科研成果

A source-oriented Community Multiscale Air Quality model was used to quantify the contributions of different sources to ground-level fine particulate matter (PM2.5) and ozone (O3) over the Yangtze River Delta (YRD) region during the EXPLORE-YRD (EXPeriment on the eLucidation of the atmospheric Oxidation capacity and aerosol foRmation, and their Effects in the Yangtze River Delta) campaign (17 May to June 17, 2018). O3 formation in most urban areas of YRD is attributed to volatile organic compounds (VOCs) (81.1%, 78.5%, 60.2%, and 55.1% in Shanghai, Nanjing, Hefei, and Hangzhou, respectively), but is affected more by nitrogen oxides (NOx) in suburban and rural areas. Industry and transportation are the two major sources of O3 and PM2.5. In addition to the two sources, NOx produced owing to power generation, and VOC emissions from biogenic sources are important source of O3. Industry contributes the most to the total mass of PM2.5 in the YRD during the study period (9–25 μg/m3), followed by transportation (2–7 μg/m3). Industry, residential emissions, and transportation are the major sources of primary organic carbon and elemental carbon, whereas industry, transportation, and power generation account for most of the sulphate (SO2− 4) and nitrate (NO− 3) in the YRD. Agriculture is the most dominant source of ammonium emissions (NH+ 4). In Shanghai, Nanjing, Hefei, and Taizhou, secondary organic aerosol (SOA) are mainly contributed by industrial emissions. However, in Hangzhou, biogenic emissions contribute more than 40% of SOA. During all types of pollution episodes, industry and transportation are generally the two greatest sources of O3 and PM2.5 in YRD. The contribution of industry is higher during high PM2.5 pollution episodes, whereas biogenic and open burning contributions are more important during high O3 episodes. Overall, anthropogenic sources dominate the formation of O3 and PM2.5 pollution in the YRD, whereas biogenic emissions contribute significantly to O3 attributable to VOC emissions (O3_VOCs) accounting for 9–20% in urban areas of the YRD. © 2021 Elsevier Ltd

During the COVID-19 lockdown in 2020, large-scale industrial and transportation emissions were reduced, but high PM2.5 concentration still occurred. This study investigated the variation of particle number size distribution during the lockdown, and analyzed the characteristics of new particle formation (NPF) events and its potential impact on haze formation. Through measurement conducted in urban Beijing during the first 3 months of 2020, and comparison with year-over-year data, the decrease of primary Aitken-mode particles was observed. However, frequencies, formation rates and growth rates of NPF events remained stable between 2020 and 2019 in the same period. As a result, >25 nm particles produced by NPF events, would play a more important role in serving as the haze formation “seeds” compared to those produced by primary emissions. This finding emphasizes the significance on the understanding of NPF mechanisms when making pollution mitigation policy in the future. © 2021. The Authors.

Introduction: The COVID-19 global epidemic caused by severe acute respiratory syndrome coronavirus (SARS-CoV-2) is a great public health emergency. Discovering antiviral drug candidates is urgent for the prevention and treatment of COVID-19. Objectives: This work aims to discover natural SARS-CoV-2 inhibitors from the traditional Chinese herbal medicine licorice. Methods: We screened 125 small molecules from Glycyrrhiza uralensis Fisch. (licorice, Gan-Cao) by virtual ligand screening targeting the receptor-binding domain (RBD) of SARS-CoV-2 spike protein. Potential hit compounds were further evaluated by ELISA, SPR, luciferase assay, antiviral assay and pharmacokinetic study. Results: The triterpenoids licorice-saponin A3 (A3) and glycyrrhetinic acid (GA) could potently inhibit SARS-CoV-2 infection, with EC50 of 75 nM and 3.17 µM, respectively. Moreover, we reveal that A3 mainly targets the nsp7 protein, and GA binds to the spike protein RBD of SARS-CoV-2. Conclusion: In this work, we found GA and A3 from licorice potently inhibit SARS-CoV-2 infection by affecting entry and replication of the virus. Our findings indicate that these triterpenoids may contribute to the clinical efficacy of licorice for COVID-19 and could be promising candidates for antiviral drug development. Keywords: COVID-19; Glycyrrhetinic acid; Licorice; Licorice-saponin A3; SARS-CoV-2.

The common pool resource (CPR) theory has made invaluable contributions to the governance of natural resources in the past decades, but few literatures have specifically paid attention to the different property right arrangements of resource system and resource units, and their relationship. In this paper, we take two types of grassland property right system on the Qinghai-Tibetan Plateau (QTP) in China, one is grassland contract system under that the previous grassland common use was given up and the other is grazing quota system under that the common use is still kept in the community level, as cases to present the different consequences on the ecological conditions, herders’ livelihoods and livestock husbandry. Furthermore, from the perspective of property rights of resource system-units, we explore why the two systems resulted in the different consequences. We find that the grazing quota system indicated by the number of livestock each household allowed to raise has more advantages in improving the herders’ livelihoods and reducing the livestock production costs, and both systems could alleviate the grazing pressure though the long-term effects of the contract system might be negative on ecological conditions. The main reason why the grazing quota system works better is that this type of individual use rights were clarified based on the resource units so the grassland could be kept common use as an integrated resource system, while the contract system was claimed by physically dividing the resource system by fencing, thus the resource system was fragmented which led to mismatch with the large scope movement needs of livestock grazing. We argue that, theoretically, the grazing quota system is a private property rights embedded in the grassland common property right system, which forms a nested property right regime. Our findings have important implications for both of the CPR theory and practical rangeland management worldwide.

A growing number of governments and companies are pledging net-zero emissions by 2050. For the US as a whole to achieve this requires eliminating or offsetting today's emission of ~6 billion tCO2e/year. There is a dearth of analysis for understanding requirements, costs, and impacts of this transition. The goal of this study is to help fill this gap by providing insights at visceral, human scales of how the nation will look following a pathway to net-zero and the localized benefits, costs, and impacts for different industries, professions, and communities. The analysis aims to inform debates on public and corporate policies needed to achieve net-zero, but specific policy recommendations are not offered.Energy service demands projected to 2050 by the EIA for 14 regions across the continental US provide the starting point for modeling. Five different pathways are constructed for meeting these demands by varying exogenously applied constraints to create the different pathways.End-use technologies to meet service demands are exogenously specified in 5-year time steps to determine final energy demands that must be delivered by the energy supply system. Pathways to net-zero emissions by 2050 are constructed by finding the energy supply mix that minimizes the 30-year NPV of total energy-system costs, subject to exogenous constraints. The model has perfect foresight and seamless integration between all sectors. These modeling results are “downscaled” to state or sub-state geographies to quantify local plant and infrastructure investments, construction activities, land-use, jobs, and health impacts, 2020 - 2050.

Microbial densities, functional genes, and their responses to environment factors have been studied for years, but still a lot remains unknown about their interactions with each other. In this study, the abundances of 7 nitrogen cycling genes in the sediments from Hangzhou Bay were analyzed along with bacterial and archaeal 16S rRNA abundances as the biomarkers of their densities. The amount of organic matter (OM) and total nitrogen (TN) strongly positively correlated with each other and microbial densities, while total phosphate (TP) and ammonia-nitrogen (NH3–N) did not. Most studied genes were density suppressed, while nirS was density stable, and nosZ and hzo were density irrelevant. This suggests eutrophication could limit inorganic nitrogen cycle pathways and the removal of nitrogen in the sediment and emit more greenhouse gases. This study provides a new insight of microbial community structures, functions and their interactions in the sediments of eutrophic bays.

Recent Chinese air pollution actions have significantly lowered the levels of fine particulate matter (PM2.5) in North China via controlling emissions of sulfur dioxide (SO2) and nitrogen oxides (NO x ) together with primary aerosols, while the emissions of another precursor, ammonia (NH3), have not yet been regulated. This raises a question that how effective the NH3 emission controls can be on the mitigation of PM2.5 pollution along with the reduction of SO2 and NO x emissions. Here we use a regional air quality model to investigate this issue focusing on the PM2.5 pollution in North China for January and July 2015. We find that the efficiency of the PM2.5 reduction is highly sensitive to the NH3 emission and its reduction intensity. Reductions in the population-weighted PM2.5 concentration (PWC) in the Beijing–Tianjin–Hebei region are only 1.4–3.8 μg m−3 (1.1%–2.9% of PM2.5) with 20%–40% NH3 emission reductions, but could reach 8.1–26.7 μg m−3 (6.2%–21%) with 60%–100% NH3 emission reductions in January 2015. Besides, the 2015–2017 emission changes (mainly reduction in SO2 emissions) could lower the PM2.5 control efficiency driven by the NH3 reduction by up to 30% for high NH3 emission conditions, while lead to no change or increase in the efficiency when NH3 emissions become low. NO x emission reductions may enhance the wintertime PM2.5 pollution due to the weakened titration effect and can be offset by simultaneously controlling NH3 emissions. Our results emphasize the need to jointly consider NH3 with SO2 and NO x emission controls when designing PM2.5 pollution mitigation strategies.