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Emission controls have substantially brought down aerosol pollution in China; however, aerosol mass reductions have slowed down in recent years in the Pearl River Delta (PRD) region, where secondary organic aerosol (SOA) formation poses a major challenge for air quality improvement. In this study, we characterized the roles of SOA in haze formation in urban Guangzhou in the PRD using year-long aerosol mass spectrometer measurements for the first time and discussed possible pathways of SOA formations. On average, organic aerosols (OA) contribute dominantly (50 %) to nonrefractory submicron aerosol mass (NR-PM 1). The average mass concentration of SOA (including by less- and more-oxidized OA, LOOA and MOOA) contributed most to NR-PM 1 , reaching about 1.7 times that of primary organic aerosols (POA, including hydrocarbon-like and cooking-related OA) and accounting for 32 % of NR-PM 1 , even more than sulfate (22 %) and nitrate (16 %). Seasonal variations of NR-PM 1 revealed that haze-formation mechanisms differed much among distinct seasons. Sulfate mattered more than nitrate in fall, while nitrate was more important than sulfate in spring and winter, with SOA contributing significantly to haze formations in all the seasons. Daytime SOA formation was weak in winter under low oxidant levels and air relative humidity, whereas prominent daytime SOA formation was observed in fall, spring and summer almost on a daily basis, suggesting important roles of photochemistry in SOA formations. Further analysis showed that the coordination of gas-phase photochemistry and subsequent aqueous-phase reactions likely played significant roles in quick daytime SOA formations. Obvious nighttime SOA formations were also frequently observed in spring, fall and winter, and it was found that daytime and nighttime SOA formations together had resulted in the highest SOA concentrations in these seasons and contributed substantially to severe haze formations. Simultaneous increases in nitrate with SOA after sunset suggested the important roles of NO 3 radical chemistry in nighttime SOA formations, and this was further confirmed by a continuous increase in the NO + / NO 2+ fragment ratio that related to measured particulate nitrate after sunset. The findings of this study have promoted our understanding of haze pollution characteristics of the PRD and laid down future directions for investigations of SOA-formation mechanisms in urban areas of southern China that share similar emission sources and meteorological conditions. [ABSTRACT FROM AUTHOR]

Both the size and mixing state of black carbon (BC)-containing aerosols are crucial in estimating the environmental, health and climate impacts of BC. Traffic emissions are a major global source of BC, however, parameterization of BC mass size distributions and mixing states associated with traffic remains lacking due to its dependence on vehicle types and driving conditions. To investigate BC mass size distributions and mixing states associated with traffic emissions, a field campaign was conducted in Guangzhou urban area during winter, which used a system coupling a differential mobility analyzer (DMA) and single-particle soot photometer (SP2) to measure BC mass size distributions in the range of 100 to 700 nm. The resolved primary organic aerosols were hydrocarbon-like organic aerosols (HOA) and cooking-like organic aerosols (COA), refractory BC (rBC) which was detected by the DMA-SP2 and correlated highly with HOA (R2=0.88), confirming that traffic emissions are the dominant source of atmospheric BC during the observations. The BC mass size distribution was found to be best fitted by a lognormal distribution, with a geometric mean (Dg,BC) of 258±16 nm, varying between 200 and 300 nm. During daytime, active formation of secondary nitrate and organic aerosols was observed, but it had little effect on the variations of BC mass size distributions. Further analyses revealed that Dg,BC was highly correlated with rBC/HOA (R=0.66) in a linear form of Dg,BC= 34×rBC⁄HOA+177, demonstrating that the BC content of traffic emissions significantly impacts the BC mass size distributions. In addition, the size-dependent fractions of BC-containing aerosols in all types of aerosols (fBCc) and the fraction of identified externally mixed (bare/thinly coated) BC particles in all BC-containing aerosols (fext) were also characterized. It was found that the daytime secondary aerosol formation reduced both fBCc and fext, with the decrease of fext being more pronounced for larger particles, possibly due to the higher relative coating thickness. Variations in fext during nighttime were mainly controlled by the emission conditions. For example, fext for 600 nm particles decreased from 0.82 to 0.46 as rBC/HOA increased from 1 to 3.5 while the mass ratios of secondary aerosols to rBC varied little, demonstrating that the BC content also significantly affects the mixing states of freshly emitted BC from traffic emissions. This study suggests that BC content likely plays a key role in parameterizing both mass size distributions and mixing states of BC from traffic emissions and hence has significant implications for accurate representation of BC from different sources when modeling the impacts of BC. [ABSTRACT FROM AUTHOR]

Rational designing and constructing multiphase hybrid electrode materials is an effective method to compensate for the performance defects of the single component. Based on this strategy, Cu2Se hexagonal nanosheets@Co3Se4 nanospheres mixed structures have been fabricated by a facile two‐step hydrothermal method. Under the synergistic effect of the high ionic conductivity of Cu2Se and the remarkable cycling stability of Co3Se4, Cu2Se@Co3Se4 can exhibit outstanding electrochemical performance as a novel electrode material. The as‐prepared Cu2Se@Co3Se4 electrode displays high specific capacitance of 1005 F g−1 at 1 A g−1 with enhanced rate capability (56 % capacitance retention at 10 A g−1), and ultralong lifespan (94.2 % after 10 000 cycles at 20 A g−1). An asymmetric supercapacitor is assembled applying the Cu2Se@Co3Se4 as anode and graphene as cathode, which delivers a wide work potential window of 1.6 V, high energy density (30.9 Wh kg−1 at 0.74 kW kg−1), high power density (21.0 Wh kg−1 at 7.50 kW kg−1), and excellent cycling stability (85.8 % after 10 000 cycles at 10 A g−1). [ABSTRACT FROM AUTHOR]

The chitinase‐producing bacteria Paenibacillus sp. was isolated from soil samples. The chitinase was purified successively by ammonia sulfate fractional precipitation followed by chromatography on DEAE 52‐cellulose column and then on Sephadex G‐75 column. The chitinase has a molecular weight of ca. 30 kDa as measured by sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) electrophoresis. Its optimum pH is 4.5, and its optimum temperature is 50 °C with colloidal chitin as a substrate. The enzyme is stable below 45 °C and in pH ranges between 4.5 and 5.5. It is activated by glucosamine, glucose, N‐acetylglucosamine, and metal ions including Ca2+, Fe2+, Fe3+, and Ni2+. It is inhibited by SDS, H2O2, ascorbic acid, Cu2+, Mg2+, Ba2+, Sn2+, Cr3+, and K+. With colloidal chitin as substrate, the Km and the Vmax of the chitinase are 4.28 mg/mL and 14.29 μg/(Min·mL), respectively, whereas the end products of the enzymatic hydrolysis are 14.33% monomer and 85.67% dimer of N‐acetylglucosamine. The viscosity of carboxymethyl chitin decreased rapidly at the initial stages when subjected to chitinase hydrolysis, which indicates that the chitinase acts in an endosplitting pattern. [ABSTRACT FROM AUTHOR]

Rational designing and constructing multiphase hybrid electrode materials is an effective method to compensate for the performance defects of the single component. Based on this strategy, Cu 2 Se hexagonal nanosheets@Co 3 Se 4 nanospheres mixed structures have been fabricated by a facile two-step hydrothermal method. Under the synergistic effect of the high ionic conductivity of Cu 2 Se and the remarkable cycling stability of Co 3 Se 4 , Cu 2 Se@Co 3 Se 4 can exhibit outstanding electrochemical performance as a novel electrode material. The as-prepared Cu 2 Se@Co 3 Se 4 electrode displays high specific capacitance of 1005 F g -1 at 1 A g -1 with enhanced rate capability (56 % capacitance retention at 10 A g -1 ), and ultralong lifespan (94.2 % after 10 000 cycles at 20 A g -1 ). An asymmetric supercapacitor is assembled applying the Cu 2 Se@Co 3 Se 4 as anode and graphene as cathode, which delivers a wide work potential window of 1.6 V, high energy density (30.9 Wh kg -1 at 0.74 kW kg -1 ), high power density (21.0 Wh kg -1 at 7.50 kW kg -1 ), and excellent cycling stability (85.8 % after 10 000 cycles at 10 A g -1 )., (© 2021 Wiley-VCH GmbH.)

Objective: To observe rice cadmium level in a contaminated area where has being continuously polluted for 19 years since last investigation., Methods: Samples of late rice (polished) grown in 2006 were collected from farmer household in contaminated and control area and its cadmium concentration were detected with IPC-MS., Results: Samples of polished rice from the polluted and control areas were detected. The average cadmium concentration from last investigation area 19 years before was 0.59 mg/kg (0.05 mg/kg for rice from control area), it upraises about 30% corresponding to average of rice from the same areas detected before 19 years. The average cadmium level of rice from whole contaminated areas (including last investigation and expanding areas) was 0.26 mg/kg and it is greater than that in control areas (0.06 mg/kg) and the limited value of national hygiene standard (< 0.20 mg/kg). There was about 64%, 23.17% and 11% of samples have higher level than 0.20 mg/kg (the limited value of national hygiene standard), 0.4 mg/kg (the limited value of Codex General Standard) and 1.0 mg/kg (cadmium-rice) respectively. There was a higher percentage (36.8%) of Cadmium-rice (greater than 1.0 mg/kg) in some heavy contamination villages., Conclusion: Environmental cadmium pollution has being existing for 19 years since last investigation. Average cadmium concentration of rice from whole country polluted areas was higher than that of national hygiene standard. Percentage of "cadmium-rice" might be higher in some villages.

Based on the available data of population survey, we review the research situation of health hazards on the environment cadmium polluted population from the threshold study of cadmium burden on human body, the chronic hazards of cadmium pollution on human health, the identification diagnosis of cadmium hazards. The information in this review could provide ideas for future study goal and development trend of health hazards in environmental cadmium pollution.