Investigating the Transport Mechanism of PM2.5 Pollution during January 2014 in Wuhan, Central China

Severe haze pollution that occurred in January 2014 in Wuhan was investigated. The factors leading to Wuhan’s PM2.5 pollution and the characteristics and formation mechanism were found to be significantly different from other megacities, like Beijing. Both the growth rates and decline rates of PM2.5 concentrations in Wuhan were lower than those in Beijing, but the monthly PM2.5 value was approximately twice that in Beijing. Furthermore, the sharp increases of PM2.5 concentrations were often accompanied by strong winds. A high-precision modeling system with an online source-tagged method was established to explore the formation mechanism of five haze episodes. The long-range transport of the polluted air masses from the North China Plain (NCP) was the main factor leading to the sharp increases of PM2.5 concentrations in Wuhan, which contributed 53.4% of the monthly PM2.5 concentrations and 38.5% of polluted days. Furthermore, the change in meteorological conditions such as weakened winds and stable weather conditions led to the accumulation of air pollutants in Wuhan after the long-range transport. The contribution from Wuhan and surrounding cities to the PM2.5 concentrations was determined to be 67.4% during this period. Under the complex regional transport of pollutants from surrounding cities, the NCP, East China, and South China, the five episodes resulted in 30 haze days in Wuhan. The findings reveal important roles played by transregional and intercity transport in haze formation in Wuhan.

Characteristic Analysis of OC and EC in PM_(2.5) of Typical Haze Weather in Wuhan City

Long-time large-area haze weather appeared in Wuhan on June 11, 2012. It was monitored that PM2.5 hourly concentration obviously rose, and peak value reached 658 μg/m3. OC and PM2.5 presented high correlation, and correlation coefficient was 0.96. OC daily average concentration occupied 10% -20% in PM2.5, and difference was big between haze and normal weather. EC occupied 5%, and difference was very small between haze and normal weather. By analyzing change trend of OC/EC, it was found that OC/EC presented increasing trend in late May and was even higher than that during 11 -15 June. It was clear that biomass combustion taking straw as the representation has started in late May. But two strong precipitation on May 29 and June 6 inhibited haze weather, and specific meteorological condition caused haze on June 11. Proportion of SOC to OC reached 14% -70%, illustrating that daily difference of secondary photochemical reaction was very big in Wuhan. OC/EC values were respectively 2.7, 3.5 and 4.2 in May, June and haze period. SOC daily means were respectively （5.33 ±4.77） and （32.5 ±23.4） μg/m^3 in May and haze period. Major pollution source of haze weather was biomass combustion, and haze occurrence had very big relationship with special meteorological condition.

Effect of Crop-Straw Derived Biochars on Pb(Ⅱ) Adsorption in Two Variable Charge Soils

Two variable charge soils were incubated with biochars derived from straws of peanut, soybean, canola, and rice to investigate the effect of the biochars on their chemical properties and Pb（II） adsorption using batch experiments. The results showed soil cation exchange capacity （CEC） and pH significantly increased after 30 d of incubation with the biochars added. The incorporation of the biochars markedly increased the adsorption of Pb（II）, and both the electrostatic and non-electrostatic adsorption mechanisms contributed to Pb（II） adsorption by the variable charge soils. Adsorption isotherms illustrated legume- straw derived biochars more greatly increased Pb（II） adsorption on soils through the non-electrostatic mechanism via the formation of surface complexes between Pb（II） and acid functional groups of the biochars than did non-legume straw biochars. The adsorption capacity of Pb（II） increased, while the desorption amount slightly decreased with the increasing suspension pH for the studied soils, especially in a high suspension pH, indicating that precipitation also plays an important role in immobilizing Pb（II） to the soils.

Adverse Effects of Exposure to Fine Particulate Matters and Ozone on Gestational Hypertension

Gestational hypertension(GH)is a common complication during pregnancy.GH is regarded as a potential public health challenge for pregnant women and infants.Limited evidence has linked ambient air pollution to an increased GH risk.However,most of the studies were conducted in developed countries,with inconsistent results obtained.The present study was performed to explore whether exposure to particulate matters with an aerodynamic diameter≤2.5(PM2.5)and ozone(O3)was related to elevated odds of GH in a Chinese population.This population-based cohort study involved 38115 pregnant women in Wuhan,China.All information was collected from the Wuhan Maternal and Child Health Management Information System,using standardized quality control.The daily air pollutant data for PM2.5 and O3 were obtained from the 20 monitoring stations of the Wuhan Environmental Monitoring Center during 2014.The nearest monitor approach was applied to individual exposure assessment of PM2.5 and O3 for each participant.After adjusting for major confounders and other air pollutants,a 10μg/m^3 increase in PM25 and O3 concentrations was found to correlate to a 1.14-fold[95%confidence interval(95%CI):1.09,1.20]and a 1.05-fold(95%CI:1.02,1.07)increase in GH risk,respectively.Additionally,stronger relationships between GH risk and PM25 and O3 exposure were observed in women who conceived in winter and summer,respectively.These findings suggest that air pollutants may contribute to the development of GH.

Isolation and Identification of Aeromonas allosaccharophila from Procambarus clarkii

In order to provide a scientific basis for the control of Aeromonas allosaccharophila from Procambarus clarkii , a dominant strain was isolated from moribund P. clarkii in some farm in Hubei Province, and designated X1. It was preliminarily identified to be A. allosaccharophila through physiological-biochemical test. Further sequence analysis showed that 16S rDNA of this bacterium shared 90% identity with 16S rDNA of A. allosaccharophila , suggesting that it is A. allosaccharophila . Drug sensitivity test showed that isolate X1 was sensitive to doxycycline, cefotaxime, norfloxacin and gentamicin. In animal regression test, the bacterium the same as that from naturally-diseased P. clarkii could be isolated, with the same disease symptoms as well.

Association between Prenatal Care Utilization and Risk of Preterm Birth among Chinese Women

It is recognized that prenatal care plays an important role in reducing adverse birth. Chinese pregnant women with medical condition were required to seek additional health care based on the recommended at least 5 times health care visits. This study was to estimate the association between prenatal care utilization（PCU） and preterm birth（PTB）, and to investigate if medical conditions during pregnancy modified the association. This population-based case control study sampled women with PTB as cases; one control for each case was randomly selected from women with term births. The Electronic Perinatal Health Care Information System（EPHCIS） and a questionnaire were used for data collection. The PCU was measured by a renewed Prenatal Care Utilization（APNCU） index. Logistic regression models were used to estimate odds ratios（OR） and the 95% confidence interval（95% CI）. Totally, 2393 women with PTBs and 4263 women with term births were collected. In this study, 695（10.5%） women experienced inadequate prenatal care, and 5131（77.1%） received adequate plus prenatal care. Inadequate PCU was associated with PTB（adjusted OR： 1.41, 95% CI： 1.32–1.84）; the similar positive association was found between adequate plus PCU and PTB. Among women with medical conditions, these associations still existed; but among women without medical conditions, the association between inadequate PCU and PTB disappeared. Our data suggests that women receiving inappropriate PCU are at an increased risk of having PTB, but it does depend on whether the woman has a medical condition during pregnancy.

Enhanced secondary organic aerosol formation during dust episodes by photochemical reactions in the winter in Wuhan

To investigate the effect of frequently occurring mineral dust on the formation of secondary organic aerosol(SOA),106 volatile organic compounds(VOCs),trace gas pollutants and chemical components of PM_(2.5) were measured continuously in January 2021 in Wuhan,Central China.The observation period was divided into two stages that included a haze period and a following dust period,based on the ratio of PM_(2.5) and PM_(10) concentrations.The average ratio of secondary organic carbon(SOC)to elemental carbon(EC)was 1.98 during the dust period,which was higher than that during the haze period(0.69).The contribution of SOA to PM_(2.5) also increased from 2.75% to 8.64%.The analysis of the relationships between the SOA and relative humidity(RH)and the odd oxygen(e.g.,O_(X)=O_(3)+NO_(2))levels suggested that photochemical reactions played a more important role in the enhancement of SOA production during the dust period than the aqueous-phase reactions.The heterogeneous photochemical production of OH radicals in the presence of metal oxides during the dust period was believed to be enhanced.Meanwhile,the ratios of trans-2-butene to cis-2-butene and m-/p-xylene to ethylbenzene(X/E)dropped significantly,confirming that stronger photochemical reactions occurred and SOA precursors formed efficiently.These results verified the laboratory findings that metal oxides in mineral dust could catalyse the oxidation of VOCs and induce higher SOA production.