How will Chinese cities reduce their carbon emissions? Evidence from spatial differences

Environmental Science and Pollution Research - Urban regions are the dominant carbon emitter in China. Although the role of urban regions is a crucial concern in peaking China’s carbon...     

再生水灌溉区土壤对头孢噻肟的吸附特征

采用批吸附实验法比较了再生水灌溉区汪洋沟流域两种土壤和底泥对头孢噻肟的吸附及其动力学特性,并探讨了土壤与底泥不同pH、阳离子强度及可溶性腐殖酸对头孢噻肟吸附能力的影响。结果表明:汪洋沟段清水灌溉土壤、污水灌溉土壤及底泥均对头孢噻肟有较强的吸附能力,对头孢噻肟的吸附能力从强到弱依次为清水灌溉土壤>污水灌溉土壤>底泥。土壤与底泥对头孢噻肟的吸附行为通过等温吸附模型模拟,其中Freundlich方程拟合效果最好。在pH 4.0~9.0的范围内,土壤与底泥对头孢噻肟的吸附系数随着pH的增大而减少;随着土壤溶液中阳离子浓度的增加,头孢噻肟的吸附量呈非线性减少趋势;添加可溶性腐殖酸后的土壤对头孢噻肟的吸附能力减弱。     

掺硼氧化银光催化剂制备及降解模拟印染废水

采用离子交换共沉淀法制备掺硼氧化银光催化剂并进行相应表征,以甲基橙为降解对象对其光催化氧化性能进行考察,并将其用于可见光下降解多种有机物及模拟印染废水。实验结果表明:掺硼氧化银光催化剂能带带隙为1.29 eV,具有很好的光催化氧化-还原能力,可见光下降解甲基橙,光照120 s可实现甲基橙完全降解;重复使用活性保持稳定;对不同有机物均可实现光催化氧化完全降解;模拟印染废水降解实验证实,在pH值5~10范围内,可见光照射下氧化银光催化剂在25 min内可实现混合染料的完全降解。掺硼氧化银是一种具有应用前景的可见光光催化剂。     

Fe-Mn基分子筛催化剂NH3低温选择性催化还原NO性能

采用柠檬酸法制备了不同Fe和Mn含量的Fe-Mn/HBeta催化剂,采用BET、XRD、SEM和XPS等方法对不同催化剂的特征参数进行表征,以氨气为还原剂,在空速为5 000 h-1的条件下,考察了活性成分负载量和焙烧温度对其活性的影响;探讨了催化剂的抗水抗硫性能.研究结果表明,焙烧温度为550℃、6%Fe-6%Mn/HBeta催化剂具有相对较优的催化活性,反应温度为90~230℃时,NO转化率为63.9%~96.99%,比表面积、孔体积和平均孔径分别为356.19 m2/g、0.61 cm3/g和16.83 nm,活性成分在催化剂表面高度分散,催化剂表面Mn主要以Mn3+和Mn4+存在,且以Mn4+居多;反应温度为180℃条件下,6%Fe-6%Mn/HBeta催化剂具有较好的抗水能力和同时抗水抗SO2能力,但单独抗SO2能力较差.     

Study on microstructure and extinction characteristics of particulate matter in diesel engine fueled with different biodiesels

Environmental Science and Pollution Research - Biodiesel combustion particulate matter (PM) is different from diesel combustion PM in terms of microscopic morphology, which directly affects the...     

动态生物滤网中胞外聚合物产量预测及滤网的污染分析

近年来,在各种膜处理技术中,用于废水或活性污泥混合液粗滤的自形成动态生物滤网(DMf)受到广泛关注。基于此,提出了一种用于估算合适的筛孔孔径的模拟方法,来预测并控制生物滤饼层在筛孔表面的形成,以提高过滤效果并减轻污染。结果表明：动态生物滤网面密度与EPS浓度之间具有显著的正相关性,可以利用滤网面密度来预测胞外聚合物(EPS)产生量;孔径为55~100 μm的筛网上形成的动态生物滤网可以阻挡泥水混合液中的大多数颗粒,但有部分细小颗粒仍可穿过滤网表层,并在滤网底层积累,从而产生EPS。CLSM分析结果表明,DMf中死细胞的比例及其厚度与网孔孔径显著相关,且在所有实验用的DMf中的活细胞层的厚度均约为20 μm。这表明有效的氧气渗透仅发生在DMf的薄层内,过厚的生物层会阻止氧气的渗透,进而导致微生物死亡而释放更多的EPS,最终加剧膜污染。     

Environmental change and fishermen’s income: is there a poverty trap

Environmental Science and Pollution Research - The unequal cost and benefit led by environmental changes may potentially set China’s rural areas a “Poverty Trap.” Therefore,...     

不同类型机动车尾气中芳香烃化合物含量分析

首次对北京市9种车辆、5种燃料在不同工况下排放芳香烃化合物的特征．进行了定量研究。结果表明,车型、燃料、净化器及工况等因素对排放量产生影响,电喷车比化油器车芳香烃化合物排放量低;汽油车排放量最高,柴油车其次,LPG及CNG车排放量最低;使用净化器可以降低芳香烃排放量;不同工况对排放量的影响随车型,燃料类型的不同而不同。     

基于MATLAB的城市表层土壤重金属污染空间分布的研究

为全面了解某城市表层土壤重金属污染的空间分布特征,对城市表层土壤中重金属元素As、Cd、Cr、Cu、Hg、Ni、Pb、Zn进行采样分析,采用域法识别特异值进行数据处理。通过Matlab软件,利用克里格法进行空间插值,绘出各重金属浓度与各坐标投影的一维空间分布图,并绘出全城等高地形图,再以数字大小标注样本点的污染浓度,拟合各元素浓度与海拔、平面坐标之间的关系模型,将重金属空间分布特征定量化、模型化。     

Enhancing sensitivity of microbial fuel cell sensors for low concentration biodegradable organic matter detection: Regulation of substrate concentration, anode area and external resistance

The relatively low sensitivity is an important reason for restricting the microbial fuel cell (MFC) sensors’ application in low concentration biodegradable organic matter (BOM) detection. The startup parameters, including substrate concentration, anode area and external resistance, were regulated to enhance the sensitivity of MFC sensors. The results demonstrated that both the substrate concentration and anode area were positively correlated with the sensitivity of MFC sensors, and an external resistance of 210 Ω was found to be optimal in terms of sensitivity of MFC sensors. Optimized MFC sensors had lower detection limit (1 mg/L) and higher sensitivity (Slope value of the linear regression curve was 1.02), which effectively overcome the limitation of low concentration BOM detection. The essential reason is that optimized MFC sensors had higher coulombic efficiency, which was beneficial to improve the sensitivity of MFC sensors. The main impact of the substrate concentration and anode area was to regulate the proportion between electrogens and nonelectrogens, biomass and living cells of the anode biofilm. The external resistance mainly affected the morphology structure and the proportion of living cells of the anode. This study demonstrated an effective way to improve the sensitivity of MFC sensors for low concentration BOM detection.