Mercury is a chemical element with symbol Hg and its atomic number 80. Mercury is also known as quicksilver or hydrargyrum. it is a heavy , silvery transition mental that exist as a liquid at or near room temperature and pressure. Before mercury is extracted is exist as cinnabar, cinnabar is actually the ore for mercury.
Mercury are actually separated into 3 different form. Firstly is element mercury; secondly is an organic mercury compound which is also known as organomercurials. It is actually mercury forming covalent bonds between carbon and mercury. For example are methylmercury and dimethylmercury. Thirdly is inorganic mercury, it is formed when element mercury combines with any elements other than carbon. For example mercury II sulphide, mercury II oxide and mercury II chloride.
Mercury is used in medical and scientific products like thermometers, barometers and manometers. It is also used in scientific research application and for dental restoration. Mercury is also used in lighting, when electricity passed through the mercury vapor in the phosphortube, it produce short-wave of uv light which is then causes the phosphor to fluoresce, making visible light. Mercury is also used for treatment in the past; it is used to treat syphilis, which is the most deadly disease in the 15 century. At that time antibiotics was not invented, so mercury was use to cure syphilis.
Mercury is a naturally occurring element that is found in air, water and soil. It exists in several forms: elemental or metallic mercury, inorganic mercury compounds, and organic mercury compounds.
Elemental or metallic mercury is a shiny, silver-white metal and is liquid at room temperature. It is used in thermometers, fluorescent light bulbs and some electrical switches. At room temperature, exposed elemental mercury can evaporate to become an invisible, odourless toxic vapour. People can be exposed to elemental mercury vapour when products that contain mercury break and expose mercury to the air, particularly in poorly-ventilated spaces.
Inorganic mercury compounds take the form of mercury salts and are generally white powder or crystals, with the exception of mercuric sulfide (cinnabar) which is red. Inorganic mercury compounds have been included in products such as fungicides, antiseptics or disinfectants. Some skin lightening and freckle creams, as well as some traditional medicines, can contain mercury compounds.
Organic mercury compounds, such as methylmercury, are formed when mercury combines with carbon. Microscopic organisms convert inorganic mercury into methylmercury, which is the most common organic mercury compound found in the environment. Methylmercury accumulates up the food chain.
The most common forms of mercury that occur naturally in the environment are metallic mercury; the inorganic salts, mercuric sulfide and mercuric chloride; and methylmercury. Microorganisms and various natural processes can change these forms of mercury, from one form to the other. Methylmercury is the most common form created by these natural processes. This compound is of particular concern because it can bioaccumulate through the food chain. That is, small organisms and plants take up methylmercury as they feed, animals higher up the food chain eat these plants and organisms, and the process continues with methylmercury levels increasing up the food chain. Of particular concern is seafood, such as fish and shellfish which had bioaccumulated mercury. This is so as there may be harmful effects on humans when they consume seafood containing mercury.
Mercury in the environment is formed by either natural or anthropogenic processes. Natural mercury arises from the degassing of the earth’s crust via volcanic emissions or by evaporation from oceans. Anthropogenic causes are combustion of fossil fuels (specially coal), gold and mercury mining, chlorine,caustic soda, mirrors and medical equipment, industrial leaks, dentistry, waste and corpse incineration.
Mercury in the air eventually settles into water or onto land where it can be washed into water. Once deposited, certain microorganisms can change it into methylmercury, a highly toxic form that builds up in fish, shellfish and animals that eat fish. Fish and shellfish are the main sources of methylmercury exposure to humans. Methylmercury builds up more in some types of fish and shellfish than others. The levels of methylmercury in fish and shellfish depend on what they eat, how long they live and how high they are in the food chain. Another less common exposure to mercury that can be a concern is breathing mercury vapour. These exposures can occur when elemental mercury or products that contain elemental mercury break and release mercury to the air, particularly in warm or poorly-ventilated indoor spaces.
Mercury poisoning is actually a term which is describe after the person had been expose to mercury. Mercury can exist in several forms, and all forms are poisonous. Mercury poisoning can result in several diseases, including acrodynia (pink disease), Hunter-Russell syndrome, and Minamata disease. Symptoms for mercury poisoning include vision, hearing and speech impairment, unable to make proper decision and lack of coordination. The type of symptoms depends on what is the concentration and the period which the person is expose.
As you know mercury exist in 3 different forms, they are element mercury, organic mercury (methylmercury) and inorganic (mercury II chloride). These 3 different types of mercury produce different types of health effects and their source of entering into your body is also different.
Acute
In acute effects, when a person inhale a high concentration of element mercury it will effects the central nerves system and the person will have tremors, insomnia, memory loss, neuromuscular changes, headaches, slow sensory and slow motor nerve function ( motor nerve is actually nerves that transfer information to the muscles to perform an action) and reduction in cognitive function ( the person is still able to continue with his/her everyday life but they have difficulty in remember things, for example, people’s name, what had he/she done the whole day).
For inorganic mercury, after consumption of inorganic mercury compounds , beside metallic taste in the mouth, nausea (uneasy in the stomach), vomiting and severe abdominal pain .
For organic mercury,it will effect your central nerve system, which is blindness, deafness and the person’s conscious level
Chronic
In chronic causes, element mercury will affect your central nerve system. The effects include erethism( increase in excitability), excessive shyness. Insomnia, gingivitis (inflammation of gum) and tremors. It also affects the kidney which will lead to proteinuria (presence of serum proteins in the urine). For children, it will cause acrodynia. The symptoms are severe leg cramps, paresthesia (sensation of prickling on the skin), painful pink fingers and peeling skins of hands, feet and nose.
For inorganic mercury, it will affect yr kidney. The reasons is because mercury-induced autoimmune glomerulonephritis (this effect the immune response to the body’s kidney tissue)
For organic mercury, the main target is actually the central nerve system. The symptoms are paraesthesia (an abnormal sensation of the skin, for example numbness, tingling, pickling, burning or even something crawling on your hand) , blurred vision and malaise (discomfort ). In higher concentration, it will cause deafness, speech difficulties and constriction of the visual field.
When mercury enters into nature, for example lakes and streams, the bacteria in the water bodies will reacts and convert some of the mercury into and organic form called methylemercury.Methylemercury is then entered thru the fishes living in the effected water bodies. When humans and other animals consume this fishes, methylemercury is enter into the consumer. Animals that consume this fishes have different effects depending what is the concentration they had consumed and other factors. Some animals population decrease, the younglings is deformed or it may even cause death
Mercury can be detected and monitored by a few methods. They are AAS( Atomic Absorption Spectrophotometry)
Atomic Absorption Spectrophotometry - AAS
Before we understand the instrument CVASS which is widely used to detect mercury, we must first understand AAS. This is because CVAAS originated from the principle of AAS.
Component of AAS • Hollow cathode lamp : A light source which emits a stable and intense light of a particular wave length which will be absorb by the sample (253.7nm for mercury lamp) • A burning unit • Monochromator : A prism to disperse and isolate emission line • A photodetector which is fixed together with an appropriate amplifier
Basic working principle of AAS
Each element can readily absorb a specific wavelength. Therefore the decrease in intensity of the light source can be use to determine the concentration of the element present in the sample. The graph of the absorbance against the concentration (standard graph) could be plot out with standard solution, thus the reading of the machine can be converted to a result.
Standard graph ( Meant for calibration)
Calibration is done by using a series of standards solution of known concentration in the same manner as the samples. A straight line would be obtained when the absorbance is plotted against concentration in standard concentration
Steps of AAS: 1.The intensity of light is first measure without the sample 2.Pre-treated sample containing mercury is being absorb into the machine 3.It is mix with a flammable gas (acetylene) and oxidising air (oxygen) in the mixing chamber 4.The mixed gas is then transported to the burner so that it could be excited and reduce to its elements status 5.Some of the light is absorb by the mercury while the rest proceed on to the photodetector 6.The reading are thus compared with standard graph to obtain the concentration of mercury
The VM-3000 Mercury Vapor Monitor measures the mercury concentration in gases continuously. It is used in the laboratory or can be installed at places where mercury has to be monitored. Industry people use the VM 3000 Mercury Sniffer as well as university researchers or safety people. It is a great tool for plenty of different applications: work place monitoring, exhaust air monitoring, emissions monitoring in the chemical industry, ground air screening of contaminated areas, quality control of hydrogen and other gases, detector for laboratory applications.
Health and Safety
Occupational Hygiene
Work Place Monitoring
Mercury Spill Screening
Mercury Surveys
Investigation of Contaminated sites
Environmental Monitoring
Hazardous Waste Inspection
Mercury Vapor Analyzer Measuring Principle
The sample gas is fed into an optical cell by a maintenance-free membrane pump. A beam of UV light passes through the optical cell, a part of it is absorbed by the mercury atoms present in the sample. This method is called "atomic absorption spectroscopy" or shortly AAS. It is extremely selective and sensitive. For mercury determination the AAS method has maintained its importance even if other methods have been worked out since the early beginnings. The AAS method is low in interference and does not require an amalgamation step or expensive carrier gases.
Analytical Performance of Mercury Vapor Monitor
The VM-3000 uses a high-frequency driven electrodeless low pressure mercury lamp as UV source. This lamp emits lines of an extremely narrow bandwidth which are congruent with the absorption lines of the Hg atoms. Cross-sensitivities are thus minimized. The extremely high stability of the UV source in the VM 3000 is a result of the reference beam feedback control method. Total background noise is less than 0.1 µg/m³.
Metal housing with sturdy handle
Option: Rack version with mounting brackets for 19" racks
Membrane pump with long service life
Input filter with easily replaceable filter membrane
Factory-calibrated- no need for frequent recalibration (short term factory recalibration service available)
4-20 mA output and RS232 communication
Alarm output
Advantages of using VM 3000
Easy to operate Mercury Vapor Detector
The user controls the VM 3000 by menu guided inputs via a waterproof membrane keypad. After switch-on the light source is stabilized (approx. 1-5 minutes). When the measurement mode is started, a zero adjustment is first carried out automatically. Then the analyzer switches to measurement and continuously indicates the measured mercury content of the gas as a numerical value and a graphic bar.
The following settings are possible in the parameters menu:
Duration and Repeat interval of zero adjustment
Selection of concentration unit (ug/m3 or ppb)
Measuring range (0.1-100, 1-1000, 1-2000 ug/m3)
Input of three different alarm levels
Calculation of a mean value over three freely selectable time intervals
Printer activation
Sample dilution factor
Display and Export of Measurement Data
The readings are displayed in real time, both numerically and graphically. Measurement data is exported as a 4-20 mA analog signal.
With addition of the optional Data Logger function, the VM 3000 can store up to 30,000 readings in the memory. The logging interval can be set from 1 to 16 seconds revealing a total recording capacity of 4 to 60 hours. The stored data can be read out to a PC using the RS232 serial interface.
Self-Diagnosis System for the VM3000 Mercury Sniffer
Important components of the VM 3000 are permanently monitored. In case of malfunctions the user is warned on the display (blinking messages: clean cell, lamp, low battery alarm) and via output signals.
Mobile Use
For Mobile use the VM 3000 is also available with a built in rechargeable battery and charging unit. This option allows mobile battery powered applications of up to approx. 6 hours.
