Photocatalytic degradation kinetics and mechanism of pentachlorophenol based on superoxide radicals

Pentachlorophenol could be photocatalytically reduced with superoxide radicals in aqueous solution under simulated sunlight irradiation.     

GEIA-STD-0009《系统设计、研制和制造可靠性大纲标准》分析

研究了GEIA-STD-0009《系统设计、研制和制造可靠性大纲标准》的制定背景,分析了该标准的制定过程,主要介绍了该标准4个可靠性目标及信息流,简述了每个目标的6个组成部分,详细阐述了13项规范性可靠性活动.     

大别山革命老区旅游地“乡土—生态”系统韧性演化规律及影响机制

探讨旅游地“乡土—生态”系统演化,为理解人地关系地域系统结构与功能演变提供了新思路。通过构建“乡土—生态”系统韧性评价体系,解析2005—2019年大别山革命老区旅游地“乡土—生态”系统韧性的演化阶段、过程、路径及机制。结果显示：（1）研究区旅游地“乡土—生态”系统经历了利用、保存、释放、重组适应性循环过程,分别对应旅游地迅速发展期（2005—2009年）、发展成熟期（2010—2012年）、发展过渡期（2013—2016年）和再发展初期（2017—2019年）。（2）在适应性循环过程中研究区县域的数量结构经历了以“较低水平韧性为主→高水平韧性为主”的转变,县域“乡土—生态”系统韧性水平呈波动上升趋势。（3）2005—2019年研究区旅游地“乡土—生态”系统韧性演化的驱动因子由经济层面转向社会文化层面。在内外源因素的作用下,旅游地“乡土—生态”系统韧性通过乡土资源禀赋（向心凝聚力）、经济发展基础（核心推动力）、社会保障功能（重要支撑力）和自然环境本底（基础约束力）的四维驱动,以人的行为为媒介在相互作用和掣肘中演进,当韧性指数超过阈值时其内核组织将打破原有边界、自我调适实现“路径突破”,进入下一阶段适应性循环,以此促进旅游地的可持续发展。     

Interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials: A review

The heterogeneous Fenton reaction can generate highly reactive hydroxyl radicals(·OH)from reactions between recyclable solid catalysts and H_2O_2 at acidic or even circumneutral pH.Hence,it can effectively oxidize refractory organics in water or soils and has become a promising environmentally friendly treatment technology.Due to the complex reaction system,the mechanism behind heterogeneous Fenton reactions remains unresolved but fascinating,and is crucial for understanding Fenton chemistry and the development and application of efficient heterogeneous Fenton technologies.Iron-based materials usually possess high catalytic activity,low cost,negligible toxicity and easy recovery,and are a superior type of heterogeneous Fenton catalysts.Therefore,this article reviews the fundamental but important interfacial mechanisms of heterogeneous Fenton reactions catalyzed by iron-based materials..OH,hydroperoxyl radicals/superoxide anions(HO_2./O_2~-.)and high-valent iron are the three main types of reactive oxygen species(ROS),with different oxidation reactivity and selectivity.Based on the mechanisms of ROS generation,the interfacial mechanisms of heterogeneous Fenton systems can be classified as the homogeneous Fenton mechanism induced by surface-leached iron,the heterogeneous catalysis mechanism,and the heterogeneous reaction-induced homogeneous mechanism.Different heterogeneous Fenton systems catalyzed by characteristic iron-based materials are comprehensively reviewed.Finally,related future research directions are also suggested.     

饮用水水源及水厂内分泌干扰物污染分析

对国内的饮用水水源地内分泌干扰物污染现状进行总结,发现我国饮用水水源地很多地区都存在着内分泌干扰物的污染,由于地域的不同,污染物的种类存在差异,但有机氯农药和多氯联苯类化合物的污染尤为严重。同时对水源地内分泌干扰物的种类、来源及生物学效应进行综述,并对内分泌干扰物的毒性作用机制进行了归纳,发现不同来源的内分泌干扰物,毒性作用机制不同,且一种内分泌干扰物可能同时存在多种作用机制。     

Levels of PCDD/Fs and trace elements in superficial soils of Pavia Province (Italy)

Trace elements and polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) were analyzed in soils from rural and light-industrialized sites (n=168) of Province of Pavia (Northern Italy). Most of the trace element values fit in typical ranges of concentrations in soils and are similar to the ones reported for rural sites in Italy or sites with no direct anthropogenic impact. Total concentrations of 2,3,7,8 chlorine substituted PCDD/Fs in superficial soils ranged between 24.4 and 1287 pg g(-1) dw (0.5-28.9 pg WHO(98)-TEQ g(-1) dw). The North Eastern part of the Province presented significantly higher levels (p<0.001) than the rest of the Province for As, Cd, Hg, Pb, Zn and PCDD/Fs. While the existence of a defined heavy metal polluting source for this specific site has been suggested, in the case of PCDD/Fs, profiles were not linked to any specific emission source fingerprint. In the whole extension of Pavia Province, OCDD/F dominated the 2,3,7,8 chlorine substituted congener soil pattern, followed by the 1,2,3,4,6,7,8 hepta-CDD/F congener. Principal Component Analysis (PCA) showed that this profile could not be associated to any described PCDD/F emission source fingerprint and was relatively similar to the baseline deposition of sites with no direct impact of PCDD/F emission sources independently of land use.     

浮萍塘中氮归趋模式模拟分析

通过模拟分析浮萍塘中氮的循环迁移过程,考察了N主要迁移途径对各形态氮的去除贡献,并确定了水环境季节变化对氮循环过程影响.模拟结果显示:浮萍塘中氮的去除主要通过硝化/反硝化作用实现,而有机氮沉降以及氨氮挥发作用对TN去除贡献仅为2.1%.浮萍塘中氨氮和硝态氮的变化主要受硝化和反硝化作用影响;有机氮主要受藻类腐败以及氨化作用影响;底泥中氮的变化主要由有机氮沉降和底泥中氮氨化过程控制.此外,浮萍塘能有效去除水体中藻类,并维持藻类的较低含量;浮萍主要通过促进硝化/反硝化速率来提高系统对TN的去除能力.     

Formation mechanisms of nitrous acid (HONO) during the haze and non-haze periods in Beijing, China

As an important precursor of hydroxyl radical (OH), nitrous acid (HONO) plays a significant role in atmospheric chemistry. Here, an observation of HONO and relevant air pollutants in an urban site of Beijing from 14 to 28 April, 2017 was performed. Two distinct peaks of HONO concentrations occurred during the observation. In contrast, the concentration of particulate matter in the first period (period Ⅰ) was significantly higher than that in the second period (period Ⅱ). Comparing to HONO sources in the two periods, we found that the direct vehicle emission was an essential source of the ambient HONO during both periods at night, especially in period Ⅱ. The heterogeneous reaction of NO₂ was the dominant source in period Ⅰ, while the homogeneous reaction of NO with OH was more critical source at night in period Ⅱ. In the daytime, the heterogeneous reaction of NO₂ was a significant source and was confirmed by the good correlation coefficients (R²) between the unknown sources (P_unknown) with NO₂, PM_2.5, NO₂ × PM_2.5 in period Ⅰ. Moreover, when solar radiation and OH radicals were considered to explore unknown sources in the daytime, the enhanced correlation of P_unknown with photolysis rate of NO₂ and OH ($J_{{\mathrm{NO}}_2}$ × OH) were 0.93 in period Ⅰ, 0.95 in period Ⅱ. These excellent correlation coefficients suggested that the unknown sources released HONO highly related to the solar radiation and the variation of OH radicals.     

数字经济何以推动乡村生态振兴？——基于中国省级面板数据的经验证据

数字经济具有生态化的本质，是提高乡村生态演进韧性、全面推进乡村振兴的关键动力。在系统梳理数字经济对乡村生态振兴影响的直接机制、中介机制基础上，本文利用2010—2020年省级面板数据，运用固定效应模型、中介效应模型等方法，多维度实证考察了数字经济对乡村生态振兴的影响机制。研究结果表明：数字经济发展显著推动了乡村生态振兴，在运用分时间段检验、剔除特殊值方法进行稳健性检验后，该结论仍然成立。数字经济发展对乡村“三生”环境的影响大小有所差异，对乡村生活绿色宜居化的影响最大，对乡村生产绿色低碳化的影响次之，对乡村生态本底品质化的影响最小。中介效应显示，农村经济增长、绿色科技创新和环境规制都是数字经济助力生态振兴的重要机制。异质性分析表明，数字经济影响乡村生态振兴的效应大小呈现出“西部>中部>东部”态势，总体上，中西部地区数字经济的绿色赋能效应更为显著。因此，应强化农村数字基础设施建设，充分发挥数字经济在农村生态经济增长点培育、企业绿色科技创新及环境监管、宣教引导等方面的作用，因地制宜以差异化的数字化策略提升赋能乡村生态振兴的有效性。