Black Carbon Size in Snow of Chinese Altai Mountain in Central Asia

Black carbon(BC)in snow plays an important role to accelerate snow melting.However,current studies mostly focused on BC concentrations,few on their size distributions in snow which affected BC’s effect on albedo changes.Here we presented refractory BC(rBC)concentrations and size distributions in snow collected from Chinese Altai Mountains in Central Asia from November 2016 to April 2017.The results revealed that the average rBC concentrations were 5.77 and2.82 ng g-1for the surface snow and sub-surface snow,which were relatively higher in the melting season(April)than that in winter(November-January).The mass median volume-equivalent diameter of rBC size in surface snow was approximately at 120-150 nm,which was typically smaller than that in the atmosphere(about 200 nm for urban atmosphere).However,there existed no specific mass median volume-equivalent diameter of BC size for sub-surface snow in winter.While during the melting season,the median mass size of rBC in sub-surface snow was similar to that in surface snow.Backward trajectories indicated that anthropogenic sourced BC dominated rBC in snow(70%-85%).This study will promote our understanding on BC size distributions in snow,and highlight the possible impact of BC size on climate effect.

Light-absorbing impurities on Keqikaer Glacier in western Tien Shan: concentrations and potential impact on albedo reduction

Light-absorbing impurities on glaciers are important factors that influence glacial surface albedo and accelerate glacier melt. In this study, the quantity of light-absorbing impurities on Keqikaer Glacier in western Tien Shan, Central Asia, was measured. We found that the average concentrations of black carbon was 2,180 ng/g, with a range from 250 ng/g to more than 10,000 ng/g. The average concentrations of organic carbon and mineral dust were 1,738 ng/g and 194 μg/g, respectively. Based on simulations performed with the Snow Ice Aerosol Radiative model simulations, black carbon and dust are responsible for approximately 64% and 9%, respectively, of the albedo reduction, and are associated with instantaneous radiative forcing of 323.18 W/m2(ranging from 142.16 to 619.25 W/m2) and 24.05 W/m2(ranging from 0.15 to69.77 W/m2), respectively. For different scenarios, the albedo and radiative forcing effect of black carbon is considerably greater than that of dust. The estimated radiative forcing at Keqikaer Glacier is higher than most similar values estimated by previous studies on the Tibetan Plateau, perhaps as a result of black carbon enrichment by melt scavenging. Light-absorbing impurities deposited on Keqikaer Glacier appear to mainly originate from central Asia, Siberia, western China(including the Taklimakan Desert) and parts of South Asia in summer, and from the Middle East and Central Asia in winter.A footprint analysis indicates that a large fraction(>60%) of the black carbon contributions on Keqikaer Glacier comes from anthropogenic sources. These results provide a scientific basis for regional mitigation efforts to reduce black carbon.

Estimating interaction between surface water and groundwater in a permafrost region of the northern Tibetan Plateau using heat tracing method

Understanding the interaction between groundwater and surface water in permafrost regions is essential to study flood frequencies and river water quality, especially in the high latitude/altitude basins. The application of heat tracing method,based on oscillating streambed temperature signals, is a promising geophysical method for identifying and quantifying the interaction between groundwater and surface water. Analytical analysis based on a one-dimensional convective-conductive heat transport equation combined with the fiber-optic distributed temperature sensing method was applied on a streambed of a mountainous permafrost region in the Yeniugou Basin, located in the upper Heihe River on the northern Tibetan Plateau. The results indicated that low connectivity existed between the stream and groundwater in permafrost regions.The interaction between surface water and groundwater increased with the thawing of the active layer. This study demonstrates that the heat tracing method can be applied to study surface water-groundwater interaction over temporal and spatial scales in permafrost regions.

Broadband Miniaturized Bandpass Filter with Circular Stubs for Compact Wireless and Mobile Communication Systems

A miniaturized square resonator bandpass filter with circular stubs is designed, fabricated, and characterized. Analytical calculations were carried out to determine the critical filter parameters and the design was optimized using a 3D electromagnetic finite-element solver. The measured results were in good agreement with the designed results. The proposed filter exhibits significant improvement in bandwidth compared to the conventional square resonator bandpass filters.

The Natural Beauty in English and Chinese Season Lyrics from the Perspective of Ecological Culture

The ecological and cultural awareness in seasonal lyrics can be seen in the comparison and analysis of the practical aspects of ecological culture construction.The importance of songs in disseminating ecological culture is self-evident.The English and Chinese lyrics about the four seasons are rich in content and the exploration space of ecological cultural factors is very large.

Teaching Research on Ideology and Politics of "New Horizon College English" proceeding from multimodality

Based on the multimodal theory,this article designs a theme teaching in one unit of college English course ideology and politics which is about”Spend or save-The student’s dilemma”.The new instructional design incorporates Mao Zedong’s quotations,Xi Jinping’s speaking and habit of saving,and celebrity saving stories in regular college English teaching,and adds three specific multimodal designs of teachers’teaching,students’learning,and teaching evaluation.Multi-modal teaching mainly performs as various modal angles other than language and pictures,practical cases in teaching design.

微塑料和纳米塑料威胁青藏高原环境

Plastic pollution is a planetary level threat which affects Earth’s environment and ecosystems.From the poles to deep ocean basins,the growth of plastic waste has already exceeded its limits.The projected increase of plastic production and waste generation over the coming years makes the situation even more daunting.Even after stagnation in 2020 due to the COVID-19 pandemic,the global plastic production has also increased from 335 to 391 million metric tons(Mt)between 2016 and 2021(Fig.S1 online);yet currently post-consumer recycled and bio-based/attributed plastics only accounts~9%of the world’s plastic production[1].Statistically.

Cryosphere as a temporal sink and source of microplastics in the Arcticregion

Microplastics(MPs)pollution has become a serious environmental issue of growing global concern due to the increasing plastic production and usage.Under climate warming,the cryosphere,defined as the part of Earth’s layer characterized by the low temperatures and the presence of frozen water,has been experiencing significant changes.The Arctic cryosphere(e.g.,sea ice,snow cover,Greenland ice sheet,permafrost)can store and release pollutants into environments,making Arctic an important temporal sink and source of MPs.Here,we summarized the distributions of MPs in Arctic snow,sea ice,seawater,rivers,and sediments,to illustrate their potential sources,transport pathways,storage and release,and possible effects in this sentinel region.Items concentrations of MPs in snow and ice varied about 1-6 orders of magnitude in different regions,which were mostly attributed to the different sampling and measurement methods,and potential sources of MPs.MPs concentrations from Arctic seawater,river/lake water,and sediments also fluctuated largely,ranging from several items of per unit to>40,000 items m^(-3),100 items m^(-3),and 10,000 items kg^(-1) dw,respectively.Arctic land snow cover can be a temporal storage of MPs,with MPs deposition flux of about(4.9-14.26)×10^(8) items km^(-2) yr^(-1).MPs transported by rivers to Arctic ocean was estimated to be approximately 8-48 ton/yr,with discharge flux of MPs at about(1.65-9.35)×10^(8) items/s.Average storage of MPs in sea ice was estimated to be about 6.1×10^(18) items,with annual release of about 5.1×10^(18) items.Atmospheric transport of MPs from long-distance terrestrial sources contributed significantly to MPs deposition in Arctic land snow cover,sea ice and oceanic surface waters.Arctic Great Rivers can flow MPs into the Arctic Ocean.Sea ice can temporally store,transport and then release MPs in the surrounded environment.Ocean currents from the Atlantic brought high concentrations of MPs into the Arctic.However,there existed large uncertainties of estimation on the storage and release of MPs in Arctic cryosphere owing to the hypothesis of average MPs concentrations.Meanwhile,representatives of MPs data across the large Arctic region should be mutually verified with in situ observations and modeling.Therefore,we suggested that systematic monitoring MPs in the Arctic cryosphere,potential threats on Arctic ecosystems,and the carbon cycle under increasing Arctic warming,are urgently needed to be studied in future.

大气污染物跨境传输及其对青藏高原环境影响

青藏高原拥有独特的多圈层环境系统与生态类型,对我国乃至亚洲具有重要的生态安全屏障作用.在青藏高原开展污染物跨境传输的科学考察研究,既是地表多圈层相互作用研究的重要组成部分,也是支撑国家生态环境安全的战略需求.针对第二次青藏高原综合科学考察研究的'南亚通道'关键区,结合长期站点监测和短期强化观测,本文全面综述了青藏高原大气污染物时空分布、传输过程和机理,以及污染物对气候和生态系统影响方面的新认识.从历史趋势上看,青藏高原黑碳和汞等记录,自20世纪50年代以来呈现快速上升,反映了亚洲区域大气污染物排放的快速增多.从传输过程上看,跨越喜马拉雅山的高空环流以及局地的山谷风是大气污染物跨境传输的重要途径.大气气溶胶-雪冰辐射反馈效应对青藏高原的气候变化带来一定的影响,外源污染物对青藏高原生态系统的负面影响业已凸显.未来研究中,亟待精确量化跨境污染物的输送量和影响范围,预测未来情景下污染物排放与环境健康风险的变化趋势.

Characteristics of carbonaceous aerosols analyzed using a multiwavelength thermal/optical carbon analyzer: A case study in Lanzhou City

Characteristics of atmospheric carbonaceous aerosols in Lanzhou City from December 2014 to November 2015 are analyzed using a multiwavelength thermal/optical carbon analyzer. Results reveal that average concentrations of black carbon (BC) and organic carbon in atmospheric aerosols at Lanzhou are 6.7 and 25.4 μg m^(-3), respectively, showing obvious seasonality (higher in winter and lower in summer). This is consistent with findings in cities of northern China. Primary organic aerosols and secondary organic aerosols respectively account for approximately 60% and 17% of carbonaceous aerosols. No significant seasonality is found for secondary organic carbon, indicating that its potential sources do not vary significantly throughout the study period. The mass absorption cross-section (MAC_(632nm)) of BC is 7.1 m^2g^(-1), slightly higher than that of immediately emitted BC. MAC values of BC at different wavelengths vary drastically; they are higher for ultraviolet and visible light (8.5–10.2 m^2g^(-1)) than for near-infrared light (4.9–5.7 m^2g^(-1)). The aerosol absorption optical depth generally declines from the near-infrared to the near-ultraviolet region. The values are higher in winter than in summer, thus showing there are different contributions of BC deposition in different seasons. Brown carbon (BrC) has an ?ngstr?m absorption exponent (AAE) value of approximately 2.75, which is similar to the AAE value of BrC generated by diesel combustion (2.3). The contribution of BrC to light absorption is as much as 34% at a wavelength of 635 nm. This study demonstrates that the multiwavelength thermal/optical carbon analyzer can quantify absorption properties of BrC in atmospheric aerosols. This can enhance understanding of carbonaceous aerosols and provide key parameters for simulations of climate models.

Carbonaceous matter in glacier at the headwaters of the Yangtze River:Concentration,sources and fractionation during the melting process

Carbonaceous matter has an important impact on glacial retreat in the Tibetan Plateau,further affecting the water resource supply.However,the related studies on carbonaceous matter are still scarce in Geladaindong(GLDD)region,the source of the Yangtze River.Therefore,the concentration,source and variations of carbonaceous matter at Ganglongjiama(GLJM)glacier in GLDD region were investigated during the melting period in 2017,which could deepen our understanding on carbonaceous matter contribution to glacier melting.The results showed that dissolved organic carbon(DOC)concentration of snowpit samples(283±200μg/L)was much lower than that of precipitation samples(624±361μg/L),indicating that large parts of DOC could be rapidly leached from the snowpit during the melting process.In contrast,refractory black carbon(rBC)concentration measured by Single Particle Soot Photometer of snowpit samples(4.27±3.15μg/L)was much higher than that of precipitation samples(0.97±0.49μg/L).Similarly,DOC with high mass absorption cross-section measured at 365 nm value was also likely to enrich in snowpit during the melting process.In addition,it was found that both r BC and DOC with high light-absorbing ability began to leach from the snowpit when melting process became stronger.Therefore,rBC and DOC with high light-absorbing ability exhibited similar behavior during the melting process.Based on relationship among DOC,rBC and K^+ in precipitation,the main source of carbonaceous matter in GLJM glacier was biomass burning during the study period.

SARS-CoV-2 triggers inflammatory responses and cell death through caspase-8 activation

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection can lead to respiratory illness and multi-organ failure in critically ill patients.Although the virus-induced lung damage and inflammatory cytokine storm are believed to be directly associated with coronavirus disease 2019(COVID-19)clinical manifestations,the underlying mechanisms of virus-triggered inflammatory responses are currently unknown.Here we report that SARS-CoV-2 infection activates caspase-8 to trigger cell apoptosis and inflammatory cytokine processing in the lung epithelial cells.The processed inflammatory cytokines are released through the virus-induced necroptosis pathway.Virus-induced apoptosis,necroptosis,and inflammation activation were also observed in the lung sections of SARS-CoV-2-infected HFH4-hACE2 transgenic mouse model,a valid model for studying SARS-CoV-2 pathogenesis.Furthermore,analysis of the postmortem lung sections of fatal COVID-19 patients revealed not only apoptosis and necroptosis but also massive inflammatory cell infiltration,necrotic cell debris,and pulmonary interstitial fibrosis,typical of immune pathogenesis in the lung.The SARS-CoV-2 infection triggered a dual mode of cell death pathways and caspase-8-dependent inflammatory responses may lead to the lung damage in the COVID-19 patients.These discoveries might assist the development of therapeutic strategies to treat COVID-19.

Multiple Roles of HIV-1 Capsid during the Virus Replication Cycle

Human immunodeficiency virus-1 capsid(HIV-1 CA) is involved in different stages of the viral replication cycle. During virion assembly, CA drives the formation of the hexameric lattice in immature viral particles, while in mature virions CA monomers assemble in cone-shaped cores surrounding the viral RNA genome and associated proteins. In addition to its functions in late stages of the viral replication cycle, CA plays key roles in a number of processes during early phases of HIV-1 infection including trafficking, uncoating, recognition by host cellular proteins and nuclear import of the viral preintegration complex. As a result of efficient cooperation of CA with other viral and cellular proteins, integration of the viral genetic material into the host genome, which is an essential step for productive viral infection, successfully occurs. In this review, we will summarize available data on CA functions in HIV-1 replication, describing in detail its roles in late and early phases of the viral replication cycle.

Facile Synthesis of α-Haloketones by Aerobic Oxidation of Olefins Using KX as Nonhazardous Halogen Source

Summary of main observation and conclusion An operationally simple and safe synthesis of a-haloketones using KBr and KCI as nonhazardous halogen sources is reported.It involves an iron-catalysed reaction of alkenes with KBr/KCl using O2 as terminal oxidant under the irradiation of visible-light.This strategy avoids the risks associated with handling halo-contained electrophiles(Cl2,Br2/NCS,NBS).The process is tolerant to several functional groups,and extended to a range of substituted styrenes in up to 89%yield.A radical reaction pathway is proposed based on control experiments and spectroscopy studies.

Sink or source? Methane and carbon dioxide emissions from cryoconite holes, subglacial sediments, and proglacial river runoff during intensive glacier melting on the Tibetan Plateau

High Mountain Asia glaciers are currently ignored in the estimation of global greenhouse gas budgets (e.g., methane (CH4) and carbon dioxide (CO_(2))). Similar to the Asian Water Tower and Third Pole, the Tibetan Plateau (TP) hosts the largest volume of glaciers outside the polar regions. These glaciers contain large reservoirs of organic carbon that can influence glacial ecosystems under rapid melting. However, no data exist on the current footprint of CH4 and CO_(2) from glaciers in the TP. Here, we report in situ observations of CH4 and CO_(2) fluxes for glacial cryoconite holes, subglacial sediments, and proglacial river runoff across the TP. Our results indicate that cryoconite holes and subglacial sediments can accelerate the export of greenhouse gasses during the melting season due to intensive glacier melting. However, to some extent, proglacial river runoff can be a significant sink of atmospheric CO_(2);this fact was not identified in previous studies. Our findings suggest that variations (source or sink) of greenhouse gasses from TP glacial basins should be considered in regional CH4 and CO_(2) budgets under climate warming.

A review on source,occurrence,and impacts of microplastics in freshwater aquaculture systems in China

Microplastic pollution has become an increasingly important environmental issue worldwide in recent years because of its ubiquitous presence in different environmental media and its potential to affect the health of organisms and ecosystems.Aquaculture contributes significantly to the world's food production and nutritional supply,especially in developing countries.Widespread occurrence of microplastics in aquaculture systems has raised great concern regarding aquaculture production and food safety issues of aquaculture products.China is a world leader in aquaculture production,with freshwater aquaculture accounting for 59.1%of total aquaculture production of the world in 2020.Therefore,this review mainly focuses on recent research progress related to microplastic pollution in freshwater aquaculture systems in China.Results from the literature show that microplastics are present in freshwater aquaculture systems at abundances comparable to natural waterbodies in China.Microplastics can be ingested and remain in the body of aquaculture products.Exposure to microplastics can adversely affect the health of aquatic organisms and aquatic ecosystem functions.However,risks of microplastics in real world environment remain uncertain.Consumption of freshwater aquaculture products is not a major pathway for human exposure to microplastics.To provide scientific guidance for governmental decision-making and pollution control,future work should focus on progress in toxicological methodology and understanding the impacts of microplastics at community and ecosystem levels.

Antibody-dependent cellular cytotoxicity response to SARS-CoV-2 in COVID-19 patients

Antibody-dependent cellular cytotoxicity(ADCC)responses to viral infection are a form of antibody regulated immune responses mediated through the Fc fragment.Whether severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)triggered ADCC responses contributes to COVID-19 disease development is currently not well understood.To understand the potential correlation between ADCC responses and COVID-19 disease development,we analyzed the ADCC activity and neutralizing antibody response in 255 individuals ranging from asymptomatic to fatal infections over 1 year post disease.ADCC was elicited by 10 days post-infection,peaked by 11-20 days,and remained detectable until 400 days post-infection.In general,patients with severe disease had higher ADCC activities.Notably,patients who had severe disease and recovered had higher ADCC activities than patients who had severe disease and deceased.Importantly,ADCC activities were mediated by a diversity of epitopes in SARS-COV-2-infected mice and induced to comparable levels against SARS-CoV-2 variants of concern(VOCs)(B.1.1.7,B.1.351,and P.1)as that against the D614G mutant in human patients and vaccinated mice.Our study indicates anti-SARS-CoV-2 ADCC as a major trait of COVID-19 patients with various conditions,which can be applied to estimate the extra-neutralization level against COVID-19,especially lethal COVID-19.

ARTICLE OPEN Viral dynamics and antibody responses in people with asymptomatic SARS-CoV-2 infection

Over 40% of the coronavirus disease 2019(COVID-19)COVID-19 patients were asymptomatically infected with severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)and the immune responses of these asymptomatic individuals is a critical factor for developing the strategy to contain the COVID-19 pandemic.Here,we determined the viral dynamics and antibody responses among 143 asymptomatic individuals identified in a massive screening of more than 5 million people in eight districts of Wuhan in May 2020.Asymptomatic individuals were admitted to the government-designated centralized sites in accordance with policy.The incidence rate of asymptomatic infection is〜2.92/100,000.These individuals had low viral copy numbers(peaked at 315 copies/mL)and short-lived antibody responses with the estimated diminish time of 69 days.The antibody responses in individuals with persistent SARS-CoV-2 infection is much longer with the estimated diminish time of 257 days.These results imply that the immune responses in the asymptomatic individuals are not potent enough for preventing SARS-CoV-2 re-infection,which has recently been reported in recovered COVID-19 patients.This casts doubt on the efficacy of forming"herd-immunity"through natural SARS-CoV-2 infection and urges for the development of safe and effective vaccines.