Atmosphere-Biosphere Interactions Toward a Better Understanding of the Ecological Consequences of Fossil Fuel Combustion (1981) / Chapter Skim
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6 Biological Accumulation and Effect of Atmospheric Contaminants
6 Biological Accumulation and Effect of Atmospheric Contaminants
Pages 87-118
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From page 87... ...
ACCUMULATION IN TERRESTRIAL ECOSYSTEMS In terrestrial ecosystems, atmospheric contaminants and pollutants are captured by plant surfaces in a variety of ways. Hairy and glandular plant surfaces can physically trap suspended matter in the form of wet or dry aerosols.
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From page 88... ...
As a result, surface films often become enriched in atmospheric contaminants such as trace metals and organic micropollutants by as much as orders of magnitude more than the concentration observed in the bulk water beneath (Duce et al. 1972, MacIntyre 1974, LiSS 1975, Andren et al.
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From page 89... ...
. Xair, XL1 and xL2, and xint denote gaseous pollutant concentrations in well-mixed surrounding air, at the upper and lower leaf surfaces, and average gas phase concentrations within the leaf mesophyll, respectively.
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From page 90... ...
NOTE: Aerosols tend to react more with outer surfaces because they do not pass through stomata as easily as gases. Gases interact more readily with the internal tissues of plants because they can rapidly diffuse into the leaf through stomata!
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From page 91... ...
On the other hand, atmospheric pollutants that accumulate in the ice cover of a lake over several months are discharged into the lake as a large pulse during ice and snow melt. Figure 6.2 shows one such pulse caused by the acid precipitation that accumulated in winter snow.
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From page 92... ...
92 pH r 7 6 5 1 976/77 M FIGURE 6.2 Seasonal changes of pH of lake water taken from the outlet of Little Moose Lake, Adirondacks, New York, and from a 3-m-deep pipe in the lake. The spring acid pulse is greater at the surface than at the 3-m-deep level.
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From page 93... ...
For example, sulfur may be released as hydrogen sulfide or clime thyl sulfide; several metals are released in a methylated form; and nitrogen is released as ammonia, nitrous oxide, and molecular nitrogen. These processes, widespread in aquatic
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From page 94... ...
Once incorporated into sediments, a pollutant cannot be flushed rapidly from a water body. Some materials may be transferred directly from sediments to pelagic biota; for example, mercury, selenium, and perhaps lead are methylated in sediments and transferred to the water column.
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From page 95... ...
Aquatic Sediments as Historical Records Aquatic sediments provide a "history" of changes in the aquatic ecosystem, its terrestrial watershed, and its airshed. The increase in heavy metals in lake sediments in this century is an excellent example (Robbing and Edgington 1977, Norton et al.
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From page 96... ...
A number of bacteria present in soils and lake waters are able to oxidize methane. Although there has been considerable study of which organisms can do so in laboratory media and of the biochemistry of the process, surprisingly little attention has been paid to the rates of biological methane oxidation under natural conditions.
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From page 97... ...
Many individual microbial species are able to metabolize carbon monoxide in laboratory culture (Nozhevnikova and Yurganov 1978, Bartholomew and Alexander 1979~. Investigations with soils suggest that, in the few soil samples investigated, the microorganisms consuming carbon monoxide are neither heterotrophs using carbon monoxide as a carbon source nor autotrophs using it as a source of energy; rather the responsible organisms co-metabolize the gas (Bartholomew and Alexander 1979, and personal communication)
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From page 98... ...
The addition of water to a dry soil decreases the rate of methyl mercaptan removal and has little effect on hydrogen sulfide removal. Both air-dried and wet soils are able to remove clime thyl disulfide, carbonyl sulfide, and carbon disulfide.
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From page 99... ...
TRANSFER OF SUBSTANCES FROM TERRESTRIAL TO AQUATIC ECOSYSTEMS Because aquatic ecosystems are repositories not only for direct atmospheric deposition but also for many of the substances leached from or initially deposited upon terrestrial drainages, aquatic ecosystems may be contaminated to a greater degree than terrestrial ecosystems. The degree to which materials entering from the atmosphere are retained by terrestrial soils and vegetation is therefore an important consideration when aquatic contamination is studied, particularly because the terrestrial portion of a watershed is usually much larger than the lake or stream which drains it.
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From page 100... ...
On the other hand, few lakes are as acid as the precipitation falling in their watersheds, which leads some authors to believe that buffering by terrestrial ecosystems may protect poorly buffered lakes from acidifying as rapidly as they might under the influence of unaltered acid precipitation upon the entire drainage basin (Gorham and McFee 1980~. The relatively high pH levels of calcareous soils neutralize the acid, while in soils below pH 5, aluminum species may be the major source of buffering (Johannessen 19801.
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From page 101... ...
The surface film in aquatic ecosystems is an area of concern. AS noted earlier, organic pollutants and heavy metals may concentrate there at orders of magnitude higher than in the atmosphere above or the bulk water beneath.
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From page 102... ...
If changes in the acidity of precipitation cause no increase in the weathering of the basic cations, Ca++ and Mg++, the relationship between the concentration of basic cations and the concentration of sulfate in lake water would be expected to move horizontally as a lake is acidified (arrow A)
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From page 103... ...
Gachter and Geiger (1979) using radioactive tracers found that 5 toxic metals, including mercury and zinC, decreased in concentration as they were passed up an aquatic food chain.
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From page 104... ...
Terrestrial Ecosystems In general, primary gaseous pollutants affect only terrestrial organisms and ecosystems. The distance over which effects are noted depends, of course, on weather conditions, the height of the stack
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From page 105... ...
Acid precipitation resulting from oxides of sulfur and nitrogen can affect terrestrial ecosystems (Drablos and Tollan 1980) , but the extent of these effects is difficult to assess.
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From page 106... ...
106 ~W / ZON 6w o o o o o o o o o cn ~r 0 ~ — o 1.
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From page 107... ...
Trace metals and other trace substances are known to be toxic at concentrations found in soils and fresh waters within a few kilometers of smelters (Hutchinson and Whitby 1977~. Toxic effects farther afield are more difficult to predict, because of inadequate background data.
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From page 108... ...
Terrestrial Ecosystems Menser and Heggestad (1966) were the first to demonstrate the synergistic effect of two gaseous pollutants upon plants.
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From page 111... ...
Among toxic metals a rather wide range of interactions occur. Nickel and copper in lake waters contaminated by the Sudbury smelters act synergistically in their effects on various green algae (Hutchinson 1973, Hutchinson and Stokes 1975~.
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From page 112... ...
112 I ° 1.00 an Lid at ~ 0.50 ° 0.30 0.23 B
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From page 113... ...
Anionic detergents plus metal had more than additive effects, while nonionic detergents plus metal had less than additive effects. On the other hand, phosphorus and nitrogen were found to increase the tolerance of algae for heavy metals, as demonstrated in the tolerance of Stigeoclonium tenue Kutz to heavy metals in South Wales (McLean 1974)
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From page 114... ...
Species that occupy a wide variety of habitats under natural conditions tend to have high genetic variability. For example, the ubiquitous algal genera Chlorella and Scenedesmus will survive concentrations of heavy metals lethal to most other algal species (Stokes et al.
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From page 115... ...
Perhaps most illustrative is the example of DOT. Before its extensive broadcast about the environment as an insecticide following World War II, its potential effects upon nontarget organisms were recognized by several scientists, including Cottam and Higgins (1946~.
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From page 116... ...
116 TABLE 6.3 Plant Processes and Characteristics That May Increase Tolerance to Acid Precipitation Exclusion Leaf orientation and morphology Chemical composition of cuticle Flower orientation Protection of sexual organs Pollination mechanism Neutralization Salts on leaf surfaces Buffering capacity of leaves Metabolic Feedback Reactions Enzymatic reactions that consume hydrogen ions or yield alkaline products SOURCE: Jacobson ( 19 80)
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From page 117... ...
The brown pelican population on Anacapa Island has shown breeding recovery since 1972 when the DDT dumping was stopped. Despite ODE residues in the sediments, the success rate for young per nest had risen from 0.04 in 1972 to 0.88 in 1975 (Schreiber 1980~.
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From page 118... ...
Gaseous pollutants have their greatest effect on terrestrial ecosystems, because the air-water interface offers to aquatic organisms some degree of protection from episodic events. When many pollutants are introduced to an ecosystem, effects are in many cases synergistic -- i.e., effects are greater than additive.
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