黄河三角洲滨海湿地的维管束植物区系特征

在2007-2008年多次实地调查并参照相关资料基础上,对黄河三角洲滨海湿地进行了植被类型划分和湿地维管束植物生态类群、生活型划分,利用统计方法分析了研究区湿地维管束植物区系的科、属构成,地理分布区成分构成.研究表明,黄河三角洲滨海湿地有71科、199属、298种维管束植物,蓼科、藜科、苋科、豆科、菊科、禾本科、莎草科等7个大科为区系主体,上述7科共76属128种,占总属数的39.38%和总种数的43.99%;区系中单种属多,属的分化程度较高.区系中有59种盐生植物、46种水生植物、44种湿生植物、144种中生植物、7种旱生植物,水生植物、湿生植物的生活型以地面芽植物、地下芽植物为主,陆地中生植物、盐生植物的生活型以一年生植物为主.从分布区类型构成来看,区系中蕨类植物区域分布成分较多,种子植物中温带分布属最多,这反映出湿地植被具有一定的地带性特征,种子植物中热带分布属、世界分布属较多分别表明海洋性气候对湿地植被特征的影响及湿地植被的隐域性特征.     

微波催化燃烧技术处理印刷包装行业VOCs

微波催化燃烧技术将微波辐照与吸波型催化剂相结合,可用于对挥发性有机化合物(VOCs)进行催化燃烧处置.研制了 Pt/CuMnCeOx/堇青石和Pt/CuMnCeOx/纳米陶瓷整体式蜂窝状催化剂,并开发了微波催化燃烧VOCs的装置,将其应用于印刷包装行业的VOCs治理.通过操作条件的优化,考察了微波催化燃烧技术对VOCs...     

Inhibition of bromate formation by reduced graphene oxide supported cerium dioxide during ozonation of bromide-containing water

GO or RGO promotes bromate formation during ozonation of bromide-containing water. CeO₂/RGO significantly inhibits bromate formation compared to RGO during ozonation. CeO₂/RGO shows an enhancement on DEET degradation efficiency during ozonation. Ozone (O₃) is widely used in drinking water disinfection and wastewater treatment. However, when applied to bromide-containing water, ozone induces the formation of bromate, which is carcinogenic. Our previous study found that graphene oxide (GO) can enhance the degradation efficiency of micropollutants during ozonation. However, in this study, GO was found to promote bromate formation during ozonation of bromide-containing waters, with bromate yields from the O₃/GO process more than twice those obtained using ozone alone. The promoted bromate formation was attributed to increased hydroxyl radical production, as confirmed by the significant reduction (almost 75%) in bromate yield after adding t-butanol (TBA). Cerium oxide (less than 5 mg/L) supported on reduced GO (xCeO₂/RGO) significantly inhibited bromate formation during ozonation compared with reduced GO alone, and the optimal Ce atomic percentage (x) was determined to be 0.36%, achieving an inhibition rate of approximately 73%. Fourier transform infrared (FT-IR) spectra indicated the transformation of GO into RGO after hydrothermal treatment, and transmission electron microscope (TEM) results showed that CeO₂ nanoparticles were well dispersed on the RGO surface. The X-ray photoelectron spectroscopy (XPS) spectra results demonstrated that the Ce³⁺/Ce⁴⁺ ratio in xCeO₂/RGO was almost 3‒4 times higher than that in pure CeO₂, which might be attributed to the charge transfer effect from GO to CeO₂. Furthermore, Ce³⁺ on the xCeO₂/RGO surface could quench Br⋅ and BrO⋅ to further inhibit bromate formation. Meanwhile, 0.36CeO₂/RGO could also enhance the degradation efficiency of N,N-diethyl-m-toluamide (DEET) in synthetic and reclaimed water during ozonation.     

3种抗生素对黑麦草种子萌发的生态毒性效应

为探明四环素、环丙沙星和磺胺嘧啶3种抗生素对黑麦草种子萌发的影响,为评价抗生素污染的生态影响提供科学依据,采用保湿培养法研究了它们对黑麦草种子萌发的影响,比较分析了抗生素的生态毒性差异和相对敏感的指标。结果表明,在种子萌发期,一定浓度范围的抗生素胁迫会引发植物种子抵抗逆境的应激反应,因此,3种抗生素在1 mg·L~(-1)处理水平下均能促进种子发芽。超过该浓度,四环素对黑麦草种子发芽仍有一定的促进作用,而环丙沙星和磺胺嘧啶则表现为抑制作用。四环素对种子发芽率的最大无作用浓度(NOEC)为5 mg·L~(-1),而环丙沙星和磺胺嘧啶对种子发芽率的NOEC为1 mg·L~(-1)。实验结束时,3种抗生素在1 mg·L~(-1)处理水平下的种子发芽率最高。3种抗生素浓度超过0.1 mg·L~(-1)时,种子根长和芽长即受到抑制,因此,它们对种子根长和芽长的NOEC均为0～0.1 mg·L~(-1)。其中,磺胺嘧啶的抑制作用最为显著。根长受到抑制的程度强于芽长。黑麦草种子萌发受3种抗生素影响程度依次为磺胺嘧啶环丙沙星四环素。     

基于模糊数学的火灾安全综合评价模型及应用

火灾每年给我国带来巨大的经济损失和人员伤亡,甚至造成严重的社会影响。基于模糊数学理论和综合评价模型的建模方法,给出火灾危险性的安全综合评价模型,由应用结果可看出该模型简单、易懂,应用方便。对企业的火灾危险性评价可以起到预防火灾的作用。     

典型喀斯特高原水库浮游植物与环境因子的关系

浮游植物的生长往往受多种环境因素共同作用,独特的地理特征也是影响其密度与群落结构变化的要素之一。为探索喀斯特高原水库浮游植物与环境因子的耦合关系,以贵州省典型喀斯特高原水库——阿哈水库为例,于2019年春(4月)、夏(7月)、秋季(10月)对水库各支流及库中心区域进行采样调查,探究了喀斯特水库基础水环境指标的量级、浮游植物群落组成、优势种变化及其密度的时空分布,进一步揭示浮游植物与环境因子的耦合关系,为喀斯特高原水库浮游植物研究以及水资源保护提供一定的科学依据。结果显示,阿哈水库浮游植物密度在3.95×10⁴-525.35×10⁴cells·L^?1,之间,以蓝藻、硅藻、绿藻、隐藻居多,伪鱼腥藻(Pseudoanabaena sp.)、水华束丝藻(Aphanizomenon flos-aquae)为主要优势种。单因素方差分析(One-way ANOVA)结果表明,浮游植物密度的季节性差异显著(P<0.01),呈夏季>春季>秋季的趋势。由一元线性回归分析可知,在春季,浮游植物密度与溶解氧、pH、钙离子浓度呈极显著线性相关(P<0.01),与透明度、氮磷比具有显著相关关系(P<0.05);然而,浮游植物密度仅与夏季的透明度关系显著(P<0.05),与秋季的所有环境因子均无显著相关关系(P>0.05)。由冗余分析(RDA)可知,影响春季浮游植物群落结构的主要环境因子为pH、钙离子浓度和总磷,夏季为透明度、总磷和氮磷比。秋季浮游植物群落结构可能受低温影响较大。     

Electro-catalytic activity of CeOx modified graphite felt for carbamazepine degradation via E-peroxone process

•CeO_x/GF-EP process had the better degradation efficiency than GF-EP process. •CeO_x/GF-EP process had the flexible application in the pH range from 5.0 to 9.0. •CeO_x could enhance surface hydrophilicity and reduce the charge-transfer resistance. •The interfacial electron transfer process was revealed. E-peroxone (EP) was one of the most attractive AOPs for removing refractory organic compounds from water, but the high energy consumption for in situ generating H₂O₂ and its low reaction efficiency for activating O₃ under acidic conditions made the obstacles for its practical application. In this study, cerium oxide was loaded on the surface of graphite felt (GF) by the hydrothermal method to construct the efficient electrode (CeO_x/GF) for mineralizing carbamazepine (CBZ) via EP process. CeO_x/GF was an efficient cathode, which led to 69.4% TOC removal in CeO_x/GF-EP process with current intensity of 10 mA in 60 min. Moreover, CeO_x/GF had the flexible application in the pH range from 5.0 to 9.0, TOC removal had no obvious decline with decrease of pH. Comparative characterizations showed that CeO_x could enhance surface hydrophilicity and reduce the charge-transfer resistance of GF. About 5.4 mg/L H₂O₂ generated in CeO_x/GF-EP process, which was 2.1 times as that in GF-EP process. The greater ozone utility was also found in CeO_x/GF-EP process. More O₃ was activated into hydroxyl radicals, which accounted for the mineralization of CBZ. An interfacial electron transfer process was revealed, which involved the function of oxygen vacancies and Ce³⁺/Ce⁴⁺ redox cycle. CeO_x/GF had the good recycling property in fifth times’ use.     

Using T-RFLP technology to analyze bacterial diversity in the rhizospheric soils of tea tree at different ages北大核心CSCD

The rhizospheric soils of Tieguanyin at different ages were used as the study materials, and terminal-restriction fragment length polymorphism (T-RFLP) was used to analyze the changes in bacterial diversity. The results showed that the number of T-RFs, Simpson index, and Shannon index decreased significantly with the age of the tea tree. Results of correlation analysis showed that 9 T-RFs from the bacterial community were significantly and positively correlated with the age of the tea tree, and included 34 species of microbes belonging to 10 classes. The 34 microbes were divided into 6 types according to their functional attributes, and included pathogenic bacteria, bacteria that improved soil texture or inhibited pathogenic bacteria, and bacteria associated with the carbon, nitrogen, or sulfur cycles, in which the percentage of pathogenic bacteria was 58.82%. Seventeen T-RFs were significantly and negatively correlated with the age of the tea tree, and included 38 species of bacteria belonging to 12 classes. The 38 bacterial species were divided into 5 types according to their functional attributes, and included pathogenic bacteria, bacteria that improved soil quality or inhibited pathogenic bacteria, and bacteria associated with the carbon cycle or nitrogen cycle, in which all the others, barring the pathogenic bacteria, accounted for 78.95% of the bacterial population. In brief, the diversity and function of bacteria in the rhizospheric soil of tea tree changed significantly with the age of the tea tree, which provides a theoretical basis for studying the interactions of bacterial communities. © 2018 Science Press. All rights reserved.     

A non-negative and high-resolution finite volume method for the depth-integrated solute transport equation using an unstructured triangular mesh

This paper proposes a new high-resolution finite volume method for solving the two-dimensional (2D) solute transport equation using an unstructured mesh. A new simple r-factor algorithm is introduced into the Total Variation Diminishing flux limiter to achieve a more efficient yet accurate high-resolution scheme for solving the advection term. To avoid the physically-meaningless negative solutions resulted from using the Green–Gauss theorem, a nonlinear two-point flux approximation scheme is adopted to deal with the anisotropic diffusion term. The developed method can be readily coupled with a two-dimensional finite-volume-based flow models under unstructured triangular mesh. By integrating with the ELCIRC flow model, the proposed method was verified using three idealized benchmark cases (i.e., advection of a circle-shaped solute field, advection in a cyclogenesis flow field and transport of a initially square-shaped solute plume), and further applied to simulate the non-reactive solute transport process driven by irregular tides in the Deep Bay, eastern Pearl River Estuary of China. These cases are also simulated by models using other existing methods, including different r-factor for advection term and the Green–Gauss theorem for diffusion term. The comparison between the results from the new method and those from other existing methods demonstrated the new method could describe advection induced concentration shock and discontinuities, and anisotropic diffusion at high resolution without providing spurious oscillations and negative values.