
Persistency:
This chemical is persistent and in the environment can change into
methylmercury, its most toxic form. Mercury mining is one of the
major anthropogenic sources of mercury released into the
environment, especially in rivers. ... these organisms can reach up
to 8.8% of the total mercury content.
Cyanide (as HCN or CN−, represented inclusively as CN) is a rapidly acting, toxic chemical that can be readily absorbed by inhalation, ingestion or dermally. After CN is absorbed, it is rapidly distributed throughout the body, causing toxic effects by mechanisms that include inhibiting cytochrome c oxidase, resulting in cellular hypoxia and cytotoxic anoxia, and can eventually result in death.
Environmental fate:
A very important factor in the impacts of mercury to the
environment is its ability to build up in organisms and up along
the food chain. Inorganic mercury can also be absorbed, but is
generally taken up at a slower rate and with lower efficiency than
is methylmercury.
Cyanide toxicity and their environmental impact are well known. Nevertheless, they are still used in the mining, galvanic and chemical industries. As a result of industrial activities, cyanides are released in various forms to all elements of the environment. In a natural environment, cyanide exists as cyanogenic glycosides in plants seeds. Too much consumption can cause unpleasant side effects. However, environmental tobacco smoke (ETS) is the most common source of cyanide. Live organisms have the ability to convert cyanide into less toxic compounds excreted with physiological fluids. The aim of this paper is to review the current state of knowledge on the behaviour of cyanide in the environment and its impact on the health and human life.
Transportation:
Mercury is introduced into the environment in three ways. First,
mercury is
emitted into the atmosphere naturally from volcanoes, the
weathering of rocks, forest fires, and soils. Second, mercury is
emitted as a result of human activities such as the burning of
fossil fuels and municipal or medical waste. Lastly, mercury can be
re-introduced into the environment through natural processes such
as evaporation of ocean water.
Once it is released into the atmosphere, mercury is transported and
deposited on the earth's surface by rain and snowstorms, as well as
wind storms and forest fires. The transport and deposition of
mercury is dependent upon many variables such as meteorological
conditions,
other chemical pollutants emitted along with mercury, and the
chemical make-up of the air mass. Deposition can occur in as little
as five to fourteen days after mercury is emitted to the air, or it
can take approximately one year during which time mercury can
reside in the air and be transported far around the globe.
The Cyanide Code focuses exclusively on the safe management of cyanide that is produced, transported and used for the recovery of gold and silver, and on mill tailings and leach solutions. The Cyanide Code addresses production, transport, storage, and use of cyanide and the decommissioning of cyanide facilities.
Complete the following with concise answers: Mercury and cyanide are two chemicals used in the extraction...