Self-purification

The data in Table V indicate that runoff of CGA-72662 from 12 applications would result in extremely low concentrations of CGA-72662 in ponds and lakes. The water column in all cases would contain all of the chemical, the sediment little or no CGA-72662. It follows from these data that exposure of CGA-72662 to aquatic organisms would be low. The data in Table V also shows that CGA-72662 would be persistent only in eutrophic lake environments. After the load is removed, the half-life of CGA-72662 in ponds, eutrophic lakes and oligotrophic lakes was 13, 62, and 5 days respectively. Self purification times were 9, 12, and 3 months respectively. 

The communities include in particular bacteria, lower aquatic plants (algae), higher aquatic plants, organisms fish feed on (e.g. water flea, amphipods etc.) and fish. They participate in the self purification of waters (reduction of residual pollution from effluent discharges like industrial drainage) and maintain the natural biological equilibrium. 

Pomeroy, R.D. and J.D. Parkhurst (1973), Self-purification in sewers. Advances in water pollution research, Proceedings of the 6th International Conference, Jerusalem, June 18—23, 1972, Pergamon Press, Elmsford, NY. 

These data show that the areas of underground oil pollution sometimes can exceed the areas of surface pollution, and underground processes of self-purification go slowly due to restricted chemical and microbiological destruction of oil components. 

Surfactant concentrations in polluted natural water bodies interfere with the self-purification process in several ways. First, certain detergents such as ABS are refractory or difficult to biodegrade and even toxic or inhibitory to microorganisms, and influence the BOD exhibited by organic pollution in surface waters. On the other hand, readily biodegradable detergents could impose an extreme short-term burden on the self-purification capacity of a water course, possibly introducing anaerobic conditions. 

Surfactant concentrations also exert a negative influence on the bio-oxidation of certain substances, as evidenced in studies with even readily biodegradable substances [7]. It should be noted that this protection of substances from bio-oxidation is only temporary and it slowly reduces until its virtual disappearance in about a week for most substances. This phenomenon serves to retard the self-purification process in organically polluted rivers, even in the presence of high concentrations of dissolved oxygen. 

Differences in mutagenic activity occur between the various locations. Local conditions may enhance self-purification processes of the river. Dilution processes play an important role, as is shown for Lake IJssel and the North Sea coast. 

Cazelles, B., D. Fontvieille, and N. P. Chau. 1991. Self-purification in a lotic ecosystem A model of dissolved organic carbon and benthic microorganisms dynamics. Ecological Modelling 5 8 91-117. 

The particularity of the natural conditions of the Black Sea lies in the fact that it the largest basin in the world with a permanent halocline and a two-layered structure of the waters. The intensive pycno- and halocline prevents the waters from vertical mixing and oxygen penetration to deeper layers even in the period of the development of the wintertime vertical convection. Therefore, the entire water column below a depth of 100-200 m represents an inanimate hydrogen sulphide zone, in which only anoxic processes take place. About 90% of the water volume does not participate in the processes of self-purification of the sea. 

The second factor is a lack of normally developed shelf along 70% of the sea coast and also the small size of the self-purification zone because in the Black Sea it is limited by the upper oxygen layer which is 120 to 150 m thick. 

The ratio of COD to BOD allows the estimation of the biodegradabihty of organic water pollutants (Huber et al., 1993). This ratio provides useful information for water monitoring concerning its self-purification process ... 

Thomas, B. R., et al.. Distribution coefficients of protein impurities in ferritin and lysozyme crystals - Self-purification in microgravity. J. Cryst. Growth 2000,... 

Dispersion of the waste gases leads to the dilution of the pollutants in the atmosphere. Self-purification mechanisms of atmospheric air also assists the... 

R.J. Benoit, Self purification in natural waters. In Water and Water Pollution Handbook, (L.L. Ciaccio, ed.), Vol. 1, pp. 141-215. Marcel Dekker, New York, 1971. 

Kuparinen, J., Tuominen, L., 2001. Eutrophication and self-purification counteractions forced by large-scale cycles and hydrodynamic processes. Ambio, 30, 190-194. 

Before 1960 the growth of water consumption in the circum-Aral region did not significantly affect the water balance of the Aral Sea and the quality of river water. The biosanitary capacity of the natural envirorunent and its natural coagulation facilitated the process of water self-purification in sources. Moreover, there was... 

The description of a number of meteorological phenomena is also based on the study of Brownian diffusion of aerosols to single solid and liquid particles. The increasing atmospheric pollution is a problem that requires understanding and description of the processes of atmospheric self-purification of chemical and mechanical pollutants and radioactive contaminants. The problem of settling aerosol particles on various collectors also arises in the analysis of filter efficiency. 

Considering the shape of UV spectra of the river water and treated wastewater, a hidden isosbestic point (HIP) can only be found after normalisation. In this case, the spectra set evolution clearly shows a dilution of anthropogenic matter discharged (and the partly self purification of river water) and of nitrate concentration of the upstream river water. The presence of an HIP is related to the quality conservation of water (see Chapter 2). 

Many of the contaminants are highly stabilized organic compounds that are not destroyed by biological or chemical treatment of wastes, and they often survive the self-purification that normally occurs in moving streams. One synthetic chemical in waste, orthonitrochloro-benzene, was detectable in the Mississippi River for a distance of over 900 miles from the point of origin.70... 

The temperature of waters in reservoirs decreases with the water depth from the surface. The temperature of surface waters varies strongly during the seasons of the year as well as during a day (within a range from 0 to f 25°C). The temperature of surface waters strongly affects the intensity of self-purification processes the lower the temperature, the slower the rate of these processes. 

The quality of water in a recipient is negatively influenced by wastewater discharge, which becomes obvious from aesthetic defects, chemical and bacterial pollution, deterioration of biocenosis, retardation of self-purification processes, sludge deposits and other negative phenoqiena. 

Chemical deterioration of water quality is caused by admixtures of soUd, Uquid or gaseous phases which are water-soluble. These particularly include free acids, nitrates, chlorides, sulphates, salts of heavy metals, cyanides and phenols, and gaseous substances. Such substances can entirely destroy biological revival and the self-purification capability of the stream as a consequence of exhaustion of dissolved oxygen from water [12-16]. 

The size (water capacity) of the recipient, degree of water pollution in it and its self-purification capability are important factors. Others factors include the number of discharged wastewaters, their quality and degree of pollution. 

The final quality of water in the recipient into which wastewaters were discharged, is considerably influenced by self-purification. This involves a series of naturally occurring physical, chemical, biological and biochemical processes through which pollutants are removed from surface waters without any activity of man. The technological and economic importance of such self-purification processes lies in the fact that they can be considered as a kind of reserve treatment for removal of residual pollution after wastewater treatment. 

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