Specify instrumental methods of environmental monitoring

Electroanalytical Techniques

These techniques are based on interaction of electrical energy with matter. Various electroanalytical techniques such as pH meter, potentiometry, cyclic voltammetry is used to monitor environmental pollution.

Potential of an electrode deeping into a solution of an electrolyte depends on the activity of ions with which it is in equilibrium, therefore potential measurement can be used to monitor water pollution.

By the application of electrochemical oxidation or reduction many of the pollutants can be removed or rendered harmless. There are various types of ion selective electrodes used in environmental monitoring. Fluoride ion selective electrode is used to monitor concentration of fluoride in ground water. Excessive fluoride in drinking water causes harmful effects on the human health. Severity depends on the concentration. Permissible limit of fluoride in potable water is 1.0 ppm, which is acceptable up o 1.5 ppm in scarcity of other water sources (Iyer, 2002). The metal ion selective electrodes are used to estimate metal ions present. All these estimations depends on the potential developed by the electrode in contact with solution Cu⁺², Ag⁺², Pb⁺², Cd⁺² ions can be monitored by these electrodes.

Voltammetric methods such as anodic stripping voltammetry is used to monitor presence of heavy metal ions such as pb⁺² and Zn⁺². In this techniques the deposition of metal on to a hanging mercury drop electrode is carried out at 0.3 to 0.4 V more negative than the reduction potential of the metal concerned, under force convention. The deposition is followed by a voltammetric scan towards more the potential during which the metal in the mercury is oxidised and the resultant current is measured.

Amperometric titrations are used for the estimation of Pb⁺² ions, its principle is identical to the voltammetric measurement at a fixed potential. In this titration the voltage applied across the electrodes in kept constant and diffusion current passing through the cell is measured and ploted against the volume of reagent added.

Optical methods

These methods are based on interaction of eletromagnetic radiations with matter. Spectroscopic methods are most commonly used in environmental monitoring.

Various organic and inorganic pollutants can form coloured complex with suitable reagents. Such species can be detected and estimated using spectophotometer. For example Cr (VI) is toxic metal which is present in tannery effluents, can be estimated using diphenyl carbazide reagent. Ni (II) which is used as a catalyst is also toxic and can form coloured complex with DMG. (Dimethyl glyoxime) phenols present in the effluents of organic or pharmaceutical companies can be estimated using ferric ion solution. Phenols are common pollutants in waste water discharged from various industries especially from coke oven, coal, gasification and coal tar plants.

Petrolium refineries and synthetic resin and dye manufacturing units (Sharma and Kaur, 1994). They are determined to water for they creates bitter taste and undesirable odour even at low concentration. Moreover, they are harmful to mankind and other organism causing pain, renal irritation, severe shock and possibly death at higher concentration (Dey, 2002).

Relatively non toxic Fe (II) can be estimated using 1,10 phenonthrolin, pesticide residue are vary harmful and can be extracted by using suitable solvent and estimated using U.V. or I.R. spectrophotometry (Meshram et al., 2002).

Chemiluminescence occurs after excitation of a molecule or ion by the energy emitted during a chemical or biochemical reaction, in which the excited species is a product. In many cases the chemically excited energetic level of a molecule is identical to the energetic level that could have been attained by absorption of electromagnetic radiation. In some molecules, however the excited levels are not identical. Chmilliminescence can occur in the ultraviolet, visible or near- infrared region.

15.Write the methods of environmental protection. Under the method of protection refers to a set of technological, technical measures aimed at the reduction or complete elimination of pollution of the biosphere.

All methods are divided into:

- Active - directly affect the sources of pollution.

- Passive - are protective in nature, these methods are not related to the source of the contamination is formed methods of dealing with pollution.

Specifications are divided into the following methods:

- Direct methods - allow us to estimate the mass, volume, density and level of contamination directly in their sources of education.

- Indirect methods - minimize or eliminate the formation of harmful substances in the following environmental conditions.

These technical methods are called to perform tasks such as: replacement of toxic wastes non-toxic, recyclable waste exchange is not recyclable and creating low-waste technologies.

1. Ways to create a low-waste technologies.

Low-waste technology - an intermediate step before creating waste-free technology, which implies an approximation of the process to a closed cycle. When low-waste technology harmful effects on the environment does not exceed the level allowed by health authorities. Part of raw materials still become waste and is subject to long-term storage or disposal. And so, the need for the creation of low-waste technologies:

1) Creation of compact systems that allow maximum use of all the ingredients of raw materials and ensuring the MPC (maximum permissible concentration) emissions into the atmosphere and hydrosphere.

2) Create flowcharts with complete water circuit, allowing the company to reduce the need to clean natural water. Thereby preserving our natural water supplies are clean and intact. As we all you know - the water for us and our entire planet is a precious substance. Without that, our life in the future is not possible.

3) Create a power technology circuits with heat recovery, which resulted in some businesses to become energy producers.

4) Technological regimes, providing a range of products that can be used in the longer term.

It is worth noting, and passive methods, without which the idea of ​​the creation of low-waste technology solved a greater share of the meaning:

1) Rational allocation of pollution sources. It assumes territorial rational distribution of economic facilities, reducing the burden on the environment.

2) Localization of sources of pollution. Localization is achieved by using a variety of environmental technologies, technical systems and devices.

3) Clean emissions into the biosphere. For example: Air emissions containing harmful substances in vapor or aerosol form, to be cleaned without fail.

2. Rational allocation of pollution sources.

Sources of pollution are placed on land unsuitable for use with the / x based on the benefits of wind or the wind rose and the possible occurrence of inversions. Place for wastewater discharge can be located downstream of the river below the residential area, taking into account the reverse flow when pressure winds.

Locating the source of contamination involves the isolation and containment and sealing material source of pollution, shielding and absorption of energy pollution, dumping of waste. And so, because of all the above, we can note the following important points that are needed to achieve the rational distribution of the source of pollution:

1) The best choice of location for the construction of industrial facilities.

2) rational allocation of production in the plant.

3) A device for the purpose of high stacks dispersion of harmful substances into the atmosphere.

4) Establish the boundaries of sanitary protection zones.