Forests pollutant source

Negative externalities arise when an action by an individual or a group implies harmful effects on others such as unintended dispersion of chemicals to land, air and water air pollution effects on health forest growth or fish reproduction. When negative externalities are generated they should be internalized into the market economy. By internalizing the externalities the economic value of environmental impacts are allocated to the pollution sources and included in the economics of the activities causing the problem. This would also allow for the market to function properly and thereby reach a socially optimal level of environmental impacts. 

Intensive investigations of the sulfur dynamics of forest ecosystems in the last decade can be attributed to the dominant role of sulfur as a component of acidic deposition. Studies in forested catchments include Fuller et al. (1986), Mitchell et al. (1989), Stam et al. (1992), and Andersson et al. (1992). Sulfur with a distinctive isotopic composition has been used to identify pollution sources (Krouse et al., 1984), and has been added as a tracer (Legge and Krouse, 1992 Mayer et al., 1992, 1993). Differences in the natural abundances can also be used in systems where there is sufhcient variation in the 5 " S of ecosystem components. Rocky Mountain lakes (USA), thought to be dominated by atmospheric sources of sulfate, have different 5 " S values than lakes believed to be dominated by watershed sources of sulfate (Turk et al., 1993). 

Air pollution sources in the United States and Canada currently emit more than 25 million tons of sulfur dioxide each year. SO2 and wet acidic deposition are believed to cause damage to aquatic life, crops, forests, and materials. The effects on materials include damages to common construction materials including galvanized steel (zinc), paint, copper, building stones and mortar, as well as damages to cultural or historic objects and buildings. 

Several observations have shown that hydrogen is affected by pollution sources. The hydrogen molecule is an important product of incomplete combustion in several anthropogenic and natural processes. The production of H2 by industrial combustion and automobiles is estimated to vary from 15 Tg H2/yr (Novelli et al., 1999) to 25 Tg H2/yr (Schmidt, 1974). According to Crutzen et al. (1979) 9 to 21 Tg H2/yr are produced by forest and savanna burning, especially for agricultural purposes in tropical regions. 

The places from which pollutants emanate are called sources. There are natural as well as anthropogenic sources of the permanent gases considered to be pollutants. These include plant and animal respiration and the decay of what was once living matter. Volcanoes and naturally caused forest fires are other natural sources. The places to which pollutants disappear from the air are called sinks. Sinks include the soil, vegetation, structures, and water bodies, particularly the oceans. The mechanisms whereby pollutants... 

An extensive source of natural pollutants is the plants and trees of the earth. Even though these green plants play a large part in the conversion of carbon dioxide to oxygen through photosynthesis, they are still the major source of hydrocarbons on the planet. The familiar blue haze over forested areas is nearly all from the atmospheric reactions of the volatile organics... 

Under low-dose conditions, forest ecosystems act as sinks for atmospheric pollutants and in some instances as sources. As indicated in Chapter 7, the atmosphere, lithosphere, and oceans are involved in cycling carbon, nitrogen, oxygen, sulfur, and other elements through each subsystem with different time scales. Under low-dose conditions, forest and other biomass systems have been utilizing chemical compounds present in the atmosphere and releasing others to the atmosphere for thousands of years. Industrialization has increased the concentrations of NO2, SO2, and CO2 in the "clean background" atmosphere, and certain types of interactions with forest systems can be defined. 

The third category for interactions is high dose (III). The effects produced by this level of interaction can be seen by the casual observer. The result of high-dose exposure is destruction or severe injury of the forest system. High-dose conditions are almost always associated with point source emissions. The pollutants most often involved are SO2 and hydrogen fluoride. Historically, the most harmful sources of pollution for surrounding forest ecosystems have been smelters and aluminum reduction plants. 

National initiatives in North America and Europe are designed to reduce pollution emissions from both stationary and mobile sources. Independently of whether they succeed in reducing pollutant loadings, the available evidence indicates that alterations in affected forests will continue. Obviously, no one knows what affected forests will be like in 50 years. There is little doubt that they will be different. And the sooner the anthropogenic causal factors - all of them - are reduced qualitatively and quantitatively, the better are the chances of retaining or regenerating forests that will have meaning and value for those who will want to use them. 

Johnson DW, Lindberg SE. 1995. Sources, sinks, and cycling of mercury in forested ecosystems. Water Air Soil Pollut 80 1069-1077. 

The purpose of this chapter is to examine in the greatest detail possible the effects of oxidant air pollutants on ecosystems. A project is now going on to study the effects on a mixed-conifer forest ecosystem in southern California, and the planning documents and early results from this study constitute the major source of information for the remainder of this chapter. Other examples of damage to agroecosystems and natural ecosystems are included. 

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