Types Of Acid Rain Research Articles

The nitrogen-sulfur ratio of acid rain modulates the leaf- and root-mediated co-allelopathy of Solidago canadensis.

The majority of allelopathic studies on invasive plants have focused primarily on their leaf-mediated allelopathy, with relatively little attention paid to their root-mediated allelopathy, especially co-allelopathy mediated by both leaves and roots. It is conceivable that the diversified composition of acid rain may influence the allelopathy of invasive plants. This study aimed to evaluate the leaf and root-mediated co-allelopathy of the invasive plant Solidago canadensis L. under acid rain with different nitrogen-sulfur ratios (N/S) on Lactuca sativa L. via a hydroponic incubation. The root-mediated allelopathy of S. canadensis was found to be more pronounced than the leaf-mediated allelopathy of S. canadensis with nitric acid at pH 4.5, but the leaf-mediated allelopathy of S. canadensis was observed to be more pronounced than the root-mediated allelopathy of S. canadensis with sulfuric-rich acid at pH 4.5. The leaf and root-mediated co-allelopathy of S. canadensis was more pronounced than that of either part alone with sulfuric acid at pH 5.6 and nitric acid at pH 4.5, but not with nitric-rich acid at pH 4.5 and sulfuric-rich acid at pH 4.5. Sulfuric acid and sulfuric-rich acid with stronger acidity intensified the leaf-mediated allelopathy of S. canadensis. Nitric acid and nitric-rich acid attenuated the leaf-mediated allelopathy of S. canadensis, and most types of acid rain (especially nitric acid and nitric-rich acid) also attenuated the root-mediated allelopathy of S. canadensis and the leaf and root-mediated co-allelopathy of S. canadensis. Sulfuric acid and sulfuric-rich acid produced a more pronounced effect than nitric acid and nitric-rich acid. Hence, the N/S ratio of acid rain influenced the allelopathy of S. canadensis under acid rain with multiple N/S ratios.

Effects of acid rain and root exclusion on soil organic carbon in Cunninghamia lanceolata and Michelia macclurei plantations.

Acid rain is one of most serious environment problems in China. The types of acid rain have gradually transformed from sulfuric acid rain (SAR) to mixed acid rain (MAR) and nitric acid rain (NAR) in recent years. Roots are one source of soil organic carbon and play an important role in the formation of soil aggregates. However, the changes in acid rain type and the effect of root removal on soil organic carbon in forest ecosystems are poorly understood. In this study, we removed roots and simulated acid rain with different types (SO42-:NO3- ratio of 4:1, 1:1, and 1:4) for three years in Cunninghamia lanceolata (CP) and Michelia macclurei (MP) plantations to analyze the changes of soil organic carbon and physical properties and to measure the size and mean weight diameter (MWD) of aggregates. Results showed that root removal in C. lanceolata and M. macclurei remarkably reduced soil organic carbon pool by 16.7 % and 21.5%, and soil recalcitrant carbon by 13.5% and 20.0%, respectively. Root removal substantially decreased the MWD and proportion and organic carbon content of soil macroaggregates in M. macclurei, but not in C. lanceolata. Acid rain did not affect soil organic carbon pool and soil aggregate structures. Our results indicated that roots promote soil organic carbon stabilization and that their contribution to the stability of soil organic carbon varies with forest types. Moreover, soil organic carbon stabilization is not affected by different types of acid rain in the short term.

What modulates the impacts of acid rain on the allelopathy of the two Asteraceae invasives?

Most of the allelopathic studies have focused on the independent allelopathy of one invasive plant, but have ignored the co-allelopathy of the two invasives. The variations in the type of acid rain can modulate the invasiveness of invasives via the changes in the allelopathy. Thus, it is vital to elucidate the allelopathy of invasives, particularly the co-allelopathy of the two invasives, under acid rain with different types, to illuminate the mechanisms driving the co-invasion of two invasives under diversified acid rain. However, little progress has been finished in this aspect presently. This study aimed to evaluate the co-allelopathy of two Asteraceae invasives Solidago canadensis L. and Erigeron annuus L. treated with acid rain with different nitrogen-to-sulfur ratios on seed germination and seedling growth of the horticultural Asteraceae species Lactuca sativa L. via a hydroponic experiment. Aqueous extracts of the two Asteraceae invasives generated obvious allelopathy on L. sativa. S. canadensis aqueous extracts caused stronger allelopathy. There may be an antagonistic effect for the co-allelopathy of the two Asteraceae invasives. Nitric acid at pH 5.6 weakened the allelopathy of the two Asteraceae invasives, but the other types of acid rain strengthened the allelopathy of the two Asteraceae invasives. The allelopathy of the two Asteraceae invasives increases with the increasing acidity of acid rain, but the allelopathy of the two Asteraceae invasives decreases with the increasing nitrogen-to-sulfur ratio of acid rain. Accordingly, the species number of invasives, and the acidity and type of acid rain modulated the impacts of acid rain on the allelopathy of the two Asteraceae invasives.

Effects of different types of acid rain on water stability of asphalt pavement

As is known to all, China is one of the countries with more acid rain in the world, and acid rain is mainly distributed in the southern humid climate area of China. However, the construction of semi-flexible asphalt pavement exposed to acid rain environment is a very realistic problem. In order to clarify the influence of different types of acid rain on the water stability of semi-flexible pavement, sulfuric acid type acid rain, nitric acid type acid rain and mixed type acid rain were prepared in this paper, and the semi-flexible specimens were soaked periodically. The water stability of semi-flexible pavement under different types of acid rain corrosion was evaluated macroscopically by standard Marshall test, immersion Marshall test, freeze-thaw splitting test and vacuum saturation test. It was concluded that the Marshall stability, immersion Marshall residual stability, freeze-thaw splitting strength ratio and vacuum saturation residual stability of semi-flexible pavement under different types of acid rain showed different degrees of decline.The reasons for the decline of water stability of semi-flexible pavement under different types of acid rain corrosion were analyzed by scanning electron microscopy and infrared spectroscopy. It was concluded that the acidification condition of rainwater was the main reason for the decrease of ductility, viscosity and plasticity of petroleum asphalt, which affected the binding force between petroleum asphalt and limestone aggregate, and ultimately led to the decline of water stability of semi-flexible pavement.Based on the molecular dynamics theory, the molecular dynamics model of acid rain corrosion asphalt mixture is established. According to the sensitivity of acid components to the main components of semi-flexible asphalt mixture, the asphalt, oil, resin and calcium carbonate with the most content in semi-flexible asphalt mixture are selected to simulate and study. The changes of bonding energy and diffusion coefficient of asphalt mixture under different types of acid rain are calculated and analyzed. It is concluded that sulfuric acid acid rain has the greatest influence on the water stability of semi-flexible specimens, followed by mixed acid rain, and the influence of nitric acid rain is relatively small.

Complex effects of different types of acid rain on root growth of Quercus acutissima and Cunninghamia lanceolata saplings

BackgroundSoil acidification caused by acid rain (AR) can damage plant roots, which in turn negatively impacts plant health. In response to changing AR types, research efforts to elucidate their specific impacts on plants have become intense.MethodsFor this study, we investigated the effects of simulated sulfuric, nitric, and mixed AR on the root systems of Quercus acutissima Carr. and Cunninghamia lanceolata (Lamb.) Hook. under different acidity levels.ResultsAs the AR S/N ratio and pH decreased, the height growth rate (HGR), basal diameter growth rate (DGR), total root length (TRL) and total root surface area (TRS) of C. lanceolata decreased, whereas the TRL and TRS of Q. acutissima remained the same. When the NO3− concentration in AR was increased, the root activity, superoxide dismutase (SOD) and catalase (CAT) activities of C. lanceolata roots revealed a downward trend; however, the root activity of Q. acutissima and the peroxidase (POD) activity of C. lanceolata roots revealed an upward trend. Further, redundant analysis and structural equation models indicated that AR pH had a greater impact on the HGR of Q. acutissima than that of C. lanceolata, while the impact of the AR S/N ratio on C. lanceolata growth rates was greater than that of Q. acutissima.ConclusionsOur results suggested that the root systems of different tree species had variable responses to AR, and the AR S/N ratio was an important factor affecting plant root growth. This might facilitate new strategies for the cultivation and protection of plantations in the future.

A critical review of the variation in rainwater acidity in 24 Chinese cities during 1982–2018

Rainwater is an essential pathway to remove fine particulate matter and dissolved atmospheric pollutants (e.g., SO2, HNO3, and NH3). Acid rain (pH < 5.6) has been a severe environmental issue in China since the 1970s, adversely impacting ecosystem health. This study focuses on the influence of anthropogenically induced anions (SO42– and NO3–) and alkaline cations (Ca2+ and NH4+) on acid rain in Chinese cities. In this review, cities with high population density east of the Hu Huanyong Line that divides China geographically according to its uneven economic development were studied. Coastal and central areas of China to the east of the line are characterized by a much faster developing economy and rapid urbanization. The observed trends and spatial variability of acidity and chemical composition in rainwater are discussed in relation to industrialization and environmental changes in China. Over the past 3½ decades, the precipitation pH in the urban regions has exhibited reduced acidity. A mixed nitric–sulfuric acid rain type has become prominent due to the significant decrease in SO42– via desulfurization. Ca2+ levels have decreased, while NH4+ has increased slightly due to more vehicular transportation. In addition, the neutralization capacity of Ca2+ and NH4+ has decreased from north to south. Overall, the acid rain problem in Chinese cities has been alleviated in recent years.

The use of Biolog Eco microplates to compare the effects of sulfuric and nitric acid rain on the metabolic functions of soil microbial communities in a subtropical plantation within the Yangtze River Delta region

China has recently undergone rapid economic development. However, it is the third-largest acid rain region in the world after Europe and North America, and the acid rain problem in the Yangtze River Delta region is particularly serious. Over recent years, the type of acid rain in the Yangtze River Delta region has changed from sulfuric acid rain (SAR) into nitric acid rain (NAR) because of SO2 and NOX emission controls. This has made ecosystems more complicated. In this study, we used Biolog Eco microplates to investigate the impact of simulated SAR and NAR on soil microbial community function over a year, beginning in March 2015. The results showed that the long-term simulated acid rain treatments reduced the average well color development (AWCD) of the carbon sources in soil microbial communities. Secondly, the effects of acid type on the utilization of polymers and amino acids increased in the later stages of the simulated acid rain treatments. Furthermore, the differences in the utilization of carbon sources caused by the simulated acid rain treatments were mainly due to soil microorganism utilization of L-serine, Tween40, D-mannitol, and N-acetyl-D-glucosamine. Finally, the physical and chemical properties of the soil were not significantly correlated with the utilization of the six C groups. Our results suggested that the two types of acid rain had different effects on soil microbial community function. When the type of acid rain changed, the stability of the ecosystem was challenged and the risk of ecosystem disruption greatly increased.

The Effects of Silicon and Different Types of Acid Rain on Root Growth and Physiology Activity of Oryza Sativa L. Seedlings.

The effect of silicon (Si) and different types of acid rain (AR) on rice seedling roots was elucidated. The results showed different types of AR had different effects. Nitrate AR at pH 3.0 could promote the growth of rice roots, increased the dry weight, improved root phenotype, boosted H2O2 contents and increased peroxidase, catalase and ascorbate peroxidase activities. Sulfate AR at pH 3.0 could significantly inhibit the growth of rice roots, decreased the dry weight, root phenotype, increased H2O2 content and autioxidant enzyme activities. Sulfate-nitrate AR at pH 3.0 spraying had no significant effect on rice roots. Under different types of AR stress, the addition of exogenous Si could significantly promote the growth of rice seedling roots. This results indicated that the effects of rice root caused by AR might be due to not only the types of AR but also the content of Si in soil.

Response of soil chemical properties and enzyme activity of four species in the Three Gorges Reservoir area to simulated acid rain

The chemical composition in the precipitation is constantly changing, thus acid rain type is gradually changing from sulfuric type to mixed type and then nitric type. The influence of the changing acid rain type on the rhizosphere soil of tree species remains unclear. A pot experiment was performed with two-year-old Pinus massoniana, Cunninghamia lanceolate, Cyclobalanpsis glauca and Phyllostachys edulis seedlings with similar growth condition. Simulated acid rain consists of sulfuric(S/N = 5), mixed(S/N = 1) and nitric(S/N = 0.2) acid rain, and each type acid rain diluted to three acid rain intensity: pH = 2.5, 3.5, 4.5. Soil pH, soil organic matter, cation exchange capacity, the exchangeable Na+, K+, Ca2+, Mg2+ and enzyme activity were inhibited by acid rain intensity, while exchangeable Al3+ and H+ were promoted. Mg2+ was most relevant index to the tolerance to acid rain and the correlation degree of soil chemical index was higher than that of enzyme activity. Response of soil chemical properties differed in tree species under different acid rain types. Soil enzyme activity of Pinus massoniana, Cunninghamia lanceolate, and Phyllostachys edulis reached lowest under nitric acid rain, and that of Cyclobalanpsis glauca reached highest. Rhizosphere soil of Cunninghamia lanceolate is tolerant to sulfuric and nitric acid rain, and that of Cyclobalanpsis glauca is tolerant to mixed acid rain.

Novel process of NO removal from simulated flue gas using a Fe/Gr periodically reversing electro-activated peroxymonosulfate system

Nitric oxide (NO) emissions seriously threaten the atmospheric ecology and cause air quality degradation, and the acid rain type has gradually changed from sulfuric acid to nitric acid in some areas of China. To this end, an efficient, facile, innovative strategy of NO removal from simulated flue gas using Fe/Gr periodically reversing electro-activated peroxymonosulfate (PMS) system is proposed for the first time. Encouragingly, we find that the graphite (Gr) electrode has the similar electrochemical property to those of the boron-doped diamond (BDD) and platinum (Pt) electrodes, converting SO42- to sulfate radicals (SO4·-), and provide direct spectroscopy evidence for the theory that the electron e- can activate PMS to generate SO4·- and hydroxyl radicals (OH) via the electron-paramagnetic resonance (ESR) tests. In addition to the two free radicals mentioned above the singlet oxygen (1O2) is detected synchronously in the electrical-activated PMS system. And the signal intensity of the radicals detected increases with increasing current intensity correspondingly. Addition of excess methanol has a greater effect on the NO removal than tert-butanol and sodium azide, demonstrating that SO4·- dominates the NO removal. Furthermore, the results show PMS concentration, current intensity, pH, in-situ generated Fe2+ and O2 concentration have the distinct effect on the NO removal. Compared with different electro-activation systems of Fe/Fe and Gr/Gr and BDD/Gr, Fe/Gr achieves the optimum NO removal effect. Finally, the reaction mechanism is proposed: direct electrode oxidation, non-radical oxidation, and radical oxidation are combined to remove NO in the electro-activated PMS reaction system.

Growth and physiological response of an endangered tree, Horsfieldia hainanensis merr., to simulated sulfuric and nitric acid rain in southern China

As nitrogen deposition increases, acid rain is gradually shifting from sulfuric acid rain (SAR) to nitric acid rain (NAR). Acid rain can severely affect plant growth, damage ecosystems, and reduce biodiversity. Thus, a shift in acid rain type presents another challenge to the conservation of endangered plant species. We investigated the effect of three acid rain types (SAR, mixed acid rain [MAR], and NAR) and pH on the growth of an endangered Chinese endemic tree, Horsfieldia hainanensis Merr., using simulated rain in a greenhouse environment. Over nine months, growth indices, chlorophyll content, antioxidant enzyme activity, malondialdehyde content, and chlorophyll fluorescence parameters were investigated for treated and control saplings. The results indicated that at a pH of 5.6, H. hainanensis could adapt to SAR and MAR, but NAR inhibited below-ground growth. At a pH of 2.5 and 4.0, SAR inhibited stem and leaf biomass accumulation, whereas NAR inhibited root biomass accumulation and altered root morphology. MAR had intermediary effects between those of SAR and NAR. Adverse effects on leaf physiology were reduced as the rain type shifted from SAR to NAR; however, roots were increasingly adversely affected. Our results suggest that conservation efforts for H. hainanensis should shift from an above-ground to a below-ground focus as acid rain transitions toward NAR.

Redistribution characteristics of atmospheric precipitation in different spatial levels of Guangzhou urban typical forests in southern China

The aims of the present study were to determine the pH variation and chemical feature of atmospheric precipitation during the research period. We also investigated the redistribution characteristics of rainfall while passing through the canopy layer, leaf-litter layer and soil layer, successively to quantify the acid rain buffering capacity of these spatial levels in the evergreen broadleaved forest (EBF), deciduous broadleaved forest (DBF) and coniferous forest (CF) in Guangzhou urban area, China. Results showed that the rainfall was typically acidic, and the acid rain type in Guangzhou urban area is converted from sulfuric acid type to mixed type of sulfuric acid and nitric acid. The major ions from the canopy to the forest floor differed within the three forest types. However, the enrichment phenomenon of base cations in soil leachate in EBF and DBF implied that nutrient loss was more serious in the broadleaved forest than in the coniferous forest. Variability of ionic concentration and pH in the vertical sequence of different tree species showed that the net ion concentration variation index has a significant conic relationship with ne pH change rate. We also built an acid rain buffering index, which combines the neutralization and interception effects of vegetation to acid rainfall. The present results indicated that the three forest types in urban Guangzhou all have certain buffering capacity to acid rain, and following the order: DBF > EBF > CF. In the meanwhile, the forest canopy is the biggest acid rain buffer in urban Guangzhou, following by the soil.

The composition, seasonal variation, and potential sources of the atmospheric wet sulfur (S) and nitrogen (N) deposition in the southwest of China.

The composition, seasonal variation, and potential sources of sulfate (S) and nitrogen (N) deposition in precipitation in the southwest of China from 2003 to 2013 were investigated. The results showed that the concentration of SO4 (2-), NO3 (-), and NH4 (+) in rainwater were 10.57-1360, 7.16-523.71, and 7.54-1020 μeq l(-1), with an annual volume-weighted mean (VWM) concentration of 103.99, 46.73, and 97.30 μeq l(-1), respectively. The annual wet deposition of SO4 (2-), NO3 (-), and NH4 (+) was 21.66, 8.16, and 17.49 kg S (N) ha(-1), respectively. The temporal variations of the ions showed that the abrupt decreasing breakpoints were in 2008 for SO4 (2-) and in 2009 for NO3 (-) and NH4 (+), and increasing trends were observed after 2010 for the three ions. These trends reflected the effect of economy recession and the policy of controlling SO2 and NOx emissions. The acid rain type of precipitation was shifted from sulfur to a mixed one. The ions of SO4 (2-), NO3 (-), and NH4 (+) presented high values in winter and spring and low values in autumn and summer. A highly positive linear correlation between SO4 (2-) and NO3 (-) (R(2) = 0.71), SO4 (2-) and NH4 (+) (R(2) = 0.74), and NO3 (-) and NH4 (+) (R(2) = 0.84) existed while a strong negative correlation was found between the three main ionic concentrations and precipitation. The SO4 (2-) was mainly from fossil fuel combustion (60.53%), aged sea salt (19.03%), agriculture (11.38%), crust (6.66%), and biomass burning (2.40%); the NO3 (-) was mainly from fossil fuel combustion (75.41%), biomass burning (9.67%), aged sea salt (7.97%), and agriculture (6.96%); and the NH4 (+) was mainly from agriculture (86.38%), fossil fuel combustion (10.52%), and aged sea salt (3.09%).

Effects of sulfuric, nitric, and mixed acid rain on litter decomposition, soil microbial biomass, and enzyme activities in subtropical forests of China

Acid rain pollution is changing gradually from sulfuric acid rain (SAR) to mixed acid rain (MAR) and then to nitric acid rain (NAR) with the rapidly growing number of motor vehicles. The influences of changed acid rain types on ecosystem functions, particularly on litter decomposition, remain unclear. Two dominant litter types from a coniferous forest and a broad-leaved forest were incubated in microcosms with original forest soils and treated by five types of acid rain with different SO42− to NO3− ratios (1:0, 5:1, 1:1, 1:5, and 0:1). During a six-month incubation period, litter mass losses, soil microbial biomass, and enzyme activities were investigated. Results showed that various acid treatments inhibited litter decomposition, soil microbial biomass, and most enzyme activities, and the inhibitory effects of NAR were more significant than those of SAR and MAR. The resistance to external acid of microbial communities in broad-leaved forest was higher than that in coniferous forest. NAR and MAR treatments slowed down soil carbon (C), nitrogen (N), and phosphorus (P) mineralization by attenuating the correlations between litter mass losses and the enzymes involved in C, N, and P cycling. Results reveal that the ratio of SO42− to NO3− in acid rain is an important factor which profoundly influences litter decomposition process. In the future, a decreasing ratio of SO42− to NO3− in acid rain will be observed in subtropical forests. Thus, soil C would accumulate as a consequence of future acid precipitation, and this may seriously affect the balance of ecosystem C, N flux.

Study on Effects of Different Types of Acid Rain on Nutritional Quality of Pakchoi

Spray sulfuric acid rain solution, nitric acid rain solution and mixed acid rain solution on pakchoi in the greenhouse. Strong acidic acid rain inhibits the formation of the nutrients in the cabbage. While week acidic acid rain promote the formation of the nutrients in the cabbage. Nitric acid rain has the greatest impact on the quality of pakchoi nutrition.