As can be observed above, the effects of alcohol as shown in the blood alcohol concentration indicates that the higher the concentration the greater the risk of discomfort, unconsciousness and possibly death at the worst.
Living with the Monster Near the end of a half-mile-long hallway connecting the four reactors of the Chornobyl Nuclear Power Plant, graph bars and squiggles flash on a monitor. Only a few yards away rises the concrete-and-steel sarcophagus sheathing the … Continue reading →
The acids in acid rain react chemically with any object they contact. Acids are corrosivechemicals that react with other chemicals by giving up hydrogen atoms. The acidity of a substance comes from the abundance of free hydrogen atoms when the substance is dissolved in water. Acidity is measured using a pH scale with units from 0 to 14. Acidic substances have pH numbers from 1 to 6—the lower the pH number, the stronger, or more corrosive, the substance. Some non-acidic substances, called bases or alkalis, are like acids in reverse—they readily accept the hydrogen atoms that the acids offer. Bases have pH numbers from 8 to 14, with the higher values indicating increased alkalinity. Pure water has a neutral pH of 7—it is not acidic or basic. Rain, snow, or fog with a pH below 5.6 is considered acid rain.
When bases mix with acids, the bases lessen the strength of an acid. This buffering action regularly occurs in nature. Rain, snow, and fog formed in regions free of acid pollutants are slightly acidic, having a pH near 5.6. Alkaline chemicals in the environment, found in rocks, soils, lakes, and streams, regularly neutralize this precipitation. But when precipitation is highly acidic, with a pH below 5.6, naturally occurring acid buffers become depleted over time, and nature’s ability to neutralize the acids is impaired. Acid rain has been linked to widespread environmental damage, including soil and plant degradation, depleted life in lakes and streams, and erosion of human-made structures.
In soil, acid rain dissolves and washes away nutrients needed by plants. It can also dissolve toxic substances, such as aluminum and mercury, which are naturally present in some soils, freeing these toxins to pollute water or to poison plants that absorb them. Some soils are quite alkaline and can neutralize acid deposition indefinitely; others, especially thin mountain soils derived from granite or gneiss, buffer acid only briefly.
The effects of acid rain on wildlife can be far-reaching. If a population of one plant or animal is adversely affected by acid rain, animals that feed on that organism may also suffer. Ultimately, an entire ecosystem may become endangered. Some species that live in water are very sensitive to acidity, some less so. Freshwater clams and mayfly young, for instance, begin dying when the water pH reaches 6.0. Frogs can generally survive more acidic water, but if their supply of mayflies is destroyed by acid rain, frog populations may also decline. Fish eggs of most species stop hatching at a pH of 5.0. Below a pH of 4.5, water is nearly sterile, unable to support any wildlife.
Land animals dependent on aquatic organisms are also affected. Scientists have found that populations of snails living in or near water polluted by acid rain are declining in some regions. In The Netherlands songbirds are finding fewer snails to eat. The eggs these birds lay have weakened shells because the birds are receiving less calcium from snail shells.
Most farm crops are less affected by acid rain than are forests. The deep soils of many farm regions, such as those in the Midwestern United States, can absorb and neutralize large amounts of acid. Mountain farms are more at risk—the thin soils in these higher elevations cannot neutralize so much acid. Farmers can prevent acid rain damage by monitoring the condition of the soil and, when necessary, adding crushed limestone to the soil to neutralize acid. If excessive amounts of nutrients have been leached out of the soil, farmers can replace them by adding nutrient-rich fertilizer.
Modern understanding of acids and bases began with the discovery in 1834 by the English physicist Michael Faraday that acids, bases, and salts are electrolytes. That is, when they are dissolved in water, they produce a solution that contains charged particles, or ions, and can conduct an electric current Ionization. In 1884 the Swedish chemist Svante Arrhenius (and later Wilhelm Ostwald, a German chemist) proposed that an acid be defined as a hydrogen-containing compound that, when dissolved in water, produces a concentration of hydrogen ions, or protons, greater than that of pure water. Similarly, Arrhenius proposed that a base be defined as a substance that, when dissolved in water, produces an excess of hydroxyl ions, OH-. The neutralization reaction then becomes: H+ + OH-⇄H2O
A number of criticisms of the Arrhenius-Ostwald theory have been made. First, acids are restricted to hydrogen-containing species and bases to hydroxyl-containing species. Second, the theory applies to aqueous solutions exclusively, whereas many acid-base reactions are known to take place in the absence of water.
The first three demonstration plants of the Department of the Interior’s program to develop methods for converting saline water to fresh water were completed during 1961. The plants at Freeport, Tex., and San Diego, Calif., use distillation processes; that at Webster, S.D., electro-dialysis. Plants are still to be completed at Roswell, N.Mex. (distillation process), and at Wrightsville Beach, N.C. (freezing process). The plants at Webster and Roswell are for converting local brackish water to potable water; the other three convert seawater. Meanwhile, Congress authorized $75 million for saline water research over the next six years, a big increase from previous government spending. Several private companies are working on conversion techniques, such as freezing and electro-dialysis, too.
The Interior Department‘s helium conservation program also got under way during 1961. Under the program, the government can buy up to $47.5 million worth of helium a year from private companies participating in the program. Contracts were signed with several gas-producing and pipeline firms, which will build plants to extract at low temperature the very small amounts of helium found in natural gas. In addition, Kerr-McGee Oil Industries is building a private plant in Arizona for recovering helium for sale on the market; this plant is not connected with the government program.
Chemical production has been growing more rapidly in many foreign countries—especially some European nations and Japan—than in the United States. As a result, overseas producers have been competing more aggressively with U.S. firms in their home markets, in the less-developed areas, and even in the United States itself.
At the same time, the rapid growth in demand overseas, lower labor and operating costs in many foreign lands, and the establishment of larger coherent market areas through such organizations as the European Common Market and the European Free Trade Association has led American firms to step up their international operations. Most major U.S. chemical firms — and many smaller ones, too—have organized international subsidiaries, built plants abroad, acquired foreign firms, or formed joint ventures overseas with foreign producers and investors. During 1960, according to the Department of Commerce, U.S. chemical companies invested nearly $250 million abroad, including $86 million in Europe and about $70 million in both Canada and Latin America.