Effect of simulated acid rain on the growth of soybean

Soybean seedlings (Glycine max) grown in a glasshouse were exposed to simulated acid rain using a solution of deionized water containing sulfate, nitrate and chloride in concentrations and proportions equivalent to those in ambient rain water. Plants were subjected to acid rain treatment twice a week during the growing season, for a 1 hr period at a rate of 5 mm hr^?1. When the acid rain was below pH 3.0, visible symptoms developed in the young trifoliate leaves. However, at a pH above 3.0 there was no evidence of visible leaf injury; also tissue dry weights and leaf areas were not affected even after 7 weeks of exposure. The number of root nodules in plants exposed to acid rain at pH 4.0 tended to be higher than those of control plants maintained at pH 5.6, but decreased subsequently with decreasing pH. Based on our results current ambient levels of rain acidity in Japan should not have an adverse impact on seedling growth in soybean.     

模拟酸雨对不同园林植物叶片生理生态特性的影响

采用盆栽方法,以自来水（pH值6.5）作为对照,研究了pH值为1.7,3.0,4.3,5.6模拟酸雨条件下新梢增长量、叶片损伤程度和叶片生理生态特性,并分析了园林植物对酸雨污染的敏感性反应。结果表明:不同pH值的酸雨对园林植物新叶片有不同程度的抑制,酸雨的酸度越大,对园林植物叶片的伤害越大,以pH值1.7的模拟酸雨对园林植物叶片的伤害最为严重,pH值5.6伤害较为轻微,但不同种类之间对酸雨的抗性有明显差异;pH值4.3~5.6处理对园林植物新梢生长率没有显著的影响和抑制作用,而pH值小于3.0处理则严重抑制了园林植物新梢生长;随模拟酸雨强度的增强,园林植物叶片的细胞质膜透性和丙二醛（MDA）含量逐渐升高,当pH值小于3.0时,细胞质膜透性和丙二醛（MDA）含量则急剧增加,当pH值为1.7时,不同园林植物叶片则严重受损;园林植物叶片叶绿素含量、叶片N和P含量随酸雨强度的增加逐渐降低,当pH值小于3.0时,园林植物叶片叶绿素含量、叶片N和P含量则急剧降低,当pH值为1.7时,不同园林植物叶片则严重受损;相关分析表明,酸雨增加了园林植物对环境的敏感性。园林植物对酸雨具有较强的抵抗能力,对园林植物生理活动影响的阈值pH值大致介于3.0~4.3,因此,本研究的6种园林植物可以作为酸雨灾害严重地区园林绿化及植被构建的物种。     

Effect of simulated acid rain on the growth of Japanese conifers grown with or without fertilizer

Three-year old cuttings of Japanese cedar (Cryptomeria japonica), Japanese cypress (Chamaecyparis obtusa) and Sawara cypress (Chamaecyparis pisifera) were grown in pots with andosol and were exposed to simulated acid rain (SAR) at pH 2.0, 3.0, and 4.0 for 23 months. Total precipitation was 2460, 3960, or 5450 mm and SAR contained sulfuric, nitric and chloric acid at equivalent ratio of 5∶2∶3. Deionized water of pH 5.6 was a control. Exposure to SAR at pH 2.0 induced visible foliar injuries, but not any visible symptoms at pH 3.0 or higher. Total dry weights of 3 conifer cuttings grown with fertilizer were about two fold of those in plants grown without fertilizer and they reduced significantly by the exposure to SAR at pH 2.0. However, Cryptomeria japonica without fertilizer increased dry weights even though plants developed reddish-brown necrosis in large parts of tops. These 3 coniferous cuttings did not show any significant growth reduction at pH 3.0 and 4.0. Soil pH after receiving 5450 mm of SAR at pH 2.0 was 4.0 and molar ratio of (K+Ca+Mg)/Al in water and 1M ammonium acetate soluble fraction of the soil was about 0.3 and 0.4. respectively. However, dry weight of root in plants grown without fertilizer did not decrease. This suggested that growth reduction in plants fertilized and exposed to pH 2.0 was due to a reduction in photosynthetic organs associated with visible injuries, but not direct linkage with root growth inhibition due to soil acidification stress.     

Phenological Disorder Induced by Atmospheric Nitrogen Deposition: Original Causes of Pine Forest Decline over Japan. Part I. Phenological Disorder,Cold Death of Apical Shoots of Red Pine Subjected to Combined Exposures of Simulated Acid Rain and Soil Acidification,and Implications for Forest Decline

Seeds of red pine (Pinus densiflora Sieb. and Zucc.) were sown in red-yellow soil artificially adjusted to pH (H₂O) 4.10, 4.60 or 5.90 by adding H₂SO₄ solution to the soil (pH 5.90), and the three-month seedlings were exposed to simulated acid rain at pH 2.0, 3.0 or 5.6 for 10 minutes once, 3 times a week, for 12 months from 4 August 1994 to 3 August 1995 alone or in combination. Significant interactive effects between acid rain and soil acidification on growth and whole-plant net photosynthetic rate, and cold death ratio of new apical shoots following a cold snap were observed in a quadratic response pattern. The simulated acid rain increased budburst, new needle spread and elongation, and new apical shoot death percentage following a cold snap, but did not induce visible injury. In the highest soil acidity treatment at a soil pH 4.1, whole-plant net photosynthetic rate and seedling height exhibited a quadratic responses with increasing rain acidities. On the other hand, soil acidification caused leaf yellowing. The death percentage of new apical shoot of seedlings exposed to rain pH 2.0 following a cold snap was linearly enlarged with increasing soil acidities. With increasing soil acidity, height and whole-plant net photosynthesis of the seedlings exposed to rain pH 3.0 exhibited a linear increase response, while height of seedlings exposed to control rain exhibited a quadratic response. It is suggested that the results provide experimental evidency for phenological disturbances and an enhancement of frost risk by direct acid rain and indirect longterm soil acidification which may be significant in forest decline.     

Impact of Simulated Acid Rain on Growth and Yield of Two Cultivars of Wheat

The present study reports the results of a field-basedexperiment conducted to assess the effect of simulated acid rain(SAR) of different pH i.e. 5.6 (control), 5.0, 4.5, 4.0 and 3.0on two cultivars of wheat (Triticum aestivum, Malviya 213(M213) and Sonalika). Shoot and root lengths significantlydeclined at pH 3.0 in both varieties. Leaf area declined at pH4.0 and 3.0 in M213 at both ages and at 75 days in Sonalika.Total biomass of 75 days plants declined significantly at pH range4.5–3.0 in M213 and at pH 4.0 and 3.0 in Sonalika. Netassimilation rate (NAR) declined significantly at pH 3.0 inboth varieties. Compared to control, yield of M213 showedsignificant reductions at pH 4.0 and 3.0, whereas Sonalikaresponded negatively at pH 3.0. The study showed that acid rainhas a significant negative effect on wheat plant performance.     

Effect of simulated acid rain on mycorrhizal infection of Pinus strobus L.

Mycorrhizal infection but not growth of white pine seedlings was reduced by application of simulated rain at pH 3.5 at 3 times ambient rates to plants grown in steamed Mardin soil inoculated with Pisolithus tinctorius. In unsteamed Mardin soil, the simulated acid rain at 3 times ambient rates had no effect on mycorrhizal infection or growth of pine seedlings if the rain was applied to the plants and soil or to only the soil before planting, except that nitrate-containing acid rain increased growth, infection and N content. In limed Mardin soil, the simulated acid rain reduced mycorrhizal infection if applied to the plants and soil as the seedlings were growing but not if applied to the soil before planting. Application of pH 3.5 rain at ambient rates had no detectable influence on mycorrhizal infection in 6 of 9 soils tested, but it stimulated infestion in 3 soils if the simulated rain contained only sulfate and in 1 soil if it had both sulfate and nitrate.     

Effect of simulated sulfuric acid rain on the chemistry of a sulfate-adsorbing forest soil

Simulated H₂SO₄ rain (pH 3.0, 3.5, 4.0) or control rain (pH 5.6) was applied for 3.5 yr to large lysimeter boxes containing a sulfate-adsorbing forest soil and either red alder (Alnus rubra Bong) or sugar maple (Acer saccharum Marsh.) seedlings. After removal of the plants and the litter layer, soil samples were obtained at 15-cm intervals to a total depth of 90 cm. Elevated SO₄ concentrations caused by the simulated H₂SO₄ rain were most pronounced for the top 15 cm, but extended down to 45 cm (maple) or 75 cm (alder). There were no effects on SO₄ concentrations at a depth of 75 to 90 em. This confirmed the existence of a sulfate front between 20 cm and 100 cm, as postulated earlier on the basis of extracted soil solutions. Decreases in Mg and Ca concentrations, base saturation, and soil pH were limited to the uppermost 15 cm and, in most cases, to the pH 3.0 treatment. Concentrations of Mg and Ca for the pH 3.0 treatments were greater than control at a depth of 15 to 30 cm, indicating transport of these cations from the soil surface. Concentrations of Na and K, and cation exchange capacity, were not affected by simulated H₂SO₄ rain. Elevated concentrations of NO₃ and extractable Zn throughout the alder systems indicated (1) either increased rates of symbiotic N-fixation or decreased rates of N immobilization; and (2) mobilization of Zn by all acid rain treatments.     

Growth and gas exchange of loblolly pine seedlings as influenced by drought and air pollutants

One-year-old loblolly pine seedlings were exposed to 0₃(≤0.025 or 0.10 μ L L^?1, 4 hr d^?1, 3 d wk^?1) in combination with simulated rain (pH 5.6 or 3.0, 1 hr d^?1, 2 d wk^?1, 0.75 cm hr^?1) for 10 wk. After the 10-wk treatment, the seedlings were submitted to two drought cycles, and water potential, net photosynthesis (Pn), and transpiration (Tr) were measured. Whole-plant fresh weight increment and relative growth rate were significantly increased in seedlings exposed to simulated rain at pH 3.0 compared to pH 5.6. An interaction between 0₃ and simulated rain occurred in height growth. Shoot height elongation was significantly less in seedlings exposed to 0.10 μL L^?1 0₃ + pH 5.6 than in any other pollutant combination after the 10-wk treatment period. There were no significant effects of 0₃ on Pn and Tr prior to the drought cycles; however, after the first drought cycle, Pn was significantly higher in seedlings pre-exposed to 0.10 μL L^?1 0₃ compared to the low 0₃ concentration. The 10-wk treatment with simulated rain at pH 3.0 significantly increased Pn and Tr. The relationship between gas exchange rates and needle water potential during the moisture stress period was affected by preexposure to pollutants. In general, Pn and Tr were more sensitive to decreasing needle water potential in seedlings exposed to pH 3.0 during the first drought cycle and to 0.10 μL L^?1 0₃ during second drought cycle.     

Effects of simulated acid rain on the growth,nutrition, foliar pigments and photosynthetic rates of sugar maple and white spruce seedlings

Sugar maple (Acer saccharum Marsh.) and white spruce (Picea glauca (Moench) Voss) seedlings were exposed to simulated acid rain (SAR) of pH 3.2, 4.3 and 5.6 for two and one-half growing seasons. Ambient rain was excluded from the treatment plots by mobile rain exclusion canopies. Sugar maple seedlings treated with pH 3.2 SAR had significantly higher foliar concentrations of nitrogen, sulphur and manganese, compared to either the pH 4.3 or 5.6 treated seedlings. The pH 3.2 treated seedlings also tended to have greater growth and photosynthetic rates compared to the pH 4.3 and 5.6 treated seedlings. In contrast, the pH 3.2 treated white spruce seedlings tended to have decreased growth and lower foliar potassium concentrations relative to the pH 4.3 and 5.6 treated seedlings. Statistically there were no significant treatment differences in seedling height, seedling diameter, foliar pigments, or photosynthetic rates in either the sugar maple or white spruce seedlings.     

模拟酸雨对小麦种子萌发和幼苗生长的影响

以中性溶液（pH=7.0）为对照,研究了pH值为1.0,2.0,3.0,4.0,5.0和6.0模拟酸雨对小麦种子萌发和幼苗生长的影响。结果表明,小麦种子萌发和幼苗生长各指标随着pH值的降低而降低,弱酸（pH5.0～6.0）条件下小麦种子能够正常萌发和生长,种子萌发和幼苗生长各指标与对照没有显著差异（P > 0.05）;在pH低于5.0时,小麦种子萌发和幼苗生长严重受阻,种子萌发和幼苗生长各指标均显著低于对照（P < 0.05）;pH为1.0时,小麦种子则完全失去活性;不同pH值模拟酸雨胁迫对小麦幼苗生理指标影响较大,叶绿素含量、类胡萝卜素含量、保护酶（SOD,POD,CAT）和非保护酶（PPO,PAL）活性随酸性的增强呈降低趋势,而相对电导率和丙二醛（MDA）含量呈上升趋势。综合分析认为,小麦幼苗生长比种子萌发对模拟酸雨的响应更为敏感。     

Effects of acidity in precipitation on terrestrial vegetation

Over the last several decades rain in the Northeastern United States has become more acidic presumably as a result of anthropogenic inputs of SO_x and NO_x to the atmosphere and their conversion to H₂SO₄ and HNO₃. Present experimental results suggest that acidic precipitation would initially affect organisms on leaf surfaces and epidermal cells of leaves of higher plants. More internal cell layers would be affected with increasing duration or frequency of exposure. Differences in responses of plant foliage among plant species to acidic precipitation appear to be due to the degree of leaf wetting and differences in responses of leaf cells to low pH rain. Moreover, within the same plant, particular structures or cell types may be more sensitive than others. If the United States is to utilize coal reserves for electric power generation that might increase rainfall acidity in the future, an assessment of the impact that acidic rain might have on terrestrial vegetation is necessary. In one experiment, field-grown soybeans were exposed to short duration rainfalls of either pH 4.0, 3.1, 2.7, or 2.3 to provide inputs of 50, 397, 998, or 2506 μeq of H⁺, respectively, above ambient levels throughout the growing season. Control plots received only ambient rainfalls. These additional H⁺ decreased seed yield, 2.6, 6.5, 11.4, and 9.5%, respectively. A treatment response function determined between H⁺ treatments and seed yield wasy=21.06?1.01 logx had a correlation coefficient of ?0.90. Researchers must design additional experiments with adequate experimental controls to assess the impact that acidic rain, at the present pH levels of 3.0 to 4.0 or at anticipated worst-case levels, that could occur if the acidity of rain should increase. Only a holistic view of the impacts that acid precipitation may have on vegetation will enable optimal energy and environmental policy decisions to be made.     

Simulated acid rain: Effects on leaf quality and yield of broadleaf tobacco

Simulated acid rains of pH 5.6, 4.0, 3.5, 3.0, 2.5, or 2.0 were applied to leaves of broadleaf tobacco twice per week for 1, 2, 3, 4, or 5 weeks. Only those plants receiving rain of pH 2.0 were injured and, among those, the plants receiving fewer applications had less severe injury. Foliar symptoms resembled weather fleck (O₃ injury) at first, but become distinguishable from them with time.     

小麦与油菜种子萌发对酸雨胁迫的反应研究

用pH2.0、2.5、3.0、3.5、4.0、5.0模拟酸雨处理小麦和油菜种子试验结果表明,pH2.0时小麦和油菜种子不发芽,pH2.5时只有小麦异状发芽,pH≥3.0时小麦和油菜种子发芽率、发芽势、发芽指数、活力指数均与pH值显著正相关,小麦异状发芽率则随pH值上升而降低。小麦和油菜的吸水值、呼吸速率、贮藏物质运转效率也与pH值显著正相关,小麦贮藏物质消耗率与pH值显著正相关,而油菜与pH值显著负相关;小麦和油菜的根、芽长抑制指数均与pH值显著负相关,且小麦抗酸雨胁迫能力强于油菜。     

酸雨对木芙蓉幼苗光合作用及抗氧化酶活性的影响

以pH 5.6为对照,采用pH 4.0、pH 3.0、pH 2.0强度的酸雨对2年生木芙蓉进行人工模拟胁迫,研究酸雨胁迫对木芙蓉叶片可见伤害、质膜透性(Membrane Permeability,MP)、叶绿素(Chlorophyll,Chl)含量、抗氧化酶系统及气体交换参数的影响.研究结果表明,pH 2.0和pH 3...     

Effect of the quantity and duration of application of simulated acid precipitation on nitrogen mineralization and nitrification in a forest soil

A study was conducted of the influence of the rate of application of simulated acid rain on N mineralization and nitrification in a forest soil. The rates were varied by applying different quantities of simulated rain for varying periods of time. The soil was exposed in the laboratory to simulated rain at pH 3.5, 4.1, or 5.6 at rates equivalent to 1.5, 2.3, 4.6, 7.1 or 15 times the average rate of precipitation in the field, and then mineralization of soil N or oxidation of added ammonium was determined. The rates of N mineralization were inhibited by precipitation at pH 3.5 or 4.1 when applied for 27 to 234 day at rates 1.5 times greater than that which occurs in nature. Nitrogen mineralization was not affected by simulated rain at pH 3.5 or 4.1 in soils exposed for 156 day at 2.3 times the natural rate of precipitation, for 27 or 81 day at 4.6 times the natural rate, for 54 day at 7.1 times the natural rate, or for 234 day at 15 times the natural rate. On the other hand, mineralization was fastest in soil exposed to pH 3.5 rain for 234 day at 4.6 times the natural rate of precipitation and for 81 day at 15 times the natural rate. Nitrate formation in soil amended with ammonium was inhibited by rain of pH 3.5 regardless of the intensity of rain or the duration of exposure. For a constant rate of rain application, the inhibition of nitrate formation in ammonium-amended soil generally increased with longer periods exposure. The data show that the use of different rates of additions of artificial rain or different periods of exposure to the simulated precipitation will lead to different conclusions on the influence of acid rain on N mineralization in soil.     

Mineral nutrition,carbohydrate content and cold tolerance of foliage of potted red spruce exposed to ozone and simulated acidic precipitation treatments

Ninety potted red spruce saplings enclosed in open-top fumigation chambers were exposed to O₃ (charcoal-filtered air, non-filtered air, 1.5 × ambient, or 2 × ambient) and simulated rain (pH 3.1, 4.1 or 5.1) for two growing seasons (June to October). Foliage was sampled for mineral nutrients, total soluble sugars, and starch in September 1988 at the end of the second season of exposures. The development of cold tolerance of individual trees was assessed using the electrolyte leakage technique. Ozone and simulated rain treatments had marginal effects on mineral nutrient concentrations of current and 1 yr old foliage. Ozone did not affect foliar carbohydrate levels but the simulated rain treatments of pH 3.1 tended to depress levels of total soluble sugars and starch in 1 yr old foliage and of starch in current year's foliage. During mid to late October, the current year's foliage of trees receiving rain of pH 3.1 was less tolerant to cold than the current year's foliage of trees receiving rain of pH 4.1 or 5.1. Following the October period, trees in all three acidic rain treatments had similar tolerances to cold.     

Soil chemical and microbial effects of simulated acid rain on clover and soft chess

Effects of simulated acid rain, comprised of HNO₃ and H₂SO₄ in the mole ratio of 3:1, at pH 5.6, 4.5, 4.0 and 3.0, were tested on the grass, soft chess (Bromus mollis L.) and on clover (Trifolium subterraneum L. var. Woogenellup) in a sandy soil of granodiorite parent material. Soft chess was grown in unfertilized soil, whereas clover was grown in both unfertilized soil and soil fertilized with NH₄NO₃ and CaSO₄·2H₂O at the rates of 224 kg ha^?1 N and 78 kg ha^?1 S. Two acid-spray irrigation periods of 31 and 26 weeks duration, each delivering 400 mm and separated by a dry period of 23 weeks, simulated typical rainfall of northern California rangeland. Plants were harvested after each of the two spray periods. There were very few deleterious effects of acid rain on plant growth or soil and microbial processes. No significant (p<0.05) effects were shown by soil microbial biomass, CO₂ production, nodules per unit weight of clover root, acetylene reduction, denitrification and nitrification potentials, or for soft chess plant weights, and N and P uptake. Mineralizable-N was unaffected also, except in one case. However, pH of soil to 10 mm depths was significantly lower in the pH 3.0 treatment after the first spray period, with a corresponding decrease in exchangeable soil Ca; these effects became significant at greater soil depth only after the second spray period. There were significant effects of acid treatments shown by clover, some of which may be advantageous. Treatments of intermediate acidity generally provided added N and S, which acted as fertilizers, and compensated for possible decreases in plant productivity attributable to acidity per se. There was also evidence of decreased P uptake in unfertilized soil at pH 3. In conclusion, effects of simulated acid rain were minimal, and in some cases were advantageous because of the added N and S having a fertilizer effect on plant nutrition and growth.     

利用冠层和叶片水平的反射光谱研究模拟酸雨对小麦的影响

通过光谱分析技术,研究了模拟酸雨（SO-42：NO-31=5：1）对小麦产量和生理特性的影响。结果表明,模拟酸雨伤害了小麦叶片的结构和功能,降低了叶绿素含量和光合速率,从而显著降低了小麦的产量,经过pH为2的酸雨处理后的小麦产量降幅达19.1%。通过对植被指数的分析可以看出,小麦冠层叶绿素含量在开花期以后逐渐降低,而旗叶的叶绿素含量则在灌浆期以后开始下降,两者的下降幅度都随着酸雨pH的下降而增大。光合速率表现出与叶绿素含量相同的变化。另外,对小麦产量与不同生育期冠层和叶片水平的植被指数的相关分析表明,灌浆期的小麦冠层水平的NDVI、mND705和WI与酸雨处理后小麦的产量显著相关。总之,利用光谱分析技术可以快速、无损伤地监测不同酸雨处理对小麦的生长和营养状况的影响。     

Effect of simulated acid precipitation on nitrogen mineralization and nitrification in forest soils

After exposure of samples of three forest soils (pH 3.4 to 3.9) from the Adirondacks region of New York to 60, 230, or 400 cm of simulated rain of pH 3.5 or 5.6 in 4, 14, or 24 weeks, respectively, the soil samples were separated into the 0 to 2 and 2 to 5 cm organic layers and further incubated. The rates of N mineralization in Woods soil exposed to the simulated precipitation were less for rain at pH 3.5 than at pH 5.6, but the inhibition decreased with increasing exposure of the 0 to 2 cm layer. In Panther soil, the rates of mineralization were usually not affected by the acidity of the simulated rain. In the upper layer of Sagamore soil, mineralization was not influenced by pH of the simulated rain, but the transformation was faster in the bottom layer of soil after prolonged exposure to simulated rain at pH 3.5 than at pH 5.6. The rate of nitrate formation in Panther and Woods soil amended with ammonium was inhibited by the more acid rain. Studies with ¹⁵NH₄ indicated that ammonium was oxidized to nitrate even though ammonium levels did not decline or declined only slightly after prolonged exposure of Panther or Woods soil to rain at pH 3.5. The growth of orchardgrass in Panther and Woods soil was inhibited by the more acid simulated rain.     

Effect of Simulated Acid Rain on Deterioration of Concrete

In the study the long-term exposure tests to simulated acid rain were performed in order to clarify the effect of acid rain on deterioration of concrete. Mortar specimens with 40 mm in width, 15 mm in thickness and 160 mm in length were used for the tests. At each time after the fixed rainfall was attained, those were tested physically and analyzed chemically. Finally total rainfall of 9000mm was given to the specimens. From the test results, it was confirmed that the eroded depth of the specimen has a good linear relation to the total rainfall under simulated acid rain with various pH. Surface erosion rates of the mortar specimens with an ordinary mix proportion under simulated acid rains with pH 3.0 and 2.5 were about 1.2 and three times larger than that under pH 5.6, respectively. It was also confirmed that flexural strength of the specimens with an ordinary mix proportion hardly changed under low pH simulated acid rain even after total rainfall of 9000mm was given.