水蚀环境植被恢复对土壤有机碳固存和团聚体稳定的影响：Meta分析

为明确水蚀环境不同条件下植被恢复策略对土壤固碳和团聚体稳定性的影响差异,通过搜集91篇论文的实验数据,以农田(或裸地)为对照,基于Meta分析评估土壤有机碳(SOC)储量和团聚体稳定性对水蚀环境退耕还林/还草措施的响应.结果表明：(1)退耕还林/还草均有利于提高SOC储量,改善土壤团聚体稳定性,但两者的优势功能存在差异,还林的固碳效应强于还草,而还草对增强团聚体稳定性的作用更强.(2)多因素Meta分析表明显著影响SOC的因素有：恢复年份、土壤黏粒含量、植被覆盖度、年平均降雨(MAP)、年平均气温(MAT)和土壤深度.其中植被恢复对SOC储量的正向效应随着植被覆盖率增加而提高;草地恢复在土壤黏粒含量为20%～32%下对SOC储量的提高效应更显著,在MAP>800 mm或MAT<15℃条件下更易促进草地固碳效应,不同恢复年限下的草地固碳效应无显著变化;而林地恢复在土壤黏粒含量>32%下对SOC储量的提高效应更显著,气候条件对林地SOC储量无限制性影响,林地恢复下的SOC储量与恢复年限间存在正向效应.(3)植被恢复在黏粒含量为20%～32%时对平均重量直径(MWD)和平均...     

上海城区二次气溶胶的形成:光化学氧化与液相反应对二次气溶胶形成的影响

二次组分是大气细颗粒物中最重要的组成部分之一.本研究旨在探究上海城区大气气溶胶颗粒物中二次组分的贡献及其形成的主要影响因素.利用高分辨率飞行时间气溶胶质谱仪(HR-TOF-AMS)对上海城区春季及夏季的亚微米颗粒物(PM_1)进行实时的在线表征,发现有机物是PM_1中最主要的组成部分,占比为55%;其次是硫酸盐(24%)与硝酸盐(10%).进一步结合正交矩阵因子解析模型(PMF)对有机组分进行了来源解析.结果表明,一次有机气溶胶(POA)与二次有机气溶胶(SOA)分别占总有机物浓度的34%与66%; POA主要来自机动车源与餐饮源的贡献,且在春季和夏季对有机物的贡献趋于稳定.观测期间共观察到3个二次气溶胶显著生成的过程:其中,春季二次组分的显著增长过程以硫酸盐和老化的有机气溶胶在正午时段上升显著为主要特征,主要受光化学氧化过程的促进;夏季二次组分的显著生成过程主要是液相反应与光化学氧化共同促进的结果,如液相反应过程中,硝酸盐浓度与颗粒相水含量有较好的相关性(R~2=0. 72),而光化学氧化期间SOA浓度与大气氧化性(O_x)有较好的相关性.总体而言,二次组分是上海城市大气气溶胶颗粒物中最重要的组成部分,二次有机与无机组分在PM_1颗粒物中占比分别为35. 5%和43%,光化学氧化与液相反应对二次组分的形成有显著的促进作用.     

碳链延长技术在有机资源回收领域的研究进展

本文综述了碳链延长技术在处理有机废料及碳资源回收领域的优势,梳理了其发展历程为后续研究提供方向指导,阐释了其生化代谢途径中物质转变、能量传递和信号传输等机理,验证了其延长为丁酸、己酸等产物的热力和动力学可行性,总结归纳了其已优化的关键反应参数和已运行的工程试验案例等方面内容.本文为揭示细胞碳链延长机制和应用碳链延长技术于实际废料治理提供理论基础和建议展望.     

Ag/TiO2光电催化降解染料及出水有机质影响机制

本研究以阳极氧化法结合电化学沉积法成功制备的具有高度整齐有序纳米管结构的Ag/TiO₂纳米管阵列（Ag/TNTAs）为阳极,碳/聚四氟乙烯为阴极构建光电催化（PEC）体系.并探究其光电催化降解甲基橙（MO）效能,结果表明,Ag/TNTAs光电催化降解能力（68.2%）远高于光催化（18.9%）、电化学氧化（38.2%）和直接光解;另外在水质净化厂出水有机质（EfOM）参与的光电体系中,当EfOM的初始浓度小于或等于1.0mgC/L时,其对光电催化降解MO起到促进作用,其中当其浓度为0.4mgC/L时促进作用最为明显.而高浓度的EfOM则抑制光电催化活性.此研究表明光电催化体系能高效催化染料降解,且EfOM能在一定阈值范围内促进光电催化降解污染物.     

太原市城区夏季VOCs来源及其对O3生成的贡献

采集太原市城区夏季VOCs样品并分析其浓度特征,使用参数修正法得到VOCs初始浓度,分析其来源及对O₃生成的贡献.结果显示：太原市城区总VOCs平均浓度为48.13 μg/m³,烷烃（25.52 μg/m³）为主要组分.VOCs浓度呈明显日变化特征,在日间（10：00~14：00）光化学产生O₃的关键时段浓度最低.油品挥发、机动车排放、燃煤、植物排放与液化石油气/天燃气（LPG/NG）使用源对修正后环境VOCs的贡献分别为26.89%、25.55%、21.14%、14.99%、11.44%,对O₃生成的贡献分别为21.44%、33.10%、24.07%、13.77%、7.62%.机动车为新鲜排放气团VOCs的重要来源,而油品挥发、燃煤的输送与本地积累是其他（混合、夜间与反应）气团VOCs的重要来源.机动车排放、油品挥发与燃煤为VOCs与O₃生成的重要贡献源,控制此类源排放可减少太原市城区环境VOCs浓度并有效降低O₃生成.     

深圳秋季大气有机气溶胶来源与挥发性研究

使用热扩散管与长飞行时间气溶胶质谱联用系统对2020年深圳市秋季亚微米级气溶胶进行在线测量,获取和分析了气溶胶的化学组成及挥发性特征,并利用正矩阵因子分析法（PMF）对有机气溶胶进行了来源解析.结果显示：观测期间,气溶胶平均质量浓度为（28.3±11.1）μg/m³（9.5~76.8μg/m³）,其中,有机物占比最高,为57.9%,其次为硫酸盐（24.7%）.PMF对有机气溶胶解析结果得到四类源,分别为烃类有机气溶胶（HOA）、餐饮源有关的有机气溶胶（COA）、低氧化性的氧化有机气溶胶（LO-OOA）和高氧化性的氧化有机气溶胶（MO-OOA）.HOA、COA、LO-OOA和MO-OOA平均分别占到总有机物的9.1%、27.2%、31.8%和31.9%.进一步采用NO⁺/NO₂⁺比值法和PMF方法估算有机硝酸酯（ON）浓度,两种方法估算结果相关性良好,ON的平均浓度为0.17~0.25μg/m³,占总有机气溶胶质量的1.5%~9.7%,说明其对深圳大气气溶胶贡献显著.ON与各有机气溶胶因子的相关性比对发现,其与LO-OOA相关性最高（R=0.80）,说明其可能来源于新鲜的二次生成反应.挥发性研究结果得出,深圳市气溶胶主要化学组分挥发性顺序为氯盐≈无机硝酸盐 > 铵盐 > 有机物 > 有机硝酸酯 > 硫酸盐,对于有机气溶胶因子,其挥发性排序为LO-OOA > HOA > COA > MO-OOA,除了LO-OOA,其余因子挥发性与其氧化态排序一致,而LO-OOA从50~70℃组分下降最多,说明其所含组分挥发性差异最为明显.     

Effects of reductive inorganics and NOM on the formation of chlorite in the chlorine dioxide disinfection of drinking water

Chlorine dioxide (ClO₂) disinfection usually does not produce halogenated disinfection by-products, but the formation of the inorganic by-product chlorite (ClO₂^–) is a serious consideration. In this study, the ClO₂^– formation rule in the ClO₂ disinfection of drinking water was investigated in the presence of three representative reductive inorganics and four natural organic matters (NOMs), respectively. Fe²⁺ and S^2– mainly reduced ClO₂ to ClO₂^– at low concentrations. When ClO₂ was consumed, the ClO₂^– would be further reduced by Fe²⁺ and S^2–, leading to the decrease of ClO₂^–. The reaction efficiency of Mn²⁺ with ClO₂ was lower than that of Fe²⁺ and S^2–. It might be the case that MnO₂ generated by the reaction between Mn²⁺ and ClO₂ had adsorption and catalytic oxidation on Mn²⁺. However, Mn²⁺ would not reduce ClO₂^–. Among the four NOMs, humic acid and fulvic acid reacted with ClO₂ actively, followed by bovine serum albumin, while sodium alginate had almost no reaction with ClO₂. The maximum ClO₂^– yields of reductive inorganics (70%) was higher than that of NOM (around 60%). The lower the concentration of reductive substances, the more ClO₂^– could be produced by per unit concentration of reductive substances. The results of the actual water samples showed that both reductive inorganics and NOM played an important role in the formation of ClO₂^– in disinfection.     

A large-scale outdoor atmospheric simulation smog chamber for studying atmospheric photochemical processes: Characterization and preliminary application

Understanding the formation mechanisms of secondary air pollution is very important for the formulation of air pollution control countermeasures in China. Thus, a large-scale outdoor atmospheric simulation smog chamber was constructed at Chinese Research Academy of Environmental Sciences (the CRAES Chamber), which was designed for simulating the atmospheric photochemical processes under the conditions close to the real atmospheric environment. The chamber consisted of a 56-m³ fluorinated ethylene propylene (FEP) Teflon film reactor, an electrically-driven stainless steel alloy shield, an auxiliary system, and multiple detection instrumentations. By performing a series of characterization experiments, we obtained basic parameters of the CRAES chamber, such as the mixing ability, the background reactivity, and the wall loss rates of gaseous compounds (propene, NO, NO₂, ozone) and aerosols (ammonium sulfate). Oxidation experiments were also performed to study the formation of ozone and secondary organic aerosol (SOA), including α-pinene ozonolysis, propene and 1,3,5-trimethylbenzene photooxidation. Temperature and seed effects on the vapor wall loss and SOA yields were obtained in this work: higher temperature and the presence of seed could reduce the vapor wall loss; SOA yield was found to depend inversely on temperature, and the presence of seed could increase SOA yield. The seed was suggested to be used in the chamber to reduce the interaction between the gas phase and chamber walls. The results above showed that the CRAES chamber was reliable and could meet the demands for investigating tropospheric chemistry.     

Application of FeIII-TAML/H2O2 system for treatment of fluoroquinolone antibiotics

Over the recent past, fluoroquinolone antibiotics (FQs) have raised extensive attention due to their potential to induce the formation of resistance genes and “superbugs”, thus various advanced oxidation techniques have been developed to eliminate their release into the environment. In the present study, the prototype tetraamido macrocyclic ligand (Fe^III-TAML)/hydrogen peroxide (H₂O₂) system is employed to degrade FQs (i.e., norfloxacin and ciprofloxacin) over a wide pH range (i.e., pH 6-10), and the reaction rate increases with the increase in pH level. The effect of dosage of Fe^III-TAML and H₂O₂ on the degradation of FQs is evaluated, and the reaction rate is linearly correlated with the added amount of chemicals. Moreover, the impact of natural organic matters (NOM) on the removal of FQs is investigated, and the degradation kinetics show that both NOM type and experimental concentration exhibit negligible influence on the oxidative degradation of selected antibiotics. Based on the results of liquid chromatography-high resolution mass spectrometry and theoretical calculations, the reaction sites and pathways of FQs by Fe^III-TAML/H₂O₂ system are further predicted and elucidated.     

Primary and secondary organic aerosol in an urban/industrial site: Sources, health implications and the role of plastic enriched waste burning

PM10 samples were collected from an urban/industrial site nearby Athens, where uncontrolled burning activities occur. PAHs, monocarboxylic, dicarboxylic, hydroxycarboxylic and aromatic acids, tracers from BVOC oxidation, biomass burning tracers and bisphenol A were determined. PAH, monocarboxylic acids, biomass burning tracers and bisphenol A were increased during autumn/winter, while BSOA tracers, dicarboxylic- and hydroxycarboxylic acids during summer. Regarding aromatic acids, different sources and formation mechanisms were indicated as benzoic, phthalic and trimellitic acids were peaked during summer whereas p-toluic, isophthalic and terephthalic were more abundant during autumn/winter. The Benzo[a]pyrene-equivalent carcinogenic power, carcinogenic and mutagenic activities were calculated showing significant (p < 0.05) increases during the colder months. Palmitic, succinic and malic acids were the most abundant monocarboxylic, dicarboxylic and hydrocarboxylic acids during the entire sampling period. Isoprene oxidation was the most significant contributor to BSOA as the isoprene-SOA compounds were two times more abundant than the pinene-SOA (13.4 ± 12.3 and 6.1 ± 2.9 ng/m³, respectively). Ozone has significant impact on the formation of many studied compounds showing significant correlations with: isoprene-SOA (r = 0.77), hydrocarboxylic acids (r = 0.69), pinene-SOA (r = 0.63),dicarboxylic acids (r = 0.58), and the sum of phthalic, benzoic and trimellitic acids (r = 0.44). PCA demonstrated five factors that could explain sources including plastic enriched waste burning (30.8%), oxidation of unsaturated fatty acids (23.0%), vehicle missions and cooking (9.2%), biomass burning (7.7%) and oxidation of VOCs (5.8%). The results highlight the significant contribution of plastic waste uncontrolled burning to the overall air quality degradation.