China has been experiencing fine particle (i.e., aerodynamic diameters ≤ 2.5 μm; PM2.5) pollution and acid rain in recent decades, which exert adverse impacts on human health and the ecosystem. ...Recently, ammonia (i.e., NH₃) emission reduction has been proposed as a strategic option to mitigate haze pollution. However, atmospheric NH₃ is also closely bound to nitrogen deposition and acid rain, and comprehensive impacts of NH₃ emission control are still poorly understood in China. In this study, by integrating a chemical transport model with a high-resolution NH₃ emission inventory, we find that NH₃ emission abatement can mitigate PM2.5 pollution and nitrogen deposition but would worsen acid rain in China. Quantitatively, a 50% reduction in NH₃ emissions achievable by improving agricultural management, along with a targeted emission reduction (15%) for sulfur dioxide and nitrogen oxides, can alleviate PM2.5 pollution by 11−17% primarily by suppressing ammonium nitrate formation. Meanwhile, nitrogen deposition is estimated to decrease by 34%, with the area exceeding the critical load shrinking from 17% to 9% of China’s terrestrial land. Nevertheless, this NH₃ reduction would significantly aggravate precipitation acidification, with a decrease of as much as 1.0 unit in rainfall pH and a corresponding substantial increase in areas with heavy acid rain. An economic evaluation demonstrates that the worsened acid rain would partly offset the total economic benefit from improved air quality and less nitrogen deposition. After considering the costs of abatement options, we propose a region-specific strategy for multipollutant controls that will benefit human and ecosystem health.
This paper investigates the correlation between the high level of coronavirus SARS-CoV-2 infection accelerated transmission and lethality, and surface air pollution in Milan metropolitan area, ...Lombardy region in Italy. For January–April 2020 period, time series of daily average inhalable gaseous pollutants ozone (O3) and nitrogen dioxide (NO2), together climate variables (air temperature, relative humidity, wind speed, precipitation rate, atmospheric pressure field and Planetary Boundary Layer) were analyzed. In spite of being considered primarily transmitted by indoor bioaerosols droplets and infected surfaces or direct human-to-human personal contacts, it seems that high levels of urban air pollution, and climate conditions have a significant impact on SARS-CoV-2 diffusion. Exhibited positive correlations of ambient ozone levels and negative correlations of NO2 with the increased rates of COVID-19 infections (Total number, Daily New positive and Total Deaths cases), can be attributed to airborne bioaerosols distribution. The results show positive correlation of daily averaged O3 with air temperature and inversely correlations with relative humidity and precipitation rates. Viral genome contains distinctive features, including a unique N-terminal fragment within the spike protein, which allows coronavirus attachment on ambient air pollutants. At this moment it is not clear if through airborne diffusion, in the presence of outdoor and indoor aerosols, this protein “spike” of the new COVID-19 is involved in the infectious agent transmission from a reservoir to a susceptible host during the highest nosocomial outbreak in some agglomerated industrialized urban areas like Milan is. Also, in spite of collected data for cold season (winter-early spring) period, when usually ozone levels have lower values than in summer, the findings of this study support possibility as O3 can acts as a COVID-19 virus incubator. Being a novel pandemic coronavirus version, it might be ongoing during summer conditions associated with higher air temperatures, low relative humidity and precipitation levels.
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•COVID-19 viral infections are positively correlated with ground level ozone.•Ground level nitrogen dioxide is inversely correlated with COVID-19 infections.•Dry air, low winds and precipitation rates supports COVID-19 virus diffusion.•Warm season will not stop COVID-19 spreading.•Outdoor airborne aerosols might be possible carriers of COVID-19.
The nitrogen input through biological N2 fixation is essential for life in vast areas of the global ocean. The belief is that cyanobacteria are the only relevant N2 -fixing (diazotrophic) organisms. ...It has, however, now become evident that non-cyanobacterial diazotrophs, bacteria and archaea with ecologies fundamentally distinct from those of cyanobacteria, are widespread and occasionally fix N2 at significant rates. The documentation of a globally relevant nitrogen input from these diazotrophs would constitute a new paradigm for research on oceanic nitrogen cycling. Here we highlight the need for combining rate measurements and molecular analyses of field samples with cultivation studies in order to clarify the ecology of non-cyanobacteria and their contribution to marine N2 fixation on local and global scales.
Nitrogen limits primary production in almost every biome on Earth
. Symbiotic nitrogen fixation, conducted by certain angiosperms and their endosymbiotic bacteria, is the largest potential natural ...source of new nitrogen into the biosphere
, influencing global primary production, carbon sequestration and element cycling. Because symbiotic nitrogen fixation represents an alternative to soil nitrogen uptake, much of the work on symbiotic nitrogen fixation regulation has focused on soil nitrogen availability
. However, because symbiotic nitrogen fixation is an energetically expensive process
, light availability to the plant may also regulate symbiotic nitrogen fixation rates
. Despite the importance of symbiotic nitrogen fixation to biosphere functioning, the environmental factors that most strongly regulate this process remain unresolved. Here we show that light regulates symbiotic nitrogen fixation more strongly than does soil nitrogen and that light mediates the response of symbiotic nitrogen fixation to soil nitrogen availability. In a shadehouse experiment, low light levels (comparable with forest understories) completely shut down symbiotic nitrogen fixation, whereas soil nitrogen levels that far exceeded plant demand did not fully downregulate symbiotic nitrogen fixation at high light. For in situ forest seedlings, light was a notable predictor of symbiotic nitrogen fixation activity, but soil-extractable nitrogen was not. Light as a primary regulator of symbiotic nitrogen fixation is a departure from decades of focus on soil nitrogen availability. This shift in our understanding of symbiotic nitrogen fixation regulation can resolve a long-standing biogeochemical paradox
, and it will improve our ability to predict how symbiotic nitrogen fixation will fuel the global forest carbon sink and respond to human alteration of the global nitrogen cycle.
This review is devoted to the analysis of works published over the past 20 years on the chemistry of saturated annulated nitrogen-containing polycyclic compounds, the molecules of which consist of ...four, five, six, and seven cycles, and contain from one to eight endocyclic nitrogen atoms.
Loss of plant diversity with increased anthropogenic nitrogen (N) deposition in grasslands has occurred globally. In most cases, competitive exclusion driven by preemption of light or space is ...invoked as a key mechanism. Here, we provide evidence from a 9‐yr N‐addition experiment for an alternative mechanism: differential sensitivity of forbs and grasses to increased soil manganese (Mn) levels. In Inner Mongolia steppes, increasing the N supply shifted plant community composition from grass–forb codominance (primarily Stipa krylovii and Artemisia frigida, respectively) to exclusive dominance by grass, with associated declines in overall species richness. Reduced abundance of forbs was linked to soil acidification that increased mobilization of soil Mn, with a 10‐fold greater accumulation of Mn in forbs than in grasses. The enhanced accumulation of Mn in forbs was correlated with reduced photosynthetic rates and growth, and is consistent with the loss of forb species. Differential accumulation of Mn between forbs and grasses can be linked to fundamental differences between dicots and monocots in the biochemical pathways regulating metal transport. These findings provide a mechanistic explanation for N‐induced species loss in temperate grasslands by linking metal mobilization in soil to differential metal acquisition and impacts on key functional groups in these ecosystems.
Lightning, one of the major sources of nitrogen oxides (NO.sub.x) in the atmosphere, contributes to the tropospheric concentration of ozone and to the oxidizing capacity of the atmosphere. Lightning ...produces between 2 and 8 Tg N yr.sup.-1 globally and on average about 250 ± 150 mol NO.sub.x per flash. In this work, we estimate the moles of NO.sub.x produced per flash (LNO.sub.x production efficiency) in the Pyrenees (Spain, France and Andorra) and in the Ebro Valley (Spain) by using nitrogen dioxide (NO.sub.2) and cloud properties from the TROPOspheric Monitoring Instrument (TROPOMI) as well as lightning data from the Earth Networks Global Lightning Network (ENGLN) and from the EUropean Co-operation for LIghtning Detection (EUCLID). The Pyrenees are one of the areas in Europe with the highest lightning frequencies, which, along with their remoteness as well as their very low NO.sub.x background, enables us to better distinguish the LNO.sub.x signal produced by recent lightning in TROPOMI NO.sub.2 measurements. We compare the LNO.sub.x production efficiency estimates for eight convective systems in 2018 using two different sets of TROPOMI research products provided by the Royal Netherlands Meteorological Institute (KNMI) and the Deutsches Zentrum für Luft- und Raumfahrt (DLR). According to our results, the mean LNO.sub.x production efficiency in the Pyrenees and in the Ebro Valley, using a 3 h chemical lifetime, ranges between 14 and 103 mol NO.sub.x per flash from the eight systems. The mean LNO.sub.x production efficiency estimates obtained using both TROPOMI products and ENGLN lightning data differ by â¼ 23 %, while they differ by â¼ 35 % when using EUCLID lightning data. The main sources of uncertainty when using ENGLN lightning data are the estimation of background NO.sub.x that is not produced by lightning and the time window before the TROPOMI overpass that is used to count the total number of lightning flashes contributing to freshly produced LNO.sub.x . The main source of uncertainty when using EUCLID lightning data is the uncertainty in the detection efficiency of EUCLID.
A new facultative anaerobic denitrifier was isolated from anoxic activated sludge and identified as Pseudomonas stutzeri strain HK13. Single-factor experiments indicated that the optimal conditions ...for nitrate removal were a C/N ratio of 8, an initial pH of 7–10, a shaking speed of 100 rpm, and a temperature of 30–40 °C. When 100 mg/L NO3--N and NO2--N were used separately as sole nitrogen sources, the strain exhibited efficient denitrification ability with total nitrogen (TN) removal efficiencies of 98.22% and 98.58%, respectively, in 15 h with the corresponding maximum removal rates of 20.03 and 21.77 mg/L/h. And there was no nitrite accumulation finally in the nitrate denitrification system. In addition, 97.42% total oxidized nitrogen (TON) was removed at 20 °C and 93.46% NO3--N was reduced at 45 °C, suggesting that strain HK13 had a wide range of temperature and pH to adapt to the environment. Moreover, strain HK13 exhibited a notable ability to tolerate high nitrate loading (initial NO3--N > 450 mg/L) with a TON removal amount of over 200 mg/L/day. These findings demonstrate that strain HK13 is effective for nitrogen removal in wastewaters containing high concentrations of nitrate and nitrite.
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•Pseudomonas stutzeri HK13 was isolated from anoxic activated sludge and identified.•It possesses efficient denitrification ability.•High removal rates and efficiencies of nitrate and nitrite.•It has a wide range of temperature and pH to adapt to the environment.•It tolerates to high nitrate and nitrite.
Acidifying species in precipitation can have severe impacts on ecosystems. The chemical composition of precipitation is directly related to the amount of precipitation; accordingly, it is difficult ...to identify long-term variation in chemical concentrations. The ratio of the nitrate (NO3−) to non-sea-salt sulfate (nss-SO42−) concentration in precipitation on an equivalent basis (hereinafter, Ratio) is a useful index to investigate the relative contributions of these acidifying species. To identify the long-term record of acidifying species in precipitation over East Asia, the region with the highest emissions worldwide, we compiled ground-based observations of the chemical composition of precipitation over China, Korea, and Japan from 2001 to 2015 based on the Acid Deposition Monitoring Network in East Asia (EANET). The spatial coverage was limited, but additional monitoring data for Japan, southern China, and northern China around Beijing were utilized. The period of analysis was divided into three phases: Phase I (2001–2005), Phase II (2006–2010), and Phase III (2011–2015). The behaviors of NO3− and nss-SO42− concentrations and hence the Ratio in precipitation were related to these precursors. The anthropogenic NOx and SO2 emissions and the NOx ∕ SO2 emission ratio were analyzed. Further, satellite observations of the NO2 and SO2 column density to capture the variation in emissions were applied. We found that the long-term trend in the NO3− concentration in precipitation was not related to the variation in NOx emission and the NO2 column. In comparison, the nss-SO42− concentration in precipitation over China, Korea, and Japan was partially connected to the changes in SO2 emissions from China, but the trends were not significant. The long-term trends of Ratio over China, Korea, and Japan were nearly flat during Phase I, increased significantly during Phase II, and were essentially flat again during Phase III. This variation in Ratio in East Asia clearly corresponded to the NOx ∕ SO2 emission ratio and the NO2 ∕ SO2 column ratio in China. The initial flat trend during Phase I was due to increases in both NOx and SO2 emissions in China, the significantly increasing trend during Phase II was triggered by the increase in NOx emissions and decrease in SO2 emissions in China, and the return to a flat trend during Phase III was caused by declines in both NOx and SO2 emissions in China. These results suggest that emissions in China had a significant impact not only on China but also on downwind precipitation chemistry during the 15-year period of 2001–2015. In terms of wet deposition, the NO3− wet deposition over China, Korea, and Japan did not change dramatically, but the nss-SO42− wet deposition declined over China, Korea, and Japan from Phase II to III. These declines were caused by a strong decrease in the nss-SO42− concentration in precipitation accompanied by a reduction in SO2 emission from China, which counteracted the increase in precipitation. These findings indicated that the acidity of precipitation shifted from sulfur to nitrogen.
Background And Objectives: Epidemiologie studies have attributed adverse health effects to air pollution; however, controversy remains regarding the relationship between ambient oxidante ozone (O₃) ...and nitrogen dioxide (NO₂) and mortality, especially in Asia. We conducted a fourcity time-series study to investigate acute effects of O₃ and NO₂ in the Pearl River Delta (PRD) of southern China, using data from 2006 through 2008. Methods: We used generalized linear models with Poisson regression incorporating natural spline functions to analyze acute mortality in association with O₃ and NO₂, with PM₁₀ (paniculate matter ≤ 10 μm in diameter) included as a major confounder. Effect estimates were determined for individual cities and for the four cities as a whole. We stratified the analysis according to high-and low-exposure periods for O₃. Results: We found consistent positive associations between ambient oxidants and daily mortality across the PRD cities. Overall, 10-μg/m³ increases in average O₃ and NO₂ concentrations over the previous 2 days were associated with 0.81% 95% confidence interval (CI): 0.63%, 1.00% and 1.95% (95% CI: 1.62%, 2.29%) increases in total mortality, respectively, with stronger estimated effects for cardiovascular and respiratory mortality. After adjusting for PM₁₀, estimated effects of O₃ on total and cardiovascular mortality were stronger for exposure during high-exposure months (September through November), whereas respiratory mortality was associated with O3 exposure during nonpeak exposure months only. Conclusions: Our findings suggest significant acute mortality effects of O₃ and NO₂ in the PRD and strengthen the rationale for further limiting the ambient pollution levels in the area.
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