A model for the reversible washout of sulfur dioxide, ammonia and carbon dioxide from a polluted atmosphere and the production of sulfates in raindrops

Zinc ferrite−silica composite powder was subjected to a series of reduction and sulfidation tests performed at mainly 450 °C in a simulated coal gas environment. In situ X-ray diffraction analyses revealed that ZnS and FeS were produced at a H2S concentration of 1 vol %, whereas only zinc sulfides were detected at 80 ppm. The scheme for sulfidation at 450 °C was essentially the same as that of pure zinc ferrite at 550 °C. The desulfurization sorbent containing the composite powder was subjected to pressurized thermobalance to determine the sulfur capacities of zinc and iron separately by applying high and low H2S concentrations for sulfidation. This method was applied to analyze the change of the zinc-related sulfur capacity of sorbent samples that experienced multiple desulfurization cycles up to 20 times. At the end of the cycles, the zinc-related sulfur capacity had fallen to about 50% of its initial value, whereas the sulfur capacity due to iron sulfidation maintained 91% of its initial value. This indicates that the residual sulfur mainly results from the production of zinc sulfate during multiple desulfurization cycles.

A time-independent model is presented which predicts the short-lived radon daughter activity of rainwater at ground level for unit concentration of radon (222Rn) in cloud. The model incorporates the physical processes of diffusive attachment of radon daughters and impact collection for cloud droplets by raindrops. It also includes consideration of cloud droplet and raindrop size spectra. It is concluded from the results from the model that the specific activity of rainwater is not affected very much by aerosol concentration, liquid water content, average radius of raindrops and height of cloud base but is affected markedly by rainfall rate. The radon concentrations in the rainclouds are estimated from the comparison between calculation and near-ground observations carried out for a period of almost 3 years. The result shows that the monthly geometric mean concentration ranges from 2 to 6 pCi·m−3 at Nagoya.

The radio signal in mm wave region is affected by rain characteristics such as rain rate, rain drop size distribution, spatial and temporal structure apart from polarization of signal. Thus, rain causes attenuation of radio signal in the mm wave region (30 GHz to 300 GHz), which becomes important as fade margin for the design of reliable communication. The rain drop size distribution (RDSD), which varies for different climatic conditions at the same rain rate, plays very important role for attenuation of radio signals in mm wave region. The tropical region such as India, Malaysia, Brazil, Nigeria, South Africa and Singapore follows log-normal rain drop size distribution. In this paper, various lognormal RDSD models of Indian Climate based on rain drop size spectra measurement at Dehradun, Kharagpur, Shillong, Ahmedabad, Hassan and Trivandrum have been discussed in respect of rain drop size spectra and compared with lognormal RDSD models of other tropical countries. Further, the specific rain attenuation model developed from different RDSD models of Indian tropical climate is described, which shows the regional variability in the specific attenuation at mm wave region due to variation in the rain characteristics. It is observed that specific rain attenuation at 100 GHz decreases less compared to 60 GHz with the increase of rain rate. The specific rain attenuation at 100 GHz is less compared to 60 GHz beyond the rain rate of 30 mm/hr depending upon the locations due to different RDSD characteristics in the Indian tropical region.

The inter-relation of rain drop size distribution with cloud base height has been investigated at a tropical location, Kolkata (22°34′N, 88°22′E). The study focuses the association of rain drop size distribution with cloud base height during the summer monsoon and pre-monsoon. It is observed that the mean diameter of the largest drop increases with the lowering of cloud base height. A notable difference between the pre-monsoon and monsoon rain events have been identified in the inter-relation of rain drop size with cloud base height. Results indicate that the large drops are more frequent in the pre-monsoon season than the monsoon.

Rain is inherently acidic, human anthropogenic activities including pollution from homes, companies, power plants, and car vehicles, which result in the release of molecules like Carbon dioxide, Nitric dioxide, and Sulfur dioxide, are making it more and more acidic. The screen house experiment was undertaken to assess how acid rain affects plants. In the lab, to create acid rain concentrated sulphuric acid (H2SO4) and concentrated nitric acid (HNO3) were mixed in a 2:1 ratio. The desired pH level was measured using a Duplex pH meter. The plant was simulated with acid rain (pH 2.5, 3.0, 3.5, and control 5.6) every three days for six weeks. ANOVA was used for the statistical analysis. The significance of the mean difference was assessed using Ducan's multiple-range tests. With increasing pH levels, plant height (FPepper = 63.835), leaf area (FPepper =60.965), stem girth (FPepper =39.3), the number of leaves (FPepper =34.265), relative growth rate (FPepper = 40.646), and chlorophyll content (FPepper = 4.6029, 7.8154, 36.746) decreased considerably (p<0.001). These findings advance our knowledge of how acid rain impacts urbanvegetation and serves as a warning to limit acid rain production

Rain is inherently acidic, human anthropogenic activities including pollution from homes, companies, power plants, and car vehicles, which result in the release of molecules like Carbon dioxide, Nitric dioxide, and Sulfur dioxide, are making it more and more acidic. The screen house experiment was undertaken to assess how acid rain affects plants. In the lab, to create acid rain concentrated sulphuric acid (H2SO4) and concentrated nitric acid (HNO3) were mixed in a 2:1 ratio. The desired pH level was measured using a Duplex pH meter. The plant was simulated with acid rain (pH 2.5, 3.0, 3.5, and control 5.6) every three days for six weeks. ANOVA was used for the statistical analysis. The significance of the mean difference was assessed using Ducan's multiple-range tests. With increasing pH levels, plant height (FPepper = 63.835), leaf area (FPepper =60.965), stem girth (FPepper =39.3), the number of leaves (FPepper =34.265), relative growth rate (FPepper = 40.646), and chlorophyll content (FPepper = 4.6029, 7.8154, 36.746) decreased considerably (p<0.001). These findings advance our knowledge of how acid rain impacts urbanvegetation and serves as a warning to limit acid rain production

Acid rain is one of the most serious environmental issues in Southern China. The composition of acid rain has gradually changed from sulfuric acid rain (SAR) to nitric acid rain (NAR) due to the rapid development of industry, and controls on SO2 emissions. However, a comprehensive understanding of how changes in the type of acid rain affect soil respiration (Rs) in forest ecosystems is still lacking. In this study, we investigated the influence of simulated acid rain with different SO42−/NO3− ratios, namely, SAR (4:1), MAR (mixed acid rain, 1:1), and NAR (1:4), on Rs in Cunninghamia lanceolata (Lamb.) Hook. (CL) and Michelia macclurei Dandy (MM) plantations from 2019 to 2020. A trenching method was used to partition Rs into heterotrophic respiration (Rh) and autotrophic respiration (Ra). The results showed that acid rain did not significantly influence Rs in the two plantations, which could be mainly attributed to the unchanged soil pH. Neither SAR, MAR, nor NAR affected Ra in the two plantations, possibly due to the unchanged root biomass. The SAR treatment only significantly increased Rh in the MM plantation, not in the CL plantation. The temperature sensitivity (Q10) of Rs and its components was not significantly different among different acid rain types in either of the plantations. Our results suggest that the impact of acid rain on Rs and its components depends on the forest ecosystem and the type of acid rain. Different biological processes complicate the response of soil CO2 emissions to acid rain pollution.

The coefficients and phase functions of sound scattering by a single rigid spherical particle whose parameter Mie changes in a wide range have been calculated with the use of exact formulas of the Mie scattering theory. Analytical expressions are given for the dependence of sound attenuation on the parameters of fog and rain and acoustic frequency. The acoustic scattering cross section of a single particle has been derived. New methods of acoustic sounding of fog and rain have been suggested and theoretically analyzed. Experimental data on the transformation of raindrop size distribution have been obtained by processing of raw spectra of acoustic signals recorded in rain for 20 s and 1, 2, 3, 5, and 25 min with cw bistatic sodars operating at frequencies of 5 and 40 kHz. The bimodal character of the raindrop size spectra was established. The position of the second maximum in the raindrop size spectrum was shifted with time toward larger raindrop sizes, from 0.3 to 1 mm. The estimated rain intensity varied from 0.5 to 1.9 mm per hour. The obtained results demonstrate that high-frequency cw bistatic sodars are very promising for measurements of fog and rain.

The effects of prolonged simulated acid rain on percentage cover of ground vegetation, and on growth and reproduction of two dominating dwarf shrubs (Emapetrum nigrum and Vaccinium vaitisidaea) were examined in a field experiment in the Finnish Subarctic, in an area with low ambient levels of sulphur and nitrogen deposition. Acid rain treatments included moderate (pH 3.8) and high (pH 2.9) concentrations of either H2 SO4 , or HNO3 , or a mixture of them, and were compared with irrigated (pH 6) and dry control plots. Long-term application of acid rain caused significant alteration in the cover and composition of ground vegetation. Effects of acid ram depended on the accompanying anion and on pH. Sub-plots under different canopy tree species differed in responses indicating that spatial heterogeneity is important in predicting the effect of acidifying pollution on this plant community. In the bottom layer, acid rain caused significant reduction in cover of the cyanobacterial lichens Nephroma arcticum and Peltigera spp. Decrease in cover of fruticose lichens, mainly composed of Cladina spp., more likely resulted from additional watering. In the field layer, acid rain containing moderate concentrations of NO- 3 caused an increase in cover of graminoid species. There were only slight alterations in growth and cover of the two dominant evergreen dwarf shrubs, Enigrum and V. vitis-idaea, indicating that these species are tolerant to acid rain of as low as pH 3. Even some positive responses of dwarf shrubs were observed, depending on canopy tree. Application of acid rain of pH 3 to plots under pine trees caused an increase in cover of I, vitis-idaea and, when the nitric acid only was applied, a short-term increase in the number of new shoots of E. nigrum. In contrast to vegetative growth, reproduction of the dwarf shrubs was more strongly affected by acid rain, but this also depended on local conditions and anion composition of acid rain. On 'pine' plots, rain of pH 3 reduced the number of berries and flower buds on terminal current shoot of E. nigrum, however, this was partially compensated by an increase in berry production at the ramet level. Simulated acid rain had mainly negative effects on berry production by V. vitis-idaea.

Sulfuric acid vapor and other cloud-related gases in the Venus atmosphere: Abundances inferred from observed radio opacity

Stabilization technology is one of widely used remediation technologies for cadmium (Cd)-contaminated agricultural soils, but stabilized Cd in soil may be activated again when external conditions such as acid rain occurred. Therefore, it is necessary to study the effect of acid rain on the performance of different stabilizing agents on Cd-polluted agriculture soils. In this study, Cd-contaminated soils were treated with mono-calcium phosphate (MCP), mono-ammonium phosphate (MAP), and artificial zeolite (AZ) respectively and incubated 3months. These treatments were followed by two types of simulated acid rain (sulfuric acid rain and mixed acid rain) with three levels of acidity (pH = 3.0, 4.0, and 5.6). The chemical forms of Cd in the soils were determined by Tessier's sequential extraction procedure, and the leaching toxicities of Cd in the soils were assessed by toxicity characteristic leaching procedure (TCLP). The results show that the three stabilizing agents could decrease the mobility of Cd in soil to some degree with or without simulated acid rain (SAR) treatment. The stabilization performances followed the order of AZ < MAP < MCP. Acid rain soaking promoted the activation of Cd in stabilized soil, and both anion composition and pH of acid rain were two important factors that influenced the stabilization effect of Cd.

Comparative effects of sulfuric and nitric acid rain on litter decomposition and soil microbial community in subtropical plantation of Yangtze River Delta region

Acid rain is precipitation with acidity, i.e., pH, below 5.6. There is an increasing interest in the degradation of the electrical properties of outdoor composite dielectric materials under severe contaminant conditions such as acid rain. In this study, the degradation effects of acid rain on the outdoor composite dielectrics are investigated by accelerated aging due to artificial acid rain. Based on the investigation of acid rain, the composition of artificial acid rain is chosen to agree with the actual composition of precipitation. The surface potential, breakdown voltage, tracking resistance, and surface discharge current of dielectric materials are studied. Furthermore, the degradation mechanisms of electrical properties of composite dielectrics are discussed by investigating the degradation of the chemical and physical microstructures of material surface using Fourier transform infrared (FTIR), the X-ray diffraction spectrum (XDS), and the metalloscope. Experimental results show that the outdoor polymeric dielectrics suffer severely and degrade due to acid rain so that their surface electrical properties deteriorate after aging. The erosion, by acid rain, of the energized dielectric materials is larger than that of outdoor materials used for other purposes.

Managing impure carbon dioxide produced by fossil fuel-based generation of electricity is required for successful implementation of carbon capture, utilization, and storage. Impurities in carbon dioxide, particularly SOx and NOx, are geochemically more reactive than the carbon dioxide and may adversely impact a carbon dioxide storage reservoir by generating additional acidity. Hydrothermal experiments are performed to evaluate geochemical and mineralogic effects of injecting SO2-CO2 fluid into a carbonate reservoir. The experimental design is based on a natural carbon dioxide reservoir, the Madison Limestone on the Moxa Arch of Southwest Wyoming, which serves as a natural analog for geologic cosequestration of sulfur dioxide and carbon dioxide. Idealized Madison Limestone (dolomite+calcite±anhydrite+pyrite) and Na-Cl-SO42− brine (I=0.5 molal, initial pH=8.5) reacted at reservoir conditions (110°C and 25 MPa) for approximately 165 days (3960 h). Carbon dioxide fluid containing 500 ppmv sulfur dioxide was injected and the experiment continued for approximately 55 days (1326 h). Sulfur dioxide partitions out of the supercritical carbon dioxide phase and dissolves into coexisting brine on the time scale of the experiments (55 days). Injecting supercritical SO2-CO2 or pure supercritical carbon dioxide into a brine-limestone system produces the same in situ pH (4.6) and ex situ pH (6.4–6.5), as measured 28 h after injection because dissolution of calcite buffers in situ pH. Precipitation of anhydrite sequesters injected sulfur and, coupled with dissolution of calcite, effectively buffers the amount of dissolved calcium to the same concentrations measured in limestone-brine experiments injected with pure carbon dioxide. Supercritical SO2-CO2 does not enhance the sequestration potential of a carbonate reservoir relative to pure supercritical carbon dioxide. Our results substantiate predictions from natural analog studies of the Madison Limestone that anhydrite traps sulfur and carbonate minerals ultimately reprecipitate and mineralize carbon in carbonate reservoirs.

A model for rain composition and the washout of sulfur dioxide