Ag_6P_2W_(18)O_(62)/TiO_2/膨胀石墨复合光催化剂的制备及甲基橙的降解

以钛酸四丁酯为钛源、膨胀石墨(EG)为载体,通过溶胶凝胶-浸渍法制备了Ag_6P_2W_(18)O_(62)/TiO_2/EG复合光催化剂。采用SEM,EDS,XRD,FTIR,UV-vis等技术对其进行表征,研究了该催化剂在紫外光及可见光下对甲基橙的降解性能。表征结果显示:Ag_6P_2W_(18)O_(62)被成功负载到TiO_2上且保持Dawson结构;经Ag_6P_2W_(18)O_(62)表面修饰后的复合光催化剂可见光吸收性能增强;EG提供的丰富孔道有利于有机污染物吸附去除。实验结果表明:在甲基橙质量浓度为20 mg/L、催化剂加入量为1.0 g/L、反应温度为25℃的条件下,n(Ag)∶n(Ti)=1∶16时的复合光催化剂(ATE-2)的紫外光、可见光催化活性最佳;紫外光下反应70 min时甲基橙去除率为96.5%,可见光下反应40 h时甲基橙去除率为83.5%;ATE-2使用5次后,反应70 min时,其甲基橙去除率仍为92.5%。     

Nitrate removal to its fate in wetland mesocosm filled with sponge iron: Impact of influent COD/N ratio

• CW-Fe allowed a high-performance of NO₃^‒-N removal at the COD/N ratio of 0. • Higher COD/N resulted in lower chem-denitrification and higher bio-denitrification. • The application of s-Fe⁰ contributed to TIN removal in wetland mesocosm. • s-Fe⁰ changed the main denitrifiers in wetland mesocosm. Sponge iron (s-Fe⁰) is a porous metal with the potential to be an electron donor for denitrification. This study aims to evaluate the feasibility of using s-Fe⁰ as the substrate of wetland mesocosms. Here, wetland mesocosms with the addition of s-Fe⁰ particles (CW-Fe) and a blank control group (CW-CK) were established. The NO₃^‒-N reduction property and water quality parameters (pH, DO, and ORP) were examined at three COD/N ratios (0, 5, and 10). Results showed that the NO₃^‒-N removal efficiencies were significantly increased by 6.6 to 58.9% in the presence of s-Fe⁰. NH₄⁺-N was mainly produced by chemical denitrification, and approximately 50% of the NO₃^‒-N was reduced to NH₄⁺-N, at the COD/ratio of 0. An increase of the influent COD/N ratio resulted in lower chemical denitrification and higher bio-denitrification. Although chemical denitrification mediated by s-Fe⁰ led to an accumulation of NH₄⁺-N at COD/N ratios of 0 and 5, the TIN removal efficiencies increased by 4.5%‒12.4%. Moreover, the effluent pH, DO, and ORP values showed a significant negative correlation with total Fe and Fe (II) (P<0.01). High-throughput sequencing analysis indicated that Trichococcus (77.2%) was the most abundant microorganism in the CW-Fe mesocosm, while Thauera, Zoogloea, and Herbaspirillum were the primary denitrifying bacteria. The denitrifiers, Simplicispira, Dechloromonas, and Denitratisoma, were the dominant bacteria for CW-CK. This study provides a valuable method and an improved understanding of NO₃^‒-N reduction characteristics of s-Fe⁰ in a wetland mesocosm.     

Surface modification of mesoporous silica nanoparticle with 4-triethoxysilylaniline to enhance seawater desalination properties of thin-film nanocomposite reverse osmosis membranes

• Mesoporous silica nanoparticle was modified with 4-triethoxysilylaniline. • AMSN-based TFN-RO membranes were prepared for seawater desalination. • Water transport capability of the AMSN was limited by polyamide. • Polyamide still plays a key role in permeability of the TFN RO membranes. Mesoporous silica nanoparticles (MSN), with higher water permeability than NaA zeolite, were used to fabricate thin-film nanocomposite (TFN) reverse osmosis (RO) membranes. However, only aminoalkyl-modified MSN and low-pressure (less than 2.1 MPa) RO membrane were investigated. In this study, aminophenyl-modified MSN (AMSN) were synthesized and used to fabricate high-pressure (5.52 MPa) RO membranes. With the increasing of AMSN dosage, the crosslinking degree of the aromatic polyamide decreased, while the hydrophilicity of the membranes increased. The membrane morphology was maintained to show a ridge-and-valley structure, with only a slight increase in membrane surface roughness. At the optimum conditions (AMSN dosage of 0.25 g/L), when compared with the pure polyamide RO membrane, the water flux of the TFN RO membrane (55.67 L/m²/h) was increased by about 21.6%, while NaCl rejection (98.97%) was slightly decreased by only 0.29%. However, the water flux of the membranes was much lower than expected. We considered that the enhancement of RO membrane permeability is attributed to the reduction of the effective thickness of the PA layer.     

放牧对祁连山高寒金露梅灌丛草甸土壤微生物的影响

以祁连山北支冷龙岭东段南麓的甘柴滩夏季牧场集体长期混合(藏系绵羊、牦牛)放牧的高寒金露梅(Potentilla fruticosa)灌丛草地为对象,采用平板涂抹分离法和氯仿熏蒸法对不同放牧压力梯度下土壤微生物(细菌、真菌和放线菌)和土壤微生物碳、微生物氮量进行研究,结果表明:不同放牧压力梯度下,金露梅灌丛和丛间草地土壤微生物以细菌占绝对优势,放线菌和真菌较少,垂直分布明显;随着放牧压力梯度的增加,金露梅灌丛和丛间草地,0～25 cm土层中的细菌、放线菌、真菌及微生物碳和微生物氮数量呈降低趋势,其降低程度与放牧压力梯度呈直线正相关.与无放牧金露梅灌丛相比0～25 cm土层的细菌、真菌、放线菌最大降幅分别为49.64%、37.76%和46.64%;金露梅灌丛土壤微生物碳量占土壤有机碳的比例变化为0.85%～0.43%,微生物氮占土壤全氮的0.90%～1.11%,微生物量对土壤营养库的贡献率较低;土壤微生物量和土壤有机质呈显著线形正相关;土壤细菌数量和土壤水分呈显著线形正相关.     

酸雨胁迫下黑壳楠Lindera megaphylla Hemsl.幼苗在夏季和秋季的生理生态特性

浙江为酸雨危害严重地区之一,而植物在酸雨胁迫下的生长和生理变化情况可以衡量其对酸雨的耐受能力,亦可作为植被引种、经营和管理的参考依据.采用盆栽法,研究了在不同季节不同强度酸雨胁迫下黑壳楠Lindera megaphylla Hemsl.的生理生态特性,设置了3个酸雨处理:重度酸雨处理(pH2.5)、中度酸雨处理(pH4.0)和酸雨对照处理(pH5.6).研究结果表明:①酸雨、季节以及酸雨和季节的交互效应对黑壳楠的株高、地径和叶绿素相对含量没有显著影响.②黑壳楠的最大净光合速率(Amax)、表观量子效率(AQE)、光补偿点(LCP)和暗呼吸速率(Rd)对酸雨胁迫敏感,而季节并未显著影响到植物的光合特性.③酸雨胁迫显著影响黑壳楠的气孔导度(Gs)、蒸腾速率(Tr)和水分利用效率(WUE).季节对黑壳楠的蒸腾速率(Tr)和水分利用效率(WUE)影响显著.酸雨和季节的交互效应极显著影响到植物的胞间CO2(Ci)浓度和蒸腾速率(Tr).研究表明夏季黑石楠受酸雨胁迫的影响比秋季严重.重度酸雨胁迫严重影响到黑壳楠的生理生长,在酸雨危害严重地区如浙江不适宜大量种植黑壳楠.     

重庆市男性PAHs和PAEs暴露与男性精液质量的相关性分析

多环芳烃(polycyclic aromatic hydrocarbons,PAHs)和邻苯二甲酸酯(phthalate esters,PAEs)是三峡库区水中主要有机污染物。为探讨这2类化学物对三峡库区男性精液质量的影响,课题组于2007年在三峡库区6个区县进行了男性生殖健康的流行病学调查。调查中共收集到有效样本1 346例,对所有样本进行了精液常规检测,选取了冬季采样的232例标本进行了尿液中4种PAHs代谢产物和5种PAEs代谢产物含量的检测,并对这些样本的精子细胞凋亡(Annexin V/PI双标法)和精子脱氧核醣核酸(DNA)损伤(彗星电泳法)进行了检测。运用Spearman等级相关,多元线性回归和logisitic回归分析等方法分析了PAHs和PAEs代谢产物与精液常规指标、精子细胞凋亡、精子DNA损伤的相关关系。结果显示,1 346名三峡库区健康男性精液常规5项指标全部达到世界卫生组织(WHO)标准的比率仅为38.9%。PAHs代谢产物的含量与男性精液常规指标间未发现相关关系,但某些PAHs代谢产物水平与精子凋亡参数及精子DNA损伤指标有一定的关联性,随着尿中PAHs代谢产物浓度的增加,正常未发生凋亡的精子减少,精子DNA的损伤增加。未发现PAEs代谢产物与精液各项参数间的相关关系。本研究结果表明,在重庆市健康育龄男性中PAHs与PAEs的暴露与精液常规指标间没有明确的相关关系,但PAHs暴露与精子DNA损伤显著相关。为明确PAHs的暴露对精子DNA的损伤作用,有必要进行较大规模的队列研究以进行验证。     

紧急启动及停炉后增压锅炉热防护砖衬结构的强度分析

针对船用增压锅炉在频繁启、停炉过程中,热防护砖衬结构中的耐火材料易出现的断裂、脱落等问题,采用有限元分析法对热防护砖衬结构进行强度校核,分析出现损伤的结构部件及耐火材料发生断裂的原因,对增压锅炉的安全使用与预防损坏具有一定的参考意义。     

消防员地震救援防护头盔的研制

本文通过对消防员地震救援过程中防护头盔的功能分析,提出了救援头盔的设计思路和需要实现的技术指标,从而为研制地震救援用防护头盔提供依据。     

超声处理后剩余污泥性质变化及分析

主要研究超声处理后剩余污泥性质的变化,探讨了污泥上清液中SCOD、BOD、TN、TP以及污泥耗氧速率OUR等随超声时间和声能密度的变化,尤其是对进一步的污泥处理处置的影响进行分析。研究表明,超声处理后的污泥结合到污水处理工艺中可以实现污泥隐性生长而达到污泥减量的目的;或者为污泥进一步处理处置提供了有利条件。     

Source emissions and climate change impacts on the multimedia transport and fate of persistent organic pollutants, Chaohu watershed, eastern China

Emission intensity and climate change control the transport flux and fate of persistent organic pollutants (POPs) in multiple environmental compartments. This study applied a multimedia model (BETR model) to explore alternations in the spatio-temporal trends of concentrations and transport flux of benzopyrene (BaP), phenanthrene (Phe), perfluorooctane sulfonates (PFOS) and polychlorinated biphenyls (PCBs) in the Chaohu watershed, located in the lower reaches of the Yangtze River, China in response to changes in source emissions and climate. The potential historic and future risks of these pollutants also were assessed. The results suggest that current trends in concentrations and transport were similar to that of their emissions between 2005 and 2018. During the next 100 years, temporal trends and spatial patterns were not predicted to change significantly, which is consistent with climate change. Based on sensitivity and correlation analyses, climate change had significant effects on multi-media concentrations and transport fluxes of BaP, Phe, PFOS and PCBs, and rainfall intensity was the predominant controlling factor. Risk quotients (RQs) of BaP and Phe-in soil increased from 0.42 to 0.95 and 0.06 to 0.35, respectively, from 2005 to 2090, indicating potential risks. The RQs of the other examined contaminants exhibited little potential risk in soil, water, or sediment. Based on spatial patterns, it was inferred that the ecosystem around Lake Chaohu is the most at risk. The study provides insights needed for local pollution control of POPs in the Chaohu watershed. In addition, the developed approach can be applied to other watersheds world-wide.