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- •Global Warming
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Global warming
Global warming refers to an unequivocal and continuing rise in the average temperature of Earth's climate system. Since 1971, 90% of the warming has occurred in the oceans. Despite the oceans' dominant role in energy storage, the term "global warming" is also used to refer to increases in average temperature of the air and sea at Earth's surface. Since the early 20th century, the global air and sea surface temperature has increased about 0.8 °C (1.4 °F), with about two-thirds of the increase occurring since 1980. Each of the last three decades has been successively warmer at the Earth's surface than any preceding decade since 1850.
Future climate change and associated impacts will vary from region to region around the globe. The effects of an increase in global temperature include a rise in sea levels and a change in the amount and pattern of precipitation, as well as a probable expansion of subtropical deserts. Warming is expected to be strongest in the Arctic, with the continuing retreat of glaciers, permafrost and sea ice. Other likely effects of the warming include more frequent extreme weather events including heat waves, droughts and heavy rainfall; ocean acidification; and species extinctions due to shifting temperature regimes. Effects significant to humans include the threat to food security from decreasing crop yields and the loss of habitat from inundation.
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.
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.
Cosmopolitans, ubikvists and endemics
The community is a totality of individuals of one species capable to self-reproduction which long exists in the certain part of area rather separately from other totality of the same species. Contacts between individuals of one community more often, than between individuals of different communities. The community is structural unit of species and unit of evolution.
A space on which the community or species as a whole meets during all ability to live is called an area of distribution. The area can be continuous or broken off (disjunctive), that is, if between its parts there are various barriers (water, orographical, etc.), the spaces are not populated by representatives of the given species. There are various centers of areas: the geometrical center; the center of species occurrence within the limits of an area; the center of abundance is a part of area to which the greatest quantity of individuals is concentrated.
Depending on size of area and character of distribution there are cosmopolitans, ubikvists and endemics. Cosmopolitans are species of plants and animals which representatives meet on a greater part of inhabitant areas of the Earth (for example, the room fly, grey rat). Ubikvists are species of plants and animals with wide ecological valency, they are capable to exist in various conditions of environment, have extensive areas (for example, a reed ordinary, the wolf). Endemics are species of plants and animals which have the small limited areas (often they are met on islands of an oceanic origin, in mountain areas and the isolated basin).