Comparative analysis of impact of human occupancy on indoor microbiomes

• Exposure to indoor microbiomes is a public health concern in educational facilities. • Indoor microbiomes were characterized in two multifunctional university buildings. • Human occupancy had significant impact on the composition of indoor microbiomes. • The skin microbiota of occupants represented important sources of indoor microbiomes. Educational facilities serve as community hubs and consequently hotspots for exposure to pathogenic microorganisms. Therefore, it is of critical importance to understand processes shaping the indoor microbiomes in educational facilities to protect public health by reducing potential exposure risks of students and the broader community. In this study, the indoor surface bacterial microbiomes were characterized in two multifunctional university buildings with contrasting levels of human occupancy, of which one was recently constructed with minimal human occupancy while the other had been in full operation for six years. Higher levels of human occupancy in the older building were shown to result in greater microbial abundance in the indoor environment and greater proportion of the indoor surface bacterial microbiomes contributed from human-associated microbiota, particularly the skin microbiota. It was further revealed that human-associated microbiota had greater influence on the indoor surface bacterial microbiomes in areas of high occupancy than areas of low occupancy. Consistent with minimal impact from human occupancy in a new construction, the indoor microbiomes in the new building exhibited significantly lower influence from human-associated microbiota than in the older building, with microbial taxa originating from soil and plants representing the dominant constituents of the indoor surface bacterial microbiomes. In contrast, microbial taxa in the older building with extensive human occupancy were represented by constituents of the human microbiota, likely from occupants. These findings provide insights into processes shaping the indoor microbiomes which will aid the development of effective strategies to control microbial exposure risks of occupants in educational facilities.     

Bacteriophages in water pollution control: Advantages and limitations

•Phages can be better indicators of enteric viruses than fecal indicator bacteria. •Multiple phages should be added to the microbial source tracking toolbox. •Engineered phage or phage cocktail can effectively target resistant bacteria. •In phage use, phage-mediated horizontal gene transfer cannot be ignored. •More schemes are needed to prevent phage concentration from decreasing. Wastewater is a breeding ground for many pathogens, which may pose a threat to human health through various water transmission pathways. Therefore, a simple and effective method is urgently required to monitor and treat wastewater. As bacterial viruses, bacteriophages (phages) are the most widely distributed and abundant organisms in the biosphere. Owing to their capacity to specifically infect bacterial hosts, they have recently been used as novel tools in water pollution control. The purpose of this review is to summarize and evaluate the roles of phages in monitoring pathogens, tracking pollution sources, treating pathogenic bacteria, infecting bloom-forming cyanobacteria, and controlling bulking sludge and biofilm pollution in wastewater treatment systems. We also discuss the limitations of phage usage in water pollution control, including phage-mediated horizontal gene transfer, the evolution of bacterial resistance, and phage concentration decrease. This review provides an integrated outlook on the use of phages in water pollution control.     

水相和冰相中不同pH条件下溶解性有机质对苊光降解的影响

以Suwannee River NOM（SRNOM）和Upper Mississippi River NOM（UMRNOM）两种水源溶解性有机质（DOM）为代表,利用500W高压氙灯作为光源模拟太阳光,进行室内光解实验.考察了冻融前后两种DOM在不同pH条件下的光谱特性参数及其与苊的结合常数（K_DOC）,同时通过苊的表观光解速率常数（K_OBS）研究冰相与水相中不同pH条件下DOM对苊的光解影响,并进行了相关性分析.结果表明,无论在冰相还是水相中,苊都可以直接进行光降解,同时两种DOM均能促进苊的光解.在水相中,随着pH的升高,两种DOM的SUVA₂₅₄、E₂/E₃、a₂₅₄、a₃₅₀与苊的K_OBS均有上升,而K_DOC则呈现下降趋势.同时K_OBS与K_DOC、a₃₅₀及SUVA₂₅₄均具有显著相关性.而冰相中,K_OBS和K_DOC随pH的变化趋势与水相一致,但SUVA₂₅₄、E₂/E₃、a₂₅₄、a₃₅₀没有明显变化趋势.K_OBS和K_DOC相比于水相也有明显下降.此外.冰相中的K_OBS仅与K_DOC存在显著相关,而与其他参数均无相关性,这也说明冰中的光化学反应可能具有更加复杂的机制.     

铁硫改性生物炭去除水中的磷

磷元素向天然水体中的过度排放引发了严重环境问题.以吸附剂为技术核心的吸附法作为一种有效的除磷方法而受到研究人员的关注.本研究中,以壳聚糖、硫酸亚铁和硫化钠为改性剂研发的污泥生物炭对水中磷的去除效果良好.批次实验表明在最佳原料配比下,298 K时材料可吸附49.32 mg·g^-1的磷.此外,实验模拟表明材料对磷的吸附符合伪二级动力学和Langmuir模型;吸附速率主要受到孔隙内部三维扩散影响;吸附方式认定为物理化学吸附;吸附机制可概括为静电吸引、孔隙填充、表面化学沉淀、氢键结合和配位体效应.本研究证明了合成的材料是一种新型的高效除磷吸附剂,为吸附剂设计以及吸附机制的探讨提供借鉴.     

互花米草对苏北滨海湿地表土有机碳更新的影响

自互花米草引入苏北滨海湿地后,逐渐替代本土植物盐蒿并形成单一植被的互花米草湿地.选择苏北地区盐蒿湿地及不同生长年限的互花米草湿地,采集其表层土壤样品,分别测定全土和分离的土壤粒径组分中总有机碳及δ13C值,分析湿地土壤有机碳浓度及其同位素组成的变化.结果表明,互花米草引入盐蒿湿地后,表层土壤有机碳浓度显著增加(增量达70%),且随着互花米草生长时间延长而明显增加.与盐蒿湿地相比,互花米草湿地土壤中大团聚体(>250mm)和微团聚体组分(53~250mm)有机碳浓度均显著增加,而粉粒组分(2~53mm)则无明显变化.互花米草湿地土壤原状土及各粒径组分的δ13C值均明显高于盐蒿土壤,源于互花米草的新碳在各粒径组分中均有分布,但主要富集在大团聚体组分中,占该组分总碳的31%~43%,说明互花米草生长对土壤有机碳浓度增加主要反映在粗粒径组分中,而对粉、黏粒组分则影响较小.     

pH对鸟粪石吸附海藻酸的影响及机制

鸟粪石结晶沉淀法回收剩余污泥中磷工艺具有良好的应用前景,但污泥中有机物,特别是大量的胞外聚合物(EPS),易吸附到鸟粪石表面对其结晶过程产生一定的影响,而pH是影响其吸附性能的关键因素.由于海藻酸化学性质与EPS相似,以海藻酸作为EPS替代物,在弱碱性条件(7.5≤pH≤11)下开展鸟粪石吸附海藻酸实验.利用自动电位滴定仪对鸟粪石进行表面酸碱滴定,借助恒电容模型计算其表面酸碱平衡常数;同时采用三层模型对吸附数据进行模拟计算,探讨pH影响鸟粪石吸附海藻酸的机制.结果表明,鸟粪石表面吸、脱附质子常数分别为7.6和-10.6,表面位密度为12个·nm~(-2);在离子强度为0.1 mol·L~(-1)NaCl条件下pH的增大抑制鸟粪石对海藻酸的吸附;鸟粪石对海藻酸吸附机理主要通过外层络合及内层络合协同作用,其中外层络合作用始终占主导优势.     

珠江入海口水体中多氯联苯的分布特征及其来源分析

为评估珠江三角洲水体中PCBs(多氯联苯)的污染水平及其生态环境影响,于2005年3月—2006年2月,采集并分析了珠江八大入海口水体中PCBs的残留状况. 结果显示,珠江八大入海口水体中ρ(PCBs)为0.19～7.04 ng/L,其中三氯联苯和四氯联苯占PCBs总量的70%以上,约40%的水样(主要为7—12月样品)ρ(PCBs)高于或接近我国《地表水环境质量标准》(GB 3838—2002)的限值(2 ng/L). 组成分析及主成分分析结果表明,珠江入海口水体中PCBs的分布特征与我国#1PCBs及国外Aroclor 1242和Aroclor 1016产品相近,低氯产品#1PCBs及Aroclor 1242和Aroclor 1016可能是水体中PCBs污染的主要来源,而废弃电容器、沉积物再悬浮、大气沉降及废水处理厂排放等输入源是水体的重要贡献者.      

上游建筑对街道峡谷内流场和污染物分布特征的影响

利用数值模拟方法研究了不同的上游阻挡建筑布局下,行列式和错列式街谷内气流速度和污染物浓度场特征.结果指出,阻挡建筑的存在改变了街谷内的二次流,从而对流场和浓度场均有明显影响.在行列式街谷中,无论上游建筑以何种布局存在,都会减小街谷内污染物浓度.若不考虑上游建筑的存在,将会过高估计行列式街谷内污染程度;在错列式街谷中,与街谷建筑并列的上游阻挡建筑会减小街谷内污染物浓度,而与街谷建筑错列布置的阻挡建筑会增大街谷内污染物浓度;数值模拟结果还表明,街谷内污染物的扩散和清除效果受气流速度和涡流特性的共同作用.     

藻源型溶解性有机氮的产生及不同时期藻类有机物的特性

研究了铜绿微囊藻藻细胞全生命周期中氮的转化过程以及藻类有机物的性质,结果表明:溶解性有机氮(DON)在藻类生长周期中总体呈现上升趋势,藻细胞在其生长初期释放量小于0.05mgDON/107cells,衰亡期释放能力约为0.40mgDON/107cells;胞外有机物(EOM)中分子量分布在对数期和衰亡期以100kDa为主,稳定期以100kDa范围内.三维荧光光谱分析表明,EOM中荧光物质主要为类腐植酸和溶解性微生物代谢产物;而IOM主要由类芳香蛋白和溶解性微生物代谢产物组成.     

基于SVM的CO2驱油藏输油管道脆弱性评价研究

CO2驱油在全国范围内的广泛开展导致内外扰动对输油管道的威胁大大增加,为指导企业发现输油管道的薄弱点从而预防事故发生,提出CO2驱油藏输油管道脆弱性概念及研究思路。将脆弱性分为5个等级并确定各级脆弱性的取值范围。深入分析脆弱性要素,从致灾因子、承灾体和灾害响应3个方面建立脆弱性评价指标体系,并确定各等级脆弱性对应的指标范围。利用MATLAB R2013a的SVM回归方法,构建脆弱性评价模型并进行实例应用。结果表明:模型训练的输出与期望输出拟合较好,均方误差为9.98052×10-7;训练好的SVM模型具有较强的泛化能力和较高的准确性,其对检验样本脆弱性进行预测的最大相对误差为0.027。利用模型得到研究区域某输油管道的脆弱性值为0.381,其脆弱性程度为不太脆弱。