New insights and reaction mechanisms on ZrO2 (110) surface enhanced catalytic hydrolysis of CFC-12: a density functional theory study.

CONTEXT: Freon, a greenhouse gas that contributes to the depletion of the ozone layer, has been the subject of investigation in this study. The catalytic hydrolysis enhancement of CFC-12 by ZrO2 was examined using a density functional theory approach. A detailed reaction mechanism and a new reaction pathway were proposed. The study found that CFC-12 is more likely to be adsorbed on the ZrO2 surface in the CFC-12-TO(F) configuration, while H2O is more likely to be adsorbed on the ZrO2 surface in the H2O-TO(H) configuration. Additionally, H2O replaces CFC-12 on the surface of ZrO2. The hydrolysis of CFC-12 is primarily determined by the first dechlorination process, while the defluorination process is comparatively easier. ZrO2 has a catalytic effect on both dechlorination and defluorination processes, with a more pronounced effect on the former. The production of C-OH bonds is inhibited, which facilitates the dechlorination and defluoridation processes. METHODS: This work was carried out in the Dmol3 program in the Material Studio 2017, including the geometric structure optimization and energy calculations. The GGA/PBE method was used in this work, along with the DNP basis, spin-polarized set, and DFT-D correction. The possible TSs were guessed based on the linear synchronous transit/quadratic synchronous transit/conjugate gradient (LST/QST/CG) method, and they were further confirmed and reoptimized to ensure that the only one imaginary frequency exists in the TSs.

Reflection on two Ambio papers by P. J. Crutzen on ozone in the upper atmosphere : This article belongs to Ambio's 50th Anniversary Collection. Theme: Ozone Layer.

We here reflect on two important articles on stratospheric ozone depletion written by P. J. Crutzen (1974) and P. J. Crutzen and D. H. Ehhalt (1977) in the early 1970s. These articles provide a clear description of the stratosphere and the most important chemical reactions involved in stratospheric ozone depletion. They present modeling results and provide recommendations for future research on stratospheric ozone depletion caused by chloro-fluoro-carbons, supersonic transport, nitrous oxide, and nuclear explosions. These two articles represent the beginning of a scientific era, which led to discovery of the Antarctic ozone hole and political action in the form of the Montreal Protocol and its amendments.

Risks to the stratospheric ozone shield in the Anthropocene : This article belongs to Ambio's 50th Anniversary Collection. Theme: Ozone Layer.

Crutzen (1974) and Crutzen and Ehhalt (1977) presented two key papers in Ambio that in Ambioexemplify how science first revealed to humankind the potential for damage to our ozone shield in the Anthropocene. Crutzen's (1974) review is a sweeping summary of the risks to the ozone layer from supersonic aircraft, chlorofluorocarbons, as well as nuclear weapons testing and nuclear war. Crutzen and Ehhalt (1977) described how the nitrous oxide produced from fertilizers could pose another threat to the stability of the stratospheric ozone layer. The two papers are part of a body of influential scientific work that led to the pioneering Montreal Protocol to Protect the Earth's Ozone Layer to phase out production of chlorofluorocarbons (in 1987), as well as national decisions that slowed or stopped production of supersonic planes (in the 1970s). They remain guideposts today for ongoing international negotiations regarding reducing emissions from fertilizer and limiting nuclear testing.

Effects of a structured educational intervention in moderate-to-severe elderly asthmatic subjects.

BACKGROUND: Adherence to inhaled drugs is linked to patients' satisfaction with their device, and an incorrect use can negatively affect the outcomes of asthma treatment. We speculated that this is particularly true in elderly asthmatic subjects. AIM: We performed a national pre-post interventional multicentre study, enrolling moderate-to-severe asthmatic subjects aged ≥65 â€‹years treated with fixed inhaled combination drugs by dry powder inhaler (DPI) or pressurized metered dose inhaler (pMDI). Adherence and critical errors were evaluated by means of validated questionnaires at first visit (V1) and after 3-6 months (V2). At V1, subjects underwent intensive training on the correct use of their device by physical demonstration. RESULTS: A total of 411 asthmatics (F/M: 238/173, mean age±SD: 72 â€‹± â€‹5 â€‹years) participated to the study. At V1, 50% of the study subjects showed an Asthma Control Test (ACT) score ≤19 despite GINA step 3 and 4 treatment, and 40% had experienced at least one severe asthma exacerbation in the previous year. Poor adherence to treatment was recorded in 43% of subjects, and at least one error in using the device was registered in 56% of subjects. At V2, available for 318 patients, both the percentage of individuals with poor adherence and with at least one critical error significantly decreased (from 46% to 25%, and from 49% to 25%, respectively; p â€‹< â€‹0.001 for both comparisons) with a significant increase of the ACT score (from 19 â€‹± â€‹4.9 to 20 â€‹± â€‹4.0, p â€‹< â€‹0.001). CONCLUSIONS: Asthma in the elderly is characterized by low levels of symptom control. Educational interventions are strongly advocated in this age group in order to increase adherence to treatment and inhaler techniques.

Rising environmental degradation and impact of foreign direct investment: An empirical evidence from SAARC region.

The Pollution Haven Hypothesis is amongst the latest discussion in economics that investigates the contribution of Foreign Direct Investment in raising environmental degradation in the host countries. Whereas, the concept of the Environmental Kuznets Curve hypothesis had been in economics since 1991 and is extensively studied under the umbrella of environmental degradation. Our present study is focused upon the role of economic growth, Foreign Direct Investment and energy consumption in increasing concentration of Carbon Dioxide in the South Asian region by using panel data from 1986 to 2014. The nascent techniques, panel ARDL, and FMOLS have been applied. The results thus obtained confirmed the existence of Pollution Heaven Hypotheses and Environmental Kuznets Curve in the short run. However, long-run analysis of the panel data confirms the absence of Pollution Heaven Hypotheses and existence of Environment Kuznets Curve. Furthermore, energy consumption in the region significantly contributing to environmental degradation. Since a major portion of the energy in South Asian countries is being generated from non-renewable energy resources. In the future, these countries are planning to meet their energy requirements through non-renewable energy resources that will inject more Carbon Dioxide to the atmosphere. The pattern of Study further refers to South Asian nations for extended co-operation in environmental R&D to mitigate future challenges. The governments in the region need to initiate environment-friendly regulations to suppress environmental degradation. Keen efforts are required by the statistical/environmental institutions in the region to set up a data collection/distribution forum so that real-time analysis be complied with, in order to accelerate the progress towards projected goals and sustainability.

Spatiotemporal distributions of halocarbons in the marine boundary air and surface seawater of the Changjiang estuary and its adjacent East China Sea.

Spatiotemporal distributions of volatile halogenated organic compounds (VHOCs) were investigated in the marine boundary air and surface seawater of the Changjiang (Yangtze River) estuary and its adjacent East China Sea in two cruises from March 11, 2015 to March 21, 2015 and from July 9, 2015 to July 20, 2015. Results revealed that the concentrations of released chlorofluorocarbons (CFCs) such as CFC-12, CFC-11, and CFC-114 in China decreased, suggesting that limitations set by the Chinese government on CFCs production and consumption have taken effect. Atmospheric concentrations of CFCs were affected by local industrial sources of emission and transport of terrestrial pollutants from coastal areas to varying degrees. Seasonal variations in atmospheric VHOCs were probably due to seasonal differences in prevalent monsoon and biogenic production. In the study periods, the investigated area was an essential source of atmospheric CH3Br and CH3I but was a net sink of CFC-12, CFC-11, and CH3Cl.

The development of environmentally acceptable fluorocarbons.

Chlorofluorocarbons (CFCs) were introduced in the 1930s as the safe replacements for the toxic and flammable refrigerants being used at that time. Subsequently, hydrochlorofluorocarbons (HCFCs) were also developed. In addition to refrigerant applications, they were used as foam blowing agents, as solvents and as propellants for many aerosols. In the 1970s and 1980s, concern developed about their environmental impact, specifically on stratospheric ozone depletion. Industry began to consider acceptable replacements. In 1987, many of the governments of the world came together and drafted the Montreal Protocol, calling upon Industry to initially phase out production of the CFCs and later HCFCs. Within 4 months of the signing of the Montreal Protocol, the 15 global major producers joined together to form the Alternative Fluorocarbons Environmental Acceptability Study (AFEAS), which sponsored research into environmental effects and the Program for Alternative Fluorocarbons toxicity Testing, PAFT), which examined the toxicology of potential replacements for the CFCs and HCFCs. Nine replacements were identified by companies and, through this international cooperation; toxicology programs were designed, conducted, and evaluated without duplication of effort and testing; consequently these new products were introduced within less than 10 years. Indeed the Montreal Protocol has been recognized as the most appropriate international treaty to phase-down HFCs. In 2016 the Kigali Amendment to the Montreal Protocol set out a phase-down schedule for the consumption and production of HFCs. In order to reduce the consumption and emissions of high GWP HFCs. Recently lower GWP HFCs and very low GWP HFOs (hydrofluoroolefins and HCFOs (hydrochlorofluoroolefins) have been introduced into a range of applications. Summaries of the toxicology profiles of some of the original CFCs and HCFCs, the replacements and the new post-PAFT replacements are described. The chemicals in this review include CFC-11, CFC-12, CFC-113, CFC-114, HCFC 22, HCFC-123, HCFC-124, HCFC-141b, HCFC-142b, HCF-32, HFC-125, HFC-134a, HFC-143a, HFC-152a, HFC-245ea, HFC-245fa, HFO-1234yf, HFO-1234ze, and HCFO-1233zd.

A quantitative assessment of distributions and sources of tropospheric halocarbons measured in Singapore.

This work reports the first ground-based atmospheric measurements of 26 halocarbons in Singapore, an urban-industrial city-state in Southeast (SE) Asia. A total of 166 whole air canister samples collected during two intensive 7 Southeast Asian Studies (7SEAS) campaigns (August-October 2011 and 2012) were analyzed for C1-C2 halocarbons using gas chromatography-electron capture/mass spectrometric detection. The halocarbon dataset was supplemented with measurements of selected non-methane hydrocarbons (NMHCs), C1-C5 alkyl nitrates, sulfur gases and carbon monoxide to better understand sources and atmospheric processes. The median observed atmospheric mixing ratios of CFCs, halons, CCl4 and CH3CCl3 were close to global tropospheric background levels, with enhancements in the 1-17% range. This provided the first measurement evidence from SE Asia of the effectiveness of Montreal Protocol and related national-scale regulations instituted in the 1990s to phase-out ozone depleting substances (ODS). First- and second-generation CFC replacements (HCFCs and HFCs) dominated the atmospheric halocarbon burden with HFC-134a, HCFC-22 and HCFC-141b exhibiting enhancements of 39-67%. By combining near-source measurements in Indonesia with receptor data in Singapore, regionally transported peat-forest burning smoke was found to impact levels of several NMHCs (ethane, ethyne, benzene, and propane) and short-lived halocarbons (CH3I, CH3Cl, and CH3Br) in a subset of the receptor samples. The strong signatures of these species near peat-forest fires were potentially affected by atmospheric dilution/mixing during transport and by mixing with substantial urban/regional backgrounds at the receptor. Quantitative source apportionment was carried out using positive matrix factorization (PMF), which identified industrial emissions related to refrigeration, foam blowing, and solvent use in chemical, pharmaceutical and electronics industries as the major source of halocarbons (34%) in Singapore. This was followed by marine and terrestrial biogenic activity (28%), residual levels of ODS from pre-Montreal Protocol operations (16%), seasonal incidences of peat-forest smoke (13%), and fumigation related to quarantine and pre-shipment (QPS) applications (7%).

A Synoptic View of the Ventilation and Circulation of Antarctic Bottom Water from Chlorofluorocarbons and Natural Tracers.

Antarctic Bottom Water (AABW) is the coldest, densest, most prolific water mass in the global ocean. AABW forms at several distinct regions along the Antarctic coast and feeds into the bottom limb of the meridional overturning circulation, filling most of the global deep ocean. AABW has warmed, freshened, and declined in volume around the globe in recent decades, which has implications for the global heat and sea level rise budgets. Over the past three decades, the use of tracers, especially time-varying tracers such as chlorofluorocarbons, has been essential to our understanding of the formation, circulation, and variability of AABW. Here, we review three decades of temperature, salinity, and tracer data and analysis that have led to our current knowledge of AABW and how the southern component of deep-ocean ventilation is changing with time.

Glacial recharge, salinisation and anthropogenic contamination in the coastal aquifers of Recife (Brazil).

Implying large residence times and complex water origins deep coastal aquifers are of particular interest as they are remarkable markers of climate, water use and land use changes. Over the last decades, the Metropolitan Region of Recife (Brazil) went through extensive environmental changes increasing the pressure on water resources and giving rise to numerous environmental consequences on the coastal groundwater systems. We analysed the groundwater of the deep aquifers Cabo and Beberibe that are increasingly exploited. The processes potentially affecting groundwater residence times and flow paths have been studied using a multi-tracer approach (CFCs, SF6, noble gases, 14C, 2H and 18O). The main findings of these investigations show that: (1) Groundwaters of the Cabo and Beberibe aquifers have long residence times and were recharged about 20,000years ago. (2) Within these old groundwaters we can find palaeo-climate evidences from the last glacial period at the tropics with lower temperatures and dryer conditions than the present climate. (3) Recently, the natural slow dynamic of these groundwater systems was significantly affected by mixing processes with contaminated modern groundwater coming from the shallow unconfined Boa Viagem aquifer. (4) The large exploitation of these aquifers leads to a modification of the flow directions and causes the intrusion through palaeo-channels of saline water probably coming from the Capibaribe River and from the last transgression episodes. These observations indicate that the current exploitation of the Cabo and Beberibe aquifers is unsustainable regarding the long renewal times of these groundwater systems as well as their ongoing contamination and salinisation. The groundwater cycle being much slower than the human development rhythm, it is essential to integrate the magnitude and rapidity of anthropogenic impacts on this extremely slow cycle to the water management concepts.

Changes in Ocean Heat, Carbon Content, and Ventilation: A Review of the First Decade of GO-SHIP Global Repeat Hydrography.

Global ship-based programs, with highly accurate, full water column physical and biogeochemical observations repeated decadally since the 1970s, provide a crucial resource for documenting ocean change. The ocean, a central component of Earth's climate system, is taking up most of Earth's excess anthropogenic heat, with about 19% of this excess in the abyssal ocean beneath 2,000 m, dominated by Southern Ocean warming. The ocean also has taken up about 27% of anthropogenic carbon, resulting in acidification of the upper ocean. Increased stratification has resulted in a decline in oxygen and increase in nutrients in the Northern Hemisphere thermocline and an expansion of tropical oxygen minimum zones. Southern Hemisphere thermocline oxygen increased in the 2000s owing to stronger wind forcing and ventilation. The most recent decade of global hydrography has mapped dissolved organic carbon, a large, bioactive reservoir, for the first time and quantified its contribution to export production (∼20%) and deep-ocean oxygen utilization. Ship-based measurements also show that vertical diffusivity increases from a minimum in the thermocline to a maximum within the bottom 1,500 m, shifting our physical paradigm of the ocean's overturning circulation.

Spatio-temporal distributions of chlorofluorocarbons and methyl iodide in the Changjiang (Yangtze River) estuary and its adjacent marine area.

Temporal and spatial distribution patterns of volatile halogenated organic compounds (VHOCs), such as dichlorodifluoromethane (CFC-12), trichlorofluoromethane (CFC-11), trichlorotrifluoroethane (CFC-113), and methyl iodide (CH3I), in the Changjiang (Yangtze River) estuary and its adjacent marine area were measured during two cruises from 21 February to 10 March 2014 and from 10 to 21 July 2014. VHOC concentrations showed seasonal variation with higher values during winter. VHOC distributions evidently decreased along the freshwater plume from the river mouth to the open sea and from inshore to offshore regions. VHOC distributions were obviously influenced by the Changjiang runoff, anthropogenic inputs, and biological release of phytoplankton. The study area was a net sink for CFC-12 and CFC-11, but a net source for atmospheric CH3I during the study periods.

Mesoporous Fluorinated Metal-Organic Frameworks with Exceptional Adsorption of Fluorocarbons and CFCs.

Two mesoporous fluorinated metal-organic frameworks (MOFs) were synthesized from extensively fluorinated tritopic carboxylate- and tetrazolate-based ligands. The tetrazolate-based framework MOFF-5 has an accessible surface area of 2445 m(2) g(-1), the highest among fluorinated MOFs. Crystals of MOFF-5 adsorb hydrocarbons, fluorocarbons, and chlorofluorocarbons (CFCs)-the latter two being ozone-depleting substances and potent greenhouse species-with weight capacities of up to 225%. The material exhibits an apparent preference for the adsorption of non-spherical molecules, binding unusually low amounts of both tetrafluoromethane and sulfur hexafluoride.

From closing the atmospheric ozone hole to reducing climate change. Lessons learned.

Global warming presents U.S. and transnational leaders with enormous political and policy challenges. World leadership addressed a similar worldwide environmental challenge in the 1980s and 1990s when scientists advised that accelerating emission of man-made chlorofluorocarbons was depleting the ozone layer of the earth's atmosphere. The process that led to global agreement on reducing depletion of the ozone layer holds valuable lessons, and some ironies, for scientists and policy makers seeking now to address global climate change. By understanding the international treaty process, how science informed that process, and how the physician community played a constructive role in the transition away from commercial use of ozone-depleting gases three decades ago, environmental activists can better understand the challenges, opportunities, and potential solutions under current consideration in affecting global climate change.

Enhanced preconcentration of selected chlorofluorocarbons on multiwalled carbon nanotubes with polar functionalities.

Chromatographic monitoring of chlorofluorocarbons in air requires the preconcentration of these highly volatile species. In this paper, we present functionalized multiwalled carbon nanotubes as effective sorbents for a microtrap designed for chlorofluorocarbons preconcentration. Among the commercial carbons and carbon nanotubes studied, functionalization via carboxylation and propyl amine was most effective for dichlorofluoromethane and trichlorofluoromethane (Freon 11), which were selected as representative chlorofluorocarbons. The results show that carbon nanotubes functionalized with a polar groups led to as much as a 300% increase in breakthrough volume and the desorption bandwidth was reduced by 2.5 times.

An outbreak of refrigerant-induced acute hepatitis in Hong Kong.

We report a cluster of acute hepatitis in five air-conditioning maintenance workers following accidental exposure to 2,2-dichloro-1,1,1-trifluoroethane (HCFC-123). They presented to us with complaints of feverishness, generalised malaise, and epigastric discomfort. Their blood biochemistry tests were compatible with acute hepatitis. Viral hepatitis serology, tests for autoimmune hepatitis, and analyses for drugs and alcohol consumption were all negative. No focal hepatic lesion was detected by ultrasound imaging. Percutaneous liver biopsy samples were taken from two of them. The patients were managed with supportive treatment. All had spontaneous, but slow, recovery. Their liver function tests returned to normal after 4 months and their outcomes were favourable. Physicians should be aware of this occupational disease entity.

Changes in the ventilation of the southern oceans.

Changes in the ventilation of the southern oceans over the past few decades are examined using ocean measurements of CFC-12 and model simulations. Analysis of CFC-12 measurements made between the late 1980s and late 2000s reveal large-scale coherent changes in the ventilation, with a decrease in the age of subtropical Subantarctic Mode Waters (SAMW) and an increase in the age of Circumpolar Deep Waters. The decrease in SAMW age is consistent with the observed increase in wind stress curl and strength of the subtropical gyres over the same period. A decrease in the age of SAMW is also found in Community Climate System Model version 4 perturbation experiments where the zonal wind stress is increased. This decrease is due to both more rapid transport along isopycnals and the movement of the isopycnals. These results indicate that the intensification of surface winds in the Southern Hemisphere has caused large-scale coherent changes in the ventilation of the southern oceans.

Efficacy and safety of eco-friendly inhalers: focus on combination ipratropium bromide and albuterol in chronic obstructive pulmonary disease.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality and its treatment is critical to improve quality of life, reduce symptoms, and diminish the frequency of COPD exacerbations. Due to the harmful environmental effects of pressurized metered-dose inhalers (pMDIs) containing chlorofluorocarbons (CFCs), newer systems for delivering respiratory medications have been developed. METHODS: A search of the literature in the PubMed database was undertaken using the keywords "COPD," "albuterol," "ipratropium bromide," and "Respimat® Soft Mist Inhaler™"; pertinent references within the identified citations were included. The environmental effect of CFC-pMDIs, the invention of the Respimat® Soft Mist Inhaler™ (SMI) (Boehringer Ingelheim, Ingelheim, Germany), and its use to deliver the combination of albuterol and ipratropium bromide for the treatment of COPD were reviewed. RESULTS: The adverse environmental effects of CFC-pMDIs stimulated the invention of novel delivery systems including the Respimat SMI. This review presents its development, internal mechanism, and use to deliver the combination of albuterol and ipratropium bromide. CONCLUSION: CFC-pMDIs contributed to the depletion of the ozone layer and the surge in disorders caused by harmful ultraviolet B radiation. The banning of CFCs spurred the development of novel delivery systems for respiratory medications. The Respimat SMI is an innovative device that produces a vapor of inhalable droplets with reduced velocity and prolonged aerosol duration that enhance deposition within the lower airway and is associated with improved patient satisfaction. Clinical trials have demonstrated that the Respimat SMI can achieve effects equivalent to pMDIs but with lower medication doses. The long-term safety and efficacy remain to be determined. The Respimat SMI delivery device is a novel, efficient, and well-received system for the delivery of aerosolized albuterol and ipratropium bromide to patients with COPD; however, the presence of longer-acting, less frequently dosed respiratory medications provide patients and providers with other therapeutic options.