Variant – 19

1. Dynamic parameters of a population: birth rate, death rate, growth rate of the population.

Dynamic parameters of community reflect the processes proceeding in the community for certain time interval. The basic parameters from them: birth rate, death rate, growth rate of the community.

Birth rate is a number of the new species who have appeared in the community for a time unit in the result of breeding.

There are the maximal and actual birth rates.

Death rate (velocity of the death rate) is a number of the species who have lost in the community for a time unit (from predators, illnesses, an old age and other reasons). Death rate is a size return to the birth rate.

There are the minimal and actual death rates.

Rate of a growth community is a change of the community number in unit of time. Rate of a growth community can be positive, zero and negative. It depends on parameters of birth rate, death rate and migration (immigrations and emigrations). The rise (profit) of number occurs in the result of the birth rate and immigration of species, and reduction (loss) of number is in the result of the death rate and emigration of species.

2. Normalization of the harmful substances, disposal with sewage.

Before disposal in a pond sewage should be cleaned up to the highest degree because under effect of natural factors the secondary products of decomposition may be formed, negatively influencing quality of water.

To carry out process it is necessary, firstly, after sewage disposal, the presence in the pond of the soluble oxygen. Chemical or bacterial oxidation of the organic substances contained in the sewage, results in decrease in concentration of oxygen, dissolved in water. (1 liter of H2O contains 8-9 sm3 of O2. Organic substances interacting with dissolved O2 are oxidized to СО2 and Н2О. Therefore, the parameter was entered allowing estimating the total quantity of pollution in water according to absorption of О2. Such parameter is biochemical demand of oxygen (BOD). BOD is equaled to quantity of O2. Depending on time there are BOD5 (five-day), BOD20 (twenty-day), BOD (full), in this case the oxidation is finished.

According to « Rules of surface waters protection from pollution » the water quality of a reservoir after sewage disposal should meet to the following basic requirements: quantity of dissolved О2 should be not less than 4 mg / l; BOD (full) at 20 С is not higher than 3 mg/l. The contents of weighed substances in water after sewage discharge should not be increased more than in 0,25 and 0,75 mg /l for reservoirs I and II correspondently, a mineral sediment is no more than 100 mg /l; including chlorides is 350, sulfates is 500 mg / l; odour and smacks of water should absent; a surface of water should not contain the floating impurities, films, spots, oils, oil products, poisonous substances.

Variant – 20

1. Dry Dust removal equipment

The dust removal equipment available may be divided into two large groups: Dry dust removal equipment and wet dust removal equipment. For both groups: A few representative examples will be discussed.

In dry dust removal equipment dust separation from the carrier gas is achieved directly i.e. in the dry state, without the use of a special dust collection agent like water drops. The collected dry dust can be directly disposed of. The use of dry dust removal equipment involves however the danger of dust explosion. Therefore, special measures have to be taken to prevent dust explosion and pressure release in case of explosion.

The separation of dust particles from a gas is mainly due too the action of three forces: inertia force, surface or adhesion force, and electrical force. In most of the dry dust separators, one force dominate over the other thus determines the separation process. According to the prevailing force there are three groups of the dry dust removal equipment:

1. Mass force separator.

2. Adhesion force separator.

3. Electrical force separator.

A typical mass force separator is the cyclone. Under the action centrifugal forces, the dust particles are separated from the gas phase. Conventional adhesion force separators are bag and pocket filters. A typical electrical force separator is the plate precipitator. The three types of dry dust separators are schematically illustrated in Fig. 1.

2. The structural organization of ecosystem

The structure of ecosystem

From the point of view of trophic structure ecosystem is divided into two circles – autotrophic and heterotrophic (Odum, 1986).

1. The top autotrophic circle, or «a green belt» is a circle of plants or their parts containing a chlorophyll where fixing of light energy, use of simple inorganic compounds and accumulation of complex organic compounds prevail.

2) The bottom heterotrophic circle, or «a brown belt» is a circle of soil and the precipitation, decompositing substances, roots and etc. in which use, transformation and decomposition of complex compounds prevail.

From the biological point of view in structure of ecosystem there are following components (Odum, 1986):

1) inorganic substances;

2) organic compounds;

3) air, water and substrate medium;

4) producers;

5) macroconsumers;

6) microconsumers.

1. Producers are the autotrophic organisms, which are capable to produce organic substances from inorganic, using photosynthesis or chemosynthesis (plants and autotrophic bacteria).

2. Consumers (macroconsumers) are the heterotrophic organisms consuming organic substance of producers or others consumers (animals, heterotrophic plants, some microorganisms). There are consumers of the first order and the second order.

3. Reducers (microconsumers, destructors) are the heterotrophic organisms, eating fossils and decomposing them to mineral substances (saprotrophic bacteria and mushrooms).

As a rule, in any ecosystem it is possible to note three functional groups of organisms: producers, consumers and reducers. In ecosystems formed only by microorganisms, consumers are absent. Each group consists of set of the populations occupying ecosystem.

In ecosystem, food and power bonds proceed in a line: producers->consumers-> reducers.

3. Frequency of equilocal genes

Genetic structure is a relationship of various genotypes and equilocal genes in the community. Totality of genes of all community species is called genofund. The genofund is characterized with frequencies of equilocal genes and genotypes. Frequency of equilocal genes is its share in all totality of equilocal genes of the given gene. The sum of frequencies of all equilocal genes is equal to unit.

According to Hard-Vainberg law, relative frequencies of equilocal genes in population are remained constant from generation to generation. Hard-Vainberg law is fair, if following conditions are observed: 1) the population is great; 2) in community free interbreeding is carried out; 3) there is no selection; 4) there are no new mutations; 5) there is no migration of new genotypes in community or from community.

The long and directed change of genetic structure of community, its genofund is called the elementary evolutionary phenomenon. Without change of the community genofund, evolutionary process is impossible.

The factors changing genetic structure of community are following:

1) Mutation is a source of new equilocal genes appearance;

2) Unequal capable of living of species (species are subjected to action of selection);

3) Not casual interbreeding;

4) Drift of genes is a change of equilocal genes frequency, which are casual and independent of selection action (for example, flashes of diseases);

5) Migrations are outflow of available genes and (or) inflow new ones