Modem environment

Petroleum products have a vast array of uses. In approximate order of importance the uses are as fuels for vehicles and industry, as heating oils, as lubricants, as raw materials in manufacturing petrochemicals and pharmaceuticals, and as solvents. By a wide margin, most products derived from petroleum find use as fossil fuels to run vehicles, to produce electricity, and to heat homes and business. About 65% of the petroleum used as fuel is consumed as gasoline in automobiles. Thus, petroleum products are ubiquitous in the modem environment, which leads to contamination problems for both the environment and in sampling activities. 

Ehrlich, H. L. In Biogeochemistry of Ancient and Modem Environments Tru-dinger, P. A. Walter, W. R. Ralph, B. J., Eds. Australian Academy of Science, Canberra, and Springer-Verlag New York, 1980. 

Oils and petroleum are ever-present pollutants in the modem environment, whether from the used oil of private motorists or spillage from oil tankers. At sea, oil slicks are responsible for the deaths of many birds. Very few birds that are badly contaminated recover, even after de-oiling and hand feeding. Oil is deposited on rocks and sand as... 

LeRoux, N. W., P. W, Dacey and K. L. Temple, 1980. The microbial role in pyrite oxidation at alkaline pH in coal mine spoil. In P. A. Truidnger, M. R. Walter, and B. J. Ralph, Eds. Biogeochemistry of Ancient and Modem Environments. Springer-Verlag, Berlin, pp. 515— 520. 

When carbon isotopic values fall below —40 per mil, the involvement of methane producing and consuming microbes is suspected. In modem environments the isotopic composition... 

Traditionally, durable concrete is vulnerable to the ravages of the modem environment, resulting in the decay of reinforced concrete. Symptoms of such decay are cracking, spalling, rusting of exposed steel reinforcement (Figure 3.1) and staining of concrete surfaces (Fosroc, 1995). All these symptoms seriously weaken the structure. The main reasons are physical... 

In modem environments, reducing conditions may exist near or at the sediment-water interface where oxygen availability is sm2tll, for example in depressions in the sea floor (Kolodny and Kaplan, 1970). The removal of uranium at such interfaces is probably one of the major factors in maintaining the uranium content of sea water at a low level, while rivers continue to add new uranium to the oceans. 

Discuss the behavior of mercury in the modem environment. Why is this metal of special attention for environmental biogeochemistry ... 

Discuss geochemical characteristics of lead and the distribution of this element in ancient and modem environments. Present evidence of accelerated migration of lead during the last centuries. 

Toluene and benzene, as well as xylenes, are fairly common solvents encountered in the modem environment. These solvents are aromatic hydrocarbons frequently used as industrial chemicals. All are components of gasoline fuels, and our modern motor vehicle-based society represents one of the main emission sources. Benzene can also be released by several combustion reactions and can be found in tobacco smoke as well as in many consumer products. Benzene is a known human cancer hazard, and the hematotoxicity of benzene has been well elucidated during the past two decades. The acute internal dose of these aromatic compounds can be estimated by determining the amount of parent compound in blood, breath, or urine however, the use of sensitive HPLC-MS procedures for measuring urinary metabolites has also been commonly reported in the literature.Table 1 displays some of... 

Frescos are old paintings embedded in plaster. In the modem environment these works of art tend to crack and important cultural artifacts are threatened. Conservators use barium to preserve and restore such art objects. A solution of barium nitrate may be sprayed over the fresco and is absorbed by the cavities in the surface. Then an additional spraying is carried out with an ammonia solution. This raises the pH, and barium hydroxide Ba(OH)2 is formed in cracks and other defective parts of the fresco. In the course of time the water evaporates and carbon dioxide from the air reacts with the hydroxide, forming white, insoluble barium carbonate. The surface of the fresco is saved and so are its delicate colors. 

The study of surface tension is really a branch of surface chemistry, and its development has been exceedingly rapid in the last decade. Thus, adhesion can be considered to be partially an exercise in wetting and spreading of liquids on solid surfaces. The flotation of ores is accomplished by gravity differences as well as by the adhesion of the solid particle to an air bubble, and it involves solid-liquid-gas interfaces. It is possible to reduce the vaporization of water from bodies of water with large surfaces such as reservoirs and lakes, by adding a monolayer of a substance such as hexadecanol or other surface-active agents. The action of soaps produces a decrease in surface tension on water. Many other applications in our modem environment can be readily identified. 

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