The environmental impact of irrigation includes the changes in quantity and quality of soil and water as a result of irrigation and the ensuing effects on natural and social conditions at the tail-end and downstream of the irrigation scheme. The impacts stem from the changed hydrological conditions owing to the installation and operation of the scheme.
Subsequent scientific investigations soon led to what is now the most widely accepted explanation of what was happening. Chlorine compounds derived mostly from chlorinated fluorocarbon gases CFCsmass-produced by industrial societies for a variety of purposes, reacted in the stratospheric clouds over Antarctica during the cold, dark, winter months to produce forms of chlorine that rapidly deplete stratospheric ozone when the first rays of the Antarctic spring sunlight arrive Solomon, Until almost the end of the nineteenth century, refrigeration was a limited technology, based almost entirely on natural sources of supply.
Urban Americans who could afford to drink chilled beverages relied on metropolitan ice markets, which cut ice from local ponds in the winter and stored it in warehouses for use during the warm months of the year.
Breweries and restaurants were the heaviest users of this stored winter ice, which was sometimes shipped hundreds of miles to provide refrigeration. Boston ice merchants, for instance, were regularly delivering ice to consumers in Charleston, South Carolina, and even the Caribbean by the fourth decade of the nineteenth century Hall, ; Cummings, ; Lawrence, Page 55 Share Cite Suggested Citation: Understanding the Human Dimensions.
The National Academies Press. In the United States, pork was the most popular form of preserved meat because of the ease with which its decay could be arrested by salt.
Beef was much less popular in preserved form, so those who ate it preferred to purchase it freshly slaughtered from local butchers.
Then, in the s, meatpackers began experimenting with ice-refrigerated railroad cars that could deliver dressed beef, slaughtered and chilled in Chicago, to consumers hundreds of miles away.
Dressed beef, which was cheaper than fresh beef for a variety of reasons, soon took the country by storm, driving many wholesale butchers out of business and giving the Chicago packing companies immense economic power.
The packers initially relied on complicated ice storage and delivery networks, cutting and storing millions of tons of winter ice along the railroad routes that delivered beef from Chicago to urban customers throughout the East.
Their investment in ice storage technology contributed to dramatic shifts in the American food supply and was soon affecting foods other than meat. Fruits and vegetables from California and Florida and dairy products from metropolitan hinterlands throughout the East, were among the most important to benefit from the new ice delivery system Cronon, ; Yeager, ; Kujovich, ; Giedion, ; Clemen, ; Swift and Van Vlissingen, ; Neyhart, ; Unfer, ; Fowler, But natural ice was unreliable: Although the principle of mechanical refrigeration, in which compressed gas was made to expand rapidly and so lower temperatures, had been known since the middle of the eighteenth century, its first application on a large commercial scale was not found until the second half of the nineteenth century Anderson, Urban brewers, especially in the warm climates of the South, were the first to make wide use of it.
As the meatpackers sought to solve their problems with erratic winter ice supply, they too adopted mechanical refrigeration on a large scale after By the first quarter of the twentieth century, the delivery of perishable foods throughout the United States—and international food shipments as well—had come to depend on mechanical refrigeration.
By drastically lowering the rate at which food decayed and hence making perishable crops available to consum- Page 56 Share Cite Suggested Citation: The most widespread early refrigeration technology depended on compressed ammonia gas, which easily produced desired drops in temperature for effective food storage.
But ammonia like other refrigerant gases such as sulfur dioxide and methyl chloride had serious problems. For maximum efficiency, it had to attain high pressures before being released, which increased the likelihood that the compression equipment might fail.
Accidental explosions were frequent, and the toxic nature of the gas caused a number of fatalities. Toxicity and the need for large expensive compressors kept mechanical refrigeration from making headway with retail customers, who represented an immense potential demand. That is why Thomas Midgely Jr.
Midgely, working at the request of the General Motors Frigidaire division, developed the new chlorinated fluorocarbon as the perfect alternative to all other refrigerant gases then on the market.
Nonflammable, nonexplosive, noncorrosive, and nontoxic, the various forms of Freon gas seemed the perfect technical solution to a host of environmental and safety problems. They also required less pressure to produce the desired cooling effect, so compressors could be smaller and less expensive.
Freon soon came to dominate the market for refrigeration and opened up new retail markets because of its diminished capital requirements. Previously, consumers had bought their refrigerated food at the store just before eating it, since efficient and reliable household refrigeration was not generally available.
Now American households could own their own refrigerators, making it possible for the food industry to shift much of its marketing apparatus toward selling chilled food in retail-sized packages. Frozen foods burst onto the American marketplace in the s, as did fresh vegetables, dairy products, and other foods that are today accepted as ordinary parts of the national diet.
Although European countries were slower to adopt these technologies, they too eventually followed suit. No less importantly, the nontoxicity of Freon made it possible for refrigeration technology to be applied to the ambient cooling of buildings, so that air conditioning came to be an ever more important market for the gas.
Air conditioning had been used in specialized industrial applications ever since Willis H. The introduction of Freon meant that air conditioning suddenly became much cheaper and safer in a way that allowed it to Page 57 Share Cite Suggested Citation:Therefore a human impact on the environment is inevitable.
By simply existing, all species - including ourselves - will imprint their mark on the world around them. By simply existing, all species - including ourselves - will imprint their mark on the world around them.
We humans emerged as a species about , years ago. Here are some of the changes we've been asked to make recently, by celebrities who like to pronounce on this sort of thing, and by.
Human impact on the environment or anthropogenic impact on the environment includes changes to biophysical environments and ecosystems, biodiversity, and natural resources caused directly or indirectly by humans, including global warming, environmental degradation (such as ocean acidification), mass extinction and biodiversity loss, ecological.
Nov 27, · It is now clear that anthropogenic environmental changes may affect both the reproductive success and the survival of many wildlife species by multiple routes and in often unpredictable ways.
Since man does not exist in isolation, these wider impacts of anthropogenic macro-environmental changes need to be understood by society at all levels. Human impact on the environment or anthropogenic impact on the environment includes changes to biophysical environments and ecosystems, biodiversity, and natural resources caused directly or indirectly by humans, including global warming, environmental degradation (such as ocean acidification), mass extinction and biodiversity loss, ecological crisis, and ecological collapse.
IMPACT OF ENVIRONMENTAL CHANGES ON BIODIVERSITY. Environmental changes have had enormous impacts on. also indirectly through their interactions with other species.