Decrease of atmospheric black carbon and CO2 concentrations due to COVID-19 lockdown at the Mt. Waliguan WMO/GAW baseline station in China.

The Coronavirus Disease 2019 (COVID-19) lockdown policy reduced anthropogenic emissions and impacted the atmospheric chemical characteristics in Chinese urban cities. However, rare studies were conducted at the high mountain site. In this work, in-situ measurements of light absorption by carbonaceous aerosols and carbon dioxide (CO2) concentrations were conducted at Waliguan (WLG) over the northeastern Tibetan Plateau of China from January 3 to March 30, 2020. The data was employed to explore the influence of the COVID-19 lockdown on atmospheric chemistry in the background-free troposphere. During the sampling period, the light absorption near-infrared (>470 nm) was mainly contributed by BC (>72%), however, BC and brown carbon (BrC) contributed equally to light absorption in the short wavelength (∼350 nm). The average BC concentrations in the pre-, during and post-lockdown were 0.28 ±â€¯0.25, 0.18 ±â€¯0.16, and 0.28 ±â€¯0.20 µg m-3, respectively, which decreased by approximately 35% during the lockdown period. Meanwhile, CO2 also showed slight decreases during the lockdown period. The declined BC was profoundly attributed to the reduced emissions (∼86%), especially for the combustion of fossil fuels. Moreover, the declined light absorption of BC, primary and secondary BrC decreased the solar energy absorbance by 35, 15, and 14%, respectively. The concentration weighted trajectories (CWT) analysis suggested that the decreased BC and CO2 at WLG were exclusively associated with the emission reduction in the eastern region of WLG. Our results highlighted that the reduced anthropogenic emissions attributed to the lockdown in the urban cities did impact the atmospheric chemistry in the free troposphere of the Tibetan Plateau.

Hepatitis B virus genotypes and genome characteristics in China.

AIM: To analyze the hepatitis B virus (HBV) characters in China, as well as the correlation between several HBV mutation and hepatitis symptoms. METHODS: A total of 1148 HBV genome sequences from patients throughout China were collected via the National Center For Biotechnology Information database (information including: genotype, territory and clinical status). HBV genotypes were classified by a direct reference from the Genbank sequence annotation, phylogenetic tree and online software analysis (http://www.ncbi.nlm.nih.gov/projects/genotyping/formpage.cgi). The phylogenetic tree was constructed based on the neighbor-joining method by MEGA5.0 software. HBV sequences were grouped based on phylogenetic tree and the distance between the groups was calculated by using the computer between group mean distance methods. Seven hundred and twelve HBV sequences with clear annotation of clinical symptoms were selected to analyses the correlation of mutation and clinical symptoms. Characteristics of sequences were analyzed by using DNAStar and BioEdit software packages. The codon usage bias and RNA secondary structures analysis were performed by RNAdraw software. Recombination analysis was performed by using Simplot software. RESULTS: In China, HBV genotype C was the predominant in Northeastern, genotype B was predominant in Central Southern areas, genotype B and C were both dominant in Southwestern areas, and the recombinant genotype C/D was predominant in Northwestern areas. C2 and B2 were identified as the two major sub-genotypes, FJ386674 might be a putative sub-genotype as B10. The basal core promoter double mutation and pre-C mutation showed various significant differences between hepatitis symptoms. In addition to ATG, many other HBV initiation codons also exist. HBV has codon usage bias; the termination codon of X, C and P open reading frames (ORF) were TAA, TAG, and TGA, respectively. The major stop codons of S-ORF were TAA (96.45%) and TGA (83.60%) in B2 and C2 subtype, respectively. CONCLUSION: This study recapitulated the epidemiology of HBV in China, and the information might be meaningful critical for the future prevention and therapy of HBV infections.

[Temporal variation of background atmospheric CO2 and CH4 at Mount Waliguan, China].

In this paper, the continuous (2009-2010) measurement of atmospheric CO2 and CH4 from the Mount Waliguan Baseline Observatory of Western China are presented. The results show that about 17% of CO2 observations are classified as polluted due to more frequently influence of regional emission on local measurement in summer time. The mean concentration of CO2 measured at the period of 2009 to 2010 was 390.72 x 10(-6) which was 17.4 x 10(-6) higher than that measured from 1995 to 2008, and the median concentration of CH4 was 1851.11 x 10(-9) which was 16 x 10(-9) higher than that from 2002 to 2006, which implied that the regional emission of CO2 and CH4 was continuously increased. The unavailable data were filled by back propagation neural network (BPNN) and optimized by genetic algorithm (GA) , which were analyzed by the Fourier analysis of time series of air temperature, wind speed, concentration of CO2 and CH4. At the daily time scale, strong spectrum peak occurred and concentration recorded at periods of 12 and 24 hours,due to the daily sun activity changes. At the monthly time scale, the spectrum gap occurred in CO2 concentration at periods of 30 day suggesting that the effect of meteorological and phenological factors on the variation of CO2 concentration was insignificant.