空分主冷凝蒸发器爆炸的故障树分析

基于故障树分析的方法,结合大量国内外曾发生的事故,以空分主冷凝爆炸事故为顶事件,采用布尔代数运算法则求解,得到8个最小割集,通过比较结构重要度得出控制系统失效和液氧排放不连续这两个基本事件的重要度最大,即控制系统失效和液氧排放不连续在故障树结构中对顶事件发生的影响程度最大.因此,为了防止主冷爆炸的发生,要连续排放一定量的液氧,且控制系统监控的准确性也是非常重要的.     

Distribution of polychlorinated biphenyls in effluent from a large municipal wastewater treatment plant: Potential for bioremediation?

This study involved an evaluation of the potential for bioremediation of polychlorinated biphenyls(PCBs) in the effluent from a large municipal wastewater treatment plant. It was focused on the presence of PCBs in two types of effluents: the continuous effluent present during dry weather conditions and the intermittently present effluent that was present during wet weather due to incoming stormwater. The annual discharge of PCBs for both types of effluent was calculated based on a five-year dataset(2011–2015). In addition, the toxicity and bioremediation potential of the PCBs in the effluent were also assessed. It was found that the continuous effluent was responsible for the majority of the discharged PCB into the receiving river(1821 g for five years), while the intermittent effluent contributed 260 g over the five years.The average number of chlorine per biphenyl for the detected PCB congeners showed a 19%difference between the two types of effluent, which indicated a potential for organohalide respiration of PCBs during the continuous treatment. This was further supported by a high level of tri-, tetra-and penta-chlorinated congeners accounting for 75% of the anaerobically respired PCBs. Potential for aerobic degradation and thus biomineralization of PCBs was identified for both effluents. Furthermore, toxicity of 12 dioxin-like PCBs showed that normal operation of the wastewater reduced the toxicity throughout the wastewater treatment plant.     

三峡库区(重庆段)菜地土壤重金属污染特征、潜在生态风险评估及源解析

为探究三峡库区菜地土壤重金属的污染特征、潜在生态风险和污染物的来源,于2021年10月采集了库区（重庆段）14个蔬菜种植区（县）菜地的表层土壤样品,分析了样本中7种重金属元素（As、Cd、Cr、Cu、Ni、Pb和Zn）的含量,分别利用单因子指数法、内梅罗综合污染指数法和潜在生态风险评价法对土壤重金属的富集状况和潜在风险进行了评估,并分析了蔬菜种植年限和栽培方式（露天和大棚）对土壤重金属累积的影响.结果表明,库区菜地土壤中重金属的含量高于重庆市三峡库区土壤背景值,但均低于《农用地土壤污染风险管控标准（试行）》（GB 15618-2018）规定的土壤污染风险管制值;单因子污染评价结果表明,区域土壤Pb、Zn、Cu和Cd处于轻微污染水平;内梅罗综合污染指数法表明,研究区处于轻度污染水平,主要污染因子为Cd和Ni,有91.4%的土壤样品存在不同程度的污染（P_N>1）,其中9.19%的样品处于重度污染;潜在生态风险评估结果指出,研究区以轻度生态风险为主,Cd中度生态风险的土壤样本数占比为9.77%,存在一定的生态风险.聚类分析结果显示Cd-Cu-Pb-Zn和As-Cr-Ni分别具有相同的污染源.菜地土壤中重金属含量随着种植年限的增加均呈上升趋势;总体上大棚土壤中重金属含量均高于露天菜地土壤.     

NaHCO3活化荞麦皮生物炭对碘帕醇的吸附

采用NaHCO₃活化荞麦皮生物炭,优化得到生物炭0.25N-BC[m（NaHCO₃）：m（荞麦皮）=0.25：1],通过SEM、BET、XRD、Raman、FTIR和XPS等方法进行表征,分析NaHCO₃对生物炭理化性质的影响,探究其对非离子型碘代X射线造影剂碘帕醇（IPM）的吸附性能和机制.结果表明,与荞麦皮生物炭相比（BC）,NaHCO₃活化生物炭的结构缺陷程度更高（比表面积和孔体积分别由480.40 m²·g^-1和0.29 cm³·g^-1增至572.83 m²·g^-1和0.40 cm³·g^-1,I_D/I_G是BC的1.22倍）,表面含碳和含氧官能团数量发生显著变化,极性增强[（N+O）/C由0.15增至0.24],能够有效吸附IPM,0.25N-BC对IPM最大吸附量达到74.94 mg·g^-1,是BC （7.88 mg·g^-1）的9.51倍.拟二级吸附动力学和Langmuir、Freundlich等温线模型可很好地拟合0.25N-BC对IPM的吸附,吸附过程主要以化学吸附和单层、非均质多层吸附为主;孔隙填充、氢键、π—π和n—π相互作用是0.25N-BC吸附IPM的主要机制.对比不同碱[KOH、Na₂CO₃、NaHCO₃、KHCO₃和Ca （HCO₃）₂]活化荞麦皮生物炭对IPM的吸附,0.25N-BC吸附效率高,达到吸附平衡时间短,能有效去除实际水体（二沉池出水和湖水）中IPM的残留,并具有良好的循环使用性能,吸附-解吸3次后对IPM的去除率仍保持在74.91%.研究表明NaHCO₃活化荞麦皮生物炭是一种绿色有效,可持续去除含碘有机物的优良吸附剂.     

Simple fabrication of carboxymethyl cellulose and κ-carrageenan composite aerogel with efficient performance in removal of fluoroquinolone antibiotics from water

● A composite aerogel was simply obtained to remove various fluoroquinolones (FQs). ● The structural and textural properties of this composite aerogel are improved. ● Its adsorption capacity was improved at a low content of coexisting Cu²⁺ or Fe³⁺ ion. ● Two substructural analogs of FQs are compared to explore the adsorption mechanisms. ● This aerogel after saturated adsorption can be reused directly for Cu²⁺ adsorption. 3D composite aerogels (CMC-CG) composed of carboxymethyl cellulose and κ-carrageenan were designed and fabricated using the one-pot synthesis technique. The optimized CMC-CG showed a good mechanical property and a high swelling ratio due to its superior textural properties with a proper chemically cross-linked interpenetrating network structure. CMC-CG was utilized for the removal of various fluoroquinolones (FQs) from water and exhibited high adsorption performance because of effective electrostatic attraction and hydrogen bonding interactions. Ciprofloxacin (CIP), a popular FQ, was used as the representative. The optimized CMC-CG had a theoretically maximal CIP uptake of approximately 1.271 mmol/g at the pH of 5.0. The adsorption capacity of CMC-CG was improved in the presence of some cations, Cu²⁺ and Fe³⁺ ions, at a low concentration through the bridging effect but was reduced at a high concentration. The investigation of adsorption mechanisms, based on the adsorption kinetics, isotherms and thermodynamic study, Fourier transform infrared spectrometry and X-ray photoelectron spectroscopy analyses before and after adsorption, and changes in the adsorption performance of CMC-CG toward two molecular probes, further indicated that electrostatic attraction was the dominant interaction rather than hydrogen bonding in this adsorption. CMC-CG after saturated adsorption of CIP could be easily regenerated using a dilute NaCl aqueous solution and reused efficiently. Moreover, the disused aerogel could still be reused as a new adsorbent for effective adsorption of Cu²⁺ ion. Overall, this study suggested the promising applications of this composite aerogel as an eco-friendly, cost-effective, and recyclable adsorbent for the efficient removal of FQs from water.     

多灾耦合作用下钢管混凝土柱承载性能研究进展∗

钢管混凝土因其优良的力学性能被广泛应用于工程结构中,而实际工程中,钢管混凝土柱并非承受单一荷载,也可能同时遭受腐蚀、冻融、火灾、撞击和地震等多重灾害的耦合作用。为进一步了解多灾耦合作用下钢管混凝土柱受力性质的改变,分析耦合作用机理,避免相关作用对结构长期使用下性能的影响,围绕国内外钢管混凝土研究进展,对钢管混凝土柱在耦合作用下的承载性能进行总结和分析,为相关研究和实际工程应用提供参考。研究结果表明,钢管混凝土柱具有良好受压和抗冲击性能,但抵抗腐蚀、冻融循环和火灾的能力稍弱;在多灾耦合作用下,钢管混凝土柱的各项承载性能表现出不同程度的退化,包括承载力、刚度、延性等;在腐蚀(火灾)?地震耦合作用下,试件的抗震性能存在轻微下降,但滞回曲线较为饱满,整体抗震性能良好;在压?弯?剪(扭)复合荷载作用下, 轴压比和剪跨比对钢管混凝土柱的破坏形态和承载性能影响较为显著。虽然有关钢管混凝土的研究取得了丰硕的研究成果,但在足尺试件性能、标准试验方法和精细化分析模型等方面的研究还有待加强。     

离子类型、强度和铁氧化物影响下微塑料的迁移行为及模型计算

土壤中的微塑料（MPs）作为一种新型污染物而被广泛关注,其迁移行为受到自身理化性质、土壤溶液化学组成和土壤矿物等因素的影响.目前,铁氧化物存在时,离子类型和离子强度对MPs迁移行为的影响机制尚不明确.通过稳定性实验和迁移实验,重点考察了离子类型、离子强度和铁氧化物对带有不同官能团聚苯乙烯微塑料（PSMPs）迁移行为的影响,并用胶体迁移模型、CD-MUSIC模型及DLVO理论探讨其迁移机制.结果表明,PSMPs在NaH₂PO₄背景下的稳定性最强,标准化浓度（c/c₀）达到0.99,而在CaCl₂背景下的稳定性相对弱,c/c₀降低至0.94.不同离子种类对PSMPs的迁移行为产生不同影响,对于阳离子Na⁺和Ca²⁺,二价Ca离子有架桥作用和较强的电荷中和作用,更能阻滞PSMPs在石英砂中的迁移,出水溶液中PSMPs回收率低至（43.83±1.71）%且第二动力学位点上的一级保留系数k_2a为1.54 min^-1,铁氧化物会进一步加剧阻滞作用,回收率降低为（6.04±0.40）%且k_2a升高为5.33 min^-1;对于阴离子Cl^-和PO₄^3-,PSMPs在纯石英砂柱中的迁移主要受其自身表面电负性的控制,Cl^-离子下PSMPs电负性更低,回收率升高［（92.95±0.63）%］且k_2a降低（0.19 min^-1）,而当铁氧化物存在时,PSMPs的迁移则受控于载铁石英砂表面的Zeta电位.CD-MUSIC模型计算结果显示PO₄^3-容易吸附在铁氧化物表面形成内圈络合物,降低载铁石英砂表面的电负性,因此PSMPs在PO₄^3-背景下的回收率升高［（76.22±1.39）%］且k_2a降低（0.66 min^-1）;同时,该内圈络合物的形态受PO₄^3-浓度的控制且不同形态的内圈络合物具有不同的表面负电荷数,因此高PO₄^3-浓度下载铁石英砂表面电负性反而高,不利于PSMPs迁移.此外,PSMPs的迁移均随着离子强度的增加而降低.最后,DLVO理论计算出不同条件下PSMPs和介质间的一级势垒变化趋势与PSMPs的迁移能力一致,即较高的一级势垒表明PSMPs和介质间较大的相互斥力有利于PSMPs的迁移,可以更好地阐明PSMPs的迁移行为.     

A lab-scale study on heterotrophic nitrification-aerobic denitrification for nitrogen control in aquatic ecosystem

Environmental Science and Pollution Research - Nitrogen (N) loss is generally caused by denitrification under anaerobic conditions and the N loss in the heterotrophic nitrification_aerobic...     

大空间建筑内火灾烟气充填的研究

对烟气在大空间建筑内的充填规律作了分析，并在中国科技大学与香港理工大学合建的大空 间火灾实验厅内进行了若干轮试验。结果表明，在着火的初期阶段，大厅上部的烟气流动比较紊 乱，但在以后的大部分时间，烟气的充填过程仍可用火灾区域模拟方法计算。     

Exploring the Use of Online Platforms for Climate Change Policy and Public Engagement by NGOs in Latin America

The engagement of environmental non-governmental groups in collaborative communication efforts and decision-making about climate change remains a significant challenge. In Latin America, the website Intercambio Climático was set up to attempt to play a breakthrough role in the region's discussion of climate change. This case study focuses on the development, accomplishments, and challenges of this unique online communication initiative among non-governmental organizations working in climate change issues in Latin America with a US-based partner, as a vehicle to achieve their goals. We used secondary data and in-depth interviews to examine this platform's role in disseminating information and influencing decision-making. The results suggest that generally the participants perceive the website positively, but there are also problematic aspects of the collaboration that are not fully recognized by the members, which prevents a more functional and effective communication strategy.