PubMed · 2114486
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A J Crane. 1990. Acid rain.. https://doi.org/10.1177/146642409011000301
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This paper describes the condition of forest ecosystems subjected to smelter pollution in the Kola peninsula. This assessment is based on the parameters of the biogeochemical cycle. The defoliation index was used to delimit three basic forest states: background, defoliating, sparse. Close to the smelter, due to expansion of the area not covered by vegetation, a fourth type of state, so-called "industrial deserts", has been observed. The concentrations of sulphur, copper and nickel in the precipitation in the forests generally declined with distance from the smelter. The defoliating forests are noted for the highest Ca, Mg, K concentrations in the summer precipitation. In sparse forests and industrial deserts a decrease in the Ca, Mg, K concentrations in the summer precipitation in comparison with the defoliating forests, despite the particle emissions, could be attributed to the reduction in forest biomass. The higher levels of soil and soil leachate carbon and acidity in the defoliating forests was due to higher litterfall and to the higher dissolution of fulvic acids by the acidic precipitation. This increase in organic matter levels affects soil cation exchange capacity and cation saturation. The pine trees demonstrated significant changes in the uptake of elements in all types of forests under pollution. Elevated levels of S, Ni, Cu and K and reduced levels of Mg, Mn and Zn were found in the needles of different age classes.
In Polar regions subject to acid precipitation, the spring flood period is swift and can be divided into three phases. In phase one, dilution and anion substitution by SO4 controls episodic acidification. Phase two is characterized by interaction of snowmelt water with the catchment. A combination of several factors contributes to declines in pH and ANC. In forest and wetland ecosystems, organic acids greatly contribute to the pH depression in the streams. In the coastal tundra and forest-tundra zones, "salt-effect" acidification predominantes. The increase in toxic forms of trace (Ni, Cu) and rare (Fe, Al, Mn) elements during pH depressions may create stress conditions for the fauna of polar fresh waters during a flood period.
Enclosure experiments aimed to assess the role of Chaoborus larvae in regulating lower trophic levels under natural and nutrient-enriched conditions were performed in situ in the dimictic, oligotrophic clearwater Lake Njupfatet, central Sweden. One experiment was performed before, and one after, whole-lake calcite treatment. In the acidic system, total planktonic biomass (TPB; the sum of phyto-, bacterio-, protozoo-, and metazooplankton), dominated by the cyanobacterium Merismopedia, was only weakly stimulated by the nutrients while the predator had no effect. In the limed environment, TPB increased strongly in response to the nutrients in combination with a negative response to the predator. Principally phytoplankton, but also bacterioplankton and protozooplankton (ciliates) were stimulated by the nutrients. It is argued that Merismopedia acted as a dead-end in the energy flow in the acidic system. Liming resulted in the disappearance of Merismopedia and this opened the flow of material to higher trophic levels. Since liming also led to a significant reduction in the concentrations of phosphorus in the lake water, it is proposed that a combination of liming and gentle fertilization might be used to restore the productivity of acidified lakes.