Simulated Acid Mist Research Articles

Mannitol can mitigate negative effects of simulated acid mist and fluoranthene in juvenile Japanese red pine (P. densiflora Sieb. et Zucc.)

The negative health effects of simulated acid mists and fluoranthene on juvenile Japanese red pine were investigated, and the methods of protection from these pollutants were examined. The needle gas exchange, chlorophyll fluorescence, chemical contents and visual damage to needles caused by acid mist applied alone or its conjunction with fluoranthene were investigated over 60 d and 20 d, respectively. Acid mist at pH 2 and 3 caused physiological and visual damage, which was enhanced by the addition of fluoranthene to the mist. However, fluoranthene and acid mist at pH 4 and 5 showed only minor effects. These findings indicate that acid mist may be more harmful to pine trees if it occurs in conjunction with polycyclic aromatic hydrocarbons. Moreover, suppression of the singular and additive effects of these compounds was achieved using mannitol, which may be widely applicable to suppression of reactive oxygen species-mediated plant damage.

BIOMASS, NITROGEN, SULFUR, AND PHOSPHORUS CONTENTS OF BEANS GROWN IN LIMED SOIL IN RESPONSE TO FOLIAR APPLICATION OF HNO3 OR H2SO4 MISTS

Bean plants (Phaseolus vulgaris L.) were subjected to simulated acid mist treatments (pH 4.5, 3.0, 2.3) in the greenhouse. Solutions containing either HNO3 or H2SO4 were applied as mists over a period of 31 days. The growth medium had a pHKCl of 7.9 and a calcium (Ca) content of 18.5 mg g−1. Plants were sampled at flowering and at ripening, for determination of length, fresh and dry weights of different plant organs, and number of nodules. The plant samples were analyzed for nitrogen (N), sulfur (S), and phosphorus (P) content. A significant reduction of stem growth was recorded as a result of the treatment. Some of the plants had interveinal chlorosis, indicating mild iron (Fe) or manganese (Mn) deficiency caused by the high soil pH. The lowest leaflet dry weight was 86% of the control at a dry matter content of 90% of the control. A reduction in shoot:root dry mass ratio was detected. Pod dry weight was not affected. High increases in leaflet N (145%) or S (204%) content were found, which were roughly proportional to the respective treatment levels of HNO3 or H2SO4. Phosphorus content and N:P ratio of leaflets responded to treatment levels and chemical composition of treatment solutions. The root S content was affected only slightly. Nodules were more sensitive to HNO3 treatment, which at pH 2.3 reduced the number of large nodules to 14% of the control at flowering. At ripening of the pods, the effect of treatments on nodules was less pronounced. H2SO4 treatment also reduced the nodule numbers at higher acidities of mist. Nodule numbers at different treatment levels covaried in all variants with stem height growth, shoot:root dry mass ratio and P content in pods. In HNO3 treated plants, the numbers of root nodules changed inversely to the S content in leaflets. It was concluded that an increase in S content in the plants was less than an increase in N content. The hypothesis that H2SO4 mist causes more disturbances in bean plants than HNO3 mist was not confirmed by the current experiments.

Effects of Simulated Acid Mist on a Sitka Spruce Forest Approaching Canopy Closure: Significance of Acidified Versus Non-Acidified Nitrogen Inputs

Effects of enhanced N, S and NS Acid additions, up to approximately 100 kg N and S ha−1 y−1, are described for a 15-year-old Sitka spruce forest growing on an acid peat in Scotland. Groups of 10 trees, replicated over 4 blocks, have been treated at canopy height on approximately 50 or 100 occasions with 2 mm precipitation equivalent, between April and November, since 1996. Relative stem volume increment (RSVI) has been consistently higher in the NS Acid treated trees compared with control or N treated trees since the second year of treatment, although no dose response was found. Litterfall was also considerably increased in the NS Acid treatments and showed a clear dose effect but was not correlated with RSVI. Base cation concentrations in soil waters, collected using zero tension lysimeters reflected the presence or absence of the spray treatments and showed a dose related increase in response to NS Acid inputs. Treatment with 2NS Acid increased NH4-N and NO3-N by an order of magnitude. Results after 4 years of treatment showed a positive growth and litterfall response to NS Acid inputs but no effect of N alone. Enhanced stemwood growth may be linked to the higher base cation and phosphate concentrations measured in the soil water in the presence of NS Acid and S treatments.

The response of Norway spruce seedlings to simulated acid mist

Four pot experiments are reported in which Norway spruce (Picea abies (L.) Karst) seedlings, of different nutrient status, were treated with acid mist for one growing season in open‐top chambers (OTCs). Combinations of H+, SO42−, NH4+ and NO3− were applied at different frequencies of application and supplying different doses of S and N kg ha−1. Plant growth, visible injury, frost hardiness and nutrient status were observed. These experiments were undertaken to improve our understanding of the interaction of environmental factors such as nutrition and mist‐exposure frequency on seedling response to N and S deposition.Both acidity (pH 2·7) and SO42− ions were necessary to induce visible injury. Mist containing SO42−, H+ and to a lesser extent NH4+ significantly reduced winter frost hardiness. Increasing the misting frequency, and to a lesser extent the overall dose, increased the likelihood of acid mist causing visible injury and reducing frost hardiness. Post‐planting stress, low N status and needle juvenility increased the likelihood of acid mist causing visible injury. Increased plant vitality, adequate N status and growth rate reduced the likelihood of acid‐mist‐induced reductions in frost hardiness.Principles underlying the responses of spruce seedlings treated in controlled conditions to acid mist are discussed.

Open-top chamber and field exposure of Sitka spruce to simulated acid mist: a comparison of results

Sitka spruce seedlings grown in pots of compost in open-top chambers (OTCs) or outside, in an agricultural loam soil, in different years, were treated with pH 2.5 acid mist comprising an equimolar solution, of H 2SO 4 and NH 4NO 3 at 1.6 mol m −3. The effects of rain, and frequency of acid mist applications on visible injury, nutrition and frost hardiness were evaluated in the OTC experiment. Similar evaluations were undertaken in the field where application frequency was dependent on windspeed, rain and direct sunlight. Rain washing significantly ameliorated the effect of acid mist on frost hardiness in OTCs. In the field experiment there was no effect of acid mist treatment. Increasing the frequency of misting in OTCs for the same exposure exacerbated the detrimental effects of acid mist, causing both visible damage and further increasing the sensitivity of the acid treated trees to freezing temperatures. The results show that the treatment environment can both ameliorate and exacerbate treatment effects.

Effects of elevated CO2, O3 and K deficiency on Norway spruce (Picea abies): nutrient supply, content and leaching

summaryTwo clones of 5‐yr‐old Norway spruce (Picea abies [L.] Karst.) were exposed to two atmospheric concentrations of CO2 (350 and 750μmol mol−1) and of O3 (20 and 75 nmol mol−1) in a phytotron at the GSF‐Forschungszentrum (Munich) over the course of a single season (April‐October). The phytotron was programmed to recreate an artificial climate similar to that at a high elevation site in the Inner Bavarian forest, and trees were grown in 40 1 containers of soil (pH 3.5) fertilized to achieve two levels of potassium nutrition; well fertilized and K‐deficient. Foliar nutrient analyses performed at the beginning of the exposure indicated that the fertilization programmes achieved their goal without significantly altering the levels of other nutrients or the soil pH. At the beginning of the fumigation, foliar K concentrations were 7–9 mg g−1d. wt for well fertilized trees and 4–5 mg g−1 d. wt for trees receiving no supplemental K. Over the course of the season, differences between K treatments intensified so that by the end of the experiment there was a five to sixfold difference between foliar K concentrations. This was associated with slight, but significant (P < 0.05), decreases in S and Zn (and of Cu in the 1989 needle year age class) and higher levels of C, N and Mg in K‐deficient trees. Foliar N concentrations were low for all trees (9–15 mg g−1needle d. wt) but were similar to levels found in the field.Elevated O3 was found to decrease significantly the C (P < 0.05) and N (P < 0.001) content of both current‐year (1989) and previous‐year (1988) needles independent of CO2 concentration, but apart from some minor changes in the concentrations of Cu and Mn in the current‐year needles no other effects of the pollutant on plant nutrient status were found. In contrast, CO2 enrichment resulted in significantly (P < 0.01) lower concentrations of K and P (effects on Mg were also on the borderlines of statistical significance) in current‐year needles, but there was no influence on the nutrient composition of the previous‐year needles (although effects on N were on the borderlines of statistical significance). CO2 enrichment also increased (P < 0.05) the C:N ratio of both current‐year and previous‐year needles. One factor contributing to the decline in foliar K at elevated CO2 appeared to be a marked increase (25–30%) in the rate at which cations were leached from the canopy by repeated simulated acid mist (pH 4.0) events, and this effect occurred independently of the O3 concentration. The information presented will aid the interpretation of parallel studies examining the effects of elevated CO2 and/or O3 on seasonal changes in photosynthesis, non‐structural carbohydrate content, antioxidants, tree growth and water use efficiency, and sheds further light on the growing scepticism concerning the role of O3 in the development of Mg and K‐deficiency symptoms characteristic of certain types of forest decline in central Europe.

The Effect of Simulated Acid Rain on Chlorophyll Fluorescence Spectra of Spruce Seedlings ( Picea abies L. Karst.)

Three-year old Norway spruce seedlings (Picea abies L. Karst), were grown in peat soil in a greenhouse and sprayed either with simulated acid mist (a mixture of H 2 SO 4 and HNO 3 , pH 2.7) or with distilled water of pH 5.6 for three months. During spraying, the soil was covered with plastic foil to avoid acidification of the soil. The photosynthetic pigment apparatus of spruce needles was analyzed using SDS-polyacrylamide gel electrophoresis, spectrophotometric determination of pigment content and low temperature chlorophyll fluorescence spectroscopy. The chlorophyll(Chl)-protein composition of spruce thylakoids was not affected by the acid treatment. Chl a/b ratio as well as the content of Chl (a + b) and total carotenoids tended to decrease in the acidified spruce seedlings but these changes were not significant. The acidification of spruce foliage resulted in a small but highly significant increase in the intensity of chlorophyll fluorescence emission of the light-harvesting complex (LHC). This increase indicates structural changes of the photosynthetic pigment apparatus resulting from direct foliage-mediated action of acid rain.

Effects of acid mist on needles from mature Sitka spruce grafts. Part II. Influence of developmental stage, age and needle morphology on visible damage

Mature grafts of five Sitka spruce ( Picea sitchensis (Bong.) Carr.) clones were exposed to simulated acid mist comprising an equimolar mixture of H 2SO 4 and NH 4NO 3 (1.6 and 0.01 mol m −3) at pH 2.5 and 5.0. Mist was applied to potted plants growing in open-top chambers on consecutive days, four times a week, at a precipitation equivalent of 1 mm per day. The total exposure to polluted mist was equivalent to three times that measured at an upland forest in SE Scotland. The aim of the experiment was to characterize the response of juvenile foliage produced by physiologically mature grafts (on seedling root stock) and compare it with the behaviour of juvenile foliage on seedlings. Development of visible foliar damage was followed through the growing season. Measurements of needle length, diameter, weight, surface area, surface was weight and wettability were made on current year needles to determine whether particular foliar characteristics increased susceptibility to injury. Significant amounts (> 10%) of visible needle damage was observed on only one of the five clones. Damage was most severe on the clone with the most horizontal branch and needle habit, but over the five clones there was no relationship between angle of branch display and damage. Likewise no combination of needle characteristics (length, width, area, amount of wax) was indicative of potential susceptibility. A comparison with previous acid misting experiments using seedlings suggests that juvenile foliage on physiologically mature trees is equally susceptible to visible injury as juvenile seedling foliage. Data of budburst differed among clones, and in this experiment exerted the over-riding influence on development of injury symptoms. Foliage exposed to a combination of strong acidity and high sulphate concentrations over the few weeks immediately following budburst suffered most visible injury. The absence of significant amounts of visible damage in UK forests probably reflects the general low susceptibility to visible injury of Sitka spruce exposed to acid mist.

The use of individual tree statistics to quantify effects in an ?acid mist? experiment with mature trees

Mature trees of a single clone of Sitka spruce (Picea sitchensis (Bong.) Carr.) growing in the field were exposed to simulated acid mist at pH 2.5 over three successive years. The growth of each tree in the acid mist treatment, in terms of the stem area increment, was related to the pattern of growth of the untreated trees at the site during 1991 and 1992. In 1993, the effects of stopping the acid mist treatment on half of the treated trees was investigated by comparing the actual growth against that predicted relative to the untreated trees on the basis of the previous years' data. The prediction of growth from one year to the next was consistently too small for the smallest acid-misted trees, suggesting that the growth rates relative to the untreated trees were increasing with time. Relative to the trees which continued to receive acid mist, however, the smaller trees which received no further acid mist in 1993 grew less than predicted, but there was a significantly greater growth than predicted for the largest ‘recovering’ trees. Results from the individual tree modelling approach showed that a 10% change in relative stem area increment would be detectable at the 5% level, using a block of 4 trees as a treatment unit. The statistical techniques used are alternatives to conventional ANOVA calculations in determining statistically significant treatment effects where numbers of replicates are small.

Causal mechanisms by which sulphate, nitrate and acidity influence frost hardiness in red spruce: review and hypothesis.

This paper summarizes results from four experiments in which red spruce seedlings (Picea rubens Sarg.) were exposed to simulated acid mist containing SO4 2- , NH4- , NO3 - and H+ ions. Seedlings were grown in compost, with or without fertilizer, in charcoal filtered air in open-top chambers near Edinburgh, Scotland. Plants were sprayed from bud burst between May and November with mist containing different concentrations and combinations of the four major ions to provide a range of doses, which were applied at different frequencies. Reductions in frost hardiness expressed in terms of the temperature which killed 50% of shoots (LT50 ) were significantly correlated with the dose of S received by the seedlings. Differences in foliar S concentrations between the controls and treated plants were correlated with S dose. Absolute S concentrations were, however, of limited use for predictive purposes. Seedlings appear to be more sensitive than older trees to S toxicity because the former have the greatest proportion of newly expanding needles which optimize conditions for foliar uptake. Seedlings are also least well equipped to export SO4 2- ions since they have a smaller resource of older foliage to supplement their assimilate pool. In conditions which promote uncontrolled SO4 2- ion uptake by foliage, i.e. high external SO4 2- concentrations and incompletely formed cuticles, the potential exists for the internal build up of SO4 2- ions. It is proposed that in the absence of sufficient assimilate and K the presence of these high concentrations of SO4 2- ions in the apoplast or cytosol can lead to protein denaturation and loss of membrane integrity. Reductions in frost hardiness appear to result through direct attack by SO4 2 ions on membrane proteins which impairs their function. Indirect effects on hardiness occur through both an increased consumption of sugars reducing the'pool'available for cryoprotection and a reduction in photosynthetic function, the ability to produce sugars. The presence of NO3- N mitigates the toxic effects of SO4 2 because SO4 2 ions are consumed in assimilation processes which both utilize and are facilitated by the presence of large amounts of fertilizer N. High concentrations of SO4 2 and H+ are found to be particularly toxic because of the synergistic effects these ions exert on their mutual uptake with devastating consequences for the control of cellular pH. Trees growing at high altitude sites are likely to be particularly sensitive to SO4 2- toxicity because (1) their carbon balance is low, (2) cuticle development is poor and (3) levels of soil available Ca2 tend to be low relative to Al3+ so that membranes may already be weakened as a result of insufficient Ca2+ ions for protein bridging.

Effects of acid mist on mature grafts of Sitka spruce. Part I. Frost hardiness and foliar nutrient concentrations

Mature grafts of five clones of Sitka spruce ( Picea sitchensis Bong. Sarg.) were exposed to simulated acid mist composed of an equimolar mixture of sulphuric acid and ammonium nitrate at pH 2·5 and pH 5·0 in open-top chambers from May to November 1991. Treatments were applied on consecutive days, four times a week. The pH 2·5 treatment provided an overall dose three times higher than that received by forests in upland areas of Britain. Frost hardiness was assessed in November by freezing detached current year shoots at a range of temperatures and assessing the rate of electrolyte leakage Foliar nutrient concentrations were determined on the same shoots. Acid mist at pH 2·5 significantly reduced frost hardiness in four of the five clones; the temperature causing 50% shoot death (LT 50) was increased by 0 to 7°C. The clones varied in their level of hardiness, one clone being exceptionally frost sensitive. The frost hardiness of the frost sensitive clone was found to be less perturbed by acid mist than the hardiness of the more frost resistant clones. Mature grafts showed a smaller reduction in hardiness at an equivalent dose than that found previously with Sitka spruce seedlings. Compared with seedlings, grafts had lower absolute concentrations of foliar sulphur. Exposure to acid mist at pH 2·5 increased %S in current year foliage by <0.05% compared with absolute increases of more than 0·10% in current year foliage of seedlings. We conclude that the effect of acid mist on frost hardiness is likely to be less on mature trees than on seedlings and that the increased frost risk to mature trees of Sitka spruce from occult deposition alone is small.

Mycorrhizae of Japanese black pine (Pinus thunbergii): protection of seedlings from acid mist and effect of acid mist on mycorrhiza formation

To determine the effects of acid precipitation on Japanese black pine (Pinus thunbergii Parl.) with and without mycorrhizae (Pisolithus tinctorius (Pers.) Coker et Couch), 1-year-old seedlings were exposed to simulated acid mist, pH 3.0, for 10 min per day twice a week for 3 or 4 months. Simulated acid mist adversely affected the transpiration rate and lowered the extractable phosphorus content of seedlings, but seedlings with mycorrhizae were less affected by acid mist than were nonmycorrhizal seedlings. Simulated acid mist also retarded mycorrhiza formation. Key words: mycorrhizae, phosphorus content, Pinus thunbergii, Pisolithus tinctorius, simulated acid mist, transpiration rate.

The effects of simulated acid mist on the growth rates of conifer aphids and the implications for tree health

AbstractScots pine trees, P. sylvestris, were sprayed with simulated acid mist in the laboratory to test the effects on the nymphal and population growth rates of three species of pine aphid, S. pineti, E. agilis and C. pini. The acid treatment was found to promote the mean relative growth rates of both S. pineti and C. pini, while population growth rates were significantly enhanced in S. pineti and E. agilis. The acid treatment was also found to cause necrosis and chlorotic mottling of needles. The only significant adverse effect of aphids on needles was shown by E. agilis, which was found to further exacerbate the chlorotic mottling of needles caused by acid mist. The possible implications of these findings for field populations of aphids and trees are discussed.ZusammenfassungZum Einfluß von simulierten sauren Niederschlägen auf die Entwicklungsrate von Nadelholzläusen im Zusammenhang mit den neuartigen WaldschädenPinus sylvestris wurde im Labor mit künstlichen sauren Niederschlägen behandelt, um deren Wirkung auf die Nymphen‐ und Populationsentwicklung von S. pineti, E. agilis und C. pini zu untersuchen. Die Behandlung begünstigte die durchschnittliche relative Wachstumsrate von S. pineti und C. pini, während die Wachstumsrate der Population von S. pineti und E. agilis signifikant erhöht wurde. Die Säurebehandlung verursachte nekrotische und chlorotische Nadelfleckungen. Nur für E. agilis konnte ein signifikant negativer Einfluß der Läuse auf die Nadeln nachgewiesen werden. Durch die Saugtätig‐keit dieser Art wurden die durch die Säaurebehandlung verursachten chlorotischen Fleckungen verstärkt. Die Bedeutung dieser Ergebnisse für Freilandpopulationen wird diskutiert.

Effect of Simulated Acid Mist on Pine Wilt Disease

Effect of Simulated Acid Mist on Pine Wilt Disease

Visible foliar injury of red spruce seedlings subjected to simulated acid mist.

Two-year-old red spruce seedlings [Picea rubens Sarg. syn. P. rubra (Du Roi) Link] were subjected to 6 simulated acid mist treatments (pH 2.5, 2.7, 3.0, 3.5, 4.0, 5.0) in a replicated experiment using open-top chambers. Acid mist solutions containing equimolar (NH4 )2 SO4 , and HNO3 were applied twice weekly for 22 weeks, each application being equivalent to 2 mm of precipitation. Visible symptoms of foliar damage were observed on the 3 most acidic mist treatments (pH 2.5, 2.7, 3.0). The inputs of nitrogen, sulphur and acidity in the most acidic treatment were 55, 42, 1,3 kg ha-1 , respectively, over a 10 week period. The plants subjected to the pH 2.5 treatment were found to be most severely damaged with approximately 40% foliar necrosis after 10 weeks of treatment. On approximately 80% of seedlings, necrosis was confined to current year needles only. These damaged needles were initially light brown or light orange in colour turning a deeper red 3 to 5 weeks after initial necrosis. Percentage foliar damage was linearly related to concentration (of NH4 + , NO3 - , SO4 2- and H+ ) with 62% foliar damage in the pH 2.5 treatment after a 22-week period. Spray application stopped in December 1987. Observations during the following spring showed that the pH 2.5 and pH 3 treatments induced earlier Hushing, requiring 60 day °C less thermal time than the pH 5-0 treatment. In 1988, this decrease in thermal requirement was equivalent to flushing 11 days earlier. There was no evidence of acid mist treatments inducing bud mortality.

Short term effects of simulated acid mist on gas exchange of Eucalyptus globulus1

AbstractThe effects of simulated acid mist treatment on net photosynthesis were determined on Eucalyptus globulus trees. Net assimilation decreased for all the three levels but after 3—4 days recovered only in the pH 3.5 one. Acidity effects are discussed in terms of morphological change to the leaves and as alteration of stomatal and mesophyll resistances. 1 Research work supported by C.N.R., Italy. Special grant I.P.R.A. sub‐project 1. paper N. 2014

RESPONSE OF BUSH BEAN EXPOSED TO ACID MIST

Bush bean plants (Phaseolus vulgaris L. cv. Contender) were treated once a week for six weeks with simulated acid mist at five pH levels ranging from 5.5 to 2.0. Leaf injury developed on plants exposed to acid concentrations below pH 3 and many leaves developed a flecking symptom similar to that caused by ozone. An adaxial, interveinal bleached area resembling SO2 injury also developed on some trifoliate leaves at the low pH treatments. Microscopic observation of injured trifoliates indicated that the palisade cells were plasmolyzed and that the chloroplasts lost structural integrity. Reductions in plant weight and chlorophyll content were detected across the pH gradient. Seed and pod growth were reduced at some intermediate acid depositions even though no visible foliar injury developed. Foliar losses of nitrogen, calcium, magnesium and phosphorous increased with decreases in acid mist pH, whereas foliar potassium concentrations were unaffected by acid mist treatment.

Response of Bush Bean Exposed to Acid Mist

Bush bean plants (Phaseolus vulgaris L. cv. Contender) were treated once a week for six weeks with simulated acid mist at five pH levels ranging from 5.5 to 2.0. Leaf injury developed on plants exposed to acid concentrations below pH 3 and many leaves developed a flecking symptom similar to that caused by ozone. An adaxial, interveinal bleached area resembling SO2 injury also developed on some trifoliate leaves at the low pH treatments. Microscopic observation of injured trifoliates indicated that the palisade cells were plasmolyzed and that the chloroplasts lost structural integrity. Reductions in plant weight and chlorophyll content were detected across the pH gradient. Seed and pod growth were reduced at some intermediate acid depositions even though no visible foliar injury developed. Foliar losses of nitrogen, calcium, magnesium and phosphorous increased with decreases in acid mist pH, whereas foliar potassium concentrations were unaffected by acid mist treatment.