Over the past three decades, Antarctic surface climate has undergone pronounced changes. Many of these changes have been linked to stratospheric ozone depletion. Here linkages between Antarctic ozone ...loss, the accompanying circulation changes, and summertime Southern Hemisphere (SH) midlatitude surface temperatures are explored. Long-term surface climate changes associated with ozone-driven changes in the southern annular mode (SAM) at SH midlatitudes in summer are not annular in appearance owing to differences in regional circulation and precipitation impacts. Both station and reanalysis data indicate a trend toward cooler summer temperatures over southeast and south-central Australia and inland areas of the southern tip of Africa. It is also found that since the onset of the ozone hole, there have been significant shifts in the distributions of both the seasonal mean and daily maximum summertime temperatures in the SH midlatitude regions between high and low ozone years. Unusually hot summer extremes are associated with anomalously high ozone in the previous November, including the recent very hot austral summer of 2012/13. If the relationship found in the past three decades continues to hold, the level of late springtime ozone over Antarctica has the potential to be part of a useful predictor set for the following summer’s conditions. The results herein suggest that skillful predictions may be feasible for both the mean seasonal temperature and the frequency of extreme hot events in some SH midlatitude regions of Australia, Africa, and South America.
the establishment of periodontitis is regulated by the primary etiological factor and several individual conditions including the immune response mechanism of the host and individual genetic factors. ...It results when the oral homeostasis is interrupted, and biological reactions favor the development and progression of periodontal tissues damage. Different strategies have been explored for reinforcing the therapeutic effect of non-surgical periodontal treatment of periodontal tissue damage. Gaseous ozone therapy has been recognized as a promising antiseptic adjuvant, because of its immunostimulating, antimicrobial, antihypoxic, and biosynthetic effects. Then, we hypothesized that the adjunct of gaseous ozone therapy to standard periodontal treatment may be leveraged to promote the tissue healing response.
to test this hypothesis, we conducted a prospective randomized study comparing non-surgical periodontal treatment plus gaseous ozone therapy to standard therapy. A total of 90 healthy individuals with moderate or severe generalized periodontitis were involved in the study. The trial was conducted from September 2019 to October 2020. Forty-five patients were randomized to receive scaling and root-planning (SRP) used as conventional non-surgical periodontal therapy plus gaseous ozone therapy (GROUP A); forty-five were allocated to standard treatment (GROUP B). The endpoint was defined as the periodontal response rate after the application of the ozone therapy at 3 months and 6 months, defined as no longer meeting the criteria for active periodontitis. Statistical analysis was performed employing SPSS v.18 Chicago: SPSS Inc.
periodontal parameters differed significantly between patients treated with the two distinct procedures at 3 months (
≤ 0.005); a statistically significant difference between groups was observed from baseline in the CAL (
≤ 0.0001), PPD (
≤ 0.0001) and BOP (
≤ 0.0001) scores.
The present study suggests that SRP combined with ozone therapy in the treatment of periodontitis revealed an improved outcome than SRP alone.
A rare disturbance of the stratospheric Antarctic polar vortex in September 2019 led to a significantly higher than usual polar total ozone column. We use assimilation of ozone, HCl, and N2O data ...from the Microwave Limb Sounder with the Global Earth Observing System (GEOS) Constituent Data Assimilation System driven by reanalysis meteorology to study the evolution of the 2019 Antarctic polar ozone. We find that the maximum 2019 ozone hole area was near 10 × 10(exp 6) ksq.m, and as little as 20% of that in 2018 in mid‐September. However, the magnitude of vortex‐averaged chemical ozone depletion was not significantly different between the 2 years despite earlier chlorine deactivation in 2019. The assimilation results show that most of the differences between 2018 and 2019 Antarctic ozone resulted from two factors: (1) the geometry of the 2019 vortex, with ozone‐rich middle‐stratospheric air masses overlying the lower portion of the vortex and leading to a significant reduction of the total column, and (2) significantly reduced vortex volume. The anomalously small ozone hole of 2019 was comparable in size to the record breaking 2002 case and the mechanisms responsible were similar in the two cases. While the 2019 sudden stratospheric warming is classified as minor, its impact on ozone was very significant.
The effect of stratospheric ozone depletion on the Amundsen Sea Low (ASL), a climatological low‐pressure center important for the climate of West Antarctica, remains uncertain. Using state‐of‐the‐art ...climate models, we here show that stratospheric ozone depletion can cause a statistically significant deepening of the ASL in summer with an amplitude of approximately 1 hPa per decade. We are able to attribute the modeled changes in the ASL to stratospheric ozone depletion by contrasting ensembles of historical integrations with and without a realistic ozone hole. In the presence of very large natural variability, the robustness of the ozone impact on the ASL is established by (1) examining ensembles of model runs to isolate the forced response, (2) repeating the analysis with two different climate models, and (3) considering the entire period of stratospheric ozone depletion, the beginning of which predates the satellite era by a couple of decades.
Key Points
We show that stratospheric ozone depletion causes a significant deepening of the Amundsen Sea Low in austral summer
The signal is small compared to the large natural variability in the region, so an ensemble of members is needed to detect the ozone effect
In both models, the ozone response emerges only when the full ozone depletion period is used, starting around 1960, before the satellite era
Dissolved ozone (O3(aq)) and residual ozone in groundwater under differently controlled parameters are two important outcomes in a lab-scale system of ferrous treatment with ozone, but they have not ...been well investigated yet. In this study, several preliminary parameters of ozone generation, types of diffusers, hydraulic retention time, and the pH in an ozone system of laboratory treatment were examined and evaluated statistically. The results showed that a venturi injector coupled with a bubble diffuser increased O3(aq) concentration to 9.05±0.28 mg/L corresponding to its diffusive coefficient of 0.195 min-1, 2.6 times higher than the bubble diffuser only. The O3(aq) decay constant in the presence of ferrous was 4.88 times higher than that in its absence. The mole stoichiometry of (DO3(aq)/DFe2+) in synthetic water during ozonation was 1.21, corresponding to its mass ratio of 1.04 mg O3(aq)/mg Fe2+. The highest efficacy of ozone on ferrous removal was achieved at pH4.0, followed by that at pH6.0; the residual iron concentration at pH6.0 was 0.230±0.149 mg/L, falling below the WHO standard for drinking water. The residual ozone at pH 4.0 and 6.0 was not statistically different and may take 186 and 300 hrs. to achieve EPA and FDA regulations, respectively. The obtained results may provide a system and information of ozone conditions applied in the treatment of iron to meet the maximum standards of iron and ozone in water.
Since about 1980, the tropical Pacific has been anomalously cold, while the broader tropics have warmed. This has caused anomalous weather in midlatitudes as well as a reduction in the apparent ...sensitivity of the climate associated with enhanced low-cloud abundance over the cooler waters of the eastern tropical Pacific. Recent modeling work has shown that cooler temperatures over the Southern Ocean around Antarctica can lead to cooler temperatures over the eastern tropical Pacific. Here we suggest that surface wind anomalies associated with the Antarctic ozone hole can cause cooler temperatures over the Southern Ocean that extend into the tropics. We use the short-term variability of the Southern Annular Mode of zonal wind variability to show an association between surface zonal wind variations over the Southern Ocean, cooling over the Southern Ocean, and cooling in the eastern tropical Pacific. This suggests that the cooling of the eastern tropical Pacific may be associated with the onset of the Antarctic ozone hole.
Tropospheric ozone (O3) pollution frequently overlaps with drought episodes but the combined effects are not yet understood. We investigated the physiological and biomass responses of an O3 sensitive ...hybrid poplar clone (‘546’) under three O3 levels (charcoal-filtered ambient air, non-filtered ambient air (NF), and NF plus 40 ppb) and two watering regimes (well-watered (WW) and reduced watering (RW), i.e. 40% irrigation) for one growing season. Water stress increased chlorophyll and carotenoid contents, protecting leaves from pigment degradation by O3. Impairment of photosynthesis by O3 was also reduced by stomatal closure due to water stress, which preserved light-saturated CO2 assimilation rate, and the maximum carboxylation efficiency. Water stress increased water use efficiency of the leaves while O3 decreased it, showing significant interactions. Effects were more evident in older leaves than in younger leaves. Water stress reduced biomass production, but the negative effects of O3 were less in RW than in WW for total biomass per plant. A stomatal O3 flux-based dose-response relationship was parameterized considering water stress effects, which explained biomass losses much better than a concentration-based approach. The O3 critical level of Phytotoxic Ozone Dose over a threshold of 7 nmol O3.m−2.s−1 (POD7) for a 4% biomass loss in this poplar clone under different water regimes was 4.1 mmol m−2. Our results suggest that current O3 levels in most parts of China threaten poplar growth and that interaction with water availability is a key factor for O3 risk assessment.
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•Interactive effects of O3 and water stress on sensitive poplar plants were investigated.•Water stress mitigates the negative effects of O3 on the poplar at leaf and plant levels.•A stomatal O3 flux-response relationship was developed including soil water limitation.•O3 flux incorporating the water stress effects performed much better than concentration metrics.•A critical level of stomatal O3 flux is thus recommended for this poplar clone.
A stomatal O3 flux-response relationship was developed considering water stress effects.
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