An overview of the direct and indirect effects of acid rain on plants: Relationships among acid rain, soil, microorganisms, and plants

Simulated acid rain (SAR) induced alterations in plant morpho-physiology, leaf ultrastructure, cell viability, and yield - A case study on Mentha arvensis L. (Wild mint)

Acid rain (AR), a secondary pollutant, a product of sulfur and nitrogen oxides fusion with the atmosphere's water vapor, comes on earth in the form of rain, poses a significant environmental threat, and affects soil characteristics and plant morphology, ultrastructure, physiology, and yield. However, its effects on aromatic and medicinal plants remain insufficiently studied. Due to their low side effects and high efficacy, the use of herbal plants for disease remedy preparation is found globally and their consumption increases year after year. Mentha arvensis is such an aromatic crop, having great economic importance due to the essential oil present in its leaf. This research examines the influence of simulated acid rain (SAR) at varying pH levels (6.0, 5.0, 4.0, and 3.0) on morphology, growth, physiology, and yield parameters in M. arvensis. Results revealed that different concentrations of SAR exposure significantly (p ≤ 0.05) reduced growth and yield parameters, photosynthetic pigments and protein content, essential mineral composition, and phytochemical levels. Conversely, antioxidants activity such as catalase (CAT), superoxide dismutase (SOD), peroxidase (POX), ascorbate peroxidase (APX), lipid peroxidation marker malondialdehyde (MDA), osmo-protectant proline content, hydrogen peroxide (H2O2) content, superoxide ions content (O2•-), and electrolyte leakage percent (EL) level increased significantly (p ≤ 0.05) as acidity intensified, particularly at pH 3.0. At pH 3.0, there was a notable reduction (p ≤ 0.05) in shoot length (55.63%), root length (55.42%), fresh weight (59.81% for shoots, 52.32% for roots), dry weight (62.88% for shoots, 55.56% for roots), number of leaves (56.13%), leaf area (60.53%), nitrate reductase (NR) activity (58.48%) and chlorophyll content (43.58% for chlorophyll 'a', 57.07% for chlorophyll 'b'). Phytochemicals such as menthol (12.08%), menthone Title page (40.07%), and menthyl acetate (33.63%) were significantly reduced while antioxidants activity such as CAT (144.71%), POX (260.37%), SOD (255.15%), APX (213.51%), MDA content (193.97%), proline content (607.18%), H2O2 content (163.69%), O2•- content (185.82%), EL percentage (57.23%) significantly (p ≤ 0.05) increased. The highest acidity level (pH 3.0) resulted in the most significant reduction in growth, yield, and the production of economically important phytochemical constituents, highlighting the harmful effects of simulated acid rain on the growth, productivity, biochemical characteristics, and commercial value of M. arvensis.

PM2.5 and NOX concentrations decrease as a result of a railway electrification

This work examines the impact of the electrification of the Holon-Bat Yam passenger train line (central Israel) on air pollutant concentrations using data collected from air quality monitoring stations that operated at the train stations across the electrified train line. We present statistically significant reduction in the annual average NO2, NO and NOX concentrations (29-45%, 79-85% and 65-75%, respectively), attributed to the electrification of the passenger train line. The drop in the NO and NOX concentrations was much stronger than in the NO2 concentrations, since NO is the main nitrogen species emitted by diesel locomotives. PM2.5 concentrations also significantly decreased, but only in two (out of the three) train stations situated along the electrified line. Following various analyses, we conclude that electrification of train lines reduces train locomotive emissions and improves the air quality at the stations, as expected, thus protecting the passengers and reducing their exposure to air pollutants. Although this study presents a specific case, the findings are expected to be applicable, at least quantitatively, to other locations, as railway electrification removes emissions associated with fossil-fuel-powered locomotives. This work supports railway electrification policy, which has the potential to substantially lower air pollution levels and diminish the passengers' exposure to harmful air pollutants.

Atmospheric precipitation chemistry and environmental significance in major anthropogenic regions globally

In order to investigate the spatiotemporal distribution and influencing factors of global precipitation chemistry, we conducted a comprehensive analysis using multiple data sources, revealing the impact of human activities on the natural environment. The results indicate a decreasing trend in global precipitation acidity over the past 20 years. The distribution of global precipitation is influenced by both natural and anthropogenic factors. Alkaline cation concentrations are higher in desert and arid regions, while high concentrations of SO42- and NO3- are primarily found in industrial areas, and agricultural areas exhibit higher NH4+ concentrations. Coastal regions have higher Na+ and Cl- concentrations compared to inland areas. However, the increased Na + and Cl- concentrations due to inland salinization should not be overlooked. Additionally, influenced by atmospheric circulation, transboundary pollution from South Asia leads to higher SO42- and NO3- concentrations in precipitation over the Tibetan Plateau. Meteorological factors have a weaker influence on precipitation chemistry compared to geographical and human activity factors, although ion concentrations in snowfall are higher than in rainfall.

Acid rain reduced soil carbon emissions and increased the temperature sensitivity of soil respiration: A comprehensive meta-analysis

Soil respiration the second-largest carbon flux in terrestrial ecosystems, has been extensively studied across a wide range of biomes. Surprisingly, no consensus exist on how acid rain (AR) impacts the spatiotemporal pattern of soil respiration. Therefore, we conducted a meta-analysis using 318 soil respiration and 263 soil respiration temperature sensitivity (Q10) data points obtained from 48 studies to assess the impact of AR on soil respiration components and their Q10. The results showed that AR reduced soil total respiration (Rt) and soil autotrophic respiration (Ra) by 7.41 % and 20.75 %, respectively. As the H+ input increased, the response rates of Ra to AR (RR-Ra) and soil heterotrophic respiration (Rh) to AR (RR-Rh) decreased and increased, respectively. With increased AR duration, the RR-Ra increased, whereas the RR-Rh did not change. AR increased the Q10 of Rt (Rt-Q10) and Rh (Rh-Q10) by 1.92 % and 9.47 %, respectively, and decreased the Q10 of Ra (Ra-Q10) by 2.77 %. Increased mean annual temperature, mean annual precipitation, and initial soil organic carbon increased the response rate of Ra-Q10 to AR (RR-Ra-Q10) and decreased the response rate of Rh-Q10 to AR (RR-Rh-Q10). However, as the AR frequency and initial soil pH increased, both RR-Ra-Q10 and RR-Rh-Q10 also increased. In summary, AR decreased Rt but increased Q10, likely due to soil acidification (soil pH decreased by 7.84 %), reducing plant root biomass (decreased by 5.67 %) and soil microbial biomass (decreased by 5.67 %), changing microbial communities (increased fungi to bacteria ratio of 15.91 %), and regulated by climate, vegetation, soil and AR regimes. To the best of our knowledge, this is the first study to reveal the large-scale, varied response patterns of soil respiration components and their Q10 to AR. It highlights the importance of applying the reductionism theory in soil respiration research to enhance our understanding of soil carbon cycling processes with in the context of global climate change.

On-site detection of infectious disease based on CaCO3-based magnetic micromotor integrated with graphene field effect transistor

A new detection platform based on CaCO3-based magnetic micromotor (CaCO3@Fe3O4) integrated with graphene field effect transistor (GFET) was construct and used for on-site SARS-CoV-2 coronavirus pathogen detection. The CaCO3@Fe3O4 micromotor, which was modified with anti-SARS-CoV-2 (labelled antibody, AntiE1), can self-moved in the solution containing hydrochloric acid (HCl) and effective to capture the SARS-CoV-2 coronavirus pathogens. After magnetic field separation, the capture micromotor was detected by GFET, exhibiting a good linear relationship within the range of 1 ag/mL to 100 ng/mL and low detection limit (0.39 ag/mL). Furthermore, the detection platform was also successfully applied to detection of SARS-CoV-2 coronavirus pathogens in soil solution, indicating the potential use in on-site application.

The Release and Migration of Cr in the Soil under Alternating Wet-Dry Conditions

In recent decades, chromium contamination in soil has emerged as a serious environmental issue, demanding an exploration of chromium's behavioral patterns in different soil conditions. This study aims to simulate the release, migration, and environmental impact of chromium (Cr) in contaminated soils under natural rainfall conditions (wet-dry cycles). Clean soils sourced from Panzhihua were used to cultivate chromium-containing soils. Simulated rainfall, prepared in the laboratory, was applied to the cultivated chromium-containing soils in indoor simulated leaching experiments. The experiments simulated three years of rainfall in Panzhihua. The results indicate that soils with higher initial Cr contents result in higher Cr concentrations in the leachate, but all soils exhibit a low cumulative Cr release. The leachate shows similar patterns in total organic carbon (TOC), pH, electrical conductivity, and Cr content changes. An analysis of the speciation of Cr in the soil after leaching reveals a significant decrease in the exchangeable fraction for each Cr species, while the residual and oxidizable Cr fractions exhibit notable increases. The wet-dry cycle has the following effects on the soil: it induces internal reduction reactions in the soil, leading to the reduction of Cr(VI) to Cr(III); it alters the binding of Cr ions to the soil, affecting the migration of chromium; and it involves microorganisms in chemical processes that consume organic matter in the soil. After three years of rainwater leaching, chromium-containing soils released a relatively low cumulative amount of total chromium, resulting in a reduced potential risk of groundwater system contamination. Most of the chromium in the chromium-containing soil is fixed within the soil, leading to less biotoxicity.

The impact of acid rain on cadmium phytoremediation in sunflower (Helianthus annuus L.)

Sunflower is an ideal crop for phytoremediation of cadmium-contaminated farmland, as it brings economic benefits while conducting soil remediation. Due to industrial emissions and car exhaust, Cd contaminated areas are often accompanied by acid rain. However, the impact of acid rain on the Cd remediation capacity of sunflowers and its potential influencing factors are unclear. An experiment was manipulated to elucidate the effects of Cd concentration (0,10,50,100 μmol/L) and acid rain (pH 4.0) on the phytoremediation ability of sunflowers, in which the properties of them were explored. The results indicated that Cd stress is the main factor affecting the growth of sunflowers. Without AR, Cd treatment decreased sunflower biomass by 67.5-85.6%. Under AR, Cd treatment decreased sunflower biomass 53.9-86.4%. Compared without AR, the relative chlorophyll content with AR increased by 22.3-23.1%, while the YII with AR decreased by 6.5-20.0%. There was an interaction between acid rain and Cd stress on antioxidant enzyme activity. With AR, CAT activity at 0 μmol/L Cd treatment increased by 25.6%, compared without AR. Whether there is acid rain or not, the POD and SOD activities were increased at 10, 50 μmol/L Cd treatment, but they were decreased at 100 μmol/L Cd treatment. Among them, acid rain exacerbated the impact of POD activity (decreased by 31.4%) at 100 μmol/L Cd treatment and SOD activity (decreased by 15.1%) at 50 μmol/L Cd treatment, compared without AR. In this experiment, the phytoremediation capacity of sunflowers mainly depended on the concentration of Ca in the leaves and their antioxidant capacity. Acid rain enhanced 77.5% the total Cd accumulation at 10 μmol/L Cd treatment, compared without AR. Acid rain exacerbated the damage of Cd to the chloroplast structure of sunflowers, and reduced the accumulation of starch particles. The study findings may be useful for improving the phytoremediation of Cd-contaminated soil.

Investigating the dynamic responses of Aegilops tauschii Coss. to salinity, drought, and nitrogen stress: a comprehensive study of competitive growth and biochemical and molecular pathways

Aegilops tauschii (Coss.) is a highly deleterious, rapidly proliferating weed within the wheat, and its DD genome composition exhibits adaptability toward diverse abiotic stresses and demonstrates heightened efficacy in nutrient utilization. Current study investigated different variegated impacts of distinct nitrogen concentrations with varied plant densities, scrutinizing the behavior of Ae. tauschii under various salinity and drought stress levels through multiple physiological, biochemical, and molecular pathways. Different physiological parameters attaining high growth with different plant density and different nitrogen availability levels increased Ae. tauschii dominancy. Conversely, under the duress of salinity and drought, Ae. tauschii showcased an enhanced performance through a comprehensive array of physiological and biochemical parameters, including catalase, peroxidase, malondialdehyde, and proline content. Notably, salinity-associated traits such as sodium, potassium, and the sodium-potassium ratio exhibited significant variations and demonstrated remarkable tolerance capabilities. In the domain of molecular pathways, the HKT and DREB genes have displayed a remarkable upregulation, showcasing a comparatively elevated expression profile in reaction to different levels of salinity and drought-induced stress. Without a doubt, this information will make a substantial contribution to the understanding of the fundamental behavioral tendencies and the efficiency of nutrient utilization in Ae. tauschii. Moreover, it will offer innovative viewpoints for integrated management, thereby enabling the enhancement of strategies for adept control and alleviation.