Environmental monitoring methods. Earth Remote Sensing

Environmental monitoring (tracking) is the process of monitoring the state of various components of the environment and assessing its current state. For a more complete and comprehensive assessment requires the proper organization of eco-monitoring, the appointment of common criteria and parameters of environmental quality. Environmental monitoring can pursue both regional and global goals. Examples of environmental monitoring can be found literally everywhere.

What is environmental monitoring?

Environmental monitoring is a rather complex technical and organizational environmental activity, in which various bodies and officials are involved. The information obtained in this case is very diverse in nature, content, forms, order of receipt, legal status and distribution methods. In Russia, it can be used by state authorities, constituent entities of the Russian Federation, and local departments. Such information is of scientific and applied value. Many forecasts are built on it, the response of various natural and anthropogenic systems to various influences is estimated. It is used for federal and targeted environmental programs.

Environmental monitoring is carried out at stationary or mobile points: specially equipped cars, posts, stations, laboratories, research centers. The information received is then processed. Environmental monitoring methods are different and depend on the tasks.

Environmental pollution

The constant growth of the world's population, coupled with an increase in the material well-being of people, sharply increases the pressure on the environment, causing various negative consequences. The reduction of natural areas and increased pollution have become the main consequences of human activities. The main factors of environmental pollution are:

Industrial emissions and effluents affecting the quality of air, water and soil, negatively affecting human health.
Emissions of greenhouse gases (carbon dioxide, methane, nitrous oxide and others), which affect the temperature of the lower atmosphere, the thickness of the oceans and the upper layer of the earth's crust.
Soil erosion due to irrational land use. It leads to pollution of river and other waters by suspended particles and harmful substances.
Household and industrial garbage, which is harmful both in itself and in the form of products of its decay. May lead to ecosystem poisoning and poor human health.
Invasive species of plants and animals that often cause great environmental damage.
Radiation pollution due to accidents at nuclear power plants, the work of radiochemical enterprises, medicine and uranium mining.
Pesticides and herbicides leading to water and soil pollution, mainly in agricultural areas.
Mining, which often becomes a source of harmful dust and water pollution.
Fires: industrial, domestic and forest. They are a significant source of air pollution and the cause of death or damage to ecosystems.
Oil and surfactant spills due to leaks and accidents. Most strongly affect the state of the seas and oceans, reduce evaporation, and hence the amount of precipitation.
In the US, there is the problem of inland water pollution with drugs. They can also cause deterioration in the quality of meat or milk.
Mass deforestation is the cause of pollution of river and groundwater, and can also increase air pollution by dust particles. It leads to a decrease in evaporation and rainfall, adversely affects the climate, increasing continentality.

Environmental assessment

The purpose of the examination is to verify the conformity of economic activities with environmental legislation. Most often applied to new projects, the implementation of which may affect the environment. Ecological expertise can be state and public. Based on its results, a conclusion is drawn on the admissibility or inadmissibility of the project. However, even if this project has passed an environmental review, environmental monitoring can be organized at the constructed facility.

History of Environmental Monitoring

For the first time, environmental monitoring was discussed in 1971 at the scientific committee on environmental problems, and then in 1972 at the UN environmental conference held in Stockholm. The relevance of such monitoring was discussed in these years in the USSR. For this, it was proposed to create a system of biosphere reserves.

In the 70s, Soviet scientists made a great contribution to the development of ideas about the principles of environmental monitoring. In this process, the head of the Hydrometeorological Center, Yu.A. Israel, took an active part. Summarizing work on this topic was published in 1975 under the authorship of Academician I.P. Gerasimov, who singled out 3 stages of monitoring:

At the first level of monitoring, in his opinion, the main attention should be paid to observations of the state of the environment and the effects on human health. The main indicators for this stage should be indicators of a person’s reaction: incidence rate, average life expectancy, birth rate and mortality, etc.
The second level involves monitoring more general indicators: biological productivity, mass and energy metabolism, and so on. Such observations should be carried out at special hospitals, training grounds, etc.
The goal of the third stage is to monitor large-scale processes and quantities: dusting the atmosphere, ocean pollution, global water vapor content, etc.

Tasks and objects of environmental monitoring

Environmental monitoring is designed to solve the following problems:

Regular monitoring of the environment and its pollution.
Forecasting and assessing the environmental situation, especially regarding climate change.

Tracking objects can be:

The environment and its components (atmosphere, hydrosphere, biosphere, lithosphere, urbosphere).
The quality of the environment, the change of which may have negative consequences.
Certain types of anthropogenic activities that can harm others.
Enterprises, landfills, technologies, nuclear power plants, etc.
Man-made disasters: oil spills, fires, accidents, incidents and other dangerous phenomena of a natural or man-made nature.
Protected natural sites.

Various environmental organizations, research institutes, authorities (both federal and local), public associations, enterprises and other economic entities, international scientific organizations (for example, NASA) can conduct environmental monitoring.

Types of monitoring

In terms of coverage, monitoring is divided into local, regional, national and global.

When local, they monitor small areas of any locality.
When regional observations are conducted on a regional scale.
At national tracking conducted within the territory of a particular state.
Global environmental monitoring involves tracking large-scale processes that are of international importance.

According to the object of observation, it can be basic, biospheric, atmospheric, hydrological, soil, radiation, hygienic, geobotanical, zoological, etc.

The main methods of environmental monitoring

Currently, environmental monitoring methods fall into 2 main categories:

Ground observations (physico-chemical, bioindication, meteorological, photographic, medical, etc.).
Remote methods of environmental monitoring (satellite sensing, tracking from drones, etc.).

Naturally, in the first case, local and regional processes are more often assessed, and in the second, large-scale and global.

Satellite monitoring

Remote sensing of the Earth uses satellite data, data from airplanes, drones, ships. Satellite data provide the widest possible coverage of the studied object, and therefore are often used to obtain information about global environmental changes. In aerospace images, the scale of deforestation, urbanization, dust pollution of the atmosphere, melting ice, etc. is clearly visible. Data from infrared detectors provide information on the temperature of various parts of the earth's surface and estimate its albedo. Reflection of radio waves and ultraviolet radiation from the surface of the water provides information on oil pollution of the oceans.

Remote sensing of the Earth is becoming an increasingly popular type of research in ecology.

But satellite monitoring can also be used to track the situation at the local level. For example, aerospace images can provide information on the state of forests, on the situation with forest fires, foci of thunderstorms, and so on, which may be sufficient to make certain practical decisions. To obtain high-quality and accurate images, drones can be involved.

Biological methods

Biological environmental monitoring methods are terrestrial tracking methods. They are also called bioindication. The main object of such monitoring is biological objects: species, communities, ecosystems, food chains, etc. For analysis, such facts as the distribution of a species, a change in its number or complete disappearance, or appearance in a new area are used. During geobotanical studies, they track the change in the range of certain species, the dynamics of biomass, bioproductivity, altitudinal and latitudinal distribution of species and communities, etc.

Bioindicators can be: the width of the annual rings, yellowing of the leaves, drying of the forest stand, the height of the trees, the presence of weeds (pioneer species) and other signs.

Biological monitoring covers all levels - from molecular and cellular to global. For research, depending on the tasks, laboratories, expeditionary studies are organized.

Before conducting biological monitoring, it is necessary to develop a methodology for its implementation and obtain the necessary data, because different biological systems respond differently to different types of exposure. Organisms or ecosystems that are most sensitive to human impact are selected. Such organisms are called indicators. Thanks to the use of biotesting, diagnostic criteria are selected to assess the level of impact of a factor on the study area.

Thus, biological monitoring uses the bioindication method. Naturally, the accuracy of such studies will be lower than when using physical methods. But, at the same time, they will make it possible to assess the total damage caused by anthropogenic activities to natural ecosystems, which cannot be achieved using other methods. As a result, it will be possible to isolate from the complex of impacts the most significant for the state of the environment and take adequate measures to reduce the anthropogenic load. To assess possible damage to public health, it is preferable to analyze toxicological samples, which relates to physicochemical monitoring methods.

For bioindication, fish, microorganisms, and algae are most often used. Crayfish are also known to prefer pure water, and therefore are a good indicator of contamination. The same applies to some species of lichen, which is also the subject of bioindication.

Biological Monitoring Capabilities

Bioindication of the environment is suitable for the following tasks:

Compilation of a comprehensive assessment of the anthropogenic impact on the nature of the studied region.
Identify accidental or latent emissions, including intentional misrepresentation by management of information about their own emissions.
Allow to assess the sensitivity of organisms to emitted pollutants or other harmful effects.
Show the response rate of biosystems and its scale.
They make it possible to map the foci of pollution and the concentration of harmful impurities.
They allow you to assess the degree of danger of specific pollutants for the environment, and with high probability for humans.
They help in rationing the maximum permissible environmental loads and, if necessary, take measures to reduce it.

Laboratory methods, sampling

Physico-chemical methods of environmental monitoring, most often, are laboratory. The analysis begins with sampling of air, soil or water, and then on special equipment conduct an anasis for the content of pollutants. It is also called instrumental analysis.

Physicochemical methods are as follows:

chromatographic indication;
infrared spectrometry;
fluorimetric methods;
electrochemical methods;
mass spectrometric methods;
luminescent analysis;
radio engineering methods.

Chromatographic Methods

These methods are often used to detect contaminants, especially when analyzing liquids. The most popular are gas-liquid, thin-layer, liquid and ion chromatography. The thin layer is easy to perform and is used to detect pesticides and organic pollutants. Gas-liquid is more effective in the analysis of volatile organic compounds. Liquid chromatography is used to detect non-volatile chemical compounds.

High sensitivity detectors based on various physicochemical methods make it possible to detect even small amounts of impurities, which is important in the detection of highly toxic compounds. In combination with chromatographic techniques, mass spectrometry and infrared spectrometry can give a good result for identifying complex combinations of contaminants. These types of analyzers connect to powerful computers. With their help, you can detect such dangerous substances as dioxins, polychlorinated biphenyls, nitrosamines and toxic pesticides.

Ion chromatography is used to analyze the ratio of cations to anions.

Spectrophotometry

This method uses infrared radiation. An analysis of the absorption, reflection, and scattering spectra makes it possible to fairly accurately determine the presence and concentration of impurities. Having a catalog of spectra of various substances makes it easy to determine the type of pollutant or beneficial substance present in a sample or product. The infrared spectrum allows even properties such as density, particle size distribution, caloric content of food products and seed germination to be determined.

Luminescent method

This is one of the most sensitive ways to identify pollutants. Using it, trace amounts of both organic and inorganic impurities in air samples are determined. It can be used to monitor the hydrosphere and biosphere, as well as to determine the content of trace elements, organic compounds and the amount of harmful substances.

The luminescent method can be used if it is required to detect the presence of polyaromatic hydrocarbons or their derivatives. To calculate the concentration of a substance, a phenomenon such as luminescence quenching is used.

However, not all compounds are determined by this method. Sometimes a chemical reaction is carried out, with the help of which the initial compound is changed so that luminescence can detect it.

Electrochemical methods

For their implementation, electrodes are used: anode and cathode. The cathode is often a mercury dripping electrode with a constantly updated surface, which makes it possible to obtain polarograms and conduct effective analysis. This method is only suitable for detecting metal ions, organic substances, carbonyl compounds, peroxides, epoxides and others. For this reason, it cannot be considered universal, but it is rather selective.