The greater roles of indigenous microorganisms in removing nitrobenzene from sediment compared with the exogenous <Emphasis Type="Italic">Phragmites australis</Emphasis> and strain JS45

The feasibility of using Phragmites australis-JS45 system in removing nitrobenzene from sediments was conducted. However, it was observed that nitrobenzene degraded rapidly and was removed completely within 20 days in native sediments, raising the possibility that indigenous microorganisms may play important roles in nitrobenzene degradation. Consequently, this study aimed to verify this possibility and investigate the potential nitrobenzene degraders among indigenous microorganisms in sediments. The abundance of inoculated strain JS45 and indigenous bacteria in sediments was quantified using real-time polymerase chain reaction. Furthermore, community structure of the indigenous bacteria was analyzed through high throughput sequencing based on Illumina MiSeq platform. The results showed that indigenous bacteria in native sediments were abundant, approximately 10¹⁴ CFU/g dry weight, which is about six orders of magnitude higher than that in fertile soils. In addition, the levels of indigenous Proteobacteria (Acinetobacter, Comamonadaceae_ uncultured, Pseudomonas, and Thauera) and Firmicutes (Clostridium, Sporacetigenium, Fusibacter, Youngiibacter, and Trichococcus) increased significantly during nitrobenzene removal. Their quantities sharply decreased after nitrobenzene was removed completely, except for Pseudomonas and Thauera. Based on the results, it can be concluded that indigenous microorganisms including Proteobacteria and Firmicutes can have great potential for removing nitrobenzene from sediments. Although P. australis - JS45 system was set up in an attempt to eliminate nitrobenzene from sediments, and the system did not meet the expectation. The findings still provide valuable information on enhancing nitrobenzene removal by optimizing the sediment conditions for better growth of indigenous Proteobacteria and Firmicutes.

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受压混凝土试件应力状态与强度分析

为研究受压混凝土试件的强度以及强度变化机理,通过数值模拟不同长径比的混凝土轴心受压试件的破坏过程,研究受压混凝土试件轴心受压时内部应力状态和裂纹的损伤演化过程,及混凝土试件不同围压作用下,强度的变化机理,分析表明, 混凝土试件随着长径比增大,强度减小,试件的破坏面逐渐减小,强度随着内部应力状态变化而变化,围压越小混凝土试件的强度越小,试件的破坏形式由剪切破坏面逐渐到受拉破坏面。推荐将长径比1∶10时为受拉破坏面为作为无侧限的受压时极限拉应变。     

平缓反倾红层边坡变形破坏机制研究

以赤水市旺隆边坡为工程实例,依据野外调查和地质分析成果建立平缓反倾红层边坡概念模型,并结合离散元数值模拟研究贵州平缓反倾红层边坡的变形破坏机制。结果表明:旺隆边坡是砂泥岩不等厚互层的典型平缓反倾红层边坡,差异风化和降雨是主要的诱发因素。边坡的变形演化过程经历4个阶段:卸荷回弹、浅表生改造局部变形、裂隙扩展延伸、裂隙贯通深部蠕滑。变形破坏机制根据不同变形阶段划分为3种不同形式:压缩—拉裂—倾倒、风化剥落—坠落、蠕滑—压致拉裂。     

基于GC-QTOF/MS的大气中有机污染物的非靶标筛查及半定量分析

本文借助气相色谱-四极杆飞行时间质谱仪(GC-QTOF/MS)开展了大气中有机污染物的非靶标筛查,并对识别出的特征污染物进行半定量分析.基于高分辨质谱数据库和NIST质谱数据库的匹配,样品中共识别出139种污染物,主要以多环芳烃(PAHs)及其衍生物、邻苯二甲酸酯(PAEs)为主;除此之外,还识别出多种尚未受到监管的杂环类化合物,例如苯并噻唑、四甲基哌啶酮、1-甲基-2吡咯烷酮、氧杂蒽等.识别出的有机污染物半定量浓度为288 ng·m-3,其中大气常规监测的16种PAHs的浓度是18.1 ng·m-3,仅占总浓度的6.28％.PAEs的浓度为44.6 ng·m-3,邻苯二甲酸二丁酯(DBP)的浓度最高(14.8 ng·m-3).以含氮、氧、硫为主的杂环化合物浓度是47.9 ng·m-3,其中苯并噻唑浓度最高,为9.51 ng·m-3;其次是1-甲基-2吡咯烷酮、四甲基哌啶酮、尼古丁和二苯并呋喃,浓度分别为9.22、8.78、5.11、4.15 ng·m-3.本研究展示了高分辨质谱技术在未知物识别中的优势,并对识别出的特征污染物进行了半定量分析,其结果能够为后期污染物的风险评估提供借鉴意义.     

成渝经济区河流表层沉积物中多溴联苯醚的分布特征

在成渝经济区内采集了19个表层沉积物样品,采用GC/MS方法对其中的PBDEs(Polybrominated Diphenyl Ethers,多溴联苯醚)进行了检测. 结果表明,沉积物中w(ΣPBDEs)(ΣPBDEs包括BDE-1,BDE-15,BDE-17,BDE-28,BDE-47,BDE-66,BDE-71,BDE-85,BDE-99,BDE-100,BDE-126,BDE-138,BDE-153,BDE-154,BDE-166,BDE-181,BDE-183和BDE-190)为0.20～6.45 ng/g,w(BDE-209)为0.44～6.29 ng/g. 与其他地区相比,成渝经济区内PBDEs的污染水平相对较低, 大部分样品中的PBDEs以BDE-209为主,说明成渝经济区河流沉积物中的PBDEs主要来自十溴联苯醚; 但PBDEs的组成特征显示,彭山岷江大桥沉积物中的PBDEs主要来自五溴联苯醚,而官渡沉积物中的PBDEs主要来自八溴联苯醚. 此外,一些以往工作较少关注的PBDEs单体,如BDE-1,BDE-15,BDE-181和BDE-190等,不但在沉积物中的检出率较高(均高于70%),而且有的含量也相对较高.      

电化学氧化杀灭水库原水中藻类的研究

由Ti/RuO2棒为阳极、不锈钢管为阴极组成电氧化管式反应装置,对电氧化杀灭水库含藻原水中的藻类进行了研究。结果显示:处理累积停留时间20 min后,叶绿素a去除率达100%,对浓缩10倍水样,藻毒素MCLR的去除率达98%以上。细胞的死亡及胞内物质的损失,导致溶液DOC值从32 mg/L上升至50 mg/L,但在电氧化作用下,可下降至12 mg/L。氧化降解产物使溶液UV254值上升,从0.09 cm-1上升至0.14 cm-1,溶液UV410值没有太大变化。处理过程中pH值从8.4迅速下降至7.4后,基本维持稳定,电导率以21μS/(cm.min)速率呈线性下降趋势,溶液离子浓度改变较大。     

蜡染印花工艺废水处理设计及运行

设计运行了整个蜡染印花废水处理工程,皂化脱蜡废水松香回收新工艺,即采用两步调pH法-周边自重力进水法,回收率可达98%以上;机械洗蜡废水分流后经双级气浮处理,蜡回收率和处理水回用率可达90%以上;洗蜡废水经蜡回收后出水与其他废水混合后经初级混凝沉淀-水解酸化-好氧生化(A/O工艺)-辐流沉淀组合工艺处理,出水ρ(COD)均值约为130 mg/L,ρ(NH3-N)为3.36 mg/L,然后进入市政管网进行深度处理。     

Species and distribution of rare earth elements in the Baotou section of the Yellow River in China

This paper analyses the contents and species distributions of rare earth elements (REEs) in the water-suspended particulate-sediment system of the Baotou section of the Yellow River, China, with known anthropogenic REE input from industrial discharges. The major forms of REEs were suspended and dissolved in the mainstream and the tributaries of the Baotou section, respectively. The concentrations of the dissolved and suspended REEs had the same trends in the overlying water along the mainstream, which increased from the Seqi section (site A) to the mouth of the Sidaosha River (site D), reaching a maximum value at site D, and tending to decrease thereafter. The contents of REEs in sediment cores showed enrichment with light rare earth elements (LREEs). The bound to carbonates and to Fe–Mn oxides are the major forms of REE in the secondary phase and the REE exhibited LREE enrichment pattern and moderate Eu depletion in suspended particulates and surface sediments. The contents and species distributions of REEs in the water-suspended particulate-sediment system of the Baotou section suggest that the anthropogenic source of REEs from Baotou city have enhanced REE accumulation to the Baotou section. This information is important for predicting possible pollution resulting from anthropogenic REE input into rivers.     

多溴联苯醚在中国的污染现状研究进展

多溴联苯醚(Polybrominated diphenyl ethers,PBDEs)作为"新POPs"逐渐受到环境科研工作者的重视.本文综合评述了PBDEs在我国各种环境介质、生物体以及人体中的污染现状.研究分析表明,PBDEs在我国的污染尚处于相对较低的水平,但在广东贵屿和浙江台州等电子垃圾拆解地PBDEs的污染较为严重.本文最后展望了我国PBDEs研究中需要加强的几个方面.     

硫酸介质中高锰酸钾氧化降解非离子表面活性剂Tween-80动力学研究

应用光谱法研究了硫酸介质中,高锰酸钾氧化降解非离子表面活性剂Tween-80(聚氧乙烯山梨糖醇酐单油酸酯)的动力学性质,探讨了高锰酸钾和硫酸浓度,以及反应温度对氧化降解过程的影响,结果表明,氧化降解反应的速率常数(k)随着硫酸浓度的增大而增大,但却随着高锰酸钾浓度的增大而减小;温度对反应速率常数的影响,较好地遵循阿累尼乌斯公式.通过对反应混合物浊点变化的分析,说明了非离子表面活性剂Tween-80分子中存在活性较高的氧乙烯结构单元,是其被高锰酸钾氧化降解的根本原因.