[Similarities and Differences of Valley Winds in the Beijing Plain and Yanqing Areas and Its Impact on Pollution].

Under certain terrain and weather conditions, mountain-valley circulation is one of the main meteorological factors affecting aerosol pollution in plain-mountain area. Based on environmental monitoring data and multi-source meteorological data for the Beijing-Tianjin-Hebei region between 2015 and 2019, the characteristics, similarities, and differences of mountain-valley winds in the Beijing Plain and Yanhuai Basin regions were compared. The results show that the mountain-valley winds recorded at the Beijing Observatory are from southwest to northeast compared to from the southeast to northeast at Yanqing station. With the aggravation of pollution levels, the mountain-valley wind intensity decreased by 17.7%-32.4%. When the wind speed at Beijing Observatory was 2-6 m·s-1, the maximum PM2.5 concentration in southeast was 83 µg·m-3, which was higher than in the southwest. When the wind speed at the Yanqing station was 2-6 m·s-1, the PM2.5 concentrations in SE-SSE area was 20-40 µg·m-3 higher than in other directions, and the concentrations in the valley winds were 10-12 µg·m-3 higher than the average value for the last five years. Taking the typical heavy pollution event on March 5-8, 2015, as an example, the influence of mountain-valley winds is mainly reflected in the high humidity and regional transmission of southeast winds during the valley wind stage. The PM2.5 concentrations at the Yanqing station increased by 100-130 µg·m-3 during the valley wind stage on March 6 and 7, 2015. The inversion temperature developed to 1000 m during the mountain wind stage, the local dew point at the Beijing Observatory and the Yanqing station rose by approximately 18℃. The peak dew point at the Yanqing station occurring 2 hours after the Beijing Observatory, and the concentrations of PM2.5 rose slightly under high humidity conditions. Meanwhile, the thermal gradient between the 400-m-high Yanqing Station and Yudu Mountain gradually decreased, and the mountain-valley wind decreased by 8% and 6%, respectively. The weakening of local circulation may be related to the bidirectional feedback mechanism of the boundary layer and high concentrations of aerosols.

[Differences in Pollution Characteristics Under the Southerly and Easterly Wind in Beijing].

In this study, the hourly meteorological factors and PM2.5 concentrations during 2014-2019 in Beijing were analyzed, in order to explore the characteristics of the prevailing wind direction of pollution, and the corresponding long-term tendency. During the study period, 67% of pollution in Beijing occurred under the influence of southerly and easterly wind, and pollution was most likely to occur in winter, followed by spring and autumn. The average pollution probability of winter, spring, autumn and summer was 45.2%, 34.1%, 32.1%, and 26.1% and 47.0%, 45.8%, 39.7%, and 29.6% for southerly and easterly wind, respectively. In Beijing, the southerly wind appeared more frequently, but the pollution occurrence probability was higher under the control of easterly wind, with the maximum difference of 11.7% (2.8%-18.6%) in spring and the minimum difference of 1.8% (-7.6%-13.9%) in winter. During the past six years, the pollution probability decreased at a rate of 4.6%-8.0% and 5.5%-7.9% per year under the southerly and easterly wind influence, respectively. This was clearly reflected in reduced moderate and above levels of pollution. An analysis of both the pollution and meteorological factors under the two wind directions indicates that the visibility, mixing layer height, wind speed, and the frequency of hourly wind speed greater than 3 m·s-1 were higher, and the relative humidity and dew point temperature were lower, when pollution occurred under the southerly wind, while the PM2.5 concentration of pollution was higher in winter and significantly lower in other seasons compared to that of the easterly wind. These findings show that when pollution occurred under the southerly wind, the carrying capacity and diffusion capacity of pollutants in the atmosphere was slightly better than that of the easterly wind, and the increased atmospheric water content under the easterly wind was more conducive to the maintenance and aggravation of pollution. Moreover, under the background of original emission levels, when adding urban heating in winter, the air mass transported by the southerly wind may be more conducive to increased PM2.5 concentration. Furthermore, pollution in Beijing tended to be an "easterly wind type" in spring, summer and autumn, but remained a "southerly wind type" in winter.

[Influence of Meteorological Conditions on Ozone Pollution at Shangdianzi Station Based on Weather Classification].

As a typical secondary pollutant, tropospheric ozone has become the primary pollutant in Beijing in spring and summer, and meteorological factors are one of the main factors affecting the change in concentration. Using atmospheric composition and meteorological observation data from 2008 to 2017, the weather types in Beijing were divided into six categories by Lamb classification and Mann-Whitney U test. Among these, the mean and extreme values of ozone concentration of SWW and C types at Shangdianzi station were the highest, and the highest frequency was from April to September, with a total of 47.4%. The main contribution weights of the two types were determined by a multiple stepwise regression equation. The southwest wind prevailed in 54.0% of SWW and C types, and the newly discharged pollutants and secondary aging air masses were continuously transported by the southwest air flow. The vertical velocity zero layer appeared near 850 hPa. The horizontal and vertical meteorological conditions were conducive to the transport, accumulation, and secondary generation of ozone. The northeast wind prevailed in 64.7% of AN and ESN types, and the air masses source was clean. The same subsidence movement and air divergence prevailed above 1000 hPa. The discharged pollutants can also be diluted and diffused quickly, and the ozone concentration was at a low value. Taking the NW type on May 3, 2015 as an example, although the northwest air flow prevailed on the ground, with clean source, the residual high concentration of ozone above the boundary layer was transported to the near ground through the vertical subsidence of the atmosphere, resulting in the high concentration of ozone on some days.

Emission characteristics of volatile compounds during sludges drying process.

The emission characteristics of volatile compounds (VCs) during municipal sewage sludge (MSS) and paper mill sludge (PMS) drying process were investigated through experiments conducted on a lab-scale tubular drying furnace and a pilot-scale paddle dryer, respectively. The result indicated that five kinds of VCs, i.e. CO(2), NH(3), C(7)H(16) (n-heptane), volatile fatty acids (VFAs) and CH(4) were emitted during the drying process. It was found that the NH(3) and CO(2) were the primary compound released from the MSS drying process. In the case of the PMS, the VFAs and CO(2) were the main compounds released. The temperature and water content of sludge had great effects on the emission rates of NH(3), C(7)H(16), CO(2) and VFAs. The pH and chemical oxygen demand (COD) of condensate from the paddle dryer were also studied. It showed that pH and COD of condensate from MSS were much higher than that from the PMS, and that the higher COD value of the MSS condensate interrelated to the higher ammonium and sulfur content of it.

The anti-apoptosis effects of daidzein in the brain of D-galactose treated mice.

The purpose of this study was to explore the neuroprotective effects of daidzein on the apoptotic pathway in the hippocampus and cortex of D-galactose treated mice. For this purpose we have examined the expression of bcl-2 mRNA, bax mRNA and caspase-3 in the hippocampus and cortex of D-galactose-treated mice after fed with 10 or 5 mg/kg of daidzein. The results of in situ hybridization experiments indicate that daidzein could help increase the transcriptions of bcl-2 and decrease the transcriptions of bax in those brain regions of D-galactose-treated mice. Furthermore, immunohistochemical studies showed that daidzein could reduce the expression of caspase-3 in both brain regions. These results suggest that daidzein in soybean can inhibit the D-gal induced apoptosis via Bcl-2/Bax apoptotic pathway and be a potential medical candidate for neurodegeneration therapy.