Identification of sources,characteristics and photochemical transformations of dissolved organic matter with EEM-PARAFAC in the Wei River of China

• The source of DOM in surface water and sediment is inconsistent. • The DOC content changes differently in surface water and sediment. • The content of DOC in the surface water is lower than that in the sediment. • The DOM in the surface water had higher photodegradation potentials than sediment. Dissolved organic matter (DOM) in rivers is a critical regulator of the cycling and toxicity of pollutants and the behavior of DOM is a key indicator for the health of the environment. We investigated the sources and characteristics of DOM in surface water and sediment samples of the Wei River, China. Dissolved organic carbon (DOC) concentration and ultraviolet absorbance at 254 nm (UV₂₅₄) increased in the surface water and were decreased in the sediment downstream, indicating that the source of DOM in the water differed from the sediment. Parallel factor (PARAFAC) analysis of the excitation-emission matrices (EEM) revealed the presence of terrestrial humus-like, microbial humus-like and tryptophan-like proteins in the surface water, whereas the sediment contained UVA humic-like, UVC humic-like and fulvic-like in the sediment. The DOM in the surface water and sediment were mainly derived from microbial metabolic activity and the surrounding soil. Surface water DOM displayed greater photodegradation potential than sediment DOM. PARAFAC analysis indicated that the terrestrial humic-like substance in the water and the fulvic-like component in the sediment decomposed more rapidly. These data describe the characteristics of DOM in the Wei River and are crucial to understanding the fluctuations in environmental patterns.     

A 100-year sedimentary record of natural and anthropogenic impacts on a shallow eutrophic lake, Lake Chaohu, China

In this study, the sediment profiles of total organic carbon, total nitrogen, C/N ratios, total phosphorus, N/P ratios, C/P ratios, particle sizes, and stable carbon and nitrogen isotopes (δ(13)C and δ(15)N) were used to investigate natural and anthropogenic impacts on Lake Chaohu over the past 100 years. Before 1960, Lake Chaohu experienced low productivity and a relatively steady and low nutrient input. The increasing concentration and fluxes of total organic carbon, total nitrogen, total phosphorus, together with changes in the δ(13)C and δ(15)N of organic material in the sediment cores, suggested that the anthropogenic effects on trophic status first started because of an increase in nutrient input caused by a population increase in the drainage area. With the construction of the Chaohu Dam, an increase in the utilization of fertilizer and the population growth which occurred since 1960, stable depositional conditions and increasing nutrient input resulted in a dominantly algae-derived organic matter source and high productivity. Nutrient input increased most significantly around 1980 following the rapidly growing population, with concomitant urbanization, industrial and agricultural development. This study also revealed that the concentration and distribution of nutrients varied between different areas of sediment within Lake Chaohu because of the influence of different drainage basins and pollution sources.     

自然灾害知觉的不安全心理特性与调适建议——基于北京大学生的调查分析

研究公众自然灾害知觉中的不安全因素,有助于开展有针对性的减灾宣教活动、构建社会预防文化。通过问卷方式,调查了北京5所高校大学生的自然灾害知觉现状及特征。统计分析显示,大学生自然灾害知觉中存在不安全心理特性,主要表现在：对自身灾害知识和经验存在过高估计的乐观偏差;在灾害预期中表现出悲观的心理噪声效应;面对自然灾害多数出现消极情绪,其应急行为倾向呈负距平状态;防灾减灾过程中对政府行为依赖性、服从性高。在此基础上,提出了通过普及正确防灾知识、完善心理防御机制、强化能动意识等重塑大学生灾害知觉、调适灾害行为的建议。     

板锥网壳结构的风振响应分析

板锥网壳结构是一种受力性能合理,技术经济效益良好的新型空间结构形式。采用谐波法模拟了Daven-port脉动风谱;采用时程分析法对板锥网壳结构进行了风振响应时程分析,并对板锥网壳结构的风振响应特性进行了全面和深入的研究,为板锥网壳结构的抗风设计提供理论上的依据,得出了可应用于工程实践的重要结论。     

应急供水的启示——日本神户市应急供水系统简介

以日本神户市的水道耐震化项目考察为基础,对该市应急供水系统的建设方法进行梳理,归纳了系统建设目标、系统方案、应急水源储备、应急水源输送和应急供水管道抗震等重要环节的建设思路和技术方法,对我国城市应急供水系统建设以及解决灾后供水有一定的借鉴作用。     

Overestimated role of sulfate in haze formation over Chinese megacities due to improper simulation of heterogeneous reactions

Environmental Chemistry Letters - Heterogeneous reactions involving aerosol water, i.e., haze chemistry, are responsible for high aerosol concentrations observed during severe haze events in...     

Variation characteristics of atmospheric methane and carbon dioxide in summertime at a coastal site in the South China Sea

● Diurnal patterns of CH₄ and CO₂ are clearly extracted using EEMD. ● CH₄ and CO₂ show mid-morning high and evening low patterns during sea breezes. ● Wind direction significantly modulates the diurnal variations in CH₄ and CO₂. Methane (CH₄) and carbon dioxide (CO₂) are the two most important greenhouse gases (GHGs). To examine the variation characteristics of CH₄ and CO₂ in the coastal South China Sea, atmospheric CH₄ and CO₂ measurements were performed in Bohe (BH), Guangdong, China, in summer 2021. By using an adaptive data analysis method, the diurnal patterns of CH₄ and CO₂ were clearly extracted and analysed in relation to the sea breeze (SB) and land breeze (LB), respectively. The average concentrations of CH₄ and CO₂ were 1876.91 ± 31.13 ppb and 407.99 ± 4.24 ppm during SB, and 1988.12 ± 109.92 ppb and 421.54 ± 14.89 ppm during LB, respectively. The values of CH₄ and CO₂ during SB basically coincided with the values and trends of marine background sites, showing that the BH station could serve as an ideal site for background GHG monitoring and dynamic analysis. The extracted diurnal variations in CH₄ and CO₂ showed sunrise high and sunset low patterns (with peaks at 5:00–7:00) during LB but mid-morning high and evening low patterns (with peaks at 9:00) during SB. The diurnal amplitude changes in both CH₄ and CO₂ during LB were almost two to three times those during SB. Wind direction significantly modulated the diurnal variations in CH₄ and CO₂. The results in this study provide a new way to examine the variations in GHGs on different timescales and can also help us gain a better understanding of GHG sources and distributions in the South China Sea.     

液膜分离在造纸黑液治理中的应用

液膜分离在造纸黑液治理中的应用潘碌亭朱亦仁（阜阳师范学院化学系，阜阳２３６０３２）吴成康（阜阳师范学院科技处）关键词液膜法；黑液；木质素．１前言目前，我国造纸工业普遍采用碱法制浆，而蒸煮制浆过程中产生的黑液含有大量的有机物和无机物，ＣＯＤ值很高，黑液...     

论可持续发展的区际关系内涵与我国西部大开发

本文在揭示可持续发展的宏观、中观、微观区际关系内涵的基础上,对我国西部大开发和如何协调区际关系,实现可持续发展提出了建议。     

模拟酸雨对峨眉山冷杉林土壤特性的研究

本文采用模拟酸雨方法,考察了峨眉山不同区域冷杉生长正常区和受害区的土壤样品,在酸沉降影响下,土壤特性所发生的改变,测定了土壤酸碱度及主要元素含量。同时以未受到酸沉降侵蚀的贡嗄山土样作为对照点,探讨由酸沉降所造成的土壤酸化,进而引起土壤特性改变与冷杉生长间的关系。