Research News
Southeast Asia’s forest clearance is climbing to higher elevations at an accelerating rate, resulting in unprecedented forest carbon stock loss
Recently, a joint research team led by the Southern University of Science and Technology (SUSTech) shows that forest clearance in Southeast Asia is accelerating during the 21st century, with clearance frontier climbing to higher elevations and steeper slopes with high forest carbon stocks. Forest losses have resulted in a tremendous biomass carbon loss (424 Tg C yr−1), potentially nudging Southeast Asian forests to be a net carbon source in the global carbon budget.Most tropical deforestation is believed to occur in lowlands where forests are easy to access and deforested lands are feasible to plantations. However, recent studies have reported new croplands and plantations converted from mountain forests in Southeast Asia, generating a deeply divided debate on forest dynamics in the region. The study, entitled “Upward expansion and acceleration of forest clearance in the mountains of Southeast Asia,” was published on June 28 in Nature Sustainability. It uncovered forest loss dynamics and associated topographical patterns using multiple high-resolution satellite products of forest change and topography.The authors found that forest clearance in the mountains of Southeast Asia has accelerated during the 21st century, accounting for a third of total forest loss in the region. New plantations primarily drove deforestation at high elevations. Zhenzhong Zeng, who led the research and works as an associate professor at SUSTech, visually interpreted high-resolution satellite imagery in Southeast Asia three years previously. He found substantial mountain forests converted to croplands, although mechanical and intensive plantations in the mountains are not technically possible and economically feasible.“I was shocked by the tremendous deforestation in the mountains and think we should contribute to the sustainable development of forests. My Ph.D. student, Yu Feng, and I worked with Zhenzhong to figure out how Southeast Asia’s forests change. We combined multiple satellite data to quantify forest dynamics and associated topography, and surprisingly found accelerating mountain forest loss in the region,” said Professor Chunmiao Zheng of SUSTech.Figure 1. Example of massive forests that have been lost for cultivations in the mountains of Southeast AsiaThe researchers discovered that the frontier of forest clearance climbed to higher elevations and steeper slopes where forests have high carbon stocks. This means that forest loss shifted to regions with high carbon stocks, resulting in more forest carbon loss than expected. Combining forest loss data with a forest biomass carbon map, they discovered that carbon loss resulting from forest clearance was mainly in the lowlands in the 2000s, e.g., Indonesia. In the 2010s, however, lowland forest carbon loss decreased while mountain forest carbon loss in regions like Myanmar and Laos increased significantly. As mountain forests hold more biomass carbon than lowland forests, accelerating mountain forest clearance exacerbated carbon stock loss in the region.“I have spent three years doing a deforestation project in Nan Province, sponsored by the Kasikornbank and Princeton University, and took many pictures of mountain deforestation there as shown above. I’m glad to see the situation is becoming much better in Nan Province according to our new findings. Unfortunately, the situation of mountain deforestation is becoming worse in many other mountain regions of Southeast Asia,” said Professor Zeng.“Forest loss in the lowlands of Southeast Asia has rightly received a lot of attention, but that has shifted focus from an emerging pattern of extensive loss in the mountains that is increasing rapidly and threatens many species found nowhere else,” said Paul Elsen, Climate Adaptation Scientist for the Wildlife Conservation Society (WCS) and one of the co-authors of the study.Although multiple lines of evidence reveal that tropical forests likely act as a neutral contributor to the global carbon cycle, the accelerating clearance of mountain forests with high carbon density portends forest carbon loss in the near future. Consequently, this could potentially nudge Southeast Asia’s forests to be a net carbon source in the global carbon budget. Most deforested lands in the mountains have been turned into croplands, which may further intensify climate warming in the region through biochemical and biophysical feedbacks. The study provides important implications for regional land-use management and climate change adaption and mitigation.Figure 2. Corn and dasheen fields converted from forests in Southeast AsiaIn addition to Associate Professor Zhenzhong Zeng, Yu Feng, Professor Chunmiao Zheng, and Dr. Paul Elsen are also co-authors of this study. Other researchers included Yang Liu, Xinyue He, and Xin Jiang of SUSTech, Professor Alan D. Ziegler of MaeJo University (MJU), and Professors Dominick V. Spracklen and Joseph Holden, both of the University of Leeds.This project was supported in part by the National Natural Science Foundation of China (NSFC) and the start-up fund provided by SUSTech.Paper link: https://www.nature.com/articles/s41893-021-00738-y
SUSTech’s Hailong Li joins international team to reveal effects of submarine groundwater discharge on coastal ecosystems
Recently, Professor Hailong Li from the School of Environmental Sciences and Engineering at the Southern University of Science and Technology (SUSTech), in collaboration with an international research team including scientists from the University of Gothenburg, Leibniz Centre for Tropical Marine Research (ZMT), and Westlake University, published a paper in Nature Reviews Earth & Environment, entitled “Submarine groundwater discharge impacts on coastal nutrient biogeochemistry”. This paper evaluates the results of numerous studies, quantifies nutrient fluxes from groundwater inputs, and explains their effects on marine ecosystems.Water quality management in the ocean often targets visible pollution sources such as rivers, atmospheric deposition, and sewage. But nutrients also enter the oceans through groundwater. The importance of Submarine Groundwater Discharge (SGD) has often been overlooked in comparison to other sources mainly because the discharge occurs below the water surface and cannot be easily observed and measured. Quantifying SGD-derived nutrient fluxes is therefore challenging and involves nuanced assumptions and interpretations, and a wide range of skills in oceanography, hydrology, and biogeochemistry.This paper evaluates the results of numerous studies. They were conducted at more than 200 sites in coastal areas worldwide, ranging from polar to tropical seas (Figure 1). Of the locations investigated, around 60% of the studies showed that nutrients such as nitrogen, phosphorus, and silicon enter the sea in greater quantities via groundwater than via rivers, the largest sources of nutrients in the oceans (Figure 2). This makes groundwater the most important nutrient supplier to coastal ecosystems at many coastal locations. Projections show that groundwater worldwide releases around 140 million tons of silicon, 40 million tons of nitrogen, and 9 million tons of phosphorus into the sea each year.Figure 1. Submarine Groundwater Discharge (SGD) rates from study cases reviewed. (a) SGD fluxes globally, color-coded by ecosystem type, where the size of the circle represents the reported SGD rate. Similar maps for each nutrient are shown in the supplementary material. Investigations where SGD rates are reported without any nutrient fluxes were not included in the compilation. (b) SGD in Hawaii, USA, with ecosystems colored and rates scaled as above. (c) SGD in the Mediterranean. (d) SGD on the east coast of the USA. (e) SGD in East Asia. (f) SGD on the eastern coast of Australia.Figure 2. River and SGD-derived nutrient inputs to the ocean. (a) Summary of global-scale fluxes compiled from the river, Fresh Submarine Groundwater Discharge (Fresh SGD) and total (mostly saline) SGD estimates. (b) Histogram of ratios between SGD and river-derived dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and dissolved silicate (DSi) fluxes summarized from the global study cases reviewed.SGD consists of a mixture of continental fresh water and saltwater that permeates from the coastal aquifer. It is an invisible hydrological link between coastal aquifers and the sea. In addition to supplying fresh water to the sea or other coastal systems (lagoons, wetlands), SGD can represent an important source of nutrients for these ecosystems. Therefore, SGD plays a critical role in their sustainment and, consequently, on the goods and services provided by these ecosystems. Due to this underground connectivity, any anthropogenic impact on coastal groundwater, such as pumping water, the use of fertilizers, or the infiltration of urban water into aquifers, can affect the transfer of nutrients to the ocean.SGD-substance inputs can be a blessing or a curse for coastal ecosystems. For example, coral reefs can benefit from the fact that carbonate dissolved in groundwater promotes coral calcification. An example of this would be the nutrient-rich groundwater sources of Australia’s “Wonky Holes”, which are hotspots for fish such as giant bass and, highlighting the importance for fishing and tourism. However, there are also negative impacts of groundwater flows on coastal ecosystems. In many places, excess nutrients lead to overfertilization of water bodies and to algal blooms (Figure 3). Such negative effects of nutrients are seen off the coast of Hawaii where the U.S. Supreme Court also recently ruled that groundwater must be better protected to guard the coastal ocean.Figure 3. The biological impacts of SGDUnderstanding the delivery of anthropogenically-derived nutrients to the coastal ocean through groundwater discharge is, therefore, crucial to ensure appropriate management of coastal waters. Researchers consider that, unfortunately, since SGD is essentially invisible and highly variable along different coastlines, decision-makers face two opposing risks; ignoring a potentially important pollution source or wasting resources on a potentially small source. In addition, since the role of SGD in ecological, economic, and societal context is not appropriately constrained, management strategies and policies cannot become effective.Climate and land-use change are expected to modify patterns of global water use, drive sea levels to rise, force seawater infiltration into coastal aquifers, and modify the chemical composition and volume of groundwater. These changes are expected to modify fluxes of nutrients from SGD, but little is known on how increased anthropogenic pressures will modify the quality and quantity of groundwater fluxes to the ocean. In addition, the slow movement of SGD relative to rivers implies that current contaminant and nutrient flows reflect past inputs, and management approaches must prepare for increasing loads in the decades to come. A proper understanding of their role in the ecological and economic context is needed to develop effective coastal management strategies.The joint study was led by Professor Isaac R. Santos at the University of Gothenburg, Sweden. Professor Isaac R. Santos is the first and corresponding author of the paper. Professor Hailong Li from the School of Environmental Sciences and Engineering at SUSTech is a member of the international team that authored this paper. His research was supported by the National Natural Science Foundations of China (NSFC) (41972260, 41430641).Paper link: https://doi.org/10.1038/s43017-021-00152-0
SUSTech Chunmiao Zheng’s team unveils role of groundwater flow in “Asian water tower” areas
The Himalayas are the greatest mountain range on Earth, but these peaks are not just a magnificent spectacle. They are also regarded as “Water towers of Asia”. The Himalayas are critical for supplying water for around two billion people who live downstream, and available water is highly sensitive to climate change. The role of the groundwater system in sustaining the northern Himalayan rivers remains unknown, and this compromises Asia’s future water sustainability.Recently, Professor Chunmiao Zheng’s research team from the Southern University of Science and Technology (SUSTech), discovered the role of groundwater flow in “Asian water tower” areas. They published their results in collaboration with top research institutions in China and internationally, including Xi’an Jiaotong University (XJTU), The University of Texas at Austin (UT Austin), Seoul National University (SNU), and the Institute of Tibetan Plateau Research (ITP), Chinese Academy of Science (CAS). Their research, entitled “Role of Groundwater in Sustaining Northern Himalayan Rivers”, was published in the high-impact journal Geophysical Research Letters. Their study models the spatial groundwater flow and discharge volume to the Yarlung Zangbo, the largest river of the Himalayas in China, based on long-term climate and streamflow observations.The research group of Professor Zheng quantifies the spatiotemporal contribution of groundwater to river flows in the Yarlung Zangbo Basin (upper reaches of Brahmaputra). Their results show that the groundwater recharge represents around 23% of mean annual precipitation, translating into around 30 km3/yr of baseflow, which contributes to around 55% of the total river discharge in the upstream reaches and 27% in the downstream reaches. The percentage of groundwater contribution is inversely related to topographic steepness and total precipitation, with the steepest topography and highest precipitation in the eastern Himalayas. This study fills a knowledge gap on subsurface flow processes in the northern Himalayas and provides a baseline for comparing changes in the stream flow under climatic warming over vulnerable water tower regions.Figure 1. Spatial distribution of groundwater flow. (a) Simulated groundwater flow paths and heads; the color of the lines represents the distance of the flow path from source to sink area, and the frequency histograms of the distance of flow path and head are showed on the left side. (b) Simulated average annual groundwater discharge volume (Qg) in the form of baseflow along streams per kilometer and groundwater recharge (R) per unit basin area, and the frequency histograms of Qg and R are shown on the left side.The groundwater flow patterns and recharge-discharge mechanisms within the aquifers of the northern Himalayans are poorly known, which limits understanding of the hydrological cycle and predictions of future changes in the sensitive “water tower” mountainous regions. A three-dimensional, physically-based regional-scale groundwater model was developed for the Yarlung Zangbo basin in the northern Himalayan mountainous region. Major study findings include that the short (<5 km) and intermediate (10–50 km) distance flow paths account for over 75% and dominate spatial flow patterns for the groundwater system of the northern Himalayans in China. It’s estimated that 124 mm/yr, around 23% of mean precipitation, recharges to groundwater, and this translates into about 30 km3/yr of baseflow.The Northern Himalayan groundwater system contributes 27%-55% of annual river discharge from west upstream to east downstream. The percentage of groundwater contribution to river discharge is inversely related to the steepness of the topography and precipitation, with the steepest topography and highest annual precipitation in the downstream reaches. These results also indicate that the groundwater recharge and discharge would increase with the projected increasing ratio of recharge to precipitation, and thawing permafrost would increase groundwater recharge and discharge. Their evaluation fills a knowledge gap in one of the most complex alpine groundwater systems and provides a baseline for extending geoscience and socio-economic studies in high mountainous regions.Figure 2. Seasonal groundwater recharge and discharge. (a) Spatial distribution of annual average ratio between recharge and precipitation. (b to h) Seasonal changes of observed river discharge (Q), groundwater discharge (Qg), precipitation (P), and groundwater recharge (R) for each sub basin. In top subfigures, the monthly averaged Q and ranges of Q are shown in dotted blue lines and transparent blue areas, respectively, and the computed Qg by digital filter algorithms and the Qg simulated by three-dimensional numerical groundwater model are shown in dotted black lines and red lines, respectively. In the bottom subfigures, the monthly average P and R are shown in transparent blue areas and red areas, and the R/P is shown in dotted black lines.Yingying Yao, an Associate Professor at XJTU is the first author of this paper. Professor Chunmiao Zheng of the School of Environmental Science and Engineering at SUSTech is the corresponding author. This work was supported by the National Natural Science Foundation of China (NSFC) and the Shenzhen Municipal Science, Technology and Innovation Committee.Paper link: http://dx.doi.org/10.1029/2020GL092354
Researchers collaborate to pinpoint sources of ozone pollution in the Beijing−Tianjin−Hebei area using adjoint modeling
A group of researchers from the Southern University of Science and Technology (SUSTech) and Peking University (PKU) collaborated to pinpoint the sources of surface ozone pollution in the Beijing-Tianjin-Hebei area using adjoint modeling. Their research, entitled “Sensitivities of Ozone Air Pollution in the Beijing−Tianjin−Hebei Area to Local and Upwind Precursor Emissions Using Adjoint Modeling”, was published in Environmental Science & Technology, a top journal in the field of environmental science.The Beijing−Tianjin−Hebei area (BTH) of China has experienced severe summertime surface ozone pollution, which poses serious public health risks. The Chinese government has recently strengthened BTH ozone pollution prevention, emphasizing the emission reductions of highly active non-methane volatile organic compounds (NMVOCs). For such efforts to be effective, there must be quantitative understandings of the sources of ozone pollution, including the contributing precursors, their spatial origins, and their emitting activities. Adjoint modeling is an efficient method to quantify the source of ozone in the receptor area and can provide speciated, sector-resolved, and spatially-resolved information on the precursors contributing to ozone.Figure 1. Quantifying the sensitivity of surface ozone pollution in the Beijing-Tianjin-Hebei area to local and upwind precursor emissions.Researchers from SUSTech and PKU used the GEOS-Chem chemical transport model’s adjoint to analyze the sensitivity of population-weighted BTH ozone to regional precursor emissions in June 2019 under three different levels of ozone pollution severity: (1) heavily polluted (exceeding 20% or more), (2) slightly polluted (exceeding 0-10%), and (3) non-exceedance.Figure 2. Sensitivities of population-weighted BTH MDA8 surface ozone concentrations to a 10% increase of precursor emissions (unit, 10−3 ppb) over North China on BTH heavily polluted days in June 2019.The study showed that during heavily polluted days (Figure 2), BTH ozone was highly sensitive to emissions from BTH and south of BTH in the Shandong, Henan, and Jiangsu region (SHJ). To mitigate heavy BTH ozone pollution, the most effective measures entailed reducing NOx (from industrial process and transportation), ≥C3 alkenes (from on-road gasoline vehicles and industrial processes), and xylenes (from paint use) emitted from both BTH and SHJ, and CO (from industrial processes, transportation, and power generation) and ≥C4 alkanes (from industrial processes, paint and solvent use, and on-road gasoline vehicles) emissions from SHJ.Figure 3. Sensitivities of BTH ozone to four anthropogenic NMVOC species (≥C4 alkanes, ≥C3 alkenes, xylenes, and toluene) on heavily polluted days. Sensitivities are segregated for the emitting activities and the provinces/cities of emission.NMVOC species are emitted from a wide range of anthropogenic activities. As such, species-based emission reductions may be difficult to implement and manage. In comparison, sector- or subsector-based emission reduction actions target key emitting activities, where emissions can be controlled by improving or substituting processes and technologies. By further mapping the sensitivities to the subsector NMVOC emissions (Figure 3), this study pointed out the key NMVOC emission activities that should be targeted: paint use (for architecture, vehicles, wood products, and other products), on-road gasoline vehicles, and industrial processes (mainly including coking, oil refinement, distribution and storage of oil/gas, and chemical production).This research pinpointed the key areas and sectors that should be targeted in regionally-coordinated emission reduction efforts and provided a concrete and feasible way for improving the ground-level ozone air quality in Beijing-Tianjin-Hebei. The methodology can also be applied to address ozone pollution issues in other parts of the country.Xiaolin Wang, a Ph.D. student at PKU, is the first author of this study. Professor Tzung-May Fu of SUSTech and Professor Lin Zhang of PKU are the corresponding authors. This work was supported by the National Natural Science Foundation of China (NSFC) and the Basic and Applied Basic Research Foundation of Guangdong Province. Computational resources were provided by the Center for Computational Science and Engineering at SUSTech.Paper link: https://pubs.acs.org/doi/abs/10.1021/acs.est.1c00131
SUSTech Zuotai Zhang’s team makes advanced progress in solid amine CO2 capture materials
China is an active participant in global climate governance and insists on promoting CO2 mitigation. General Secretary Xi Jinping put forward the ambitious goal of striving to achieve carbon neutrality by 2060 at the 75th United Nations General Assembly. The development of CO2 capture and storage (CCS) technology can avoid CO2 emissions from industrial emission point sources and reduce the CO2 already in the atmosphere. It is an important part of achieving the goal of “carbon neutrality”, and is of great significance for deep decarbonization, large-scale production of low-carbon hydrogen energy, low-carbon power supply, and realization of negative emissions.Recently, Professor Zuotai Zhang and Research Assistant Professor Feng Yan from the School of Environmental Science and Engineering (ESE) at the Southern University of Science and Technology (SUSTech), innovatively prepared a series of low-cost, green, and efficient porous nano-SiO2/Al2O3 supported solid amine CO2 adsorbents using solid waste as the main raw materials. These results have been published in the well-known journals of Environmental Science & Technology and Chemical Engineering Journal in the environmental and energy fields.Figure 1. Preparation and carbon neutralization application of solid waste-derived nano-Al2O3 supported solid amine CO2 adsorbentsThe porous nano-Al2O3 support was firstly synthesized from high-aluminum coal fly ash, and the active PEI was then impregnated on the nano-Al2O3 support to prepare the solid amine CO2 adsorbent, which possessed a superior CO2 adsorption capacity of 136 mg·g-1. Significantly, this solid amine CO2 adsorbent showed stable adsorption capacity even regenerated under the pure CO2 atmosphere, and its CO2 adsorption capacity still maintained as high as 111 mg·g-1 adsorbent after 10 cycles, which was 5.5 times higher than that of traditional nano-SiO2 supported solid amine adsorbents. Therefore, this technical route, which can realize the high-value utilization of coal fly ash and significantly improve the cyclic stability of solid amine adsorbent regenerated under the pure CO2 atmosphere, has broad application prospects in CO2 capture and separation processes such as industrial source CO2 capture and biogas upgrading. This research, entitled “Highly efficient and stable PEI@Al2O3 adsorbents derived from coal fly ash for biogas upgrading”, was published in the Chemical Engineering Journal.On this basis, the research group continued to study in-depth the interaction mechanism of support-organic amine and the anti-urea chain formation mechanism of nano-Al2O3 supported solid amine CO2 adsorbents. The results have shown that the unique cross-linking reaction between nano-Al2O3 support and organic amine molecules significantly inhibited the formation of urea chains in nano-Al2O3 supported solid amine CO2 adsorbents during the cyclic adsorption-regeneration process, thereby greatly improving the cyclic stability of CO2 adsorption capacity.The study further verified the long-term cyclic stability of nano-Al2O3 supported solid amine CO2 adsorbents, whose adsorption capacity decreased by only 29% after 100 cycles regenerated under the pure CO2 atmosphere. This work not only clarifies the CO2 adsorption cycle stabilization mechanism of nano-Al2O3 supported solid amine CO2 adsorbents, but also provides design ideas for the development of new high-stable solid amine CO2 adsorbents with anti-urea properties. This research, entitled “Biogas Upgrading via Cyclic CO2 Adsorption: Application of Highly Regenerable PEI@nano-Al2O3 Adsorbents with Anti-Urea Properties”, was published in Environmental Science & Technology.Figure 2. The cross-linking mechanism between nano-Al2O3 support and organic amine moleculeChunyan Li, a master’s student from the ESE at SUSTech, and Xuehua Shen, a doctoral student supported by the joint Ph.D. program between SUSTech and Harbin Institute of Technology (HIT), are the first authors of these two papers, respectively. Professor Zuotai Zhang and Research Assistant Professor Feng Yan from the ESE at SUSTech are the co-corresponding authors. SUSTech is also the first affiliation and communication affiliation of these papers.These studies were supported by the National Natural Science Foundation of China (NSFC), the National Key R&D Program of China, Shenzhen Science, Technology and Innovation Committee (SZSTI), and the Pearl River Scholars Funding Program for Higher Education Institutions in Guangdong Province.Paper links:Chemical Engineering Journal link: https://doi.org/10.1016/j.cej.2020.128117Environmental Science & Technology link: https://doi.org/10.1021/acs.est.0c07973
China is an active participant in global climate governance and insists on promoting CO2 mitigation. General Secretary Xi Jinping put forward the ambitious goal of striving to achieve carbon neutrality by 2060 at the 75th United Nations General Assembly.
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 Michigan State University, published findings for a new method that is used to extract high-resolution drainage network. The paper, entitled “Basin-scale high-resolution extraction of drainage networks using 10-m Sentinel-2 imagery” was published in Remote Sensing of Environment, a renowned academic journal that focuses on remote sensing studies.Extraction of drainage networks is an important element of river flow routing in hydrology and large-scale estimates of river behaviors in Earth sciences. Emerging studies with a focus on greenhouse gases reveal that small rivers can contribute to more than half of the global carbon emissions from inland waters (including lakes and wetlands). However, large-scale extraction of drainage networks is constrained by the coarse resolution of observational data and models, which hinders assessments of terrestrial hydrological and biogeochemical cycles.Figure 1: (a) Lancang-Mekong River networks extracted in this study. (b) State-of-the-art Landsat-based river centerlines extraction (GRWL) in the study area with breakpoints (river centerline disconnections).Recognizing that the Sentinel-2 satellite can detect surface water up to a 10-m resolution over large scales, they proposed a new method named Remote Sensing Stream Burning (RSSB) to integrate high-resolution observational flow location with coarse topography to improve the extraction of the drainage network. In RSSB, satellite-derived input is integrated in a spatially continuous manner, producing a quasi-bathymetry map where relative relief is enforced, enabling a fine-grained, accurate, and multitemporal extraction of the drainage network. RSSB was applied to the Lancang-Mekong River basin to derive a 10-m resolution drainage network, with a significant reduction in location errors as validated by the river centerline measurements.Figure 2: Location errors of river networks generated by the RSSB method and conventional method (non-RSSB). The closer the CDF curve near the top left, the better.The high-resolution extraction resulted in a realistic representation of meanders and detailed network connections. Furthermore, RSSB enabled a multitemporal extraction of river networks during wet/dry seasons and before/after the formation of new channels. The proposed method is fully automated, meaning that the network extraction preserves basin-wide connectivity without requiring any postprocessing, hence facilitating the construction of drainage network data with openly accessible imagery.Figure 3: Comparisons of 90-m and 10-m drainage networks, including flow direction, flow accumulation, and extracted river vector.The RSSB method provides a basis for the accurate representation of drainage networks that maintains channel connectivity, allowing a more realistic inclusion of small rivers and streams. This enables a greater understanding of complex but active exchange between inland water and other related Earth system components.Zifeng Wang, a doctoral student supported by the joint Ph.D. program between SUSTech and HKU, and Junguo Liu, Chair Professor at SUSTech, are the first and corresponding authors, respectively, of this paper. Jinbao Li and Hongsheng Zhang from HKU, Ying Meng from SUSTech, and Yadu Pokhrel from Michigan State University are the co-authors.This study was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, the National Natural Science Foundation of China (NSFC), and SUSTech.Paper link: https://doi.org/10.1016/j.rse.2020.112281
ESE Professor wins 2nd prize in 2019 Environmental Protection Science and Technology Award
In recent days, Professor Qing HU (Environmental Science and Engineering) won second prize in the 2019 Environmental Protection Science and Technology Award. She earned the award for participating in the project, “Key Technology and Application of Groundwater Pollution Risk Monitoring and Emergency Response” (the project). The project sought to overcome the scientific problems and technical difficulties faced by China’s groundwater pollution monitoring and early warning and emergency response. It is based on the migration path of groundwater, to examine the source, pathway, and target of pollution. The project is focused on overcoming three key technologies. Those technologies are China’s groundwater pollution-risk source identification, pollution monitoring and warning, and emergency response. The Environmental Protection Science and Technology Awards are the highest accolades in ecological environment science and technology. The Awards Committee approved 39 achievements and awarded four 1st prizes, thirty-three 2nd prizes, and two Science Popularization Prize. Professor Qing HU is the director of the SUSTech Engineering Innovation Center (Beijing). She has won many awards and sits on several expert committees.
SUSTech environmental scientist offers perspective on ending arsenic exposure from well water
In 2010 the U.N. agreed to a resolution declaring the human right to “safe and clean drinking water and sanitation.” The safety of drinking water is a vital issue for many communities around the world. Chair Professor Yan Zheng, School of Environmental Science and Engineering from Southern University of Science and Technology (SUSTech) was invited to publish a perspective article, titled “Global Solutions to a Silent Poison” in Science (IF = 37.2). Her article accompanied “Global Threat of Arsenic in Groundwater” by Joel E. Podgorski and Michael Berg of the Swiss Federal Institute of Aquatic Science and Technology Yan Zheng is an expert in water and health, with a focus on groundwater quality. Her experience extends from a Ph.D. in earth and environmental sciences from Columbia University to a water and sanitation specialist for the United Nations Children’s Fund in Bangladesh. She has held academic appointments at Peking University, City University of New York (CUNY), and Columbia University. She has been named a Fellow of the Geological Society of America. Zheng’s article in Science discussed widespread drinking water arsenic exposure stemming from reliance on domestic wells for supply in many rural communities around the world. There is a desperate need for screening for arsenic in domestic well water in these communities, even in wealthy countries like the United States of America. Her article called to identify people suffering from arsenic exposure as part of a larger plan to eliminate arsenic exposure in drinking water. Zheng had previously covered this issue in a paper she wrote with her former student Sara V Flanagan (Columbia University) and former colleague Richard B Johnston (now with the World Health Organization). Their paper was titled “Arsenic in tube well water in Bangladesh: health and economic impacts and implications for arsenic mitigation.” That paper was published in the Bulletin of the World Health Organization (IF = 6.8). In that paper, the authors found that 45 million people were drinking well water containing unsafe levels of arsenic. It was leading to 1 death in every 18 adult deaths (about 6%). Yet, incomplete data meant that global information on this problem was highly inconsistent. Zheng’s article in Science also looked at the most recent WHO provisional guideline values for drinking water at ten micrograms of inorganic arsenic per liter. It is encouraging that many countries have revised their drinking water standard down from 50 micrograms per liter, with several adopting more health-protective five micrograms as their standards. However, in Bangladesh, and parts of India, and even China, the less health-protective 50 microgram standard is still permitted for dispersed rural population due to the lack of high-quality water sources. The diverse range of standards is highly concerning, given that inorganic arsenic is highly toxic. It has been listed as a class I carcinogen by the International Agency for Research on Cancer for many years. Its colorless, tasteless and odorless nature, when dissolved in water, has given it the unfortunate title of “the king of poisons” and “the poison of kings.” Long-term exposure of inorganic arsenic has been shown to affect the development of the fetus and infants, with long-lasting effects later in life. Plenty of studies have shown adverse health effects on many parts of the human body, possibly involving the epigenome as a mechanism of inorganic arsenic’s toxicity. Yan Zheng assessed the Podgorski and Berg paper that was also published in today’s issue of Science. Their paper compiled more than two hundred thousand well water arsenic data points in 67 countries. They developed a statistical model that suggested that between 94 and 220 million people, 94% of which live within the Asian continent, are at risk of drinking well water that contains more than ten micrograms of arsenic per liter. Their model also identifies potential areas around the world where the local water supply exceeds five micrograms of arsenic per liter. However, few countries carry out national arsenic screening of their domestic well water supplies, so this study highlights the gap between known and unknown arsenic screening. In closing her article, Yan Zheng emphasizes the desperate need to screen for arsenic in domestic wells, particularly in predicted high-risk areas. The development of sensitive, reliable, inexpensive, and user-friendly testing methods will improve screening methodologies while identifying exposed populations. It is also cheaper to minimize the impact of arsenic through prevention, rather than treat the impact of arsenic exposure. Article link: https://science.sciencemag.org/content/368/6493/818 Yan Zheng’s homepage: http://faculty.sustech.edu.cn/yan.zheng/en/
Reduced springtime rainfall in southern China linked to human activity
Human activities produce large amounts of atmospheric pollutants, which can also have complex impacts on climate. A team of researchers from Southern University of Science and Technology (SUSTech) has found that human activity may have significantly reduced the amount of springtime rainfall over Southern China since the 1980s. On February 29, Professor Tzung-May Fu‘s research group from the School of Environmental Science and Engineering (ESE) at SUSTech published a paper in the high-impact academic journal, Geophysical Research Letters (IF = 4.58), a leader in Earth sciences. It was published under the title, “Anthropogenic Aerosols Significantly Reduce Mesoscale Convective System Occurrences and Precipitation over Southern China in April.” Since the 1980s, aerosols emitted by human activities into the atmosphere in China have doubled. Aerosols can affect precipitation and climate, both directly by scattering solar radiation and indirectly by changing cloud microphysics. However, due to the complexity of convective systems (weather systems where heavy rainfall comes about due to the vigorous upward motion of warm air), the impact of aerosols on convective systems and convective precipitation has been an important unresolved scientific question in climate research. Mesoscale convection systems (MCSs) cause severe weather such as heavy rain, hail, and strong wind, all of which can be very damaging to people’s safety and livelihood. Observations indicated that late spring precipitation in South China had decreased significantly since the 1980s, with 90% of that precipitation coming from MCSs. Professor Tzung-May Fu ‘s research group put forward a hypothesis based on the significant increase in aerosol emissions in China in recent decades. The increased aerosol emissions may have caused changes in springtime MCSs over Southern China, which led to the reduced rainfall. The research team compared the rainfall records in South China during the relatively cleaner period of 1979 to 1989 with those during the relatively polluted period of 2001 to 2011. They found that rainfall in South China had decreased by 25% in April between the two periods, which was mainly manifested by decreased occurrences of heavy rain (Figure 1a). The team applied the meteorology-chemistry model, WRF-Chem, to carry out experiments and developed an objective diagnostic algorithm for MCSs. They found that the large increase in aerosol emissions since the 1980s led to the simulated occurrences of MCS to decline by 21% to 32% (Figure 1b). Figure 1. Simulated April precipitation in South China: (a) Probability distribution of precipitation intensity; (b) Hours of occurrences of mesoscale convective system (MCS). Through further simulations, the team was able to elucidate the mechanism by which aerosols reduced MCSs in South China (Figure 2). The increased aerosol in the regional atmosphere enhanced the scattering of short-wave radiation from the sun. At the same time, more aerosols formed more liquid cloud droplets, which increased the amount of solar radiation reflected by clouds. Both mechanisms reduced solar radiation reaching the surface, making the surface cooler and more stable. Ultimately, this suppressed the occurrence of MCS, thereby reducing regional rainfall. This paper is pivotal in pointing out that aerosols affect MCSs not only directly, but also indirectly by altering the interactions between MCSs and the ambient atmosphere. These findings help advance the scientific understanding of the impacts of aerosol on precipitation and climate. Figure 2. Schematic diagram of the effect of carbon emissions on the April mesoscale convective system in South China Zhang Lijuan, a doctoral student at Peking University and a visiting student of SUSTech, is the first author; Professor Tzung-May Fu is the corresponding author. The study was financially supported by the National Natural Science Foundation of China (NSFC). Article link: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL086204
Predicting rainfall-induced landslides becomes easier for all
Research led by the School of Environmental Science and Engineering (ESE) at Southern University of Science and Technology (SUSTech) had discovered new mechanisms for predicting landslides related to intensive rainfall. ESE Founding Dean Chunmiao Zheng has cooperated with the Swiss Federal Institute of Technology Zurich (ETH Zurich) to develop a new model for simulating rainfall-induced landslides. This model combines catchment hydrology (flow of water in the catchment) and soil mechanics (mechanical properties and behaviors of soil) to investigate how rainfall intensity temporal patterns affect where a landslide may occur, where it is expected to go, and how it evolves. The outcomes of this research are of significant importance, both practically and scientifically, for predicting geological disasters. High-impact journal Geophysical Research Letters (IF = 4.58), a leader in Earth sciences, published the paper under the title, “Rainfall Intensity Temporal Patterns Affect Shallow Landslide Triggering and Hazard Evolution.” Rainfall-induced landslides are severe natural disasters that frequently occur around the world, causing significant losses to human life and properties. Rainfall-induced landslides are associated with rainwater infiltration that may load and weaken soil mantle and lead to a sudden mass soil release, also known as a landslide. The rainfall intensity temporal patterns may affect the rainfall infiltration process and soil mechanical responses to rainfall loading. It continues to exert a tremendous influence on landslide dynamics and hazard evolution. Previous research often focused on the role of rainfall duration and average intensity on landslide initiation, neglecting the effects of rainfall intensity temporal patterns on landslides. Chunmiao Zheng and his team addressed the question of: “How rainfall intensity temporal patterns affect landslide triggering and hazard evolution?” The researchers first employed a stochastic process simulation technique to generate artificial time series of rainfall intensity with different temporal patterns but the same volume of rain over the same period. Then, they used these artificial rainfall time series as input for a novel Landslide Hydromechanical Triggering (LHT) model to simulate the landslide triggering and hazard evolution under different rainfall scenarios. The results showed that rainfall intensity temporal patterns alter the total amount of rainfall infiltration into the soil and affect soil mechanical strength and behaviors. It resulted in a wide range of landslide volumes, even though the total applied rainfall amount and duration are the same (Figure 1). Figure 1. Rainfall intensity temporal patterns affect total amount of rainfall infiltration and landslide volume The team also discovered that advanced rainfall pattern (peak rainfall intensity occurring at the beginning of a rainfall event) are more likely to promote landslide initiation, compared with delayed rainfall scenario (peak rainfall intensity at the later stage of rainfall) (Figure 2). These results not only yield insights into the triggering mechanisms of rainfall-induced landslides but also provide a scientific basis for establishing regional landslide warning systems. Figure 2. Dynamic evolution of landslide hazard under different rainfall dynamics The first author and corresponding author of the paper was ESE Research Fellow Dr. Fan Linfeng. Other key centers involved in this research were the Guangdong Provincial Key Laboratory of Soil and Groundwater Pollution Control, the State Environmental Protection Key Laboratory of Integrated Surface Water-Groundwater Pollution Control, and the Soil and Terrestrial Environmental Physics (STEP), Institute of Biogeochemistry and Pollutant Dynamics (IBP), ETH Zurich. The research received support from the National Key R&D Program of China, the National Natural Science Foundation of China, and the State Environmental Protection Key Laboratory of Integrated Surface Water‐Groundwater Pollution Control of China. Paper link: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL085994    
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