The main objective of this paper is to analyse regeneration regularities of damaged trees during the period of decreased environmental pollution load. Investigations concentrated on Scots pine tree height and radial increment, branch length increment, amount of branches on the verticil and needle and whole crown mass. Model trees were selected in 3 stands located on 3.5, 10 and 21 km from the plant according to their development classes and condition

The results showed that the hydrogen load had a very significant variation between the two monitoring years. In 1999-00 water year, hydrogen load was 4.72 kmol/ha, while in 2000-01 it was 1.70 kmol/ha. Although the observed pH values of rainwater never got over 7.0, high values around 6.0 were determined in summer moonths. The average equivalent concentrations of measured ions were calculated and an equilibrium between anions and cations was found

The increasing microplastics (MPs) pollution and continuous acid rain coincide in many areas of the world. However, how MPs interact with acid rain is still unclear. Herein, we conducted a microcosm experiment to decipher the combined effect of polyethylene (PE) MPs (1%, 5%, and 10%) and acid rain (pH 4.0) on the agricultural soil ecosystem of Southern China, in which edaphic property, microbial community, enzymatic activity and CO₂ emission were investigated. The results showed that PE MPs significantly decreased soil water retention and nitrate nitrogen content regardless of acid rain. Soil total nitrogen significantly decreased under the co-exposure of 10% PE MPs and acid rain. However, PE MPs did not alter soil microbial biomass, i.e., the content of microbial biomass carbon, total phospholipid fatty acids, with or without acid rain. 10% PE MPs and acid rain treatment significantly increased the activity of catalase and soil CO₂ emission. PE MPs addition did not affect the temperature sensitivity (Q₁₀) of soil CO₂ emission regardless of acid rain. These findings suggest that MPs may interact with acid rain to affect soil ecosystems, thus underscoring the necessity to consider the interaction between MPs and ambient environmental factors when exploring the impact of MPs on the soil biodiversity and function.

The current recovery of mountain lakes from atmospheric acidification is increasingly affected (both accelerated and/or delayed) by climate change. We evaluated long-term trends in the ionic composition of 30 lakes situated in the alpine zone of the Tatra Mountains, and compared the rates of their recovery with model (MAGIC) simulations done 20 years ago for the 2003–2020 period. The observed recovery was faster than the model forecast, due to greater reductions in acidic deposition than projected. Trends in water composition were further modified by climate change. Rising temperatures increased the length of the growing season and retention of inorganic N and SO₄²⁻ more in soil-rich compared with soil-poor catchments. In contrast, elevated precipitation and an increase in rainfall intensity reduced water residence time in soils, and consequently reduced N retention, especially in soil-poor catchments. It is likely that increases in rainfall intensity and annual number of days without snow, along with air temperatures fluctuating around the freezing point elevated the physical erosion of rocks, especially in high-elevation, steep, and scree-rich areas where rocks are not thermally insulated and stabilized by soils. Weathering of exposed accessory calcite in the eroded granodiorite bedrock was a source of Ca²⁺ and HCO₃⁻, while S-bearing minerals likely contributed to lake water SO₄²⁻ and partly mitigated its deposition-related decrease in scree-rich catchments. The extent of climate effects on changes in the water composition of alpine lakes recovering from acidic deposition thus depended on elevation and cover of soil and scree in catchments. Our results highlight the need for incorporating dominant climate-related process into existing process-based models to increase their reliability in predicting the future development of lake water composition.

China continues to suffer from severe acid deposition, despite the government implying a series of policies to control air pollution. In this study, rainwater samples were collected from 2011 to 2016 in Sichuan province to measure the pH values and the concentrations of nine inorganic ions (SO₄²⁻, NO₃⁻, NH₄⁺, Cl⁻, Na⁺, Ca²⁺, K⁺, Mg²⁺, and F⁻), and then to investigate their spatiotemporal variations. Besides, the dominant sources for the acidic ions in the precipitation were also revealed by statistical model. The results showed that the rainwater continued to be highly acidic, and the Volume-Weighted Mean (VWM) pH value was calculated to be 5.18 during 2011 and 2016. NH₄⁺, Ca²⁺, NO₃⁻, and SO₄²⁻ were the dominant water-soluble inorganic ions, accounting for 79.2% of the total ions on average. The remarkable decrease in NO₃⁻ and SO₄²⁻ concentrations (from 75.9 to 54.3 μeq L⁻¹ and from 285 to 145 μeq L⁻¹, respectively) resulted in an increase in the pH value of rainwater from 5.24 in 2011 to 5.70 in 2016. The concentrations of SO₄²⁻, NO₃⁻, F⁻, Na⁺, and K⁺ showed remarkably seasonal variation, with the highest value observed in winter, followed by spring and autumn, and the lowest value observed in summer. High VWM concentration of these ions in winter were mainly due to adverse meteorological conditions (e.g., rare rainfall, lower planetary boundary height, and stagnant air) and intensive anthropogenic emissions. SO₄²⁻, NO₃⁻, and F⁻ ions peaked in the southeastern Sichuan province, which is a typical industrial region. NH₄⁺ concentrations decreased from 268 μeq L⁻¹ in the east to 10.4 μeq L⁻¹ in the western Sichuan province, which could be related to the development of agriculture in the eastern Sichuan province. Ca²⁺ peaked in southeastern Sichuan province due to intensive construction activities and severe stone desertification. On the basis of Positive Matrix Factorization (PMF) analysis, four sources of inorganic ions in rainwater were identified, including anthropogenic source, crust, biomass burning, and aging sea salt aerosol. Geographically Weighted Regression (GWR) was used to find the spatial correlations between the socio-economic factors and ions in the rainwater. At the regional scale, the influence of fertilizer consumption and Gross Agricultural Production (GAP) on NH₄⁺ increased from east to west; moreover the influence of Gross Industrial Production (GIP) on SO₄²⁻ and NO₃⁻ also increased.

Acid rain is one of the severest environmental issues globally. Relative to other global changes (e.g., warming, elevated atmospheric [CO2], and nitrogen deposition), however, acid rain has received less attention than its due. Soil fauna play important roles in multiple ecological processes, but how soil fauna community responds to acid rain remains less studied. This microcosm experiment was conducted using latosol with simulated acid rain (SAR) manipulations to observe potential changes in soil fauna community under acid rain stress. Four pH levels, i.e., pH 2.5, 3.5, 4.5, and 5.5, and a neutral control of pH 7.0 were set according to the current pH condition and acidification trend of precipitation in southern China. As expected, we observed that the SAR treatments induced changes in soil fauna community composition and their ecological niches in the tested soil; the treatment effects tended to increase as acidity increased. This could be attributable to the environmental stresses (such as acidity, porosity and oxygen supply) induced by the SAR treatments. In addition to direct acidity effect, we propose that potential changes in permeability and movability of water and oxygen in soils induced by acid rain could also give rise to the observed shifts in soil fauna community composition. These are most likely indirect pathways of acid rain to affect belowground community. Moreover, we found that nematodes, the dominating soil fauna group in this study, moved downwards to mitigate the stress of acid rain. This is probably detrimental to soil fauna in the long term, due to the relatively severer soil conditions in the deep than surface soil layer. Our results suggest that acid rain could change soil fauna community and the vertical distribution of soil fauna groups, consequently changing the underground ecosystem functions such as organic matter decomposition and greenhouse gas emissions.

Atmospheric acid deposition is a global environmental issue. China has been experiencing serious acid deposition, which is anticipated to become more severe with the country's economic development and increasing consumption of fossil fuels in recent decades. We explored the spatiotemporal variations of acid deposition (wet acid deposition) and its influencing factors by collecting nationwide data on pH and concentrations of sulfate (SO4²⁻) and nitrate (NO3⁻) in precipitation between 1980 and 2014 in China. Our results showed that average precipitation pH values were 4.59 and 4.70 in the 1990s and 2010s, respectively, suggesting that precipitation acid deposition in China has not seriously worsened. Average SO4²⁻ deposition declined from 40.54 to 34.87 kg S ha⁻¹ yr⁻¹ but average NO3⁻ deposition increased from 4.44 to 7.73 kg N ha⁻¹ yr⁻¹. Specifically, the area of severe precipitation acid deposition in southern China has shrunk to some extent as a result of controlling the pollutant emissions; but the area of moderate precipitation acid deposition has expanded in northern China, associated with rapid industrial and transportation development. Furthermore, we found significant positive correlations between precipitation acid deposition, energy consumption, and rainfall. Our findings provide a relatively comprehensive evaluation of the spatiotemporal dynamics of precipitation acid deposition in China over past three decades, and confirm the idea that strategies implemented to save energy and control pollutant emissions in China have been effective in alleviating precipitation acid deposition. These findings might be used to demonstrate how developing countries could achieve economic development and environmental protection through the implementation of advanced technologies to reduce pollutant emissions.

Underground coal fires start naturally or as a result of human activities. Besides burning away the important non-renewable energy resource and causing financial losses, burning coal seams emit carbon dioxide, carbon monoxide, sulfur oxide and methane, and is a leading cause of smog, acid rain, global warming, and air toxins. In the U.S. alone, the combined cost of coal-fire remediation projects that have been completed, budgeted, or projected by the U.S. Department of the Interior's Office of Surface Mining Remediation and Enforcement (OSM), exceeds $1 billion. It is estimated that these fires generate as much as 3% of the world's annual carbon dioxide emissions and consume as much as 5% of its minable coal. Considering the magnitude of environmental impact and economic loss caused by burning underground coal seams, we have developed a new, safe, reliable surface measurement of coal fire gases to assess the nature of underground coal fires. We use a drone mounted with gas sensors. Drone collected gas concentration data provides a safe alternative for evaluating the rank of a burning coal seam. In this study, a new method of determining coal rank by gas ratios is developed. Coal rank is valuable for defining parameters of a coal seam such as burn temperature, burn rate, and volume of burning seam.

Following Europe and North America, East Asia has become a global hotspot for acid deposition, with very high deposition of both sulfur (S) and nitrogen (N) occurring in large areas of southwest and southeast China. This study shows that the outflow flux of sulfate (SO42−) in three major tributaries of the Upper Yangtze River in the Sichuan Basin in southwest China has been increasing over the last three decades, which implies the regional soil acidification caused by increasing sulfur dioxide (SO2) emissions. Since 2005, the outflow of SO42− to the Upper Yangtze River from the Sichuan Basin has even reached the atmospheric SO2 emission from the basin. In contrast to S emissions, the rapid increase in nitrogen (N) emissions, including nitrogen oxides (NOx) and ammonia (NH3), have resulted in only a slight increase in nitrate (NO3−) concentrations in surface waters, indicating a large retention of N in the basin. Although N deposition currently contributes much less than S to soil acidification in this area, it is possible that catchments receiving a high input of N may be unable to retain a large fraction of the N deposition over long periods.

Rigorous studies of recovery from soil acidification are rare. Hence, we resampled 97 old-growth beech stands in the Vienna Woods. This study exploits an extensive data set of soil (infiltration zone of stemflow and between trees area at different soil depths) and foliar chemistry from three decades ago. It was hypothesized that declining acidic deposition is reflected in soil and foliar chemistry. Top soil pH within the stemflow area increased significantly by 0.6 units in both H2O and KCl extracts from 1984 to 2012. Exchangeable Ca and Mg increased markedly in the stemflow area and to a lower extent in the top soil of the between trees area. Trends of declining base cations in the lower top soil were probably caused by mobilization of organic S and associated leaching with high amounts of sulfate. Contents of C, N and S decreased markedly in the stemflow area from 1984 to 2012, suggesting that mineralization rates of organic matter increased due to more favorable soil conditions. It is concluded that the top soil will continue to recover from acidic deposition. However, in the between trees areas and especially in deeper soil horizons recovery may be highly delayed. The beech trees of the Vienna Woods showed no sign of recovery from acidification although S deposition levels decreased. Release of historic S even increased foliar S contents. Base cation levels in the foliage declined but are still adequate for beech trees. Increasing N/nutrient ratios over time were considered not the result of marginally higher N foliar contents in 2012 but of diminishing nutrient uptake due to the decrease in ion concentration in soil solution. The mean foliar N/P ratio already increased to the alarming value of 31. Further nutritional imbalances will predispose trees to vitality loss.