New insights into black carbon light absorption enhancement: A comprehensive analysis of two differential behaviors.

High uncertainty in optical properties of black carbon (BC) involving heterogeneous chemistry has recently attracted increasing attention in the field of atmospheric climatology. To fill the gap in BC optical knowledge so as to estimate more accurate climate effects and serve the response to global warming, it is beneficial to conduct site-level studies on BC light absorption enhancement (Eabs) characteristics. Real-time surface gas and particulate pollutant observations during the summer and winter over Wuhan were utilized for the analysis of Eabs simulated by minimum R squared (MRS), considering two distinct atmospheric conditions (2015 and 2017). In general, differences in aerosol emissions led to Eabs differential behaviors. The summer average of Eabs (1.92 ± 0.55) in 2015 was higher than the winter average (1.27 ± 0.42), while the average (1.11 ± 0.20) in 2017 summer was lower than that (1.67 ± 0.69) in winter. Eabs and RBC (representing the mass ratio of non-refractory constituents to elemental carbon) constraints suggest that Eabs increased with the increase in RBC under the ambient condition enriched by secondary inorganic aerosol (SIA), with a maximum growth rate of 70.6% in 2015 summer. However, Eabs demonstrated a negative trend against RBC in 2017 winter due to the more complicated mixing state. The result arose from the opposite impact of hygroscopic SIA and absorbing OC/irregular distributed coatings on amplifying the light absorbency of BC. Furthermore, sensitivity analysis revealed a robust positive correlation (R > 0.9) between aerosol chemical compositions (including sulfate, nitrate, ammonium and secondary organic carbon), which could be significantly perturbed by only a small fraction of absorbing materials or restructuring BC through gaps filling. The above findings not only deepen the understanding of BC, but also provide useful information for the scientific decision-making in government to mitigate particulate pollution and obtain more precise BC radiative forcing.

Validation, analysis, and comparison of MISR V23 aerosol optical depth products with MODIS and AERONET observations.

The latest Multi-angle Imaging Spectro Radiometer (MISR) Version (V) 23 aerosol optical depth (AOD) products were released, with an improved spatial resolution of 4.4 km, providing an unprecedented opportunity for the refined regional application. To ensure the reliability of their applications and build a scientific reference for the further optimization, it is imperative to conduct a comprehensive evaluation, especially for the unique size-resolved AOD products: small-size AOD (AODS, representing the contribution of fine-mode aerosols), medium-size AOD (AODM), and large-size AOD (AODL), and AODM+L represents the AOD part of coarse-mode aerosols. AErosol RObotic NETwork (AERONET) and MODerate-resolution Imaging Spectroradiometer (MODIS) Collection (C) 6.1 aerosol products from 2001 to 2020 are utilized for the validation, analysis, and inter-comparison, considering three spatial scales and four key factors. In general, MISR V23 aerosol products show a good accuracy compared with AERONET. The best performance for all AOD products appears in forest units (the highest R ~ 0.93, data percentage within Expected Error bounds, %EE > 93), related to the inactive human activity and dark underlying surface. Dependences of retrieval deviations illustrate that the performance of MISR AOD deteriorates as aerosol loading increases. Namely, with the increase of aerosols, total AOD (AODT) and AODS show increasing negative deviations, while increasing positive deviations are observed for AODM+L. This suggests that the Empirical Orthogonal Functions do not perform well in this situation, since numerous aerosol particles can obstruct the underlying reflection and reduce the surface spectral contrast. In addition, AODT and AODS often exhibit anomalous positive deviations in areas with low vegetation cover, such as deserts, revealing that MISR will overestimate aerosol content over bright surfaces and in environments dominated by coarse-mode particles. The above findings not only deepen the understanding of MISR aerosols products from multiple perspectives, but also provide useful information for the product improvement.

Aerosol optical properties of haze episodes in eastern China based on remote-sensing observations and WRF-Chem simulations.

The ability for remote-sensing sensors and global/regional models to describe aerosol optical properties (AOPs) is critical to reducing the uncertainty in aerosol radiative forcing associated with climate change, and improving model prediction accuracy. In this study, remote-sensing observations and WRF-Chem simulations were used to evaluate AOPs over Eastern China during a severe winter haze event, in terms of aerosol optical depth (AOD), Ångström exponent (AE) and aerosol extinction profiles (AEP). This study also characterizes whether the inclusion of aerosol radiative feedbacks (ARFs) may improve the ability of WRF-Chem to acquire AOPs during haze episodes. Three simulation scenarios were considered: the non-radiation feedback (NRF), aerosol direct effect (ADE), as well as combined ADE and aerosol indirect effect (ADE + AIE). The results indicate that the satellite AOD products could represent the spatiotemporal distribution characteristics of the haze event. The AOD retrieved by the MODIS C6.1 DB algorithm was highly consistent with ground-based observations. A comparison between simulations and observations demonstrated that WRF-Chem, including the ADE or ADE + AIE scheme, may improve AOPs simulation in heavily polluted areas. The most significant improvements occurred in the Sichuan basin (SB) and North China Plain (NCP) (AOD = 50-70%; AE = 10-20%). In particular, the ADE + AIE scheme was the most obvious for AOD improvement, followed by AE. The AEP was also qualitatively analyzed through simulations and observations, and the result showed that the model overestimates aerosol extinction coefficients in NCP. However, the model is still able to represent the entire AEP contour over East China. Similar to AOD and AE, the model can also improve AEP simulation by adding ADE or ADE + AIE scheme, especially in SB. In summary, it is found that the ability of WRF-Chem to simulate the AOPs was significantly enhanced, particularly for regions loading with heavy aerosol during haze events in Eastern China.

[The impact of gender factor on the candidate gene study of essential hypertension].

OBJECTIVE: To study the impact of gender factor on the candidate gene study of essential hypertension (EH). METHODS: The polymerase chain reaction (PCR) was performed to analyze the ACE gene I/D polymorphism of hypertensive patients (50 men and 50 women) and normal controls (50 men and 50 women). The investigation was further focused on possible influence of sex proportion on the conclusion of this kind of research. RESULTS: The frequency of DD genotype in male hypertensive patients is significantly higher than that in male normal controls (chi(2) = 6.98, P = 0.004). The frequency of D allele in male EH group is significantly higher than that of male normal controls (chi(2) = 6.87, P = 0.009), while no significant difference was observed for II and ID genotype between male EH group and control group (P > 0.05). For female EH group and normal controls, there were no significant differences in frequency of genotype and allele (P > 0.05), the distribution ratio of DD genotype in male EH group is significantly different from that of female EH group (chi(2) = 4.06, P = 0.044). Furthermore, males with DD genotype in EH group had higher SBP and PP than that of males with II and ID genotype (P < 0.05). However, there was no significant difference in DBP in all three genotypes (P > 0.05). At the same time, there was no difference in SBP, DBP and PP (P > 0.05) between II and ID genotype in male EH group. In female hypertensive patients, there was no significant difference in SBP, DBP and PP between all three genotypes (P > 0.05). CONCLUSIONS: The relationship between DD genotype in male and EH (especially SBP and PP) is closer than any other genotype-EH relationships in both male and female. The gender factor, as a probable confounding factor, can affect many candidate gene studies of essential hypertension including ACE gene I/D polymorphism, and thus biases the conclusion.

[A cohort study on the predictive value of factors influencing cardio-cerebro vascular death among people over 40 years of age].

OBJECTIVE: To explore the factors influencing cardio-cerebro vascular death events among people over 40 years of age in Shandong area, China. METHODS: Baseline survey was carried out in 1991. A total number of 11,008 adults over 40 years old had been studied in Shandong province. Data on cardiocerebro death was collected. The correlation between influencing factors and cardio-cerebro vascular death events was analyzed by Cox regression model. RESULTS: Totally, 434 cardio-cerebro death events occurred among the 11,008 subjects during the 8-year follow-up study. Cardio-cerebro death events were related to systolic blood pressure, diastolic blood pressure, smoking, stroke history and age. Data from Cox regression analysis showed that the relative risk (RR) for cardio-cerebro vascular death events increased by 2.862 [95% confidence interval (CI): 1.976-4.144] times for those people having stroke history. When systolic blood pressure, diastolic blood pressure increased by every 10 mm Hg, the relative risk for cardio-cerebro vascular death events increased by 1.171 (95% CI: 1.033-1.328), 1.214 (95% CI: 1.044-1.413) respectively. it was found that a 1.239 (95% CI: 1.088-1.553) times higher in smokers than non-smokers on relative risk for cardio-cerebro vascular death events. However, the predictive values of the influencing factors for cardio-cerebro vascular death were different among population of different years of age. The relative risk for cardio-cerebro vascular death events increased by 1.366 (95% CI: 1.102-1.678) times for each 10 mm Hg increase of diastolic blood pressure in 40-59 years old population. However, the effect was taken place by systolic blood pressure in 60-74 years old population,with a relative risk of 1.201 (95% CI: 1.017-1.418) for each 10 mm Hg increase. Age seemed the only significant factor for cardio-cerebro vascular death events on population aged more than 75 years old. Conclusion The predictive values of the risk factors were different among age groups. The different risk factors should be taken care according to the difference of age.