Ozone Depletion Research Articles

Temperature distribution in the crevasse-drainage systems of the Antarctic glaciers: A case study of the Perunika Glacier

Discovered only about 200 years ago, Antarctica is the poorest and most isolated ecosystem on Earth. Its thinner atmosphere, due to the centrifugal forces of Earth’s rotation, the ozone hole, and stronger solar radiation, creates a natural laboratory that provides information about the state and trajectory of Earth’s climate condition. This study aimed to determine the depth of heat penetration from the surface of the glacier into the crevasses in the ablation zone and establish the zone of constant temperatures in the glacier. It explored the relationship between the air temperature at the glacier surface and the temperature distribution in the crevasses, including the temperature gradient at different levels and the direction of the airflow. We used autonomous data loggers for measuring and recording temperature and relative humidity. The measured depth reached 18 m in the central part of the glacier and 9 m in the periphery. An ultrasonic anemometer was installed in the deepest crevasse in to the center of the glacier to determine the size and direction of air flows. Meteorological parameters such as air temperature, humidity, atmospheric pressure, and solar radiation were measured on-site using autonomous sensors and recording devices mounted on installations on the glacier surface and at depth using alpine techniques. The results show a temperature gradient through 3-meter layers, a relatively clear boundary of the constant temperature zone, and a significant infiltration of cold air through the crevices driven by turbulent wind processes. Additionally, a weak negative correlation was found between solar activity and temperatures in the crevasses. It appears that as solar activity increases, the temperature decreases. There are also weak but consistently positive correlations with air movement both upward and downward. The temperature becomes constant with the increase of the depth until a zone of constant temperatures is determined and the temperature variance becomes insignificant. This zone varies in different crevаsses, meaning it is influenced by the specific characteristics of each crevasse location. At shallow depths, temperature is influenced by external temperature, but with the depth increasing this influence decreases. On windy days, the zone of constant temperature expands. During higher solar activity, air circulation accelerates—both upward and downward. The relationship between solar activity and climatic processes in glacier drainage systems adds new insights to solar-terrestrial physics.

Phenolic Foam Preparation Using Hydrofluoroolefin Blowing Agents and the Toughening Effect of Polyethylene Glycol.

In this work, a new class of fourth-generation, zero ozone depletion potential, hydrofluoroolefin-based blowing agents were used to prepare phenolic foam. While hydrofluoroolefin blowing agents have been used previously to prepare polyurethane foams, few studies have been reported on their use in phenolic foams. We introduce an effective method for foam preparation using two low-boiling blowing agents, cis-1,1,1,4,4,4-hexafluoro-2-butene and trans-1,1,1,4,4,4-hexafluoro-2-butene, and their combinations with hexane. Traditionally, phenolic foams have been prepared using chlorofluorocarbons and hydrochlorofluorocarbons, which can have harmful effects on the environment due to their high ozone depletion potential or global warming potential. Conductor-like screening model for real solvents (COSMO-RS) modeling studies were performed to understand the effects of different blowing agent combinations on their boiling points. A series of phenolic foams were prepared by varying the concentration of the hydrofluoroolefin and the hydrofluoroolefin-hexane blowing agent combinations. The concentrations of the surfactant, Agnique CSO 30, and the toughening agent, polyethylene glycol, were also varied to yield a formulation with the optimal properties. The foams formulated with the hydrofluoroolefin-hexane mixture displayed a higher compressive strength and a lower thermal conductivity than those prepared with either hydrofluoroolefin or hexane alone. The cell microstructure of all the foams was examined using scanning electron microscopy. By introducing flexible chains into the resin matrix, PEG facilitates proper distribution of hydrofluoroolefin-hexane blowing agents and other reagents and thereby increases the mechanical strength of the foam.

FP8.2 - Sustainability Within the Abscess Pathway

Abstract Background Global warming and the current climate crisis remain a threat to global health. It is estimated that 5% of the total carbon footprint of an acute NHS organisation was attributable to general anaesthetic (GA) gases, which contributes to ongoing ozone depletion. Aims To review current practices in managing abscesses and improve sustainability within the abscess pathway in our trust. Methods Retrospective data on all patients who underwent incision and drainages (I&D) between January – July 2022 were collected and analysed. A new abscess pathway was introduced in June 2023 and departmental teaching provided to junior doctors on incision and drainage of abscesses under local anaesthetic (LA). Data on patients who underwent I&D between June – September 2023 were collected and analysed to assess the impact of the new abscess pathway. Results In the first-cycle audit, 162 patients underwent I&D, of which 119 (92%) were done under GA. Of these, 71 (60%) were suitable for LA I&Ds, 91% were admitted for their procedures. The estimated carbon footprint was 4525kg CO2e/year. In the second-cycle audit, 68 patients underwent I&D, of which 37 (76%) were done under GA. Of these, 31 (46%) were suitable for LA I&Ds, 41% were admitted for their procedures. The estimated carbon footprint was 3735kg CO2e/year. Conclusions Following implementation of the new abscess pathway, we reduced the number of patients having general anaesthetic procedures and inpatient admission. This not only improves the sustainability of our practice, but makes treatment and recovery quicker for patients, and has a lower financial burden.

Ecosocialism and Its Implication to the Nigerian State

The environmental crisis remains unabated. It is still raging on in phenomena such as gas flaring, deforestation, depletion of the ozone layer, climate change, desertification, unplanned urbanization, and so forth. The impact of the crisis is felt in every region of the world including Nigeria. Nigeria has experienced many environmental problems like the ones mentioned above. Others are soil erosion, illegal mining, environmental insecurities, violent struggles over natural resources, etc. Various ideologies have been proposed for curbing the environmental crisis such as communalism, socialism, capitalism, nationalism, democracy, communism, ecofeminism, ecowomanism, and so forth. This paper critically and hermeneutically examines the ideology of ecosocialism and its appropriateness to the Nigerian state. The paper shows why ecosocialism has some positive ideas that should inspire the Nigerian state in ecological protection, it should not be adopted in an uncritical manner hook, line, and sinker. The paper reveals that Nigeria is troubled by many environmental problems. It concludes that the good points of ecosocialism should be adopted and used to create an environmentally friendly Nigerian state.

Forage conservation is a neglected nitrous oxide source.

Agricultural activities are the major anthropogenic source of nitrous oxide ( ), an important greenhouse gas and ozone-depleting substance. However, the role of forage conservation as a potential source of has rarely been studied. We investigated production from the simulated silage of the three major crops-maize, alfalfa, and sorghum-used for silage in the United States, which comprises over 90% of the total silage production. Our findings revealed that a substantial could be generated, potentially placing forage conservation as the third largest source in the agricultural sector. Notably, the application of chlorate as an additive significantly reduced production, but neither acetylene nor intermittent exposure to oxygen showed any impact. Overall, the results highlight that denitrifiers, rather than nitrifiers, are responsible for production from silage, which was confirmed by molecular analyses. Our study reveals a previously unexplored source of and provides a crucial mechanistic understanding for effective mitigation strategies.

Seaweed as a feed additive to mitigate enteric methane emissions in ruminants: Opportunities and challenges1

Cutting farming-related methane emissions from ruminants is critical in the battle against climate change. Since scientists initially investigated the potential of marine macroalgae to reduce methane emissions, using seaweeds as an anti-methanogenic feed additive has become prevailing in recent years. Asparagopsis taxiformis is the preferred species because it contains a relatively higher concentration of bromoform. As a type of halogenated methane analogue, bromoform contained in A. taxiformis can specifically inhibit the activity of coenzyme M methyltransferase, thereby blocking the ruminal methanogenesis. However, bromoform is a potential toxin and ozone-depleting substance. In response, current research focuses on the effects of bromoform-enriched seaweed supplementation on ruminant productivity and safety, as well as the impact of large-scale cultivation of seaweeds on the atmospheric environment. The current research on seaweed still needs to be improved, especially in developing more species with low bromoform content, such as Bonnemaisonia hamifera, Dictyota bartayresii, and Cystoseira trinodis. Otherwise, seaweed is rich in bioactive substances and exhibits antibacterial, anti-inflammatory, and other physiological properties, but research on the role of these bioactive compounds in methane emissions is lacking. It is worthy of deeper investigation to identify more potential bioactive compounds. As a new focus of attention, seaweed has attracted the interest of many scientists. Nevertheless, seaweed still faces some challenges as a feed additive to ruminants, such as the residues of heavy metals (iodine and bromine) and bromoform in milk or meat, as well as the establishment of a supply chain for seaweed cultivation, preservation, and processing. We have concluded that the methane-reducing efficacy of seaweed is indisputable. However, its application as a commercial feed additive is still influenced by factors such as safety, costs, policy incentives, and regulations.

Effects of Carbon Dioxide and Nitrogen Oxides on Climate Change in Afghanistan

Climate change is a global threat to the environment and human health. Two of the main greenhouse gases that cause the greenhouse effect and raise global temperatures are carbon dioxide and nitrogen oxides. In this review paper, we investigated the effects of carbon dioxide and nitrogen oxides on climate change and the effects of climate change on Afghanistan. We found that high concentrations of carbon dioxide, which is now CO2 levels, have increased by 50% than before the Industrial Revolution, contributing to a rise in global temperature and precipitation. At the same time, Nitrous oxide is an important greenhouse gas, with 310-fold higher potential for global warming than CO2 and leads to the depletion of stratospheric Ozone and other Nitrogen oxides, has a significant impact on plant health, including effects on chlorophyll levels, oxidative stress, and antioxidant responses. Afghanistan’s climate change is predicted to increase the country’s prevalence of illnesses linked to dust storms and poor air quality, especially in Kabul, the nation’s capital. In addition, air pollution in Kabul is also likely to increase as a result of climate change. The alarming impacts of air pollution, with more than 3,000 deaths attributed to air pollution annually. Additionally, at least 700,000 individuals in Kabul have experienced various respiratory diseases. Due to climate change, Afghanistan’s total glacier area has shrunk by 13.8%. In 2023, Afghanistan experienced early snow melt and below-average precipitation, causing second-season and irrigated crops to have less access to water. Reducing emissions and coping with the changing climate are essential steps towards tackling the complex issues these gases present and their wider effects on the environment and human health.

Ultraviolet-induced melanisation in lichens: physiological traits and transcriptome profile.

Lichens are important components of high-latitude boreal and Arctic habitats. While stress tolerant, they are among the most sensitive ecosystem components to climate change, in particular, an increase in ultraviolet light (UV) arising from polar ozone depletion and deforestation. This study is the first to explore the effects of UV-B on gene expression in lichens to predict metabolic pathways involved in tolerance. Using transcriptome profiling and bioinformatic analyses, here we studied the effects of UV-B on gene expression in lichens using Lobaria pulmonaria (L.) Hoff. as a model species. UV-B exposure causes significant browning of the upper cortex of the thallus, which correlates to an increased expression of biosynthetic gene clusters involved in the synthesis of eu- and allomelanins and melanin precursors. Based on transcriptome analyses, we suggest that the biosynthesis of melanins and other secondary metabolites, such as naphthalene derivates, tropolones, anthraquinones, and xanthones, is a trade-off that lichens pay to protect essential metabolic processes such as photosynthesis and respiration. Expression profiles of general stress-associated genes, in particular, related to reactive oxygen species scavenging, protection of proteins, and DNA repair, clearly indicate that the mycobiont is the more UV-B-responsive and susceptible partner in lichen symbiosis. Our findings demonstrate that UV-B stress activates an intricate gene network involved in tolerance mechanisms of lichen symbionts. Knowledge obtained here may enable the prediction of likely effects on lichen biodiversity caused by climate change and pollution.

Leading the Transition from Halogen Refrigerants to Natural Refrigerants in Indonesia (Pertamina Plaju Refinery as a Pioneer)

Abstract Climate change has become a worldwide concern, prompting Indonesia to take ambitious actions to reduce emissions and control rising temperatures. The rapid growth of the Refrigeration and Air Conditioning (RAC) industry in Indonesia has led to higher greenhouse gas emissions. To tackle these environmental challenges, Pertamina Plaju Refinery is manufacturing natural refrigerants, specifically Musicool (Propane) and Breezone (Propylene), providing sustainable replacements for R-22 and R-32. Pertamina Plaju Refinery has made several process modifications and optimizations to support the production of Musicool and Breezone in the Alkylation and Purification Units. These modifications involve optimizing operating conditions and implementing necessary infrastructure changes. In general, Pertamina’s natural refrigerants consume 20-30% less energy than halogen refrigerants while offering similar cooling capacity to R-22 and R-32. Propane and Propylene-based refrigerants have the lowest impact on global warming and are eco-friendly due to their easy degradation process. Musicool and Breezone, having an ODP of 0.0, with maximum GWP of 3.3, indicating minimal contribution to ozone depletion. Pertamina’s efforts to engage and reach potential customers on these natural refrigerants, involve collaborative efforts among various organizations, including with all District Office Plaju, South Sumatra.

Environmental impact assessment of different power generation strategies in Oman: A comparative life-cycle analysis

This paper presents a comparative environmental impact assessment considering different power generation strategies in Oman. The Life-Cycle Assessment (LCA) methodology, and the OpenLCA tool, were employed in carrying out comprehensive analysis, and evaluation of the various environmental aspects in filling the research gap, by replacing conventional diesel generators with natural gas alternatives in Oman. The obtained results indicate that utilizing natural gas significantly reduces environmental impacts, including a decrease in global warming potential to 2.27 million kg CO2 eq, fossil fuel depletion to 34.5 million kg oil-eq, and ozone depletion to 0.13 kg CFC-11 eq. This study would help in policy decision-making to support a potential shift in power generation system, transitioning from the current use of diesel generator sets to flared produced Natural Gas across crude oil processing plants. Thus, mitigating operational cost, and improving efficiencies, for sustainable developments. Another salient part of this study is the implementation of more sustainable energy practices that supports the broader application of LCA in evaluating industrial environmental impacts. Furthermore, the results obtained in this work are in line with recent global climate change commitments and Oman's Vision 2040, in achieving cleaner energy sources to minimize environmental harm in the oil and gas sector.

A Study on the Environmental Impact Assessment According to the Material Change of the Debris Barrier using Life Cycle Analysis: Focusing on the Case of Yanggu-gun, Gangwon-do

Objectives : The purpose of this study is to evaluate and analyze the environmental performance of an debris barrier installed in Yanggu-gun, Gangwon-do through life cycle analysis. Throughout the entire process of the debris barrier, the six major environmental categories, including greenhouse gas emissions, will be quantitatively evaluated and based on the derived alternatives, it is intended to help improve environmentality to the extent applicable to future plans for the installation of the debris barrier.Methods : In this study, the major environmental categories (Resource Footprint, Carbon Footprint, Ozone Depletion, Acidification, Eutrophication and Photochemical Smog) for each scenario were calculated and evaluated for changes to major materials of debris barrier according to the methodology of the Environmental Product Declaration Preparation Guidelines. Considering the characteristics of debris barrier, the life cycle evaluation stage considered raw material collection and production stages, and exclude the use stage and disposal stage.Results and Discussion : As a result of analyzing environmental feasibility after setting scenarios for each major material (ready-mixed concrete, natural stone) derived through life cycle evaluation for the debris barrier that is the subject of this study, the maximum difference was resource footprint 4.45E+02 kg Sb-eq., carbon footprint 1.46E+05 kg CO2–eq., ozone Depletion 6.97E-03 kg CFC-11-eq., acidification 2.16E+02 kg SO2–eq., eutrophication 3.94E+01 kg PO43-–eq., photochemical smog was evaluated as 5.28E-01 kg C2H4–eq.Conclusion : It was found that it was possible to reduce the environmental category by up to 64.54% or more when changing construction materials during the construction of an debris barrier. Among these, the carbon footprint was the highest at over 70%, which confirmed that the environmental impact of the ready-mix concrete production process was significant. Based on the results of this study, it is believed that in order to improve the environment when planning the installation of an debris barrier, it is necessary to minimize the use of ready-mixed concrete, introduce eco-friendly materials such as natural stone, and improve eco-friendly technology and construction methods.

Life Cycle Assessment of Natural Gas Production in Java Sea-East Java Province, Indonesia

Energy products including natural gas play a very important role in the context of global economic, industrial, and infrastructure development. However, it is undeniable that the production process from raw material extraction to ready-to-use products has an impact on the environment. This study was conducted to evaluate the environmental impact of natural gas production in the Kepodang field, East Java Province, Indonesia. The next objective is to analyze the magnitude and significance of the impact or hotspot analysis. The characterization results for 4 main categories show: Global Warming Potential 70.02 kg CO₂ eq, Ozone Layer Depletion 1.11E-06 kg CFC-11 eq, Acidification Potential 0.65 mol H+ eq, Marine Eutrophication 0.30 kg N eq, and Freshwater Eutrophication 2.17E-03kg P eq. The results also show that throughout the life cycle of this product, the largest contributor to environmental impacts is in the downstream phase, especially the user gas metering unit process. This is due to the 200 km of pipelines for product transportation from the Central Processing Platform (CPP) to the user gate. Pipeline parameters (Ecoinvent database) refer to long-distance pipelines with high capacity. In addition, hotspots were also identified in the core phase: gas measurement and chromatography, gas turbine generators, and flare gas.

Review on Assessment and Performance Mechanism Evaluation of Non-Structural Concrete Incorporating Waste Materials

This research seeks to solve the multi-faceted problem of waste disposal by analysing the application of waste plastic and tyre material within non-structural concrete to ensure more sustainability and less environmental degradation. The study focusses on material properties, including specific gravity, water absorption, and bulk density and characteristics of the concrete that is produced by the utilization of the above waste aggregates, including workability, compressive strength, flexural strength, and tensile strength. This paper employs results from published past research from the literature and MATLAB (R2021b) in the analysis of the findings, pointing to the fact that the mechanical properties reduce with the level of waste content yet emphasizing the green aspect of such materials. Thus, a complex and diverse effect is demonstrated by the life cycle assessments (LCA) for global warming, ozone depletion, terrestrial ecotoxicity, and acidification. Furthermore, the utilization of waste materials decreases the compressive, flexural, and tensile strength, but it provides distinct ecological benefits which prove the importance of proper mix proportions for concrete performance. The outcomes of this research will be useful for further investigation in the application of the concept as well as to call for the development of new ideas for the improvement of bonding of wastes to aggregates in concrete.

Life Cycle Assessment Analysis Based on Material Selection in Sustainable Airport Buildings

Sustainable airport buildings aim to minimize environmental impacts through energy efficiency, water conservation, and waste management. This is achieved by employing green building materials and utilizing renewable energy sources to reduce their carbon footprint. In this study, life cycle assessment (LCA) was conducted to assess the environmental impacts of three main construction materials—concrete, steel, and wood—used in sustainable airport buildings. These materials were selected for their widespread use in eight different airport terminal buildings with sustainability certifications. The environmental impacts of these materials were calculated and compared using OpenLCA 1.9.0 software and the ECOinvent database, adhering to the standards set forth by the Environmental Product Declaration (EPD) initiative. The findings indicate that wood, as a construction material, has a significantly lower impact on global warming compared to steel and concrete, with a global warming potential (GWP) ratio of less than 60%. Steel, with a GWP of approximately 90% of that of concrete, also showed a lower impact than concrete. Additionally, other environmental impacts, such as stratospheric ozone depletion potential (ODP) and acidification potential (AP), were also examined, highlighting the trade-offs associated with each material.

Environmental life cycle assessment of corn production in tropical regions

Corn growing is an important cultural and traditional system in the Iran that has considerable environmental impacts. This study was conducted to determine the environmental effects of corn production using life cycle assessment methodology. In the present study, the data have been collected from face-to-face interviews and completing a questionnaire among corn farmers in Ilam province of Iran, in 2021. The functional unit for analysis was defined as one ton of corn produced in the region. As a result, energy efficiency, energy productivity, net energy and specific energy were equal to 4.41, 0.20 kg MJ−1, 675,379.84 MJ ha−1 and 4.88 MJ kg−1 respectively. Direct, indirect, renewable and non-renewable energies was 61.59, 38.41, 16.03 and 83.97%, respectively. In this study, the amount of global warming potential per ton of product produced is estimated to be 4747,505 kg CO2 equivalent. After normalization and weighting, the highest environmental pollutants are related to the marine aquatic ecotoxicity index with 225,273 kg 1,4-dichlorobenzene equivalent and the lowest pollutants are related to the depletion of ozone layer 1,19 × 10–5 kg CFC-11 equivalent. Result showed that chemical fertilizers and electricity led to the highest contaminating emissions.

NosZ II/nosZ I ratio regulates the N2O reduction rates in the eutrophic lake sediments

Nitrous oxide (N2O) is a more potent greenhouse gas with an atmospheric lifetime of 121 years, contributing significantly to climate change and stratospheric ozone depletion. Lakes are hotspots for N2O release due to the imbalance between N2O sources and sinks. N2O-reducing bacteria are the only biological means to mitigate N2O emission, yet their roles in lakes are not well studied. This study investigated the potential for N2O reduction, keystones of typical and atypical N2O-reducing bacterial communities, and their correlations with environmental factors in the sediments of Lake Taihu through microcosm experiments, high-throughput sequencing of the nosZ gene, and statistical modeling. The results showed that potential N2O reduction rates in sediments ranged from 13.71 to 76.95 μg N2O g−1 d−1, with lower rates in December compared to March and July. Correlation analysis indicated that the nosZ II/nosZ I ratio and the trophic lake index (TLI) were the primary factors influencing N2O reduction rates and N2O-reducing bacterial community structures. The genera Pseudogulbenkiania and Ardenticatena were identified as the most abundant typical and atypical N2O-reducing bacteria, respectively, and were also recognized as the keystone taxa. Quantitative real-time PCR (qPCR) results revealed that nosZ II was more abundant than nosZ I in the sediments. Partial least squares path modeling (PLS-PM) further demonstrated that atypical N2O-reducing bacteria had significant positive effects on N2O reduction process in the sediments (p < 0.05). Overall, this study highlights the crucial ecological roles of atypical N2O-reducing bacteria in the sediments of the eutrophic lake of Taihu, underscoring their potential in mitigating N2O emissions.

Spontaneous Molecular Bromine Production in Sea‐Salt Aerosols

AbstractBromine chemistry is responsible for the catalytic ozone destruction in the atmosphere. The heterogeneous reactions of sea‐salt aerosols are the main abiotic sources of reactive bromine in the atmosphere. Here, we present a novel mechanism for the activation of bromide ions (Br−) by O2 and H2O in the absence of additional oxidants. The laboratory and theoretical calculation results demonstrated that under dark conditions, Br−, O2 and H3O+ could spontaneously generate Br and HO2 radicals through a proton–electron transfer process at the air–water interface and in the liquid phase. Our results also showed that light and acidity could significantly promote the activation of Br− and the production of Br2. The estimated gaseous Br2 production rate was up to 1.55×1010 molecules cm−2 ⋅ s−1 under light and acidic conditions; these results showed a significant contribution to the atmospheric reactive bromine budget. The reactive oxygen species (ROS) generated during Br− activation could promote the multiphase oxidation of SO2 to produce sulfuric acid, while the increase in acidity had a positive feedback effect on Br− activation. Our findings highlight the crucial role of the proton‐electron transfer process in Br2 production; here, H3O+ facilitates the activation of Br− by O2, serves as a significant source of atmospheric reactive bromine and exerts a profound impact on the atmospheric oxidation capacity.

Effect of temperature on the production and degradation of bromoform and other brominated methanes by marine microorganisms

Brominated methanes such as bromoform (CHBr3) are known to be important carriers of bromine from the ocean to the atmosphere. Bromine released from brominated methanes by photolysis has been shown to catalyze ozone depletion. Marine phytoplankton has been reported as a source of CHBr3 and marine bacteria as a sink for CHBr3. The effects of temperature on both CHBr3 production by phytoplankton and CHBr3 degradation by bacteria have yet to be investigated. We investigated the effects of temperature on CHBr3 production and CHBr3 degradation by marine microorganisms. The marine diatom Ditylum brightwellii (CCMP358) was cultured at 15 °C, 20 °C, 24 °C, and 30 °C. The maximum CHBr3 production rate at 24 °C was 1.57–2.39 pmol (μg chlorophyll a)−1 d−1, several times higher than that at 15 °C (0.25–0.41 pmol (μg chlorophyll a)−1 d−1). Higher rates of CHBr3, CHBr2Cl, and CHBrCl2 production were observed in the late exponential phase (and stationary phase) than in the early exponential phase at each temperature. These results suggest that temperature affects the rate of CHBr3 production during plankton growth. We then cultured the marine α-proteobacterium Phaeobacter gallaeciensis (JCM 21319) and the γ-proteobacterium Pseudomonas sp. HKF-4 at 10 °C, 15 °C, 20 °C, and 25 °C for up to 15 days to analyze temperature effects on spiked 13CHBr3 degradation. The degradation rate of 13CHBr3 by P. gallaeciensis increased with increasing temperature from 10 °C to 25 °C. The half-life of 13CHBr3 at 25 °C was about 1.1 d, which is about 6 times shorter than the half-life at 10 °C (about 6.9 d). On the other hand, the change in the half-life of the degradation of 13CHBr3 by HKF-1 was relatively small as the temperature increased from 10 °C (half-life: about 5.5 d) to 25 °C (half-life: about 1.8 d). Considering the rate of CHBr3 production and degradation at each temperature, we estimated how much of the CHBr3 produced by D. brightwellii for 7 days was degraded by the coexisting bacteria and how much remained after 7 days at each temperature. When coexisting with P. gallaeciensis, the residual CHBr3 concentration in the culture was relatively higher at 20–25 °C. Similarly, when coexisting with HKF-4, it was relatively higher at 20–25 °C. To estimate the impact of future warming on CHBr3 concentrations in the oceans, we assume a 5 °C increase in sea surface temperature, with two sea surface temperatures, 15 °C and 20 °C, changing to 20 °C and 25 °C, respectively. Under this assumption, the residual concentration of CHBr3 produced by D. brightwellii in seawater would be “increased” (or, less likely, “no change”) when P. gallaeciensis coexisted in these areas. Similarly, the total amount of CHBr3 residuals produced by D. brightwellii in the seawater areas where HKF-4 coexisted increased as the temperature increased by 5 °C. If, as the present results suggest, there is a temperature effect on microbial CHBr3 production and degradation in the oceans, then future increases in surface seawater temperature could result in an upward trend in CHBr3 concentrations in the open oceans, although such effects would be greatly influenced by both the phytoplankton species and coexisting bacterial species.

Andean Lakes: endangered by natural and anthropogenic threats

The Andes mountains extend North-South in a latitudinal gradient of 8,500 km. Due to the great climatic variety and the peculiar north-south orographic distribution, lakes are very diverse, including different lake origins and very contrasting morphometries. Here, we reviewed more than 700 ecological studies on Andean lakes to identify the main threats to these freshwater systems. The most important threats are UV radiation, changes in water balance, eutrophication, all three interacting with climate change, alien species introduction, and mining. Ultraviolet radiation is an important factor in Andean lakes not only because of the altitude but also because many lakes are included in the Antarctic ozone hole. The introduction of alien species, particularly exotic salmonids, also had detrimental effects, affecting native fish populations and behaviour, and endemic species by disrupting the indigenous food web. Eutrophication and browning caused by human activities, including land use interacting with climate change, are increasing in Andean lakes causing a decrease in water quality. Finally, mining can cause water contamination (both groundwater and surface water) by chemicals emitted from mining processes thus, producing a loss of biodiversity. Although an important number of Andean lakes have been declared as RAMSAR sites because of their uniqueness and their extreme conditions, they are subject to significant human impacts. Here, for the first time, we identify these impacts all along the Andes, however, further studies at different scales are mandatory if we pretend to understand, conserve, and manage Andean lakes.

The Influence of Stratospheric Hydration From the Hunga Eruption on Chemical Processing in the 2023 Antarctic Vortex

AbstractWe use measurements of trace gases from the Microwave Limb Sounder and polar stratospheric clouds (PSCs) from the Cloud‐Aerosol Lidar with Orthogonal Polarization to investigate how the extraordinary stratospheric water vapor enhancement from the 2022 Hunga eruption affected polar processing during the 2023 Antarctic winter. Although the dynamical characteristics of the vortex itself were generally unexceptional, the excess moisture initially raised PSC formation threshold temperatures above typical values. Cold conditions, especially in early July, prompted ice PSC formation and unusually severe irreversible dehydration at higher levels (500–700 K), while atypical hydration occurred at lower levels (380–460 K). Heterogeneous chemical processing was more extensive, both vertically (up to 750–800 K) and temporally (earlier in the season), than in prior Antarctic winters. The resultant HCl depletion and ClO enhancement redefined their previously observed ranges at and above 600 K. Albeit unmatched in the satellite record, the early‐winter upper‐level chlorine activation was insufficient to induce substantial ozone loss. Chlorine activation, denitrification, and dehydration processes ran to completion by July/August, with trace gas evolution mostly following the climatological mean thereafter, but with chlorine deactivation starting slightly later than usual. While cumulative ozone losses at 410–550 K were relatively large, probably because of the delayed chlorine deactivation, they were not unprecedented. Thus, ozone depletion was unremarkable throughout the lower stratosphere. Although Hunga enhanced PSC formation and chemical processing in early winter, saturation of lower stratospheric denitrification, dehydration, and chlorine activation (as is typical in the Antarctic) prevented an exceptionally severe ozone hole in 2023.