Solubilization of mixed polycyclic aromatic hydrocarbons through a rhamnolipid biosurfactant

The solubilization of phenanthrene (PHE) and pyrene (PYR) by rhamnolipid biosurfactant was systematically investigated. The solubilities of both polycyclic aromatic hydrocarbons (PAHs) were increased linearly with the biosurfactant concentration at above critical micelle concentration. A competitive effect was observed between PHE and PYR. The solubility of PHE in a mixed system was lower than that in a single PAH system, whereas the solubility of PYR in a mixed system was enhanced. This is because the hydrophobicity of PYR is higher than that of PHE, so PYR is favored in the competitive solubilization. The combined effect of biosurfactant and dissolved organic matter (DOM) on PAH solubilization was also examined. Two kinds of DOM (derived from soil and from compost) were used. There was an obvious enhancement of solubility for PHE and PYR in systems with concurrence of DOM and biosurfacrant compared with systems with only DOM or biosurfactant; however, the enhancement in the mixed system was less than their additive. This could be explained as the formation of a DOM-biosurfactant complex. In addition, the solubility enhancement of PAHs in a compost-DOM system was higher than that in a soil-DOM system. This could be explained as functional group differences of two DOM types.     

Effects of salinity and organic matter on the partitioning of perfluoroalkyl acid (PFAs) to clay particles

The influence of salinity and organic matter on the distribution coefficient (K(d)) for perfluorooctane sulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) in a brackish water-clay system was studied. The distribution coefficients (K(d)) for PFAs onto inorganic clay surfaces increased with salinity, providing evidence for electrostatic interaction for the sorption of PFAs, whereas the relationship between K(d) and organic carbon content (f(oc)) suggested that hydrophobic interaction is the primary driving force for the sorption of PFAs onto organic matter. The organic carbon normalized adsorption coefficient (K(oc)) of PFAs can be slightly overestimated due to the electrostatic interaction within uncoated inorganic surfaces. In addition, the dissolved organic matter released from coated clay particles seemed to solvate PFA molecules in solution, which contributed to a decrease in K(d). A positive relationship between K(d) and salinity was apparent, but an empirical relationship for the 'salting-out' effect was not evident. The K(d) values of PFAs are relatively small compared with those reported for persistent organic pollutants. Thus, sorption may not be a significant route of mass transfer of PFAs from water columns in estuarine environments. However, enhancement of sorption of PFAs to particulate matter at high salinity values could evoke potential risks to benthic organisms in estuarine areas.     

我国自然灾害时空分布及其粮食风险评估

分析了旱灾、水灾、风雹灾、霜冻灾、台风灾和农业病虫害、草害、鼠害8种自然灾害的时空分布情况,计算了其造成的历年粮食减产量,并在此基础上评估2020年自然灾害对粮食产量的影响。结果表明,2020年不同自然灾害对我国各省粮食生产的影响程度不同。旱灾风险区集中在我国北方地区,分布在黄淮海区、西北区等;涝灾风险区集中在我国南方地区,分布在长江中下游区等;风雹灾风险区对我国粮食产量影响相对较小,主要分布在新疆和青海;台风灾风险区集中在我国南方沿海地区;农业病虫害风险区集中在我国的南方地区,分布在华南沿海区和西南区等;而霜冻灾、农业草害、鼠害对粮食生产的影响范围和影响程度较小。     

Progress in quantitative research on the relationship between atmospheric oxidation and air quality

Atmospheric oxidizing capacity (AOC) is an essential driving force of troposphere chemistry and self-cleaning, but the definition of AOC and its quantitative representation remain uncertain. Driven by national demand for air pollution control in recent years, Chinese scholars have carried out studies on theories of atmospheric chemistry and have made considerable progress in AOC research. This paper will give a brief review of these developments. First, AOC indexes were established that represent apparent atmospheric oxidizing ability (AOIe) and potential atmospheric oxidizing ability (AOIp) based on aspects of macrothermodynamics and microdynamics, respectively. A closed study refined the quantitative contributions of heterogeneous chemistry to AOC in Beijing, and these AOC methods were further applied in Beijing-Tianjin-Hebei and key areas across the country. In addition, the detection of ground or vertical profiles for atmospheric OH·, HO₂·, NO₃· radicals and reservoir molecules can now be obtained with domestic instruments in diverse environments. Moreover, laboratory smoke chamber simulations revealed heterogeneous processes involving reactions of O₃ and NO₂, which are typical oxidants in the surface/interface atmosphere, and the evolutionary and budgetary implications of atmospheric oxidants reacting under multispecies, multiphase and multi-interface conditions were obtained. Finally, based on the GRAPES-CUACE adjoint model improved by Chinese scholars, simulations of key substances affecting atmospheric oxidation and secondary organic and inorganic aerosol formation have been optimized. Normalized numerical simulations of AOIe and AOIp were performed, and regional coordination of AOC was adjusted. An optimized plan for controlling O₃ and PM_2.5 was analyzed by scenario simulation.     

Influence of particle size on the aggregation behavior of nanoparticles: Role of structural hydration layer

More and more attention has been paid to the aggregation behavior of nanoparticles, but little research has been done on the effect of particle size. Therefore, this study systematically evaluated the aggregation behavior of nano-silica particles with diameter 130–480 nm at different initial particle concentration, pH, ionic strength, and ionic valence of electrolytes. The modified Smoluchowski theory failed to describe the aggregation kinetics for nano-silica particles with diameters less than 190 nm. Besides, ionic strength, cation species and pH all affected fast aggregation rate coefficients of 130 nm nanoparticles. Through incorporating structural hydration force into the modified Smoluchowski theory, it is found that the reason for all the anomalous aggregation behavior was the different structural hydration layer thickness of nanoparticles with various sizes. The thickness decreased with increasing of particle size, and remained basically unchanged for particles larger than 190 nm. Only when the distance at primary minimum was twice the thickness of structural hydration layer, the structural hydration force dominated, leading to the higher stability of nanoparticles. This study clearly clarified the unique aggregation mechanism of nanoparticles with smaller size, which provided reference for predicting transport and fate of nanoparticles and could help facilitate the evaluation of their environment risks.     

汽车用材料——PA66及其玻璃纤维复合材料在不同介质中的老化行为研究

在三种介质（二次水，汽油，乙二醇，50℃温度）条件下对PA66及PA66／GF进行95天左右的人工模拟材料在汽车使用环境下的加速试验，对不同老化时间的PA66及PA66／GF试样进行了宏观力学测试及吸湿性测试，并进一步利用示差扫描量热法（DSC），红外光谱及扫描电镜等手段分析老化前后试样的微观结构及组织差异。结合老化前后试样的力学性能变化，揭示了PA66及复合材料的老化规律和机理。实验表明，PA66及PA66／GF在三种介质中拉伸强度呈现下降趋势。其主要机理是介质溶液对试样渗入的结果影响，降低了分子间的相互作用力（范德华力）从而使材料机械性能下降；同时未发现化学作用对材料的力学性能有明显的变化。     

Functional flax fiber with UV-induced switchable wettability for multipurpose oil-water separation

● A PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed. ● The property of flax fiber could be switched from hydrophobicity to hydrophilicity. ● The mechanism of the acquired UV-induced switchable wettability was discussed. ● The developed flax fiber was successfully used for multipurpose oil-water separation. The large number of oily wastewater discharges and oil spills are bringing about severe threats to environment and human health. Corresponding to this challenge, a functional PAA-ZnO-HDTMS flax fiber with UV-induced switchable wettability was developed for efficient oil-water separation in this study. The developed flax fiber was obtained through PAA grafted polymerization and then ZnO-HDTMS nanocomposite immobilization. The as-prepared PAA-ZnO-HDTMS flax fiber was hydrophobic initially and could be switched to hydrophilic through UV irradiation. Its hydrophobicity could be easily recovered through being stored in dark environment for several days. To optimize the performance of the PAA-ZnO-HDTMS flax fiber, the effects of ZnO and HDTMS concentrations on its switchable wettability were investigated. The optimized PAA-ZnO-HDTMS flax fiber had a large water contact angle (~130°) in air and an extremely small oil contact angle (~0°) underwater initially. After UV treatment, the water contact angle was decreased to 30°, while the underwater oil contact angle was increased to more than 150°. Based on this UV-induced switchable wettability, the developed PAA-ZnO-HDTMS flax fiber was applied to remove oil from immiscible oil-water mixtures and oil-in-water emulsion with great reusability for multiple cycles. Thus, the developed flax fiber could be further fabricated into oil barrier or oil sorbent for oil-water separation, which could be an environmentally-friendly alternative in oil spill response and oily wastewater treatment.     

Product identification and toxicity change during oxidation of methotrexate by ferrate and permanganate in water

• Oxidation of methotrexate by high-valent metal-oxo species was first explored. • Fe(VI) presented a higher reactivity to MTX than Mn(VII) at pH 8.0. • Ketonization and cleavage of peptide bond were two initial reaction pathways. • Products of MTX were not genotoxic, neurotoxic, or endocrine-disrupting chemicals. • The less biodegradable products exhibited developmental and acute/chronic toxicity. Accompanying an annual increase in cancer incidence, the global use of anticancer drugs has remarkably increased with their worldwide environmental prevalence and ecological risks. In this study, the oxidation of methotrexate (MTX), a typical anticancer drug with ubiquitous occurrence and multi-endpoint toxicity, by ferrate(VI) (Fe(VI)) and permanganate (Mn(VII))) was investigated in water. Fe(VI) exhibited a higher reactivity with MTX (93.34 M⁻¹ s⁻¹) than Mn(VII) (3.01 M⁻¹ s⁻¹) at pH 8.0. The introduction of Cu(II) and Fe(III) at 1.0 mM improved the removal efficiency of 5.0 μM MTX by 100.0 μM Fe(VI) from 80% to 95% and 100% after 4 min, respectively. Seven oxidized products (OPs) were identified during oxidative treatments, while OP-191 and OP-205 were characterized as specific products for Fe(VI) oxidation. Initial ketonization of the L-glutamic acid moiety and cleavage of the peptide bond of MTX were proposed. Additionally, a multi-endpoint toxicity evaluation indicated no genotoxicity, neurotoxicity, or endocrine-disrupting effects of MTX and its OPs. Particularly, serious developmental toxicity in zebrafish larvae was observed in the treated MTX solutions. Based on the acute and chronic aquatic toxicity prediction, OP-190, OP-192, OP-206, and OP-208 were deemed toxic or very toxic compared to harmful MTX. Furthermore, the reduced biodegradability index from 0.15 (MTX) to −0.5 to −0.2 (OP-192, OP-206, and OP-468) indicated the formation of lower biodegradable OPs. Overall, this study suggests that Fe(VI) and Mn(VII) oxidation are promising treatments for remediating anticancer drug-contaminated water. However, the environmental risks associated with these treatments should be considered in the evaluation of water safety.     

Effects of ambient temperature on outpatient visits for dermatitis in Xinxiang,China: a time-series analysis

Environmental Science and Pollution Research - Previous studies have reported regional variations in the relationship between ambient temperature and dermatitis, which therefore remain...     

Construction,renovation, and demolition waste in landfill: a review of waste characteristics,environmental impacts,and mitigation measures

Environmental Science and Pollution Research - With the increase in global population, industrialization, and urbanization, waste from construction, renovation, and demolition (CRD) activities has...