Flow and transport in fractured tuff at Yucca Mountain: numerical experiments on fast preferential flow mechanisms

Recent discovery of bomb-related ³⁶Cl at depth in fractured tuff in the unsaturated zone at the Yucca Mountain candidate high-level waste (HLW) repository site has called into question the usual modeling assumptions based on the equivalent continuum model (ECM). A dual continuum model (DCM) for simulating transient flow and transport at Yucca Mountain is developed. In order to ensure properly converged flow solutions, which are used in the transport simulation, a new flow solution convergence criteria is derived. An extensive series of simulation studies is presented which indicates that rapid movement of solute through the fractures will not occur unless there are intense episodic infiltration events. Movement of solute in the environs of the repository is enhanced if the properties of the tuff layer at the repository horizon are modified from current best-estimate values. Due to a large advective–dispersive coupling between the matrix and fractures, the matrix acts as a major buffer which inhibits rapid transport along the fractures. Consequently, fast movement of solutes through the fractures to the repository depth can only be explained if the matrix–fracture coupling term is significantly reduced from a value that would be calculated on the basis of data currently available.     

Bacteria inactivation by sulfate radical: progress and non-negligible disinfection by-products

● Status of inactivation of pathogenic microorganisms by SO₄^•− is reviewed. ● Mechanism of SO₄^•− disinfection is outlined. ● Possible generation of DBPs during disinfection using SO₄^•− is discussed. ● Possible problems and challenges of using SO₄^•− for disinfection are presented. Sulfate radicals have been increasingly used for the pathogen inactivation due to their strong redox ability and high selectivity for electron-rich species in the last decade. The application of sulfate radicals in water disinfection has become a very promising technology. However, there is currently a lack of reviews of sulfate radicals inactivated pathogenic microorganisms. At the same time, less attention has been paid to disinfection by-products produced by the use of sulfate radicals to inactivate microorganisms. This paper begins with a brief overview of sulfate radicals’ properties. Then, the progress in water disinfection by sulfate radicals is summarized. The mechanism and inactivation kinetics of inactivating microorganisms are briefly described. After that, the disinfection by-products produced by reactions of sulfate radicals with chlorine, bromine, iodide ions and organic halogens in water are also discussed. In response to these possible challenges, this article concludes with some specific solutions and future research directions.     

Genome-resolved metagenomic analysis reveals different functional potentials of multiple Candidatus Brocadia species in a full-scale swine wastewater treatment system

● Four Ca. Brocadia species were observed during the spontaneously enrichment. ● Novel anammox species SW510 and SW773 dominated the full-scale ecosystem. ● Urease and cyanase genes were detected in the new anammox genomes. ● Functional differentiation potentially facilitated co-occurrence of anammox species. The increasing application of anammox processes suggests their enormous potential for nitrogen removal in wastewater treatment facilities. However, the functional potentials and ecological differentiation of cooccurring anammox species in complex ecosystems have not been well elucidated. Herein, by utilizing functional reconstruction and comparative genome analysis, we deciphered the cooccurring mechanisms of four Candidatus Brocadia species that were spontaneously enriched in a full-scale swine wastewater treatment system. Phylogenetic analysis indicated that species SW172 and SW745 were closely related to Ca. Brocadia caroliniensis and Ca. Brocadia sapporoensis, respectively, whereas the dominant species SW510 and SW773, with a total average abundance of 34.1%, were classified as novel species of the genus Ca. Brocadia. Functional reconstruction revealed that the novel species SW510 can encode both cytochrome cd₁-type nitrite reductase and hydroxylamine oxidase for nitrite reduction. In contrast, the detected respiratory pentaheme cytochrome c nitrite reductase and acetate kinase genes suggested that SW773 likely reduced nitrite to ammonium with acetate as a carbon source. Intriguingly, the presence of genes encoding urease and cyanase indicated that both novel species can use diverse organic nitrogen compounds in addition to ammonia and nitrite as substrates. Taken together, the recovery and comparative analysis of these anammox genomes expand our understanding of the functional differentiation and cooccurrence of the genus Ca. Brocadia in wastewater treatment systems.     

农药在土壤－水环境中归宿的主要支配因素──吸附和脱附

综述了近年来农药在土壤－水环境中吸附－脱附研究的实验方法、影响因素、数学描述、作用机理等方面的工作。重点讨论了农药与土壤粘土矿物、有机物（腐殖酸、富菲酸等）的物理化学键合机理。     

环境毒物检测方法──细菌培养顶空气相色谱法及其应用研究

用顶空气相色谱技术测定环境毒物对大肠杆菌（Ｅ．Ｃｏｌｉ）代谢产物ＣＯ２的抑制程度,以ＩＣ５０（５０％抑制浓度）判断毒性大小,旨在探索一种快速检测环境污染物毒性的方法。本试验选择最佳条件为;细菌浓度１０９个／ｍｌ,ｐＨ值７２—７．４,顶空管气液比１：２．５,培养４ｈ,以及适宜的ＣＯ２测定色谱条件。用该方法检测８种离子毒性,ＩＣ５０值顺序为Ｈｇ２＋（０．８６×１０—６）＞Ｃｕ２＋（８．００×１０—６）＞Ｃｄ２＋（８．３９×１０－６）＞ＣＮ－（１０．２０×１０－６）＞Ｐｂ２＋（１１．２０×１０－６）＞Ｓｎ２＋（２０．１０×１０－６）＞Ｎｉ２＋（３９．７０×１０－６）;研究了Ｃｄ２＋、Ｈｇ２＋、Ｃｕ２＋、Ｚｎ２＋和ＣＮ－５种离子间联合毒性作用,大多数表现为相加作用,也有协同和拮抗作用;芳香族化合物结构活性与毒性两者间有密切关系,取代基种类和数目不同,毒性各异;探讨硝基废水处理过程中毒性随硝基苯类化合物的浓度、ＣＯＤ值降低而减弱。     

Sensitized effect of β-cyclodextrin on the fluorescence in the determination of carbaryl

Based on the significant enhancement of fluorescence intensity of carbaryl in inclusion complex, a spetrofluorimetric method with high sensitivity was developed for the determination of carbaryl in aqueous solution. Under the optimum conditions, the complex had excitation and emission maxima at 278 nm and 332 nm, respectively. The linear range of the method was 7.0 ng/ml-1500 ng/ml with a detection limit of 1.2 ng/ml. The proposed method was successfully used to determine quantitatively of carbaryl in cottonseeds.     

含氟有机化合物的生态迁移及转化

含氟有机化合物的众多特性使得其在各方面得到越来越广泛的应用,同时也成为了一种较普遍的环境污染物。本文列举了含氟有机化合物的应用类型及相应的应用特点;指明其污染途径和毒性特征;从含氟有机物的分子结构特征、降解茵的类型、外部因素三方面阐明了其生物降解特性;总结了酶作用于碳氟键使得含氟有机物发生降解的四种作用;并介绍了含氟有机污染物的生物处理和生态修复的一般方法。     

微系统人机界面的安全信息流模型构建及其应用

为提高系统安全水平,进一步丰富安全系统学理论内容,对微系统内人机界面的安全信息流过程、模型及其应用进行深入研究。论述安全信息流与人机交互过程理论,为模型构建奠定理论基础;运用安全模型原理,从信息传播角度建立人机界面的安全信息流模型并分析模型的内涵和意义;将所建模型应用于具体情景的仿真模拟,以验证其适用性和合理性。研究结果表明:模型刻画了系统内安全信息流动轨迹,有利于揭示系统安全演化行为机理,对提高系统安全水平具有重要的理论指导意义。     

The secret life of pets: The intersection of animals and organizational life

Although often overlooked, pets and other animals intersect with organizations in interesting, important ways. We seek to define how various animals intersect with organizations, highlight opportunities for theory development, and illustrate important areas for future research. We also explore how pandemics such as COVID-19 might affect the animals we highlight.     

On a combined theory of pay level satisfaction

For decades, research on pay level satisfaction has focused on two theories and one approach: the direct link theory, the discrepancy theory, and the no‐difference‐scores approach. However, there are still unsolved puzzles facing pay level satisfaction research. We develop a combined theory to consider the impact of the interaction of reported pay and pay discrepancy. With this newly developed theory, we expect that (a) both reported pay and pay discrepancy have main effects on pay level satisfaction; (b) reported pay and pay discrepancy also interact with each other, in that the effect of pay discrepancy on pay level satisfaction decreases as pay level increases; (c) equitable payment is more related to pay level dissatisfaction when pay level is low; and (d) overpayment in general is related to pay level satisfaction, not dissatisfaction. An empirical study (N = 481) using four types of comparison standards was conducted, and the results supported our predictions. The findings of our study have important implications for both academic research and management practice.