The Environmental Problems of the Delta Areas (on the Example of the Delta of the Volga)
Authors: Anna V. Fedotova, Lyudmila V. Yakovleva, Elena G. Loktionova
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The ecosystem of the Lower Volga exists and grows depending on the variable and peculiar mode of the river Volga. The levels of floods and their duration are directly dependent on the flow of the Volga and the level of the Caspian Sea. In the period of intense uplift of the Caspian Sea and the Volga flow increased the height of spring-summer floods and their duration significantly increased, which caused the redistribution of soluble salts in the soil. Adapting to such a mode of soil when the soil depending on the location and the intensity of floods is salinizated or desalinizited, on this part of the delta the unique biocenosis forme. The observations carried out by the authors, suggest that changes in the structure and thecomposition of the plant communities have a directional character. During the lowering of the Caspian Sea and the low flood the halophytizatongrass occurs, and with increasing water content of the area (and reducing the salt content) of the soil are as in flood plain. The industrial complex of the city is represented in shipbuilding, timber and fish processing industry. The leading industries is engineering, electric power, food processing. The region has extensive natural resources (fish, minerals, land). The region is almost inexhaustible supplies of gas, oil, sulfur and salt. In the region there are five oil and gas fields, and one gray-gas condensate, which is the largest in Europe. Compared with other regions, Astrakhan is located in a region with relatively high average annual temperature that causes high activity of biological organisms in the aquatic complexes.
Urbanization leads to a change in the hydrological regime of urban ponds and streams, affect the water balance, hydrochemical regime change due to discharge of sewage: industrial, household, stormwater, wastewater from construction sites. All this calls for an objective assessment of its current state. The hydrochemical analysis showed that the content of pollutants in the municipal water reservoirs significantly exceeds the background values, whereby an aqueous medium becomes unsuitable for living organisms. The high toxicity of the environment and confirm the results of the parallel bioassay. The existing work has revealed an extremely unfavorable ecological situation in the territory of Astrakhan. The conducted comparative analysis of content in water reservoirs of all intra-toxic substances identified the trend of ecological deterioration of the situation in terms of time.