Simulated acid rain

Pennanen T, Fritze H, Vanhala P, Kiikkila O, Neuvonen S, Baath E (1998) Structure of a microbial community in soil after prolonged addition of low levels of simulated acid rain. Appl Environ Microbiol 64 2173-2180... 

Kohno, Y., Matsumura, H., Kobayashi, T. (1998). Differential sensitivity of 16 tree species to simulated acid rain or sulfur dioxide in combination with ozone. In Bashkin, V. N., Park,... 

Zinc and zinc-coated products corrode rapidly in moisture present in the atmosphere. The corrosion process and its mechanism were studied in different media, nitrate [283], perchlorate [259], chloride ions [284], and in simulated acid rain [285]. This process was also investigated in alkaline solutions with various iron oxides or iron hydroxides [286] and in sulfuric acid with oxygen and Fe(III) ions [287]. In the solution with benzothia-zole (BTAH) [287], the protective layer of BTAH that formed on the electrode surface inhibited the Zn corrosion. 

Disc N. B. and Verry E. S. (2001) Supression of peatland methane emission by cumulative sulfate desposition in simulated acid rain. Biogeochemistry 53, 143-160. 

Gaud V., Disc N., and Fowler D. (2002) Controls on suppression of methane flux from a peat bog subjected to simulated acid rain sulfate deposition. Global Biogeochem. Cycles 16, 4-1-4-12. 

Single extractants water and simulated acid rain at pH 4... 

North Thailand Forest ecosystems. The input of < 1 meq/lOOg soil to the forest soil in the northern part of Thailand, with the organic content of 1.33 percent, has no changes in pH value due to existing hydrogen buffering capacity. Simulated acid rain... 

Elemental Analysis of Simulated Acid Rain Stripping of Indiana Limestone, Marble, and Bronze... 

Acid rain has been shown to effect woody plants at all stages of their development. Seedlings, immature through older, fully expanded leaves and needles, as well as annual rings of woody plants have been shown to be injured by simulated acid rain. 

In a field study it was found that, while simulated acid rain at pH 2.5 damaged Empire apple blssoms and reduced pollen germination, it did not influence fruit set (4). 

Several woody plant species will react to exposure of simulated acid rain by forming foliar lesions. While the pH level of simulated acid rain that produced these lesions varies from species to species, the lesions themselves are generally yellow to brown necrotic spots or regions (see Table 1). Additionally, on two clones of poplar, galls were formed in response to simulated acid rain. Surface characteristics such as stomatal presence and density, trichome density, type and amount of epicuticular wax, leaf surface wettability and buffering capacity have all been shown to influence foliar injury by simulated acid rain. However, it may be... 

The previous studies and almost all of the simulated acid rain experiments discussed herein were designed to quickly produce symptoms and obtain threshholds for plant injury. To date there has been no documented field identification of ambient acid rain injury to forest trees or woody plants (8). Among many potential reasons, this may be due either to the fact that ambient acid rain is often accompanied by other atmospheric pollutants, thus injury symptoms are different, or that changes are occurring subtly over time ... 

TABLE 1. A partial list of woody plants which developed foliar lesions after exposure to simulated acid rain. 

Rain and mist, acid or otherwise, have been shown to leach nutrients from the foliage of woody plants (19). Wood Bormann (13) found that when sugar maple seedlngs were exposed to pH 3.0 (leaf injury), 3.3, and 4.0 of simulated acid rain, there were significant increases in leaching of K, Mg " and Ca " ions. Cronan (21) found that in coniferous throughfall which was exposed to ambient rain of pH 4.0, there was an increase in H, Ca , Mg, K+, Mn, S0 3" and Cl" as compared to bulk precipitation. In contrast, throughfall... 

Additional information on how leaf litter potentially interacts with acid rain was contributed by Lee V7eber (2 ). In their experiments, acid rain was simulated in a field situation on sugar maple and red alder. Rain as throughfall was allowed to interact with leaf litter and the leachate was collected. Litter leachate was found to be higher in S0 , Ca+ and Mg+, and the pH was found to have increased. Thus, they hypothesized that the litter was neutralizing the simulated acid rain, with red alder litter being more effective than sugar maple. 

These few experiments are not enough, however, to define the effects of simulated acid rain on the woody host disease pathogen... 

Preliminary work using loblolly pine seedlings growing in sand, explored the effect of simulated acid rain on the infection of roots by ectomycorrhizae. Shafer et al. ( ) found that simulated acid rain of pH 4.0 and 3.2 was inhibiting ectomycorrhizal infection when compared to roots exposed to pH 5.6. At pH 2.4 there appeared to be stimulatory effects on infection. The authors suggested that increased soil acidity was the cause of the enhanced ectomycorrhizal infection, as other experiments have shown that, if substrate acidity is increased, so will infection. The authors did caution, however, that this short term greenhouse study was just preliminary. 

Tveite and Abraham (42) also observed a stimulation in height and diameter of Scots pine saplings when pH levels 2, 2.5 and 3.0 of simulated acid rain were supplied. There were no effects on Norway spruce or lodgepole pine. The authors suggested that the growth of Scotch pine may be due to increased uptake of nitrogen from the soil. 

The research available to date presents a partial view of the impacts of acid rain on woody plants. Many of the impacts are still only potential impacts, as simulation studies versus field studies present a conflicting view. However, one thing appears quite clear - more research is needed. As many researchers have found, the effect of acid rain is not going to be one of simple cause and effect, but rather one of a multiple factor interaction. Thus, future work should be statistically designed to test the inter-action(s) rather than main effects. Work needs to be done over both the short and long term to assess injury. Basic physiological work across disciplines with the standardization of techniques used (e.g. one set type of simulator for all researchers to produce simulated acid rain) must be employed in order for different experimental results to be comparable. If we can discover how plants will react to given combinations of stresses, only then will we be able to propose an appropriate course of action. 

Peng CX, Peng CL. Effects of simulated acid rain on seed germination and seedling growth of three crops. J Trop Subtrop Bot 2003 4 400-4. 

Chung S. W., Bae J. O., Koh K. S., et al, 1992. Effects on the stracture on productivity of Pinus rigida stands and the responses of Pinus densiflora seedlings to simulated acid rain. In A study on the assessment of damage by air pollutants and acid rain (II), Report of National Institute of Environmental Research Repubhc of Korea, 137-209. 

Botanieal Gardens, transplanted material, simulated acid rain... 

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