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Biochemistry, Nanotechnology, and the Future Help (page 2)

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By — McGraw-Hill Professional
Updated on Aug 29, 2011

Environment

For centuries, the environment was so vast and scarcely populated that to humans it was limitless. Wood was used freely, refuse was left wherever convenient, and as long as you are upstream, you could dump whatever you wanted into the rivers and the ocean. Now due largely to better medicines and health care, people are living to their seventh, eighth, and ninth decades. Entire populations are no longer getting wiped out by disease.

Scientists began to look at humankind’s impact on this planet as the world’s population swelled to 6 billion and more. Chemists are becoming mystery investigators. The environment is a very complex mixture of elements with different concentration spikes in many areas. Industrial cities have higher levels of metals and acids in their air than rural countryside areas. Scientists must work together to combine all available information from air and water samples as well as those from industrial emissions in order to piece together the puzzle of total environmental impact. The interconnectedness of all forms of life also affects the complexity of environmental pollution.

In 1995, three chemists, Mario Molina, Sherman Rowland, and Paul Crutzen, warned world leaders of damage being done to the O 3 (ozone) layer. This natural layer of O 3 molecules, located from 9 to 30 miles up into the atmosphere, protects the Earth from cancer-causing and damaging ultraviolet radiation from the sun. They discovered that human-made compounds of nitrogen oxides and chlorofluorocarbon (CFC) gases, used as refrigerants and propellants in spray cans, reacted with atmospheric ozone and reduced it. For their work, they received the 1995 Nobel Prize for Chemistry.

In response to the ozone depletion problem, chemists began looking for replacement refrigerants that didn’t affect ozone. Substitutes were found and the environmental problem lessened.

Many of the elements used today were discovered using cutting-edge technology and equipment. Since the 1960s, many of the elements added to the Periodic Table were human-made and not found in nature. These molecules have unheard of uses that many research and applications chemists and biochemists are just beginning to understand.

Chemists working in the plastics industry came under heavy criticism when landfills became overloaded with the new, disposable containers of plastic and a softer compound called Styrofoam. Environmentalists sounded the alarm for consumers to think before they bought products, especially fast food, that came in these containers.

In order to meet the new concern, chemists doubled their interest in the biodegradability of plastic products. They found that the addition of complex carbohydrates (polysaccharides) to plastics allowed microorganisms to break down the plastic products.

Molecules that can be broken down into simpler elements by microorganisms are called biodegradable.

Carbohydrates make up a large group of organic compounds containing carbon, oxygen, and hydrogen.

Carbohydrates have the general formula of C x (H 2 O) y . There are three main groups of carbohydrates. The first are the simple sugars or monosaccharides . Some of these are the simple fruit sugars, fructose and glucose, with the formula C 6 H 12 O 6 . The simple milk sugar that many people with milk sensitivities have trouble with is lactose. The second group is known as the complex sugars or disaccharides . These are combined sugars that make up honey and table sugar, sucrose and maltose (C 12 H 22 O 11 ). Complex carbohydrates with complicated, folded structures make up the starch added to plastics, as well as cellulose of plant cell walls and rayon (processed cellulose). They have the formula (C 6 H 10 O 5 ) n where n is an extremely large number. These are commonly called macromolecules because of the number of elements and huge size compared to simple molecules. Figure 18.2 shows the structure of glucose and cellulose.

Biochemistry, Nanotechnology, and the Future Environment

Fig. 18.2. Carbohydrates like glucose and cellulose serve many functions in organic organisms

Radioactive Waste

One major drawback to most of the radioactive elements discovered and produced in greater than the extremely small amounts found in nature is that they accumulate in the environment. Land, water, and air are affected by radioactive contamination. Depending on the wind or water flow, radioactive levels remain in place or are spread over a wide region. Different elements have very different decay rates .

Radioactive decay occurs when certain element isotopes are lost and there is a release of energy in the form of radiation (alpha and beta particles and gamma rays).

The three main types of radiation given off during the breakdown of radioactive elements are alpha (α) and beta (β) particles, and gamma (γ) rays. Gamma rays are high-energy electromagnetic waves like light, but with a shorter, more penetrating wavelength. Though alpha and beta particles are dangerous to living things since they penetrate cells and damage proteins, gamma rays are much more penetrating and harmful, stopped only by thick, dense metals like lead.

The waste produced in different forms of matter transformation must eventually be broken down. This is an area of ongoing concern and study for many governments who are trying to figure out how to dispose of radioactive wastes from nuclear power plants and atomic weapons. Protecting their populations from handling accidents or terrorist nuclear threats will continue to promote research in understanding the reactivity and degradation of radioactive compounds and elements.

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