Ozone pollution threatens bird populations to collapse:an imminent ecological threat?

While bird populations are declining,the factors associated with this decline are unclear.Based on laboratory experiments,air pollution has long been recognized as a factor causing oxidative stress and adversely aff ecting bird health.Recently,studies employing an epidemiological approach have reported signifi cant declines in avian populations in Central Europe and the United States due to air pollution,and ozone in particular.We advocate that urgent actions are needed to mitigate these eff ects,which threaten biodiversity and environmental health,and propose a series of measures which can enlighten the path toward mitigating air pollution eff ects on avian populations.

Recent Advances in Microbial Degradation of 4-hydroxybenzoate-a Review

4-Hydroxybenzoate （4HBA） is a naturally occurring aromatic compound, as a key intermediate metabolite not only for natural products but also for arti- ficial products. There are four metabolic pathways for 4HBA： protocatechuate cleavage pathway; catechol cleavage pathway; anaerobic degradation pathway in anaerobes ; and gentisate cleavage pathway. The last pathway including a NIH shift reaction remains to be elucidated. In this review we emphasized on the NIH shift reaction involved in the 4HBA degrdation. The key enzymes of each 4HBA metabolic pathway also were introduced. Finnaly, we described the thermophilic Bacillus sp. B1 strain which was capable of degrading varous aromatic compounds including gHBA, and presented a direction for the research of NIH shift reaction.

Latest Achievements on Climate Change and Forest Interactions in a Polluted Environment

The COST Action FP0903 “Climate Change and Forest Mitigation and Adaptation in a Polluted Environment (MAFor)” involved 29 countries and created a platform for information exchange with experts from different fields, with the following main objectives: 1) to increase understanding of the state and potential of forest mitigation and adaptation to climate change in a polluted environment and 2) to reconcile process-oriented research, long-term monitoring and applied modelling at comprehensive forest research sites. In particular, MAFor translated the existing European knowledge on climate and air pollution dynamics into prospects for forest research and monitoring, with focus on the carbon, ozone, nitrogen and water budgets. The aim of this paper is to summarize scientific activities and achievements of MAFor: the creation of a meta-database for highlighting the available data and integrating the information from European forest research/monitoring networks;the development of a new concept of forest sites for research and monitoring (Supersites);the identification of the main knowledge gaps;and the definition of priorities for forest adaptation to climate change in a polluted environment. The action also increased European capacity building in this sector by organizing five conferences, granting 64 short-term scientific missions, organizing four training schools and publishing more than 100 papers.

Large variability in ambient ozone sensitivity across 19 ethylenediurea-treated Chinese cultivars of soybean is driven by total ascorbate

The sensitivity of Chinese soybean cultivars to ambient ozone（O3） in the field is unknown,although soybean is a major staple food in China. Using ethylenediurea（EDU） as an O3 protectant, we tested the gas exchange, pigments, antioxidants and biomass of 19 cultivars exposed to 28 ppm·hr AOT40（accumulated O3 over an hourly concentration threshold of40 ppb） over the growing season at a field site in China. By comparing the average biomass with and without EDU, we estimated the cultivar-specific sensitivity to O3 and ranked the cultivars from very tolerant（〈 10% change） to highly sensitive（〉 45% change）, which helps in choosing the best-suited cultivars for local cultivation. Higher lipid peroxidation and activity of the ascorbate peroxidase enzyme were major responses to O3 damage, which eventually translated into lower biomass production. The constitutional level of total ascorbate in the leaves was the most important parameter explaining O3 sensitivity among these cultivars. Surprisingly, the role of stomatal conductance was insignificant. These results will guide future breeding efforts towards more O3-tolerant cultivars in China, while strategies for implementing control measures of regional O3 pollution are being implemented. Overall, these results suggest that present ambient O3 pollution is a serious concern for soybean in China, which highlights the urgent need for policy-making actions to protect this critical staple food.

Review of Chinese atmospheric science research over the past 70 years: Atmospheric physics and atmospheric environment

Since the founding of the People’s Republic of China 70 years ago,the subject of atmospheric physics and atmospheric environment has developed rapidly in China,providing important support for the development of atmospheric science and guarantee for the development of national economy.In this paper,the general advancement of atmospheric physics and atmospheric environment in last 70 years was described.The main research progress of atmospheric physics and atmospheric environment in the past 40 years of reform and opening-up was reviewed,the outstanding research achievements since the 21 st century were summarized,the major problems and challenges are pointed out,and the key directions and suggestions for future development are put forward.

Arbuscular mycorrhizal fungi alter the response of growth and nutrient uptake of snap bean(Phaseolus vulgaris L.) to O_3

The effects of arbuscular mycorrhizal fungi（AMF） Glomus mosseae on the responses to elevated O3 in growth and nutrition of snap bean（Phaseolus vulgaris L.cv Guangzhouyuan） were investigated.Exposure was conducted in growth chambers by using three O3 concentrations（20（CF）,80（CFO1） and 120 nL/L（CFO2）;8 hr/day for 75 days）.Results showed that elevated O3 slightly impacted overall mycorrhizal colonization,but significantly decreased the proportional frequency of hypha and increased the proportional frequency of spores and vesicles,suggesting that O3 had significant effects on mycorrhizal structure.Elevated O3 significantly decreased yield,dry mass and nutrient contents（N,P,K,Ca and Mg） in both non-mycorrhizal and mycorrhizal plants.However,significant interactive effects were found in most variables due to that the reduction by O3 in the mycorrhizal plants was less than that in the non-mycorrhizal plants.Additionally,AMF increased the concentrations of N,P,Ca,and Mg in shoot and root.It can be concluded that AMF alleviated detrimental effects of increasing O3 on host plant through improving plant nutrition and growth.

Emerging challenges of ozone impacts on asian plants:actions are needed to protect ecosystem health

Context:Ozone concentrations near the land surface are rising in Asia while they are declining or stagnating in Europe and North America.Ozone is the most widespread air pollutant negatively affecting vegetation,and its increased concentrations pose a major threat to food quality and production and other ecosystem services in Asia.Method:In this review,we provide an overview of scientific challenges in the impacts of ozone pollution on Asian vegetation,and synthesize the challenges toward mitigation of the impacts.Result:We argue that new policy initiatives need to seek both reduction of ozone levels and enhancement of plant tolerance to ozone to maintain food quality and ensure food supplies.Conclusion:The scientific advancements must be transferred to actions by two types of institutions:a)environmental agencies for reducing ozone levels and b)agricultural research institutions for enhancing plant tolerance to ozone.In connecting the scientific advancements with the institutional actions,scientists in Asian countries should play the key role taking advantages of interdisciplinary and international collaborations.

Biogenic volatile organic compound emissions from leaves and fruits of apple and peach trees during fruit development

Biogenic volatile organic compounds(BVOCs)are widely involved in a variety of atmospheric chemical processes due to their high reactivity and species diversity.To date,however,research on BVOCs in agroecosystems,particularly fruit trees,remains scarce despite their large cultivation area and economic interest.BVOC emissions from different organs(leaf or fruit)of apple and peach trees were investigated throughout the stages of fruit development(FS,fruit swelling;FC,fruit coloration;FM,fruit maturity;and FP,fruit postharvest)using a proton-transfer-reaction mass spectrometer.Results indicated that methanol was the most abundant compound emitted by the leaf(apple tree leaf 492.5±47.9 ng/(g·hr),peach tree leaf 938.8±154.5 ng/(g·hr)),followed by acetic acid and green leaf volatiles.Beside the above three compounds,acetaldehyde had an important contribution to the emissions from the fruit.Overall,the total BVOCs(sum of eight compounds studied in this paper)emitted by both leaf and fruit gradually decreased along the fruit development,although the effect was significant only for the leaf.The leaf(2020.8±258.8 ng/(g·hr))was a stronger BVOC emitter than the fruit(146.0±45.7 ng/(g·hr))(P=0.006),and there were no significant differences in total BVOC emission rates between apple and peach trees.These findings contribute to our understanding on BVOC emissions from different plant organs and provide important insights into the variation of BVOC emissions across different fruit developmental stages.

Functional traits of poplar leaves and fine roots responses to ozone pollution under soil nitrogen addition

Concurrent ground-level ozone(O_(3))pollution and anthropogenic nitrogen(N)deposition can markedly influence dynamics and productivity in forests.Most studies evaluating the functional traits responses of rapid-turnover organs to O_(3) have specifically examined leaves,despite fine roots are another major source of soil carbon and nutrient input in forest ecosystems.How elevated O_(3) levels impact fine root biomass and biochemistry remains to be resolved.This study was to assess poplar leaf and fine root biomass and biochemistry responses to five different levels of O_(3) pollution,while additionally examining whether four levels of soil N supplementation were sufficient to alter the impact of O_(3) on these two organs.Elevated O_(3) resulted in a more substantial reduction in fine root biomass than leafbiomass;relative to leaves,more biochemically-resistant components were present within fine root litter,which contained high concentrations of lignin,condensed tannins,and elevated C:N and lignin:N ratios that were associated with slower rates of litter decomposition.In contrast,leaves contained more labile components,including nonstructural carbohydrates and N,as well as a higher N:P ratio.Elevated O_(3) significantly reduced labile components and increased biochemically-resistant components in leaves,whereas they had minimal impact on fine root biochemistry.This suggests that O_(3) pollution has the potential to delay leaf litter decomposition and associated nutrient cycling.N addition largely failed to affect the impact of elevated O_(3) levels on leaves or fine root chemistry,suggesting that soil N supplementation is not a suitable approach to combating the impact of O_(3) pollution on key functional traits of poplars.These results indicate that the significant differences in the responses of leaves and fine roots to O_(3) pollution will result in marked changes in the relative belowground roles of these two litter sources within forest ecosystems,and such changes will independently of nitrogen load.

Effects of elevated ozone and nitrogen addition on leaf nitrogen metabolism in poplar

Aims Ozone(O_(3))pollution and nitrogen(N)deposition/fertilization often simultaneously affect plant growth.However,research of their interactive effects on leaf N metabolism is still scarce.We investigated their interactive effects,aiming to better understand plant N metabolism processes and biogeochemical cycles under high 03 pollution and N deposition/fertilization.Methods Poplar saplings were exposed to two O_(3)levels(NF,non-filtered ambient air;NF60,NF+60 ppb O_(3))and four N treatments(NO,no N added;N50,NO+50 kg N ha^(-1)yr^(-1);N100,NO+100 kg N ha^(-1)yr^(-1);N200,NO+200 kg N ha^(-1)yr^(-1)in open-top chambers for 95 days.The indicators related to leaf N metabolism were analyzed,including the activities of N-metabolizing enzymes and the contents of total N,NO_(3)^(-)-N,NH_(4)^(+)-N,total amino acid(TAA)and total soluble protein(TSP)in the leaves.Important Findings NF60 stimulated the activities of nitrate reductase(NR)by 47.2%at August relative to NF,and stimulated glutamine synthetase(GS)by 57.3%when averaged across all N treatments and sampling times.In contrast,O_(3)did not significantly affect TSP and even reduced TAA content in August.Relative to NO,N200 significantly increased light-saturated rate of CO_(2)assimilation(Asat)by 24%,and increased total N content by 70.3%and 43.3%in August and September,respectively,while it reduced photosynthetic N-use efficiency by 26.1%in August.These results suggest that the increase in Asat and total N content are uncoupled,and that the surplus N is not used to optimize the capacity for carbon assimilation under high N treatment.Simultaneously,high N treatment significantly promoted leaf N metabolism by increasing NO_(3)^(-)-N contents,NH_(4)^(+)-N contents,TAA contents and the activities of NR and GS.There was no significant interaction between O_(3)and N for all variables.

Air pollution affects food security in China:taking ozone as an example

Air pollution is becoming an increasingly important environmental concern due to its visible negative impact on human health.However,air pollution also affects agricultural crops or food security directly or indirectly,which has not so far received sufficient attention.In this overview,we take ozone(O3)as an example to analyze the principles and extent of the impact of air pollution on food security in China based on a review of the literature.Current O3 pollution shows a clear negative impact on food security,causing around a 10%yield decrease for major cereal crops according to a large number of field studies around the world.The mean yield decrease of winter wheat is predicted to be up to 20%in China,based on the projection of future ground-level O3 concentration in 2020,if no pollution control measures are implemented.Strict mitigation of NOx and VOCs(two major precursors of O3)emissions is crucial for reducing the negative impacts of ground-level O3 on food security.Breeding new crop cultivars with tolerance to high ground-level O3 should receive serious consideration in future research programs.In addition,integrated soil-crop system management will be an important option to mitigate the negative effects of elevated ground-level O3 on cereal crop production and food quality.