Impact Of Simulated Acid Rain Research Articles

Impact of simulated acid rain on chemical properties of Nyalau series soil and its leachate

Greenhouse gases can cause acid rain, which in turn degrades soil chemical properties. This research was conducted to determine the effects of simulated acid rain (SAR) on the chemical properties of Nyalau series (Typic paleudults). A 45-day laboratory leaching and incubation study (control conditions) was conducted following standard procedures include preparing simulated acid rain with specific pH levels, followed by experimental design/plan and systematically analyzing both soil and leachate for chemical changes over the 45-day period. Six treatments five of which were SAR (pH 3.5, 4.0, 4.5, 5.0, and 5.5) and one control referred to as natural rainwater (pH 6.0) were evaluated. From the study, the SAR had significant effects on the chemical properties of the soil and its leachate. The pH of 3.5 of SAR treatments decreased soil pH, K+, and fertility index. In contrast, the contents of Mg2+, Na+, SO42−, NO3−, and acidity were higher at the lower SAR pH. Furthermore, K+ and Mg2+ in the leachate significantly increased with increasing acidity of the SAR. The changes in Ca2+ and NH4+ between the soil and its leachate were positively correlated (r = 0.84 and 0.86), whereas the changes in NO3− negatively correlated (r = − 0.82). The novelty of these results lies in the discovery of significant alterations in soil chemistry due to simulated acid rain (SAR), particularly impacting soil fertility and nutrient availability, with notable positive and negative correlations among specific ions where prolonged exposure to acid rain could negatively affect the moderately tolerant to acidic and nutrient-poor soils. Acid rain can negatively affect soil fertility and the general soils ecosystem functions. Long-term field studies are required to consolidate the findings of this present study in order to reveal the sustained impact of SAR on tropical forest ecosystems, particularly concerning soil health, plant tolerance, and potential shifts in biodiversity and ecological balance.

Impact of Simulated Acid Rain on Soil Base Cations Dissolution between Eucalyptus Pure Plantations and Eucalyptus–Castanopsis fissa Mixed Plantations

The soils of Eucalyptus pure plantations and Eucalyptus–Castanopsis fissa mixed plantations were studied using soil column leaching experiments with acid solutions to mimic the effects of acid rain on the soils. This helped researchers learn more about how soil base ions react to acid deposition and their ability to protect the soil from excessive acidity under pure and mixed-species plantations. The results showed that acid rain leaching increased the leaching loss, desorption, and desorption rate of soil base ions while decreasing the soil pH value, adsorption, and adsorption rate of soil base ions. The soil pH value and the leaching loss ranges of K+, Na+, and Mg2+ were all greater in the pure plantations than in the mixed plantations, while the leaching range of Ca2+ was greater in the mixed plantation than in the pure plantations. In the two types of plantations, the adsorption rates of Ca2+ and Na+ in the mixed plantations were higher than in the pure plantations, while K+ and Mg2+ showed higher adsorption rates in the pure plantations than in the mixed plantations. Therefore, soil pH and base ions were greatly affected by the pH value of acid rain. Compared with the pure plantations, the establishment of Eucalyptus–Castanopsis fissa mixed plantations can slow soil acidification and leaching of K+, Na+, and Mg2+ and contribute to the adsorption of Ca2+ and Na+, which is beneficial for the soil nutrient fixation of Eucalyptus plantations. The mixed plantations were found to increase the exchange reaction between H+ and base ions, thereby improving the acid buffer performance of the soil. This, in turn, helped to mitigate the decline in soil fertility. Therefore, establishment of Eucalyptus–Castanopsis fissa mixed-species plantations can slow down the impact of acid rain on soil acidification in artificial plantation land to a certain extent and play an important role in optimizing the plantation structure of Eucalyptus stands and maintaining their productivity.

Acid Rain and Seed Germination: A Predictive Model Using ML-based CART Algorithm

The impact of acid rain on the germination of seeds is a significant concern in agricultural and environmental studies. Acid rain, characterized by elevated acidity levels due to pollutants like sulfur dioxide and nitrogen oxides, can adversely affect the germination process of various plant species. The objective of this study was to evaluate the impact of simulated acid rain (SAR) on the germination of Brinjal (Solanum melongena Linn.) and Cowpea (Vigna unguiculata ssp. cylindrica L. Walpers) crops. The experiments were conducted using eight plastic trays of approximately 25 cm. x 30 cm dimensions. Four trays were used for experiments with brinjal seeds (Set I), while the other four were used for cowpea seeds (Set II). One tray from each set was used as positive control and treated with normal pH 5.6, while the other three trays from each batch were treated with SAR solutions of pH 4.5, 3.5, and 2.5. Brinjal seed germination percentage and seed vigor were inferior to Cowpea seeds. The seeds treated with SAR (pH 4.5, 3.5, and 2.5) showed hindered seed germination. Furthermore, a more significant inhibitory effect was observed at lower pH values. The mean germination percentage of seeds was highest for standard SAR (pH 5.6) in the case of Brinjal seeds, while it was recorded lowest for Cowpea seeds. The results indicate that plants do not respond uniformly to SAR. To investigate the behavior of the simulated acid rain data, a Machine Learning-based Decision Tree Algorithm was employed to identify and optimize conditions. Cowpea was predicted to get 95% seed germination, whereas brinjal would only be 64% in acid rain of pH value 5.05 for 36 hours. In conclusion, utilizing a Machine Learning-based CART algorithm has provided valuable insights into predicting the germination behavior of seeds under the influence of acid rain.

Impact of simulated acid rain on the growth of three species Brassica integrifolia, Brassica rapa, Brassica juncea in Hanoi, Vietnam.

Over the past decade, the extent and magnitude of acid rain in Vietnam and other Asian countries have become more apparent. In this study, the effect of simulated acid rain (pH 5.0, 4.0, and 3.0) and control treatment (pH 6.0) are observed for three species Brassica integrifolia, Brassica rapa, and Brassica juncea in Hanoi. The pot experiment was conducted for 42days and arranged according to a randomized complete block design (RCBD), replicated 3 times with acid rain exposure being supplied every 4days. The results show that acid rain causes direct damage to leaves. Observations reveal white spots on leaves; leaves getting discolored and gradually turning yellow, curling leaf marginals, and turning dark blue, with the most severe symptoms being necrotic leaves. Parameters of the shoot and root length, leaf area, biomass, and chlorophyll content all decrease as pH drops. However, the accumulation of proline content in leaves tends to increase with greater acidity. In conclusion, Brassica rara has the highest resistance capability to acid rain compared with Brassica integrifolia and Brassica juncea, especially its proline content is the highest at pH 3.0 in three Brassicaceae species.

Impact of simulated acid rain on the composition of soil microbial communities and soil respiration in typical subtropical forests in Southwest China

The relationship between soil respiration (SR) and microbial community structure (MCS) is relevant to changes in forest soil ecosystem stability and chemical cycling under acid rain. Simulated acid rain treatments of pH 4.5 (control), 4.0, 3.25 and 2.5 were applied to two forest stands in the Three Gorges Reservoir Area of Jinyun Mountain, Chongqing. We used phospholipid fatty acid (PLFA) analysis to observe the MCS in the 0–10 cm soil layer and measured SR in situ from January 2016 to December 2017. Additionally, we determined the effects of soil properties on the MCS and SR. Acid rain simulation significantly increased the fungal PLFA abundance and decreased the bacterial PLFA abundance in the mixed coniferous and broad-leaved forest (CF). However, in the evergreen broad-leaved forest (BF), the abundance of bacterial and fungal PLFAs did not differ significantly among treatments. Redundancy analysis (RDA) showed that significant changes in the MSC were mainly due to the C/N ratio, hydrolysable N content, content, fine root biomass and sucrase activity. Acid rain simulation in the CF and BF significantly inhibited SR, but the SR sensitivity to simulated acid rain differed among forests. In 2017, the annual mean SR in the CF under the pH 4.0, 3.25 and 2.5 treatments decreased significantly by 6.1%, 19.2% and 28.9%, but in the BF, SR decreased significantly by 25.6% only under pH 2.5. The structural equation model showed that the relationship between the MCS and the variation in SR was closer and more direct than that with soil nutrients. The microbial community structure was an important factor driving the response of soil respiration to acid rain.

Effect of simulated acid rain on growth and micronutrient uptake of okra (Abelmoschus esculentus) on coastal plain sands in Abia State, South-eastern, Nigeria

The study was conducted in April, 2019 at Umudike to examine the impact of simulated acid rain (SAR) and frequency of SAR spray on growth and micronutrients content of okra (Abelmoschus esculentus (L.) Moench) in an ultisol at Umudike. The treatments consisted of three (3) pH levels: Coca-cola solution (pH 2.7) and SAR (pH 3.5 and 5.5) as well as control (water) and; three (3) frequency of foliar spray at 1, 2 and 3 day weekly, arranged according to their respective pH values and spray treatments in a completely randomized design (CRD) replicated three times. Plant leaves were analysis for micronutrients (Cu, Fe, Mn and Zn) content. The result shows that, under the stress of SAR and frequency of SAR application, growth parameters measured; leaf number, shoot height and leaf area were significantly reduced, compared to the control treatment. Nutritional analysis of the leaves also revealed that, the content micronutrients in okra, increased with declining pH value of AR and frequency of application, from pH 5.5 to pH 2.7. Coke solution (pH 2.7) and three (3) days per weekly application of SAR gave the highest reduction in plant growth parameter in Okra but, had higher increased in micronutrients content, respectively. Further result showed that okra (Abelmoschus esculentus (L.) Moench) is resistant to SAR from pH ≥5.5 in terms of growth and nutritional values.

Effects of sulfuric, nitric, and mixed acid rain on Chinese fir sapling growth in Southern China

The influence of acid rain on plant growth includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in root growth. In addition, the concentration of NO3- in acid rain increases along with the rapid growth of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO42-/NO3- (S/N) ratios, which were 1:0, 5:1, 1:1, 1:5 and 0:1, on Chinese fir sapling growth from March 2015 to April 2016. Results showed that Chinese fir sapling height growth rate (HGR) and basal diameter growth rate (DGR) decreased as acid rain pH decreased, and also decreased as the percentage of NO3- increased in acid rain. Acid rain pH significantly decreased the Chlorophyll a (Chla) and Chlorophyll b (Chlb) content, and Chla and Chlb contents with acid rain S/N 1:5 were significantly lower than those with S/N 1:0 at pH 2.5. The chlorophyll fluorescence parameters, maximal efficiency of Photosystem II photochemistry (Fv/Fm) and non-photochemical quenching coefficient (NPQ), with most acid rain treatments were significantly lower than those with CK treatments. Root activities first increased and then decreased as acid rain pH decreased, when acid rain S/N ratios were 1:1, 1:5 and 0:1. Redundancy discriminant analysis (RDA) showed that the Chinese fir DGR and HGR had positive correlations with Chla, Chlb, Fv/Fm ratio, root activity, catalase and superoxide dismutase activities in roots under the stress of acid rain with different pH and S/N ratios. The structural equation modelling (SEM) results showed that acid rain NO3- concentration and pH had stronger direct effects on Chinese fir sapling HGR and DGR, and the direct effects of acid rain NO3- concentration and pH on HGR were lower than those on DGR. Our results suggest that the ratio of SO42− to NO3− in acid rain is an important factor which could affect the sustainable development of monoculture Chinese fir plantations in southern China.

Comparative effects of simulated acid rain of different ratios of SO42 − to NO3− on fine root in subtropical plantation of China

The influence of acid rain on forest trees includes direct effects on foliage as well as indirect soil-mediated effects that cause a reduction in fine-root growth. In addition, the concentration of NO3− in acid rain increases with the rapidly growing of nitrogen deposition. In this study, we investigated the impact of simulated acid rain with different SO42−/NO3− (S/N) ratios, which were 5:1 (S), 1:1 (SN) and 1:5 (N), on fine-root growth from March 2015 to February 2016. Results showed that fine roots were more sensitive to the effects of acid rain than soils in the short-term. Both soil pH and fine root biomass (FRB) significantly decreased as acid rain pH decreased, and also decreased with the percentage of NO3− increased in acid rain. Acid rain pH significantly influenced soil total carbon and available potassium in summer. Higher acidity level (pH=2.5), especially of the N treatments, had the strongest inhibitory impact on soil microbial activity after summer. The structural equation modelling results showed that acid rain S/N ratio and pH had stronger direct effects on FRB than indirect effects via changed soil and fine root properties. Fine-root element contents and antioxidant enzymes activities were significantly affected by acid rain S/N ratio and pH during most seasons. Fine-root Al ion content, Ca/Al, Mg/Al ratios and catalase activity were used as better indicators than soil parameters for evaluating the effects of different acid rain S/N ratios and pH on forests. Our results suggest that the ratio of SO42− to NO3− in acid rain is an important factor which could affect fine-root growth in subtropical forests of China.

Impact of Simulated Acid Rain on the Growth, Yield and Plant Component of Abelmoschus caillei

This study was undertaken to observe the effects of simulated acid rain (SAR) on the growth, yield and plant component of Abelmoschus caillei. The plants were exposed to different levels of simulated acid rain acidified at pH 6.0 (control), 5.5, 4.5, 3.5 and 2.5. The results indicated that under the stress of simulated acid rain, growth parameters measured such as leaf number, shoot height, fresh and dry weight and stem girth were significantly reduced in plant subjected to SAR when compared with the control treatment. There was a gradual decline in chlorophyll content index as the level of acidity increased. Plants treated with pH 6.0 and pH 5.5 SAR had good growth and yield. Simulated acid rain (SAR) induced morphological changes such as chlorosis and necrosis in A. caillei. It was concluded that growth, yield and plant component were adversely affected when A. caillei was exposed to simulated acid rain with pH value 4.5 below.

Effects of simulated acid rain on microbial characteristics in a lateritic red soil.

A laboratory experiment was performed to examine the impact of simulated acid rain (SAR) on nutrient leaching, microbial biomass, and microbial activities in a lateritic red soil in South China. The soil column leaching experiment was conducted over a 60-day period with the following six SAR pH treatments (levels): 2.5, 3.0, 3.5, 4.0, 4.5, and 5.0 and one control treatment (pH = 7). Compared with the control treatment, the concentrations of soil organic matter, total nitrogen, total phosphorus, total potassium, soil microbial biomass carbon (MBC), soil microbial biomass nitrogen (MBN), and average well color density (AWCD) in the Ecoplates were all significantly decreased by leaching with SAR at different pH levels. The decrease in MBC and MBN indicated that acid rain reduced the soil microbial population, while the decrease in AWCD revealed that acid rain had a negative effect on soil bacterial metabolic function. Soil basal respiration increased gradually from pH 4.0 to 7.0 but decreased dramatically from pH 2.5 to 3.0. The decrease in soil nutrient was the major reason for the change of soil microbial functions. A principal component analysis showed that the major carbon sources used by the bacteria were carbohydrates and carboxylic acids.

Leachability of phenanthrene from soil under acid rain and its relationship with dissolved organic matter

Acid rain is a serious environmental problem in the world. Soil columns were leached with simulated acid rain (SAR) at pH ranging from 2.5 to 5.6. The impact of SAR on the release of phenanthrene from red soil and its correlation with dissolved organic carbon (DOC) in eluates were investigated. The results showed that the leaching loss of phenanthrene was affected by both the leaching volume and acidity of SAR. When the leaching volume was less than 500 mm, the phenanthrene concentration in eluates decreased rapidly with increasing leaching volume, indicating a high rate of leaching loss at the beginning of leaching; then with continuous leaching, the phenanthrene concentration decreased slightly and reached zero when the leaching volume reached 875 mm. The lower pH of SAR was, the higher release rate of phenanthrene was. The change of DOC in eluates was similar to that of the phenanthrene concentration. The phenanthrene concentration had a significantly positive correlation with DOC in all eluates (the squared correlation coefficient R 2 varied between 0.952 and 0.997). Three-dimensional fluorescence analysis revealed that phenanthrene was associated with humic acid and fulvic acid, and was released with dissolved organic matters leached by SAR.

Impact of simulated acid rain on soil microbial community function in Masson pine seedlings

Accompanying its rapid economic development and population growth, China is the world's third largest acid rain region, following Europe and North America. The effects of acid rain on forest ecosystem were widely researched, including the growth, the nutrient of the leaf and soil, and so on. However, there are few reports about the effects of acid rain on the soil microbial diversity. This study investigated the effects of acid rain on soil microbial community function under potted Masson pine seedlings (Pinus massoniana Lamb). After 7 months of treatment with simulated acid rain, the low acid load treatment (pH 5.5) stimulated soil microbial activity, and increased soil microbial diversity and richness, while the higher levels of acid application (pH 4.5, pH 3.5) resulted in lower soil microbial activity and had no significant effects on soil microbial diversity and richness. Principal component analysis showed that there was clear discrimination in the metabolic capability of the soil microbial community among the simulated acid rain and control treatments. The results obtained indicated that the higher acid load decreased the soil microbial activity and no effects on soil microbial diversity assessed by Biolog of potted Masson pine seedlings. Simulated acid rain also changed the metabolic capability of the soil microbial community.

Impact of Simulated Acid Rain on Trace Metals and Aluminum Leaching in Latosol from Guangdong Province, China

Acid rain is one of the most serious ecological and environmental problems worldwide. This study investigated the impacts of simulated acid rain (SAR) upon leaching of trace metals and aluminum (Al) from a soil. Soil pot leaching experiments were performed to investigate the impacts of SAR at five different pH levels (or treatments) over a 34-day period upon the release of trace metals (i.e., Cu, Ni, Pb, Zn, and Fe) and Al from the Latosol (acidic red soil). The concentrations of trace metals in the effluent increased as the SAR pH level decreased, and were highest at the SAR pH = 2.0. In general, the concentrations of Cu, Pb, Fe, and Al in the effluent increased with leaching time at the SAR pH = 2.0, whereas the concentrations of Zn, Fe, and Al in the effluent decreased with leaching time at the SAR pH ≥ 4.0. The increase in electrical conductivity (EC) with leaching time at five different SAR pH levels was primarily due to the concentrations of Al and Fe in the effluent. There were good linear correlations between the effluent Al concentrations and the effluent pH at the SAR pH = 2.0 (R2 = 0.87) and pH = 3.0 (R2 = 0.83). More soil trace metals and Al were activated and released into the soil solution as the SAR pH level decreased.

The host plant‐mediated impact of simulated acid rain on the development and reproduction of Tetranychus cinnabarinus (Acari, Tetranychidae)

Abstract: The host plant‐mediated impact of simulated acid rain (pH 3.0, 3.5, 4.0, 5.6, and 6.8) on the behaviour, development, and reproduction of carmine spider mite, Tetranychus cinnabarinus (Boisduvals), were evaluated at 25°C in a series of laboratory trials. The results indicated that the adults of carmine spider mite prefer to aggregate on pH 4.0 acid rain‐treated eggplant leaves. The developmental times of nymph, larva and the pre‐oviposition period of the mite on kidney bean leaves were significantly affected by acid rain treatments. The developmental times for the immature stages ranged from 11.4 days on pH 4.0 acid rain‐treated leaves to 12.7 days on other acid rain‐treated leaves. The survival of immatures varied from 85.14% on pH 4.0 acid rain‐treated leaves to 78.83% on deionized water‐treated leaves (pH 6.8). The mites feeding on acid rain‐treated leaves (pH 3.0–5.6) had significantly greater reproductivity and longevity than those feeding on deionized water‐treated leaves. The average greatest reproductivity (74.6 eggs per female) and longest female longevity (8.9 days) were recorded on pH 4.0 acid rain‐treated leaves. Accordingly, the intrinsic rate of increase (rm) for the mite on pH 4.0 acid rain‐treated leaves was the highest. Jackknife estimates of rm varied from 0.201 on pH 4.0 acid rain‐treated leaves to 0.158 on pH 5.6 acid rain‐treated leaves. The results implied that the population growth of the mite were enhanced by application of acid rain (pH 3.0–5.6) on host plants.

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.

The Impact of Simulated Acid Rain on Soil Leachate and Xylem Chemistry in a Jack Pine (Pinus Banksiana Lamb.) Stand in Northern Ontario, Canada

The impact of simulated acid rain on soil leachate and xylem chemistry in a young Jack pine (Pinus banksiana Lamb.) stand in the boreal forest of northern Ontario was evaluated. Permanent plots (5 × 2 m) were established in 1981 which were sprayed twice monthly with simulated acid rain, adjusted to pH 5.6, 4.0, 3.5, 3.0 or 2.5 with a 2:1 molar ratio of sulphuric (H2SO4) to nitric acid (HNO3) in addition to ambient rainfall. Sprays were applied between June and September for 5 yr. Unsprayed plots were also monitored. The pH of soil leachate collected between 1981–1985 was reduced significantly by the acid sprays and concentrations of sulphate (SO42-), nitrate (NO3-), calcium (Ca), magnesium (Mg), aluminium (Al), manganese (Mn), and zinc (Zn) increased in the A, B and C horizons. The soil recovered rapidly from the spray treatments, although residual effects were found in soil leachate samples collected during 1986–1987, particularly in the C horizon. Trees receiving spray acidified to pH 2.5 had higher concentrations of Ca, Mn, Cd and Rb in tree-rings formed between 1981–1985 compared to trees receiving spray acidified to pH 4.0 or to trees receiving ambient rainfall alone. Some of the changes in soil chemistry resulting from the application of acidic sprays are reflected in the chemistry of Jack pine tree rings and these chemical signals in tree rings may be used as indicators of soil acidification.

The Impact of Simulated Acid Rain and Fertilizer Application on a Mature Sugar Maple (Acer Saccharum Marsh.) Forstt in Central Ontario Canada

The effects of two year's addition of simulated acid precipitation, with and without added fertilizer, on mycorrhizae, litter decomposition and soil and tree chemistry in a sugar maple (Acer saccharum Marsh.) dominated forest were investigated. The forest floor beneath mature sugar maple trees was irrigated at monthly intervals between May and September with local lake water acidified to pH 3, pH 4 or untreated lakewater of pH 4.9. In addition, a commercial organic slow-release fertilizer (Maple Gro) was added to the soil prior to irrigation with pH 3 spray. Trees to which no experimental spray was applied were also included as controls. Eight trees were used for each of the five treatments. Application of the acid spray alone did not acidify surface soil nor cause visible symptoms of decline in trees. The pH of the soil solution and soil leachate was increased by addition of acidified lakewater. An increase in the concentration of sulphate (SO42-), calcium (Ca), and magnesium (Mg) in soil leachate was only recorded in plots irrigated with water acidified to pH 3 + Maple Gro. The initial rate of litter decomposition tended to be higher following application of the acid sprays, although mycorrhizal infection of sugar maple roots was reduced in the pH 3 and pH 4 treatments. Concentrations of zinc (Zn), chromium (Cr) and nickel (Ni) were highest in wood formed during the period irrigated with water acidified to pH 3. Foliar nitrogen (N) concentrations tended to be higher in all irrigated treatments, although there were no differences between treatment in any of the other nutrients measured in foliage after two years of treatment. It is concluded that the application of simulated acid rain under field conditions results in a complex interaction of events which are not reproduced in pot trials and must be fully understood before the impact of acid rain on sugar maple forests can be evaluated.

Impact of simulated acid rain on microbial respiration, biomass, and metabolic quotient in a mature sugar maple (Acersaccharum) forest floor

Effects of simulated acid rain on forest floor microbiological processes were investigated in an old-growth sugar maple (Acersaccharum Marsh.) woods at Turkey Lakes Watershed, northern Ontario, Canada. Sulphate and NO3− in ambient precipitation received on four replicate plots were augmented with additions of dilute (0.02 N) H2SO4 and HNO3, applied alone and in combination periodically during the growing seasons of 1993 and 1994. The equivalent load of SO42− applied in the present experiment was ca. 6 times that in ambient precipitation in the H2SO4-only treatment and half that in the combined treatment over the study period. In situ soil respiration measured during the summer and fall of 1994 showed no adverse effects of acid treatment. In the laboratory, soil microbial respiration, biomass (as determined by substrate-induced respiration), and microbial biomass carbon: organic carbon (Cmic/Corg ratios were significantly depressed in the L or FH layers of the forest floor when H2SO4 was applied alone or in combination with HNO3. No effects of HNO3 were detected when applied alone. Microbial respiration, substrate-induced respiration, and Cmic/Corg ratios were significantly correlated with forest floor pH. Microbial metabolic quotients (respiration:biomass ratios) were not adversely affected by any of the treatments. The observed deleterious effects of H2SO4 application under experimental conditions suggest the possibility of adverse effects in the field over the long-term.

Assessment of the impact of simulated acid rain and alkaline effluent discharge on pond biota with respect to larvae of AmphibianRana tigrina

The metamorphosing tadpoles of amphibian Rana tigrina were grown in simulated environments of urban ponds perturbed or unperturbed by acid rain and alkaline wastewater. The impacts were studied in terms of behavioural responses, food consumption, growth, and computer‐aided mortality analysis. The studies reveal that the pH range of 6.5–9.0 recommended by regulatory agencies, such as United States Environmental Protection Agency for the protection of aquatic life in water bodies receiving acidic or alkaline pollutants, is only partially adequate; the upper limit of pH 9.0 appears too liberal and may need to be lowered. The pH standards for irrigation and domestic waters may also need revision.

Impact of simulated acid rain on yield of a field-grown oat crop

A study was conducted in 1985 to determine the impact of acid rain on the productivity of Avena sativa L. cv. Ogle. Oat plants were grown under standard field practices and received 0.32 cm simulated rain treatments at pH 3.0, 3.6, 4.2 or 4.8 three times a week for 10.5 weeks. In a “no rain” treatment, plants received an equivalent volume of water at the soil surface. Each treatment was replicated eight times. Plants were harvested and allowed to dry when oat kernels reached the soft dough stage. There were no significant effects of acidity of rain on vegetative yield/ha, number of tillers/ha, seeds/ha, seed weight/ha, number of seed/head, bushels/ha or harvest index.