Economic impacts of ambient ozone pollution on wood production in Italy

Spatiotemporal evolution and key driver analysis of ozone pollution from the perspectives of spatial spillover and path-dependence effects in China

In recent years, ozone (O3) has emerged as the primary air pollutant in China, superseding PM2.5. Previous studies have concentrated on the spatiotemporal variation of ozone pollution, the analysis of its sources and drivers, as well as its environmental impacts and health benefits. Since ozone pollution can be dynamically transferred through industrial activities and meteorological factors, it is crucial to scientifically identify the spatial spillover and path-dependent effects of ozone pollution in China. However, existing studies have not yet addressed this issue. Therefore, we investigate the spatiotemporal evolution and the spatial spillover of ozone pollution by means of the exploratory spatial data analysis (ESDA) using panel data of 30 Chinese provinces from 2013 to 2020 in this study. The dynamic spatial Durbin model (SDM) was employed to reveal the key drivers of ozone pollution from the perspectives of spatial spillover and path-dependence effects. The direct and spillover effects of each driver on ozone pollution are systematically analyzed. The results show that from 2013 to 2020 ozone concentrations followed a fluctuating upward trend at national and provincial scales. Ozone pollution presented significant spatial spillover and path dependence effects. The direct effects indicated that economic growth, technological level, industrial structure, energy structure, ventilation coefficient, relative humidity and precipitation were the key drivers of local ozone pollution. The spillover effects indicated that population density, technology level, industrial structure, environmental regulations, ventilation coefficient, sunshine hours and relative humidity had significant spatial spillover effects on ozone pollution of surrounding regions. These findings will contribute to the understanding of the spatial spillover and path-dependent effects of O3 pollution, and provide scientific guidance for regional synergy and long-term ozone control policies in China.

Changes in tropospheric air quality related to the protection of stratospheric ozone in a changing climate

Ultraviolet (UV) radiation drives the net production of tropospheric ozone (O3) and a large fraction of particulate matter (PM) including sulfate, nitrate, and secondary organic aerosols. Ground-level O3 and PM are detrimental to human health, leading to several million premature deaths per year globally, and have adverse effects on plants and the yields of crops. The Montreal Protocol has prevented large increases in UV radiation that would have had major impacts on air quality. Future scenarios in which stratospheric O3 returns to 1980 values or even exceeds them (the so-called super-recovery) will tend to ameliorate urban ground-level O3 slightly but worsen it in rural areas. Furthermore, recovery of stratospheric O3 is expected to increase the amount of O3 transported into the troposphere by meteorological processes that are sensitive to climate change. UV radiation also generates hydroxyl radicals (OH) that control the amounts of many environmentally important chemicals in the atmosphere including some greenhouse gases, e.g., methane (CH4), and some short-lived ozone-depleting substances (ODSs). Recent modeling studies have shown that the increases in UV radiation associated with the depletion of stratospheric ozone over 1980-2020 have contributed a small increase (~ 3%) to the globally averaged concentrations of OH. Replacements for ODSs include chemicals that react with OH radicals, hence preventing the transport of these chemicals to the stratosphere. Some of these chemicals, e.g., hydrofluorocarbons that are currently being phased out, and hydrofluoroolefins now used increasingly, decompose into products whose fate in the environment warrants further investigation. One such product, trifluoroacetic acid (TFA), has no obvious pathway of degradation and might accumulate in some water bodies, but is unlikely to cause adverse effects out to 2100.

Silicic and Ascorbic Acid Induced Modulations in Photosynthetic, Mineral Uptake, and Yield Attributes of Mung Bean (Vigna radiata L. Wilczek) under Ozone Stress

Most of the world's crop production and plant growth are anticipated to be seriously threatened by the increasing tropospheric ozone (O₃) levels. The current study demonstrates how different mung bean genotypes reacted to the elevated level of O₃ in the presence of exogenous ascorbic and silicic acid treatments. It is the first report to outline the potential protective effects of ascorbic and silicic acid applications against O₃ toxicity in 12 mung bean {Vigna radiata (L.) Wilken} varieties. Under controlled circumstances, the present investigation was conducted in a glass house. There were four different treatments used: control (ambient O₃ concentration of 40-45 ppb), elevated O₃ (120 ppb), elevated O₃ with silicic acid (0.1 mM), and elevated O₃ with ascorbic acid (10 mM). Three varieties, viz. NM 20-21, NM 2006, and NM 2016, showcased tolerance to O₃ toxicity. Our findings showed that ascorbic and silicic acid applications gradually increased yield characteristics such as seed yield, harvest index, days to maturity, and characteristics related to gas exchange such as transpiration rate, stomatal conductance, net photosynthetic activity, and water-use efficiency. Compared to the control, applying both growth regulators enhanced the mineral uptake across all treatments. Based on the findings of the current study, it is concluded that the subject mung bean genotypes responded to silicic acid treatment more efficiently than ascorbic acid to mitigate the harmful effects of O₃ stress.

Ante- and post-mortem cellular injury dynamics in hybrid poplar foliage as a function of phytotoxic O3 dose

After reaching phytotoxic levels during the last century, tropospheric ozone (O3) pollution is likely to remain a major concern in the coming decades. Despite similar injury processes, there is astounding interspecific-and sometimes intraspecific-foliar symptom variability, which may be related to spatial and temporal variation in injury dynamics. After characterizing the dynamics of physiological responses and O3 injury in the foliage of hybrid poplar in an earlier study, here we investigated the dynamics of changes in the cell structure occurring in the mesophyll as a function of O3 treatment, time, phytotoxic O3 dose (POD0), leaf developmental stage, and mesophyll layer. While the number of Hypersensitive Response-like (HR-like) lesions increased with higher O3 concentrations and POD0, especially in older leaves, most structural HR-like markers developed after cell death, independent of the experimental factors. The pace of degenerative Accelerated Cell Senescence (ACS) responses depended closely on the O3 concentration and POD0, in interaction with leaf age. Changes in total chlorophyll content, plastoglobuli and chloroplast shape pointed to thylakoid membranes in chloroplasts as being especially sensitive to O3 stress. Hence, our study demonstrates that early HR-like markers can provide reasonably specific, sensitive and reliable quantitative structural estimates of O3 stress for e.g. risk assessment studies, especially if they are associated with degenerative and thylakoid-related injury in chloroplasts from mesophyll.

Air pollution as a substantial threat to the improvement of agricultural total factor productivity: Global evidence

OBJECTIVE

This study aims to provide empirical evidence about whether and to what extent air pollution affects the global agricultural total factor productivity (TFP).

METHODS

The research sample covers 146 countries all over the world during 2010-2019. Two-way fixed effects panel regression models are used to estimate air pollution's impacts. A random forest analysis is conducted to assess the relative importance of independent variables.

RESULTS

The results show that, on average, a 1% increase in fine particulate matter (PM_2.5) and tropospheric ozone (O₃) concentration would cause the agricultural TFP to decline by 0.104% and 0.207%, respectively. Air pollution's adverse impact widely exists in various countries with different development levels, pollution degrees, and industrial structures. This study also finds that temperature has a moderating effect on the relationship between PM_2.5 and agricultural TFP. PM_2.5 pollution's detrimental impact is weaker (stronger) in a warmer (cooler) climate. In addition, the random forest analysis confirms that air pollution is among the most crucial predictors of agricultural productivity.

CONCLUSIONS

Air pollution is a substantial threat to the improvement of global agricultural TFP. Worldwide actions should be taken to ameliorate air quality, for the sake of agricultural sustainability and global food security.

Low sensitivity of Pinus mugo to surface ozone pollution in the subalpine zone of continental Europe

High altitudes have been exposed to enhanced levels of surface ozone (O₃) concentrations over recent decades compared to the pre-industrial era. The responses of vegetation to this toxic pollutant are species-specific and depend on the climate conditions. In this paper, we explored the reaction of Pinus mugo (P. mugo) to O₃-induced stress in the continental climate of an ozone-rich mountain area in the High Tatra Mountains (Western Carpathians). The effects of O₃ doses modelled by a deposition model, O₃ concentrations and other factors on P. mugo were identified from (a) satellite-based data via NDVI (normalised differenced vegetation index) over 2000-2020 and (b) visible injury on needle samples gathered from P. mugo individuals at ground-truth sites in 2019 and 2020. Analysing the NDVI trend, we observed non-significant changes (p > 0.05) in the greenness of P. mugo despite growing in an environment with the average seasonal O₃ concentration around 51.6 ppbv, the maximum hourly concentrations more than 90 ppbv and increasing trend of O₃ doses by 0.1 mmol m^-2 PLA (plant leaf area) year^-1. The visible O₃ injury of samples collected at study sites was low (mean injury observed on 1-10% of needles' surface), and the symptoms of injury caused by other biotic and abiotic factors prevailed over those caused by O₃. In addition, the correlation analyses between NDVI and the climatic factors indicated a significant (p < 0.05) and positive relationship with photosynthetic active radiation (R = 0.45) in July, and with stomatal conductance (R = 0.52) and temperature factor (R = 0.43) in August. Therefore, we concluded that the positive effect of climate conditions, which support the growth processes of P. mugo, may suppress the negative effect of the mean O₃ doses of 17.8 mmol m^-2 PLA accumulated over the growing season.

Spatiotemporal variations of ozone exposure and its risks to vegetation and human health in Cyprus: an analysis across a gradient of altitudes

Ground-level ozone (O₃) affects vegetation and threatens environmental health when levels exceed critical values, above which adverse effects are expected. Cyprus is expected to be a hotspot for O₃ concentrations due to its unique position in the eastern Mediterranean, receiving air masses from Europe, African, and Asian continents, and experiencing a warm Mediterranean climate. In Cyprus, the spatiotemporal features of O₃ are poorly understood and the potential risks for forest health have not been explored. We evaluated O₃ and nitrogen oxides (NO and NO₂) at four regional background stations at different altitudes over 2014-2016. O₃ risks to vegetation and human health were estimated by calculating accumulated O₃ exposure over a threshold of 40 nmol mol^-1 (AOT40) and cumulative exposure to mixing ratios above 35 nmol mol^-1 (SOMO35) indices. The data reveal that mean O₃ concentrations follow a seasonal pattern, with higher levels in spring (51.8 nmol mol^-1) and summer (53.2 nmol mol^-1) and lower levels in autumn (46.9 nmol mol^-1) and winter (43.3 nmol mol^-1). The highest mean O₃ exposure (59.5 nmol mol^-1) in summer occurred at the high elevation station Mt. Troodos (1819 m a.s.l.). Increasing (decreasing) altitudinal gradients were found for O₃ (NO_x), driven by summer-winter differences. The diurnal patterns of O₃ showed little variation. Only at the lowest altitude O₃ displayed a typical O₃ diurnal pattern, with hourly differences smaller than 15 nmol mol^-1. Accumulated O₃ exposures at all stations and in all years exceeded the European Union's limits for the protection of vegetation, with average values of 3-month (limit: 3000 nmol mol^-1 h) and 6-month (limit: 5000 nmol mol^-1 h) AOT40 for crops and forests of 16,564 and 31,836 nmol mol^-1 h, respectively. O₃ exposures were considerably high for human health, with an average SOMO35 value of 7270 nmol mol^-1 days across stations and years. The results indicate that O₃ is a major environmental and public health issue in Cyprus, and policies must be adopted to mitigate O₃ precursor emissions at local and regional scales.