China National Environmental Monitoring Center Research Articles

Analysis of the Aerosol Optical Depth and the Air Quality in Qingdao, China

Air quality plays an important role on human everyday life. Aerosols in the atmosphere can directly affect the air quality. Researches have already shown that the aerosol optical depth (AOD) or aerosol optical thickness (AOT) has relation to the air quality. The AOT can be retrieved from the multi-channel satellite data. MODIS data is used in this paper. Data for the Qingdao, Shandong area is selected. Further process is necessary to extract data that cover this area. The Air Pollution Index (API) can be obtained from China National Environmental Monitoring Centre. It is published for the main cities of China everyday. AOD data for each day from 2008 to 2009 is collected in this paper, the API in the same time range is also collected. We discussed the relationship between AOD and API. For part of the 2008 data, we get a correlation coefficient of 0.80. For the year 2009, the correlation coefficient of the whole year is 0.47, with p=0.12. The correlativity is not very well. Data from June to December is analyzed separately. Perfect result is obtained. The correlation coefficient is 0.87, with p=0.01. We also get the linear relation by regression.

Background value of soil heavy metal in the Three Gorges Reservoir District

The background values of soil heavy metals (As, Cd, Cr, Cu, Hg, Ni, Pb and Zn) were investigated based on extensive investigation in the Three Gorges Reservoir District (TGRD). After analyzing the samples under strict quality control and assurance procedures, the heavy metal concentrations in the soils were calculated using simple statistical method. The background soil values of the heavy metals in TGRD are 5.835 mg·kg-1 for As, 0.134 mg·kg-1 for Cd, 78.03 mg·kg-1 for Cr, 25.00 mg·kg-1 for Cu, 0.046 mg·kg-1 for Hg, 29.47 mg·kg-1 for Ni, 23.88 mg·kg-1 for Pb and 69.88 mg·kg-1 for Zn. Compared with the recommended background value by China National Environmental Monitoring Center (CNEMC) in 1990, As and Hg are low, Pb and Zn slightly lower, while Cd and Cr are high and Cu and Ni slightly higher than CNEMC standards. Based on the research, actual conditions are only realistically reflected by continuous field environmental quality appraisal in TGRD, which favors soil environmental quality management.

Microbial degradation of phthalic acid esters under anaerobic digestion of sludge

The microbial degradation by anaerobic sludge of three phthalates, priority pollutants, listed by both China National Environmental Monitoring Center and the U.S.EPA, namely, dimethyl (DMP), di- n-butyl (DBP) and di- n-octyl (DOP) phthalates was investigated. The experimental results indicated that the biodegradation rate and the biodegradability of three phthalates under anaerobic conditions appeared to be related to the length of the alkyl-side chains. More than 90% of DMP and DBP with the short alkyl-side chain phthalates can be degraded, whereas the DOP degradation appeared to be relatively slow under the same experimental conditions. The quantity of methane produced was measured and the results showed that both the ester groups and the phthalate ring were mineralized at a significant rate. The kinetics study demonstrated that the biodegradation of three phthalates conformed to the first-order model with respect to their concentrations.

Biodegradation of phthalic acid esters by acclimated activated sludge

The microbial degradation by acclimated activated sludge of three phthalates, priority pollutants listed by both the China National Environmental Monitoring Centre and the U.S. EPA, i.e., dimethyl (DMP), di-n-butyl (DBP), and di-n-octyl (DOP) phthalate was investigated. The experimental results demonstrated that DMP and DBP with the shorter alkyl-side chain phthalic acid esters (PAEs) can be rapidly degraded—nearly 90% within 3 d for DMP and 8 d for DBP. However, the degradation rate of DOP was slow. The degradation of PAEs can be described by the first-order reaction model. The first-order rate constants (k 1) of three PAEs determined in this study can correlate with the corresponding second-order hydrolysis rate constants (K OH).

Reply to comment of D. J. Seery and C. T. Bowman

To prevent the spread of the COVID-19 epidemic, the Chinese megacity Wuhan has taken emergent lockdown measures starting on January 23, 2020. This provided a natural experiment to investigate the response of air quality to such emission reductions. Here, we decoupled the influence of meteorological and non-meteorological factors on main air pollutants using generalized additive models (GAMs), driven by data from the China National Environmental Monitoring Center (CNEMC) network. During the lockdown period (Jan. 23 – Apr. 8, 2020), PM2.5, PM10, NO2, SO2, and CO concentrations decreased significantly by 45 %, 49 %, 56 %, 39 %, and 18 % compared with the corresponding period in 2015–2019, with contributions by S(meteos) of 15 %, 17 %, 13 %, 10 %, and 6 %. This indicates an emission reduction of NOx at least 43 %. However, O3 increased by 43 % with a contribution by S(meteos) of 6 %. In spite of the reduced volatile organic compound (VOC) emissions by 30 % during the strict lockdown period (Jan. 23 – Feb. 14, 2020), which likely reduced the production of O3, O3 concentrations increased due to a weakening of the titration effect of NO. Our results suggest that conventional emission reduction (NOx reduction only) measures may not be sufficient to reduce (or even lead to an increase of) surface O3 concentrations, even if reaching the limit, and VOC-specific measures should also be taken.

Magnesium and electric lights as applied to photo-micrography

The strict control measures and social lockdowns initiated to combat COVID-19 epidemic have had a notable impact on air pollutant concentrations. According to observation data obtained from the China National Environmental Monitoring Center, compared to levels in 2019, the average concentration of NO2 in early 2020 during COVID-19 epidemic has decreased by 53%, 50%, and 30% in Wuhan city, Hubei Province (Wuhan excluded), and China (Hubei excluded), respectively. Simultaneously, PM2.5 concentration has decreased by 35%, 29%, and 19% in Wuhan, Hubei (Wuhan excluded), and China (Hubei excluded), respectively. Less significant declines have also been found for SO2 and CO concentrations. We also analyzed the temporal variation and spatial distribution of air pollutant concentrations in China during COVID-19 epidemic. The decreases in PM2.5 and NO2 concentrations showed relatively consistent temporal variation and spatial distribution. These results support control of NOx to further reduce PM2.5 pollution in China. The concurrent decrease in NOx and PM2.5 concentrations resulted in an increase of O3 concentrations across China during COVID-19 epidemic, indicating that coordinated control of other pollutants is needed.