餐厨垃圾厌氧消化过酸化系统微生态特征的宏基因组学分析

过酸化失稳是困扰有机废物厌氧消化（AD）过程高效稳定运行的一大难题.为探析不同诱导方式造成过酸化的AD系统微生态特征差异,在餐厨垃圾中温AD反应器中分别引入负荷扰动（R2）、温度及搅拌扰动（R3）以诱发系统过酸化,利用宏基因组学测序技术,对比考察稳定与酸化系统微生物群落结构及主要产甲烷功能路径差异.结果表明,两种方式均成功诱发系统过酸化失稳,过酸化系统中挥发性脂肪酸（VFA）过量富集（R2、R3系统中分别高达（12.53±1.96） g·L^-1和（8.00±0.81） g·L^-1）的同时,丙酸等多碳VFA组分比例大幅升高.R2、R3系统酸化后其产甲烷菌及相关酶受到高浓度VFA的显著抑制,酸积累程度更高的R2受抑制更为明显.且经相关性分析发现,多碳酸尤其是丙酸是抑制产甲烷作用的关键因素.与R2相比,R3具有更高的耗氢能力,耗氢微生物如可耗H₂产酸的Treponema属和氢营养型产甲烷菌Methanoculleus属、Methanospirillum属等相对丰度显著高于R2.酸化系统均以乙酸营养型产甲烷为主要的产甲烷途径,并以Methanosaeta属为主要的乙酸型产甲烷菌.酸化系统中更高含量的乙酸产甲烷途径的AK-PTA酶有利于促进对乙酸的利用,增强厌氧消化微生物菌群对高浓度乙酸的耐受 能力.本研究中的相关结果可为提高有机废物AD微生态抗酸化能力提供理论依据和数据支撑.     

Seasonal differences in sources and formation processes of PM2.5 nitrate in an urban environment of North China

Nitrate (NO₃⁻) has been the dominant ion of secondary inorganic aerosols (SIAs) in PM_2.5 in North China. Tracking the formation mechanisms and sources of particulate nitrate are vital to mitigate air pollution. In this study, PM_2.5 samples in winter (January 2020) and in summer (June 2020) were collected in Jiaozuo, China, and water-soluble ions and (δ¹⁵N, δ¹⁸O)-NO₃⁻ were analyzed. The results showed that the increase of NO₃⁻ concentrations was the most remarkable with increasing PM_2.5 pollution level. δ¹⁸O-NO₃⁻ values for winter samples (82.7‰ to 103.9‰) were close to calculated δ¹⁸O-HNO₃ (103‰ ± 0.8‰) values by N₂O₅ pathway, while δ¹⁸O-NO₃⁻ values (67.8‰ to 85.7‰) for summer samples were close to calculated δ¹⁸O-HNO₃ values (61‰ ± 0.8‰) by OH oxidation pathway, suggesting that PM_2.5 nitrate is largely from N₂O₅ pathway in winter, while is largely from OH pathway in summer. Averaged fractional contributions of P_N2O5+H2O were 70% and 39% in winter and summer sampling periods, respectively, those of P_OH were 30% and 61%, respectively. Higher δ¹⁵N-NO₃⁻ values for winter samples (3.0‰ to 14.4‰) than those for summer samples (-3.7‰ to 8.6‰) might be due to more contributions from coal combustion in winter. Coal combustion (31% ± 9%, 25% ± 9% in winter and summer, respectively) and biomass burning (30% ± 12%, 36% ± 12% in winter and summer, respectively) were the main sources using Bayesian mixing model. These results provided clear evidence of particulate nitrate formation and sources under different PM_2.5 levels, and aided in reducing atmospheric nitrate in urban environments.     

Transformations in carbon and nitrogen-forms in peat subjected to progressive thermal stress as revealed by analytical pyrolysis

To study the characteristic N-forms of humic-type materials, samples of sapric peat from Galicia (northern Spain) were heated at 350 °C for 60, 90, 120, 150 and 180 s, and studied by Curie-point Py-GC/MS, solid-state CPMAS ¹³C-NMR and ¹⁵N-NMR spectroscopies. NMR analysis of the peat samples in the progressive heating stages showed the concentration of heterocyclic N-forms, the maximum structural transition amide-to-heterocyclic forms being observed in samples heated for 120 s (56% heterocyclic N and 34% aromatic C). Under more drastic conditions all N-forms were depleted. Correlation between spectroscopic and pyrolytic data betrayed specific pyrolytic markers for the different N-forms. The intensity of the ¹⁵N-NMR amide peak tended to be positively correlated to the yield of indoles, imidazoles and pyrazoles, and negatively correlated to those of benzonitriles and pyrazines. Analytical pyrolysis also showed a progressive enrichment in lipids and alkyl macromolecules with increasing heating intensity, and a decrease in lignin-derived, polysaccharide-derived and N-containing compounds. The relative abundance of non-methoxyphenolic aromatic compounds did not change. The N-compounds in peat samples unheated or heated for 60–90 s released methylpyrazole, dimethylpyrroline, methyldiphenylindole and pyrazole, whereas peat samples heated for 120 s mainly yielded methylpyrazine and methyldiphenylindole. Dimethylpyrroline and pyrazine prevailed in samples heated for 150 s, whereas samples heated for 180 s yielded mainly pyrrole. Pyrolysis data presented low possibilities for forecasting the extent of the O-alkyl domain, but reflected quantitatively the transformations in the lignin-like moiety. Both techniques coincide in pointing out the accumulation of a recalcitrant alkyl domain possibly derived from abiotic condensations or inherited lipid biomacromolecules.     

Transport of silver nanoparticles (AgNPs) in soil

The effect of soil properties on the transport of silver nanoparticles (AgNPs) was studied in a set of laboratory column experiments, using different combinations of size fractions of a Mediterranean sandy clay soil. The AgNPs with average size of ∼30 nm yielded a stable suspension in water with zeta potential of −39 mV. Early breakthrough of AgNPs in soil was observed in column transport experiments. AgNPs were found to have high mobility in soil with outlet relative concentrations ranging from 30% to 70%, depending on experimental conditions. AgNP mobility through the column decreased when the fraction of smaller soil aggregates was larger. The early breakthrough pattern was not observed for AgNPs in pure quartz columns nor for bromide tracer in soil columns, suggesting that early breakthrough is related to the nature of AgNP transport in natural soils. Micro-CT and image analysis used to investigate structural features of the soil, suggest that soil aggregate size strongly affects AgNP transport in natural soil. The retention of AgNPs in the soil column was reduced when humic acid was added to the leaching solution, while a lower flow rate (Darcy velocity of 0.17 cm/min versus 0.66 cm/min) resulted in higher retention of AgNPs in the soil. When soil residual chloride was exchanged by nitrate prior to column experiments, significantly improved mobility of AgNPs was observed in the soil column. These findings point to the importance of AgNP-soil chemical interactions as a retention mechanism, and demonstrate the need to employ natural soils rather than glass beads or quartz in representative experimental investigations.     

生活垃圾焚烧二噁英排放对人群健康影响研究进展

综述了二噁英对人体健康的危害特性, 以及我国生活垃圾焚烧厂二噁英排放浓度水平，及其周边环境空气和土壤中二噁英污染浓度水平、人群暴露途径、剂量和健康影响。指出，现有研究显示，我国生活垃圾焚烧排放的二噁英浓度在合理范围之内，垃圾焚烧厂周边人群二噁英暴露量普遍低于世界卫生组织（WHO）推荐的容许标准，但也有研究发现，垃圾焚烧会导致周边环境介质中二噁英浓度水平增高。提出，应重点关注垃圾焚烧排放二噁英的长期低剂量暴露对人群健康的影响。     

电子束辐照降解水中氧氟沙星的研究

应用电子直线加速器初步探索了水体中氧氟沙星的辐照降解影响条件及降解机理.对初始浓度为20mg/L的氧氟沙星水溶液进行了辐照降解研究,分别选取了0.5kGy,1.0kGy,2.0kGy,3.0kGy,5.0kGy共5个剂量组,以研究辐照吸收剂量对降解效率的影响,同时分别对氧氟沙星水溶液进行空气饱和（水合电子清除剂）、氮气饱和、添加0.005mol/L及0.05mol/L氯化钠、添加0.05mol/L叔丁醇（羟基自由基清除剂）、添加0.005mol/L碳酸钠、添加0.005mol/L硫酸钠等方法进行处理,以探究降解过程中辐照水体产生自由基对氧氟沙星降解的贡献率.结果表明,以空气饱和进行处理,可提高氧氟沙星的降解率,辐照吸收剂量为2.0kGy时降解率可达99%.反之,加入氯化钠、叔丁醇和碳酸钠抑制了氧氟沙星的降解,加入硫酸钠则影响不大,表明羟基自由基在氧氟沙星降解中起关键作用.通过应用超高效液相色谱-质谱（UPLC-MS）对降解产物的分析鉴定,推测出了氧氟沙星的降解转化途径.     

New insights into FeS/persulfate system for tetracycline elimination: Iron valence, homogeneous-heterogeneous reactions and degradation pathways

In this study, complete tetracycline（TTC） and above 50% of total organic carbon（TOC） were removed by Fe S/PS after 30 min under optimized conditions. Although free radicals and high-valent iron ions were identified to generate in the process, the apparent similarity between intermediate products of Fe S/PS, Fe/PS, and UV/PS systems demonstrated that the degradation of TTC was due to sulfate radicals(SO₄^·-) and hydroxyl radicals（ ·OH）. Based on the reaction between free radi...     

企业碳中和行动的驱动力与模式

碳中和已成为我国气候治理和可持续发展的重要目标。尽管碳中和是国家面向2060年的长期愿景,尚未转换成针对企业的政策约束,但全球很多企业已经快速响应,主动制定自身的碳中和战略。本文从企业环境行为的驱动理论出发,分析了企业做出碳中和承诺的内部和外部驱动因素,论证了企业"化被动为主动"、自主实行碳中和战略,不但有助于在未来更加严格的气候政策规制中获得先机、赢得行业竞争优势、拓宽绿色市场份额、规避可能的经济风险,而且具有体现企业社会责任感、树立良好品牌形象、提升企业创新能力和核心竞争力等积极作用。在此基础上,梳理了能源密集型、资源密集型和高新技术企业的碳中和战略及模式,总结分析了国内企业实现碳中和承诺的机遇和挑战,为国内企业制定零碳发展战略、实现碳中和目标提出了路径建议。     

Air Pollution Potential: Regional Study in Argentina

/ Air pollution potential is a measure of the atmospheric conditions that are unable to transport and dilute pollutants into the air, independently of the existence of sources. This potential can be determined from two atmospheric parameters: mixing height and transport wind. In this paper a statistical analysis of the mixing height and transport wind, in order to determine the areas with high or poor atmospheric ventilation in Argentina, is presented. In order to achieve this, meteorological data registered during 1979-1982 at eight meteorological stations were used. Daily values of the maximum mixing height were calculated from observations of daily temperatures at different heights and maximum surface temperature. At the same time as the maximum mixing height, the values of the transport wind were determined from the surface windspeed and the characteristics of the ground in the surroundings of each meteorological station. The mean seasonal values for both parameters were obtained. Isopleths of the mean seasonal of the maximum mixing heights were drawn. The percentage of seasonal frequencies of poor ventilation conditions were calculated and the frequency isopleths were also drawn to determine areas with minor and major relative frequencies. It was found that the northeastern and central-eastern regions of Argentina had a high air pollution potential during the whole year. Unfavorable atmospheric ventilation conditions were also found in the central-western side of the country during the cold seasons (37.5% in autumn and 56.9% in winter). The region with the greatest atmospheric ventilation is located south of 40 degrees S, where the frequency of poor ventilation varies between 8.0% in summer and 10.8% in winter.     

膜传质的统计力学模型研究

本文根据压力驱动膜分离过程的特点,采用统计力学传质模型,通过相关的热力学理论和数学方法,建立了考虑粘性流动在内的适用于任意浓度非理想多组分溶液的可实际应用的统计力学膜传质模型,并通过实验对该模型进行了检验,结果表明该模型与实验结果符合的较好。