Recently, the city of Shenzhen celebrated International Labor Day (May 1st) and held a commendation ceremony. Junguo LIU, Chair Professor of the School of Environmental Sciences and Engineering at the Southern University of Science and Technology (SUSTech

Recently, Chair Professor Junguo Liu’s research group from the School of Environmental Sciences & Engineering at the Southern University of Science and Technology (SUSTech), in collaboration with scholars from the University of Hong Kong (HKU) and Michiga

A group of researchers from the Southern University of Science and Technology (SUSTech) and the Hong Kong University of Science and Technology (HKUST) collaborated to develop the first global simulation of atmospheric levoglucosan, explicitly accounting for its chemical degradation, and evaluated the impact on levoglucosan’s use in quantitative aerosol source apportionment. Their research, entitled “Impacts of Chemical Degradation on the Global Budget of Atmospheric Levoglucosan and Its Use As a Biomass Burning Tracer,” was published in Environmental Science & Technology, a top journal in the field of environmental science.Levoglucosan (1,6-anhydro-β-d-glucopyranose), a water-soluble anhydrosugar produced by the thermal breakdown of cellulose, has been widely used as a molecular tracer for biomass burning. Many studies have used the measured abundance of levoglucosan relative to organic carbon aerosols (OC) to estimate the contribution of biomass burning to the ambient OC at a receptor site. Laboratory experiments show that levoglucosan can be oxidized in the gas and aqueous phases or on aerosol surfaces. However, previous assessments have not accounted for levoglucosan’s degradation in the atmosphere, and thus may have underestimated the contribution of biomass burning to ambient aerosols.By constructing the first global model of atmospheric levoglucosan, researchers from SUSTech and HKUST showed that the global burden of atmospheric levoglucosan is 19 Gg. The atmospheric lifetime of levoglucosan (burden divided by total removal rate) is 1.8 days, which is much shorter than what it would have been without chemical degradation (7.3 days). The simulated concentrations reproduced the observed sharp decline in particulate levoglucosan concentrations from near-source to remote sites only when atmospheric degradation processes are included (Figure 1 and 2). The researchers further examined the impacts of levoglucosan’s degradation on the particulate levoglucosan to OC concentration ratio ([L]/[OC]) (Figure 2b), and the particulate levoglucosan to K+ concentration ratio ([L]/[K+]) (Figure 2c). Again, the decreasing ratios from near-source to remote sites can only be simulated when considering the levoglucosan’s chemical degradation (Figure 3).Figure 1. Simulated (filled contours) annual mean particulate levoglucosan concentrations (a) with and (b) without atmospheric degradation, compared to the observations (symbols coded by site types). Symbols with blue outlines show annual mean observations and symbols with black outlines show seasonal observations, which may be biased toward intense biomass burning influence.Figure 2. Comparisons of observed (black) and simulated values of (a) particulate levoglucosan concentrations, (b) particulate levoglucosan to OC concentration ratios, and (c) particulate levoglucosan to K+ concentration ratios at global surface sites. Red and blue lines indicate simulations with and without atmospheric degradation of levoglucosan, respectively.Researchers further defined a correction factor, x (x =[L]/[LNOCHEM]), representing the freshness of particulate levoglucosan at a receptor site. They then parametrized x as a function of the simulated molar ratio of NOx to NOy and L to biomass burning K+ to correct for the effects of aging in observed levoglucosan concentrations.Figure 3. Scatterplots of the simulated [L]/[LNOCHEM] ratio (≡ x) (a) versus the simulated [NOx]/[NOy] ratio and (b) versus the simulated [L]/[K+BB] ratio, where [K+BB] is the concentration of K+ emitted from biomass burning. The black lines show the reduced major axis linear regression lines; the slopes (S), intercepts (C), and correlation coefficients (R) are shown inset.By applying the parametrizations to the particulate levoglucosan measurements in Lin’an District in Hangzhou, China, and Chichijima, Japan, the researchers demonstrated the improved use of levoglucosan measurements for aerosol source apportionment. The assessment of the contribution of biomass combustion to local organic aerosols increased from 2.3%-5.6% to 14%-33% (Lin’an) and 0.3%-0.8% to 3.4%-8.3% (Chichijima), respectively, which were more consistent with other observed evidence of biomass combustion in the two receptor areas. This study improved the quantitative traceability method for the contribution of biomass combustion to organic aerosols.Yumin Li, a Ph.D. student supported by the joint doctoral program between SUSTech and HKUST, is the first author. Professor Tzung-May Fu of SUSTech and Professor Jian Zhen Yu of HKUST are the corresponding authors. This work was supported by the National Natural Science Foundation of China (NSFC) and the Shenzhen Science and Technology Innovation Committee. Computational resources were provided by the Center for Computational Science and Engineering at SUSTech.Paper link: https://pubs.acs.org/doi/10.1021/acs.est.0c07313

A fracture in geologic terms is a broken part of the Earth’s crust. Fractures can be as small as a cracked boulder or as large as a continent. Fluid-driven fracturing has long been a major topic in geoscience and geo-resources engineering. Accurate numerical modeling of fracture propagation and deflection in porous media is important in the development of geo-resources.Recently, Professor Dongxiao Zhang’s research group of the Southern University of Science and Technology (SUSTech) has been working on the topic of the evolution of mechanical discontinuities in the Earth’s crust, which is common in nature but can be dramatically challenging in modeling. A novel coupled geomechanics and fluid flow model was proposed to elucidate the mechanisms of multi-scale fracture swarms’ growth and typical mechanical interactions between propagating fractures. Their research outcomes have been published in leading scientific journals of geosciences such as the Journal of Geophysical Research: Solid Earth and Geophysical Research Letters.Figure 1. Numerical results of three-dimensional fracture swarms’ propagation driven by kerogen maturation in shale rocksThe fluid-driven fracturing nature phenomena include the meltwater-induced collapse of the ice sheet, magma intrusions by fluid-induced fracture of the lithosphere, evolution of echelon faults/fractures, etc. The reason why petroleum and mining engineers pay close attention to this topic lies in the extensive use of multi-stage fracturing in horizontal wells. Massive fracturing treatments stimulate the revolution of shale gas in the United States and change their energy structure. This technique has also been widely employed in the development of China’s shale gas reservoirs, located at Fuling, Weiyuan, Jiaoshiba, etc.The high-efficiency development of shale gas could relieve the problem of contradiction between supply and demand of China and therefore ensure energy security of China. In addition, fluid-driven fracturing is also involved in some other engineering problems, such as extraction of geothermal energy, development of gas hydrate, evaluation of the potential of carbon dioxide sequestration, and deep mining of metal deposits. Thus, investigation of fluid-driven fracturing facilitates a better understanding of geological phenomena across scales in the Earth’s crust, as well as to effectively develop geo-resources such as hydrocarbons and geothermal energy.Based on theories of fracture mechanics, rock mechanics, and fluid mechanics, Prof. Zhang’s group derive and build a novel numerical model, which is verified by analytical solutions in the toughness- and viscosity-dominated regions. This model enables the precise simulation of the propagation, interplay, and coalescence of the fracture swarms with variable apertures and geometries via solving fluid flow, fracture growth, and stress interference. This work was published in the Journal of Geophysical Research: Solid Earth, entitled “Development of 3-D Curved Fracture Swarms in Shale Rock Driven by Rapid Fluid Pressure Buildup: Insights from Numerical Modeling.”Figure 2. Illustration of the model setup and model verification resultsTo better understand fracture propagation behaviors associated with rapid fluid generation in source rocks, Prof. Zhang’s research group adopted the newly developed fracturing model to investigate the evolution of fracture swarms. Their work illustrated why non-planar, interconnected fracture swarms created during kerogen maturation, revealed five typical mechanical interaction modes between growing fractures, and elucidated mechanical mechanisms that determine the simultaneous, alternant, and differential growth of curved fracture swarms. This work yields an improved understanding of fluid-driven fracture swarms’ development in organic-rich shale due to rapid fluid generation, which was published in Geophysical Research Letters, entitled “Development of 3-D Curved Fracture Swarms in Shale Rock Driven by Rapid Fluid Pressure Buildup: Insights From Numerical Modeling.”Figure 3. Fracture aperture distributions of the fracture swarms and the statistics of individual fracture surface area under various initial dip anglesSanbai Li, Research Associate Professor at SUSTech, is the first author of the above papers. Chair Professor Dongxiao Zhang’s research team at SUSTech is the corresponding author, with SUSTech as the first affiliation. Professor Abbas Firoozabadi at Rice University is the co-corresponding author of the first piece of work.The above research was funded by the National Natural Science Foundation of China (NSFC).Paper links:https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2020JB020115 https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021GL092638

Recently, Professor Yuanyuan Tang’s research group of the Southern University of Science and Technology (SUSTech) has been working on topics of environmental pollution of plastics and has delivered a series of publications in this area, including the health impact of e-waste plastics and the medical waste problems, especially during the COVID-19 pandemic. The research outcomes have been published in leading scientific journals in the environmental field such as Environmental Science & Technology, Critical Reviews in Environmental Science and Technology, Resources, Conservation & Recycling, etc.With increasing medical waste generated by the COVID-19 pandemic, the first publication demonstrated available knowledge and current practices in medical and healthcare waste management worldwide. This study conducted a meta-analysis of medical and healthcare waste management practices in 78 countries and identified impediments and challenges facing the integration of medical waste management into a prospective circular economy.According to statistical correlations with human development index (HDI), life expectancy (LE), healthcare expenditure (HE) per capita of gross domestic product (GDP), and environmental performance index (EPI), the obtained results highlight the importance of knowledge and awareness of best practices on infection and injury prevention for waste management among workers. Plastic materials constituted about 35% of medical waste, presenting an opportunity for sustainable resource recovery and recycling. Their research suggests that all countries should adopt environmentally sustainable management of medical waste to prevent catastrophic stockpiling of infectious waste during and after pandemics. Additionally, this work also presented an outline for future studies on medical waste generation rate and various socio-economic and environmental parameters that should be investigated in future work to promulgate an inventory of the database for sustainable management of medical and healthcare waste.Figure 1. The management status and practices of medical waste in different countries. This includes the data on the risk of injury, medical waste management knowledge and awareness among the workers, training programs of workers in-service for the medical waste management, and the quantity of medical waste generation and segregation at the source.The second and third publications focused on environmentally sound management of personal protective equipment (PPE) such as face masks, gloves, goggles, gowns, and aprons. Early in the pandemic, challenges in international supply chains and stay-at-home orders affected both the availability of PPE and procedures for waste collection and management. Countries worldwide were struggling with the strategies and infrastructure for proper disposal of medical waste including the PPE due to the rapid increase in generation caused by the COVID-19 pandemic.Furthermore, the study also published the key takeaway from the experience of medical waste management during the COVID-19 outbreak in Wuhan. Generally, the COVID-19 pandemic has strained solid waste management globally, while also highlighting the bottleneck supply chain challenges regarding PPE manufacture, demand-supply use, and disposal. PPEs will continue to be in high demand, and this is the time to invest in research and development for new PPE materials that reduce waste generation, and for improved strategies for safe and sustainable management of used PPE with policy guidance at a global level.Figure 2. Medical waste generation and compositions in ChinaThe fourth and fifth publications focused on discarded plastics and consumer electronics which have led to increased concerns about the potential impact on human health. By delivering a systematic review, the fourth publication assesses the effects of e-waste exposures on pregnancy outcomes and neonate’s health. Outcomes from the study showed a possible association between exposure to e-waste and pregnancy and adverse neonatal health outcomes including sex-specific differences in infants’ growth, placental transfer of toxicants, thyroid hormones disruption, DNA methylation and oxidative damage, ALAD genotypes, carcinogenic risks, and sex hormones disruption in pregnant women and developing fetus. The results support evidence that e-waste exposure is associated with negative effects on pregnancy and neonatal health outcomes.The research outcomes of the fifth publication evaluated the toxicity of e-waste plastics, showing that the levels of Pb, Cd, Be, Sb, As, Hg, and BFRs in the plastics of discarded mobile phones do not pose a major danger if they were collected and recycled properly. However, a higher concentration of total Br could pose a potential danger to the environment and human health if the plastics end up in open burning. Hg and Pb contributed to the major risk for carcinogens and non-cancer disease in the plastic of mobile phones.Figure 3. Potential consequences for human health from toxic substances contained in e-waste plasticsFigure 4. Adverse effects of e-waste exposures on pregnancy outcomes and neonate’s healthNarendra Singh, Research Assistant Professor at SUSTech, is the first author of the above papers. Associate Professor Yuanyuan Tang’s research team at SUSTech is the corresponding author, with SUSTech as the first affiliation. The co-authors of the paper include Professor Chunmiao Zheng and Professor Zuotai Zhang of SUSTech, and Professor Oladele A Ogunseitan from the University of California, Irvine (UCI).The above research was funded by the National Natural Science Foundation of China (NSFC), the Post-Doctoral Program in Shenzhen, the State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, and the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control.Paper links:First publication: http://dx.doi.org/10.1080/10643389.2021.1885325Second publication: https://doi.org/10.1016/j.resconrec.2020.105071Third publication: https://dx.doi.org/10.1021/acs.est.0c03022Fourth publication: http://dx.doi.org/10.1080/10643389.2020.1788913 Fifth publication: https://doi.org/10.1016/j.envint.2020.105559  

Recently, the team led by Professor Zuotai Zhang of the School of Environmental Sciences and Engineering at the Southern University of Science and Technology (SUSTech) has made significant progress in the advanced treatment of wastewater. The results have been published in the highly influential academic journal Environmental Science & Technology, entitle “Atomically Dispersed Cobalt Sites on Graphene as Efficient Periodate Activators for Selective Organic Pollutant Degradation.”In recent years, non-radical pathway-based advanced oxidation technologies for the decontamination of recalcitrant organic pollutant has gained significant research interests. Compared with the conventional free-radical species-based oxidation process, the non-radical oxidation process possesses huge advantages in practical applications.Firstly, non-radical species such as singlet oxygen (1O2) normally display an excellent selectivity toward electron-rich pollutants or bacteria. Secondly, the non-radical-based advanced oxidation process shows strong resistance to external interference, that is, it is less affected by water pH conditions and coexisting background substances (e.g., inorganic anions and natural organic matter). Lastly, in the process of non-radical oxidation, the utilization efficiency of oxidants is much higher, which can reduce the overall cost of water treatment technology. Therefore, it is of great significance to develop novel and effective advanced oxidation technology systems based on the non-radical oxidation pathway.In this work, the team developed a novel non-radical-based advanced oxidation technology using a single-cobalt-atom activator catalyzed periodate oxidation process. According to their results, the single-cobalt-sites on carbon carriers effectively activated periodate to selectively degrade organic pollutants through an electron-transfer-based non-radical pathway.Based on the experimental and theoretical data, it was proposed that the periodate molecule was first adsorbed on the activator surface to produce a metastable activator-periodate complex that possessed a high oxidation potential. Then, the above-formed complex extracted electrons from the aromatic organic pollutants such as phenol, 4-chlorophenol, and rhodamine B thereby resulted in pollutant degradation and mineralization. The developed system possesses a wide pH adaptability and strong resistances to external interference in the complex water matrix, therefore opening new directions to design high-performance non-radical oxidation technology for wastewater treatment.Yangke Long, a postdoctoral fellow from the School of Environmental Sciences and Engineering at SUSTech, is the first author of the paper. Professor Zuotai Zhang from SUSTech is the corresponding author.This work was supported by the China Postdoctoral Science Foundation, National Natural Science Foundation of China (NSFC), Shenzhen Science and Technology Innovation Committee, and the Shenzhen Peacock Plan Project.Paper link: https://pubs.acs.org/doi/10.1021/acs.est.0c07794

Research Associate Professor Weiyi Li of the School of Environmental Sciences and Engineering at the Southern University of Science and Technology (SUSTech) aims at the exploration of novel materials and processes for membrane separations. Prof. Li and his colleagues recently employed optical coherence tomography (OCT) to analyze the scaling behavior of calcium sulfate (CaSO4) in membrane distillation (MD). They developed various methods for quantifying the dynamical effects of scaling and proposed an improved MD model for assessing the effects of the Spatio-temporal evolution of CaSO4 on the flux decline. Their research was published in Water Research and Journal of Membrane Science, which are high-impact journals in the fields of water treatment and membrane separations.Figure 1. OCT-based in-situ characterization for the scaling of calcium sulfate in membrane distillationMD is an emerging technique of membrane separations and offers special advantages in the treatment of high salinity brines and brackish waters. However, the advancement of MD is challenged by the scaling of sparingly soluble inorganic salts. In particular, there is a lack of effective methods for tackling the scaling of non-alkaline salts, e.g., CaSO4, primarily owing to the poor understanding of the underlying mechanisms. The occurrence of scaling would not only induce a significant flux decline but also give rise to irreversible damage to the membrane. Providing deeper insights into the scaling behavior in MD entails novel characterization techniques.OCT is an advanced technique that enables the optical sectioning for the semitransparent medium at micron scales and high scan rates, thereby offering a powerful tool for studying the scaling behavior in MD. This study developed a series of numerical algorithms to interpret the OCT datasets in an effort to resolve the scaling layer with a high resolution. It was for the first time that dissipative structures were revealed during the deposition of the scalants. This work was recently published in Water Research, entitled “Analyzing scaling behavior of calcium sulfate in membrane distillation via optical coherence tomography.”The scaling-induced deformation was successfully tracked by numerically analyzing the OCT datasets, thereby enhancing the accuracy of digitalizing the scaling layer. The digitalized scaling layer was exploited to estimate the surface coverage, the specific deposit, and the average cake thickness as a function of time. The growth and deposition of the CaSO4 were then analyzed in association with conventional characterization (including the measurement of vapor flux and conductivity over time). What stands out is that periodic patterns were unraveled by mapping the distribution of the local deposition rate. It indicates that secondary flows were induced by the complex coupling of the heat and mass transfer in the boundary layer.Figure 2. Schematic demonstrating the analysis of the CaSO4 scaling in MD via OCT (graphical abstract in WR)OCT offers a straightforward way to explore the scaling behavior of CaSO4 in MD, thereby providing more fundamental information for establishing the underlying mechanisms. It was therefore motivated to improve the classical MD model, which was incorporated with various characterization approaches to assess the relative importance of different mechanisms accounting for the flux decline in MD. This work was recently published in the Journal of Membrane Science, entitled “Flux decline induced by scaling of calcium sulfate in membrane distillation: Theoretical analysis on the role of different mechanisms.”This study highlighted the nonlinear effects of the mass and heat transfer while accounting for the presence of a scaling layer and a hydrophilic support layer. The geometrical characteristics of the scaling layer were correlated by the model to offer a tool for simulating the interplay between the scaling-layer growth and the vapor flux through the MD membrane. The modeling results were compared with the characterization results to evaluate the roles of temperature polarization, hydraulic resistance, and various interfacial effects in the scaling-induced flux decline. The comparison supports the hypothesis that the vapor depression should be dominated by the interfacial solidification resulting from the growth of CaSO4 crystals.Figure 3. Schematic of analyzing the scaling-induced flux decline by combining characterization and modeling (graphical abstract in JMS)All the studies shed light on the formation and evolution of a scaling layer in MD, whereby the MD-based applications would be improved to inject impetus into sustainable development.Jie Liu, a Ph.D. student supported by the joint doctoral program between SUSTech and HIT, is the first author of both papers. Dr. Weiyi Li, a Research Associate Professor at SUSTech, is the corresponding author of both papers. This work was supported by the National Natural Science Foundation of China (NSFC), Program for Guangdong Introducing Innovative and Entrepreneurial Teams, Shenzhen Science, Technology and Innovation Commission (SZSTI), and the Department of Education of Guangdong Province.Paper link in Water Research: https://doi.org/10.1016/j.watres.2021.116809Paper link in Journal of Membrane Science: https://doi.org/10.1016/j.memsci.2021.119257

In March 2021, a joint research team led by Professor Jeong Sujong from Seoul National University (SNU) and Professor Chunmiao Zheng from the Southern University of Science and Technology (SUSTech) revealed the impacts of climate change on tea production across China. The study findings were published in the renowned international journal Environmental Research Letters, entitled “Effects of extreme temperature on China’s tea production.” This study, for the first time, quantified the relationships between temperature extremes and tea production in China by integrating multisource datasets and a panel regression model with 21 global climate models, demonstrating the vulnerability of tea production to both cold and heat extremes.Tea is the second most consumed beverage globally and one of the most important cash crops in developing countries. China as the largest tea-producing country accounts for around 41% of the world’s production in 2016. As a result, tea cultivation is of considerable socio-economic importance for rural development and poverty alleviation. However, the production of tea is susceptible to extreme weather events. Unfavorable weather conditions can be detrimental to tea production and substantially reduce tea yields and quality. Despite the vital importance of tea production in China, research efforts to understand the impacts of climate change on tea production are considerably limited, especially with regards to temperature extremes.In this study, the joint research team collected a new long-term, fine-resolution, prefecture-scale tea production dataset and merged it with weather data, which covers ~70% of the tea-growing regions in China. The team deployed a classic regression model approach to analyze the nonlinear responses of tea yield to historical weather variability. Subsequently, a total of 21 global climate models were used to estimate future temperature extremes and their consequent impacts on tea yields under the 1.5 °C and 2.0 °C warming scenarios.Figure 1. The impact of cold waves in different provinces of China on tea productionThe study uncovers that in the present climate (1990-2016), dominating cold extremes influence more than 50% of China’s tea production, with a maximum of 56.3% reduced annual production. In the near future, the team predicts positive net impacts of climate change on tea yield in all study regions at both the 1.5 °C and 2.0 °C global warming levels. However, new areas of yield reduction by intensified heat extremes will emerge at the Yangtze River and southern China regions. This study provides scientific evidence to mitigate negative extreme temperature effects on China’s tea industry and guidelines to adapt tea production to climate change.Figure 2. The impact of cold wave, high temperature, and precipitation on tea production under the scenarios of 1.5°C and 2°C temperatures in the futureThe joint study was completed by Professor Chunmiao Zheng’s research group at SUSTech and Professor Jeong Sujong’s research group at SNU. Professor Chunmiao Zheng and Professor Jeong Sujong are the corresponding authors. Dr. Yulin Yan from Professor Jeong Sujong’s team is the first author. SUSTech Professor Junguo Liu and former members Dr. Chang-Eui Park and Dr. Jaewon Joo from Professor Chunmiao Zheng’s laboratory contributed to the study. This work was supported by the National Key R&D Program of China and other projects.Paper link: https://iopscience.iop.org/article/10.1088/1748-9326/abede6/meta

Recently, Professor Junguo Liu from the School of Environmental Science & Engineering (ESE) at the Southern University of Science and Technology (SUSTech), in collaboration with an international research team including scientists from ETH Zurich (Switzerland), SUSTech (China), NIES (Japan), University of Adelaide (Australia) and 15 other institutes, published a paper in Science, a high-impact journal, entitled “Globally observed trends in mean and extreme river flow attributed to climate change.” River flow has changed significantly worldwide in recent decades and this research team has now demonstrated that it is climate change, rather than water and land management, that plays a crucial role at a global level.Climate change is affecting the water balance of our planet. Depending on the region and the time of year, this can influence the amount of water in rivers potentially resulting in more flooding or drought. River flow is an important indicator of water resources available to humans and the environment. The amount of available water also depends on further factors, such as direct interventions in the water cycle or land-use change. For example, if the water is diverted for irrigation or regulated via reservoirs or forests are cleared and monocultures have grown in their place, this can have an impact on river flow.However, how river flow has changed worldwide in recent years was so far not investigated using direct observations. Similarly, the question of whether globally visible changes are attributable to climate change or to water and land management had not been clarified.Comparison of observed and reconstructed regional median river flow trends (1971–2010)Now, the international research team has succeeded in breaking down the influence of these factors after analyzing data from 7,250 measuring stations worldwide. The study demonstrates that river flow changed systematically between 1971 and 2010. Complex patterns were revealed; some regions such as the Mediterranean and north-eastern Brazil had become drier, while elsewhere the volume of water had increased, such as in Scandinavia.Chair Professor Junguo Liu from the School of Environmental Science & Engineering (ESE) at SUSTech is a member of the international team that authored this paper. His research was supported by the National Natural Science Foundation of China (NSFC) and the Strategic Priority Research Program of the Chinese Academy of Sciences.Paper link: https://science.sciencemag.org/content/371/6534/1159

Recently, Lei Zhu’s research group from the School of Environmental Science and Engineering (ESE) at the Southern University of Science and Technology (SUSTech) published a paper titled “Global Significant Changes in Formaldehyde (HCHO) Columns Observed from Space at the Early Stage of the COVID-19 Pandemic” in Geophysical Research Letters, a top journal in the field of geosciences. It reports on the significant changes and causes of global formaldehyde columns in the early stages of the COVID-19 pandemic.Satellite HCHO data is widely used as a reliable proxy of non-methane volatile organic compounds (NMVOCs) to understand the chemistry and emissions from biogenic sources, anthropogenic sources, and open fires. However, due to complex sources, sensitivity to atmospheric oxidation capacity, and unignorable noise in the retrieval process, it is still challenging to use HCHO to constrain NMVOCs emission.The COVID-19 pandemic outbreak has reshaped normal social and economic activities dramatically, resulting in sudden changes in the emissions of air pollutants and their precursors, as well as providing a unique experiment for HCHO research. This research uses TROPOspheric Monitoring Instrument (TROPOMI) satellite observations and GEOS-Chem 3-D chemical transport model to examine global significant changes in HCHO columns at the early stage of the COVID-19 pandemic (defined as January–April 2020) compared with the same period in 2019.The result shows that the HCHO columns’ changes over Northern China are affected by decreasing anthropogenic emissions and changing atmospheric oxidation capacity under massive lockdown at the early pandemic stage. In other regions, significant HCHO column changes are mainly impacted by temperature and open fires when the lack of anthropogenic signals was correlated with not implementing lockdown at the same period.In particular, HCHO columns decreased in the Northern China Plain (-11%) caused by a joint effect of meteorology, reduced anthropogenic NOx (-36%), and decreased NMVOCs (-15%) emissions during the lockdown. HCHO columns change near Beijing (+8.4%) due mainly to elevated hydroxyl radical as NOx emission decreases in a NOx-saturated regime. HCHO columns change in Northwestern China (+14.2%) is likely attributed to temperature variations (Figure 1).Figure 1. Significant changes in mean TROPOMI HCHO columns at the early stage of the pandemic (defined as January–April 2020) in (a) Northern China and its respective relations to (b) changes in TROPOMI NO2 columns and (c) anthropogenic NMVOC emissions.The impact of temperature and meteorology on HCHO columns is observed in India, Southern Africa, Eastern Brazil, Southern Cone, and Northeastern Thailand of Southeast Asia. Regional changes in Southeastern Australia, Northeastern Myanmar of Southeast Asia, Central Africa, and Central America are likely driven by open fire activities (Figure 2).Figure 2. Global significant changes in HCHO columns at the early stage of the pandemic (January–April 2020) compared with the same period in 2019.This research reveals significant changes in HCHO columns worldwide at the early stage of the COVID-19 pandemic. It provides evidence of changing atmospheric oxidizing capacity and NMVOC emissions in the Northern China Plain due to the lockdown. Meanwhile, this work emphasizes the value of TROPOMI satellite observation in understanding anthropogenic emissions and provides an important reference for using HCHO to constrain NMVOCs emissions.Wenfu Sun, a Research Assistant from the School of Environmental Science and Engineering (ESE) at SUSTech, is the first author of the paper. Dr. Lei Zhu, Assistant Professor from ESE at SUSTech is the corresponding author. The co-authors of this paper include Dr. Isabelle De Smedt of the Royal Belgian Institute for Space Aeronomy (BIRA-IASB), and Professors Xin Yang and Tzung-May Fu, both from ESE at SUSTech. Contributions were also made by Dr. Xiaofei Wang from Fudan University.This work is supported by the Center for Computational Science and Engineering at SUSTech and the Guangdong University Youth Innovation Talent Project.Paper links:http://dx.doi.org/10.1029/2020GL091265https://www.acmrsg.org/publications/.