Forest ecosystems pollutants

Receptors. The receptor can be a person, animal, plant, material, or ecosystem. The criteria and hazardous air pollutants were so designated because, at sufficient concentrations, they can cause adverse health effects to human receptors. Some of the criteria pollutants also cause damage to plant receptors. An Air QuaUty Criteria Document (12) exists for each criteria pollutant and these documents summarize the most current Hterature concerning the effects of criteria pollutants on human health, animals, vegetation, and materials. The receptors which have generated much concern regarding acid deposition are certain aquatic and forest ecosystems, and there is also some concern that acid deposition adversely affects some materials. 

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 interactions of air pollutants with forests at low-dose concentrations result in imperceptible effects on the natural biological cycles of these species. In some instances, these interactions may be beneficial to the forest ecosystem. Forests, as well as other natural systems, act as sinks for the removal of trace gases from the atmosphere. 

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. 

Smith, W, H., "Air Pollution and Forests Interaction between Air Contaminants and Forest Ecosystems," 2nd ed. Springer-Verlag, New York, 1990. 

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

Huchinson T.C., Whilby L.M. The effects of acid rainfall and heavy metals particulates on a boreal forest ecosystem near the Sudbury smelting region of Canada. Water Air Soil Pollut 1977 7 421 438. 

BIOGEOCHEMICAL CYCLING OF ELEMENTS AND POLLUTANTS EXPOSURE IN FOREST ECOSYSTEMS... 

In the southern direction the Podzols are transferred into Podzoluvisols and Distric Phaerozems. These soils have less acidity and less pronounced migration of various elements. Accordingly, this determines the exposure pathways of pollutants, like heavy metals, in soil compartments of forest ecosystems. 

We can see that the Tropical Rain Green Forest ecosystems occupy about 1/5 of the African equatorial belt, whereas about 1/2 of this area is Woody and Tall Grass Savanna ecosystems. The rest of the area are occupied by various Dry Steppe and Dry and even Extra-Dry Desert ecosystems, like the Sahara, with annual rainfall less than 200 mm. As it has been mentioned above, the amount of precipitation is of high significance for exposure pathways of pollutants. 

The main specificity of biogeochemical cycling and exposure pathways in Tropical Rain Forest ecosystems is related to its almost closed character. This means that almost the total number of nutrients and/or pollutants is re-circulating in biogeochemical cycles (Figure 1). 

Critical load calculation and mapping of S and N acidity and eutrophication compounds in the vast area of Eurasia along the natural gas pipeline Yamal-West were conducted to estimate the environmental risks due to pollutant emission. The taiga forest ecosystems are predominant in the area of potential impact and accordingly for >60% of ecosystems the CL(S) are 500-1,000 eq/ha/yr. Ecosystems with CL(Nnutr) values <750 eq/ha/yr are predominant, and >50% have critical loads <500 eq/ha/yr. 

Priputina, I., Abramychev, A., Orlinskii, D. (2003). Critical loads of heavy metals for forest ecosystems for the European Russia stand-still and effect based approaches//Proceedings of 4th Training Workshop on Calculation and Mapping of Critical Loads for Air Pollutants Relevant for the UN/ECE Convention on LRTAP in East and South-East European Countries. Sudak, Ukraine (Crimea), 27-31 October 2002. Simpheropol, pp. 55-61. 

Taylor, O. C. (Principal Investigator) Oxidant Air Pollutant Effects on a Western Coniferous Forest Ecosystem. Task C Report Study Site Selection and On-Site Collection of Background Information. EPA-R3-73-043B. Riverside University of California, Statewide Air Pollution Research Center, 1973. (189 pp.J... 

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. 

One of the predicted effects of pollutants on eco stems suggested by Woodwell is a reduction in the standing crop of organic matter, which would lead to a reduction in nutrient elements held within the living system. The evidence discussed earlier definitely shows that primary production is much lower in an ozone>stressed conifer-forest ecosystem. This result would be anticipated in all similarly stressed natural ecosystems or agroecosystems. 

Kkkert. R. N.. P. R. MUler. O. C. Taylor, J. R. McBride. J. Barbieri, R. Arkley. F. Cobb, Jr., D. Dahlsten, W. W. WUcox. J. Wenz, J. R. Panneter, Jr., R. F. Luck, and M. White. Photochemical Air Pollutant Effects on Mixed Conifer Forest Ecosystems. A Progress Report. CERL-026. Contract No. 684)3-0273. Corvallis. Oregon Corvallis Environmental Research Laboratory, U.S. Environmental Protection Agency, [1976]. 275 pp. 

Smith, W. H. Air Pollution Effects on the Quality and Resilience of the Forest Ecosystem. Paper Presented at the AAAS (American Association for the Advancement of Science) Symposium on Temperate Climate Forestry and the Forest Ecosystem An Environmental Issue Held in Washington, D.C., 1972. 

The most important research needs are related to the determination of the responses of natural ecosystems and agroecosystems to chronic exposure to oxidant pollutants. In particular, chronic-dose-response models are needed to understand the responses of the dominant primary-producer species constituting forest ecosystems in both the eastern and the western United States. The resulting alteration of interactions with other sub ems-—e.g., consumers and decomposers—must also be investigated. 

Outbreaks of insect pests, particularly in forest ecosystems, have often been linked to air pollutants (57). 

Brummer, G., and Herms, U. (1983). Influence of soil reaction and organic matter on the solubility of heavy metals in soils. In Effects of Accumulation of Air Pollutants in Forest Ecosystems, Ulrich, B., and Pankrath, eds., Reidel Dordrecht, pp. 233-243. 

Effect of local-scale, regional-scale and global-scale air pollution on forest ecosystems... 

---