Man-made releases

Obviously, this is not an insignificant amount of power. Ten terawatts was the entire global power production from all sources in 1990. In addition, if atmospheric carbon dioxide emissions are to be stabilized, there will be an even greater need for renewable energy. For example, if man-made releases of carbon dioxide are to be stabilized at 550 ppm—twice the preindustrial level of carbon dioxide in the atmosphere—20 to 30 TW of carbon-neutral primary power would be needed.4... 

Global man-made releases or arsenic into the atmosphere have been estimated by several authors in the past and also more recently. These data were - and still are -divergent as they suffer from large uncertainties due to limited information available. In the first edition of this book, the total anthropogenic As emission per annum was estimated at around 124000 tons, of which about 50000 tons was due to combustion of fossil fuels, mainly from data reported in the late 1970s (Leonard 1991). 

Nuclear weapon tests in the atmosphere from 1945 to 1980 have caused the greatest man-made release of radioactive material to the environment. The most intensive nuclear weapon tests took place before 1963 when a test-ban treaty signed by the UK, USA and USSR came into force. France and China did not sign the treaty and continued some atmospheric tests, but after 1980 no atmospheric tests have taken place. 

Anthropogenic (man-made) releases of plutonium are the primary sources of plutonium to the atmosphere. Atmospheric testing, fires involving plutonium-containing materials, and routine releases due to normal activities at processing and generating plants are all potential sources of airborne plutonium. Resuspension of plutonium sorbed to contaminated surface soils via fugitive dust emissions is an indirect pathway by which plutonium may be re-released into the atmosphere (Harley 1980). 

On June 24, 2003, a major fire took place at the mine. After burning for a month, 300,000 tonnes of sulfur inventory had been destroyed. The massive sulfur dioxide plume spread over 1,000 km, and was tracked by satellite. The 600,000 tonne gas cloud was the largest man-made release of sulfur dioxide in history. Hussain s troops had added to the problem by flooding the mines with bitumen. 

Since man-made emissions of CO are dominated by releases from motor vehicles. It Is considered that global emissions have risen along with the rapid growth In vehicle numbers since the 1940s. In the US for example, the number of motor vehicles Increased by a factor of 4 between 1940 and 1970 while the CO emissions rose from 73 to more than 100 million tons per year over the same period (24). Since about the m1d-70s, control strategies have been Initiated which have resulted In reductions In CO emissions. The outcome of these controls has been a gradual decrease of CO emissions In North America and some Western European countries despite Increases In traffic density. For example In the USA, emissions have declined by approximately 1.5% per year since 1975, which by 1984 represented an overall decrease of more than 11 million tons. 

The release of man-made materials into the environment can have numerous harmful effects, as well as beneficial ones, but the cautious and conservative approach is to assume that any change in the environment could be potentially harmful unless proven otherwise. Actually, there is no way to prove that all the changes from the introduction of a product can be investigated within a given time period and are beneficial or neutral so, in effect, a strict application of this principle would mean a total ban on all product innovations and many existing products. 

The process of redesigning the European Union s Chemical Policy was triggered by several factors. A large number of man-made chemicals has been released into the environment, is still being and will inevitably be released in the near future. There are several cases of chemicals which had been considered to be safe but which due to their persistent nature manifested environmental harm in areas outside of their initial assessment. 

The release of man-made CFCs in the atmosphere has lead to an increase of chlorine containing reservoir molecules such as CIONO, (chlorine nitrate) and HC1 in the stratosphere. Under normal nonpolar conditions, the reaction between both species is extremenly slow. However in the presence of cold surfaces, the following reactions are believed to occur on the PSCs [33] ... 

PAHs enter the environment from both natural and man-made sources, and the anthropogenic point and nonpoint sources are the major sources. The nonpoint sources are diffuse sources disseminated through the air and waterways. In aquatic systems, PAH-enriched particles or floes may settle to the lake s bottom under calm conditions and accumulate in the sediments. Once the PAH-enriched particles have accumulated in the lake s floor, they may undergo a number of changes that are mediated by chemical or microbial activities. As a result, the bound PAHs can be released from the sediment into the water phase. Once they enter the water column, they may also enter phytoplankton. The PAHs in phytoplankton may then bioaccumulate in the food web. This can cause both acute and chronic effects in fish, birds and other mammals that feed on aquatic organisms (Zhang, 1998). 

Water mixed with waste matter usually released by man-made activities, townships, municipal treatment plants and industries. Volume 1(14). 

Details of the sources and individual behaviour of radionuclides within the environment are beyond the scope of this chapter and worthy accounts of these topics have previously been given by Bowen (1979) and Whicker and Schultz (1982). It is worth stressing the point that was alluded to in the previous section, however, that the two major groups of radionuclides which exist are those from natural and man-made sources. Radioecologists have primarily been concerned with the behaviour of the latter category and, as a result, the bulk of radioecological literature concerns radionuclides which have been released to the environment as a result of man s activities. The production of all these radionuclides is either a direct result of the nuclear fission process, or indirectly the result of activation of elements by neutron bombardment within reactors or decay of both fission and activation products. 

Some environmentalists and former environmental regulators I have spoken to are reluctant to embrace a dramatic increase in methanol use, in part because it is used to make mtbe, a gasoline additive now being phased out in California because of environmental concerns such as groundwater contamination (although in fairness to methanol, which exists in nature and degrades quickly, mtbe, in contrast, is a complex, man-made compound that exhibits little degradation once released into the environment). 

Because of their low densities, most of the plastic objects released at sea remain on the surface, where they slowly break apart into smaller and smaller pieces. In fact, the surface of the ocean contains a large volume of plastic refuse, the most common man-made objects sighted. Much of it is in the BB-shot-to-fingernail size range. This phenomenon is significant enough that the term nurdle was created to describe these small pieces of plastic flotsam. Some of the nurdles are mistaken for food by animals such as turtles, fish, whales, and birds, whose stomachs often contain sizable amounts of plastic trash (Krajick 2001). One study estimates that the near-shore water off the beaches near Los Angeles contains more than one million nurdles per mile. 

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