Stringent quarantine measures during the Coronavirus Disease 2019 (COVID-19) lockdown period (January 23, 2020 to March 15, 2020) have resulted in a distinct decrease in anthropogenic source emissions in North China Plain compared to the paralleled period of 2019. Particularly, 22.7% decrease in NO2 and 3.0% increase of O3 was observed in Tianjin, nonlinear relationship between O3 generation and NO2 implied that synergetic control of NOx and VOCs is needed. Deteriorating meteorological condition during the COVID-19 lockdown obscured the actual PM2.5 reduction. Fireworks transport in 2020 Spring Festival (SF) triggered regional haze pollution. PM2.5 during the COVID-19 lockdown only reduced by 5.6% in Tianjin. Here we used the dispersion coefficient to normalize the measured PM2.5 (DN-PM2.5), aiming to eliminate the adverse meteorological impact and roughly estimate the actual PM2.5 reduction, which reduced by 17.7% during the COVID-19 lockdown. In terms of PM2.5 chemical composition, significant NO3? increase was observed during the COVID-19 lockdown. However, as a tracer of atmospheric oxidation capacity, odd oxygen (Ox = NO2 + O3) was observed to reduce during the COVID-19 lockdown, whereas relative humidity (RH), specific humidity and aerosol liquid water content (ALWC) were observed with noticeable enhancement. Nitrogen oxidation rate (NOR) was observed to increase at higher specific humidity and ALWC, especially in the haze episode occurred during 2020SF, high air humidity and obvious nitrate generation was observed. Anomalously enhanced air humidity may response for the nitrate increase during the COVID-19 lockdown period. 相似文献
Environmental Science and Pollution Research - Advanced oxidation processes (AOPs) are efficient methods for water purification. However, there are few studies on using peroxymonosulfate (PMS) to... 相似文献
The Yellow River Delta is the largest and youngest estuarine and coastal wetland in China and is experiencing the most active interactions of seawater and freshwater in the world. Bacteria played multifaceted influence on soil biogeochemical processes, and it was necessary to investigate the intermodulation between the soil factors and bacterial communities. Soil samples were collected at sites with different salinity degree, vegetations, and interference. The sequences of bacilli were tested using 16S rRNA sequencing method and operational taxonomic units were classified with 97% similarity. The soil was highly salinized and oligotrophic, and the wetland was nitrogen-restricted. Redundancy analysis suggested that factors related with seawater erosion were principal to drive the changes of soil bacterial communities and then the nutrient level and human disturbance. A broader implication was that, in the early succession stages of the coastal ecosystem, seawater erosion was the key driver of the variations of marine oligotrophic bacterial communities, while the increasing nutrient availability may enhance in the abundance of the riverine copiotrophs in the late stages. This study provided new insights on the characteristics of soil bacterial communities in estuarine and coastal wetlands.
Microbial communities are important for high composting efficiency and good quality composts. This study was conducted to compare the changes of physicochemical and bacterial characteristics in composting from different raw materials, including chicken manure (CM), duck manure (DM), sheep manure (SM), food waste (FW), and vegetable waste (VW). The role and interactions of core bacteria and their contribution to maturity in diverse composts were analyzed by advanced bioinformatics methods combined sequencing with co-occurrence network and structural equation modeling (SEM). Results indicated that there were obviously different bacterial composition and diversity in composting from diverse sources. FW had a low pH and different physiochemical characteristics compared to other composts but they all achieved similar maturity products. Redundancy analysis suggested total organic carbon, phosphorus, and temperature governed the composition of microbial species but key factors were different in diverse composts. Network analysis showed completely different interactions of core bacterial community from diverse composts but Thermobifida was the ubiquitous core bacteria in composting bacterial network. Sphaerobacter and Lactobacillus as core genus were presented in the starting mesophilic and thermophilic phases of composting from manure (CM, DM, SM) and municipal solid waste (FW, VW), respectively. SEM indicated core bacteria had the positive, direct, and the biggest (>?80%) effects on composting maturity. Therefore, this study presents theoretical basis to identify and enhance the core bacteria for improving full-scale composting efficiency facing more and more organic wastes.
