基于正交试验方法的毛细矩形槽道平均流速影响因素分析

目的 分析毛细矩形槽道平均流速的影响因素.方法 通过公式推导毛细矩形槽道平均流速的有关影响因素,并且从中提取出部分因素,选用三因素三水平的正交试验表对流速进行分析,三因素分别为槽道宽度、槽道深度、槽道长度.通过CFX仿真得出对应的平均流速.结果 得到了各因素水平变化对毛细矩形槽道平均流速的影响程度.槽道宽度及槽道深度对...     

Fine particle-bound PAHs derivatives at mountain background site (Mount Tai) of the North China: Concentration, source diagnosis and health risk assessment

Ten nitrated polycyclic aromatic hydrocarbons (nPAHs) and 4 oxygenated polycyclic aromatic hydrocarbons (oPAHs) in fine particulate matter (PM_2.5) samples from Mount Tai were analyzed during summer (June to August), 2015. During the observation campaign, the mean concentration of total nPAHs and oPAHs was 31.62 pg/m³ and 0.15 ng/m³, respectively. Two of the monitored compounds, namely 9-nitro-anthracene (9N-ANT) (6.86 pg/m³) and 9-fluorenone (9FO) (0.05 ng/m³) were the predominant compounds of nPAHs and oPAHs, respectively. The potential source and long-range transportation of nPAHs and oPAHs were investigated by the positive matrix factorization (PMF) method and the potential source contribution function (PSCF) methods. The results revealed that biomass/coal burning, gasoline vehicle emission, diesel vehicle emission and secondary formation were the dominant sources of nPAHs and oPAHs, which were mainly from Henan province and Beijing-Tianjin-Hebei region and Bohai sea. The incremental life cancer risk (ILCR) values were calculated to evaluate the exposure risk of nPAHs and oPAHs for three group people (infant, children and adult), and the values of ILCR were 7.02 × 10^?10, 3.49 × 10^?9 and 1.41 × 10^?8 for infant, children and adults, respectively. All these values were lower than the standard of EPA (Environmental Protection Agency) (<10^?6), indicating acceptable health risk of nPAHs and oPAHs.     

Isolation and characterization of a strain with high microbial attachment in aerobic granular sludge

Aerobic granule is a special microbial aggregate associated with biofilm structure. The formation of aerobic granular sludge is primarily depending on its bacterial community and relevant microbiological properties. In this experiment, a strain with high microbial attachment was isolated from aerobic granular sludge, and the detailed characteristics were examined. Its high attachment ability could reach 2.34 (OD_600nm), while other low attachment values were only around 0.06-0.32, which indicated a big variation among the different bacteria. The strain exhibited a very special morphology with many fibric fingers under SEM observation. A distinctive behaviour was to form a spherical particle by themselves, which would be very beneficial for the formation and development of granular sludge. The EPS measurement showed that its PN content was higher than low attachment bacteria, and 3D-EEM confirmed that there were some different components. Based on the 16S rRNA analysis, it was identified to mostly belong to Stenotrophomonas. Its augmentation to particle sludge cultivation demonstrated that the strain could significantly promote the formation of aerobic granule. Conclusively, it was strongly suggested that it might be used as a good and potential model strain or chassis organism for the aerobic granular sludge formation and development.     

亚热带丘陵区人工湿地底栖动物群落特征研究

以湖南长沙亚热带丘陵区为研究区域,以处理农村综合污水(含畜禽养殖废水、农村生活污水及农田排水)为主要目的,通过野外小区控制试验,设置梭鱼草(Pontederia cordata)、绿狐尾藻(Myriophyllum elatinoides)、梭鱼草+绿狐尾藻组合(Pontederia cordata +Myriophy...     

新冠期间河北省典型钢铁企业大气污染影响

基于国家气象局气象预报数据,建立了基于AERMOD的钢铁企业污染预报模型,模拟了新冠疫情管控期(2020年2～3月)及解封后期(2020年4～10月)河北省某钢铁企业对大气污染的影响,并结合空气质量实测数据进行模型验证.结果 显示,不利风向条件下,该钢铁厂大气污染物排放对当地3个国控站点SO2、NOx和PM10的平均浓...     

生物炭施用两年后对热带地区稻菜轮作土壤N2O和CH4排放的影响

通过探究生物炭施用两年后对海南典型稻菜轮作模式土壤氧化亚氮（N₂O）和甲烷（CH₄）排放的影响,旨在明确生物炭在该模式下对温室气体排放的长期效应,可为我国热带地区稻菜轮作系统N₂O和CH₄减排提供理论依据.田间试验共设置4个处理,分别为：不施氮肥对照（CK）、施氮磷钾肥（CON）、施氮磷钾肥配施20 t·hm^-2生物炭（B1）和施氮磷钾肥配施40 t·hm^-2生物炭（B2）处理.结果表明：①相较于CON常规施氮处理,B1和B2添加生物炭处理显著减少了早稻季32%和54%的N₂O排放,但在晚稻季B1和B2处理显著增加了31%和81%的N₂O排放,辣椒季N₂O的累积排放量则显著高于早稻和晚稻季,且B1处理显著减少了35%的 N₂O的排放,B2处理相较于CON处理无显著性差异;②B1和B2比CON处理显著减少了早稻季63%和65%的CH₄排放,在晚稻季B2处理显著增加了41%的CH₄排放,B1处理相较于CON处理无显著性差异,辣椒季各处理CH₄的累积排放量无显著性差异;③晚稻季贡献了稻菜轮作系统主要的总增温潜势（GWP）,CH₄的排放量决定了GWP和温室气体排放强度（GHGI）的大小.生物炭施用两年后,B1降低了整个稻菜轮作系统的GHGI,B2增加了GHGI,并达到显著水平,但B1和B2处理在早稻季和辣椒季显著降低了GHGI,仅B2处理在晚稻季增加了GHGI;④B1和B2相较于CON处理显著增加了早稻产量33%和51%,且B1和B2处理显著增加辣椒季产量53%和81%,晚稻季除不施氮肥CK处理外,其它处理产量无显著性差异.研究结果表明,热带地区稻菜轮作系统温室气体排放的大小主要取决于晚稻季的CH₄排放,而生物炭施用两年后仅低量生物炭配施氮肥有显著的减排作用,但高低量生物炭配施氮肥对早稻和辣椒季作物增产具有持续性.     

基于AHP-熵权法的水环境承载力模糊综合评价

针对水环境承载力评价存在的不确定性和模糊性问题,该研究采用层次分析法和熵权法进行组合赋权,利用模糊综合评价法对粤港澳大湾区9个城市的水环境承载力进行评价,并引入障碍度模型确定影响水环境承载力的主要障碍度因素.结果 表明:2013-2018年9个城市的水环境承载力总体呈上升趋势,但城市间的变化差异明显;9个城市水环境承载力的障碍指标差异明显,其中人均水资源量以20.7％的障碍度均值成为首要障碍度指标;通过障碍度频率分析可得9个城市的主要障碍度指标包括人均水资源量、生态用水率、万元GDP污(废)水排放量和第三产业比重,这4项指标的频率均为89％.将该方法应用于区域水环境承载力的评价,其结果可为区域水环境的管理和相关政策的制定提供依据.     

基于垂直观测数据融合的广州市臭氧污染过程分析

了解O₃污染的垂直分布对于充分理解O₃在大气中的扩散和输送具有重要意义.本研究利用最优插值法实现了高塔与激光雷达O₃观测数据的融合,并基于垂直观测融合数据对2021年10月广州市一次O₃污染过程进行分析,结果表明：(1)不同时刻的O₃浓度均大致呈现出随高度上升先升后降的变化趋势,平均相对高值主要分布在300～500 m,最高值出现在400 m附近.(2)结合边界层高度分析可知,白天的O₃生成和扩散基本均在边界层以内进行,夜间普遍存在O₃残留问题,而在污染日尤其显著,表明白天光化学反应生成的高浓度O₃是夜间残留层中O₃的来源.(3)污染期间,不同大气污染物形成了不同的垂直分层,具体表现为较高浓度的PM_2.5和NO₂在中、低层积累,而高层(约200～600 m)则维持高浓度O₃的污染垂直分布结构.推测原因在于南北气流对峙及夜间稳定...     

溶解性微生物产物在GO/PVDF杂化膜面的污染行为

为了解析溶解性微生物产物（SMP）在GO/PVDF杂化膜面的污染特性,对膜片进行了宏观污染实验,并采用耗散石英微晶天平（QCM-D）从微观角度分析了SMP在自制镀膜芯片上的吸附规律和污染层结构变化.结果表明,GO含量为0.5wt%的膜污染恢复率最高（79.95%）,抗污染能力最强.QCM-D实验发现,GO含量为0wt%镀膜芯片表面SMP吸附量最大,污染较为严重.膜片亲水性越强,吸附频率变化越小,抗污染能力越强.此外,GO含量为0.5wt%镀膜芯片表面的污染物结构比较疏松和柔软,其他膜表面的污染物结构较为坚硬和致密.     

南海ODP1144孔微玻璃陨石物理化学性质及母源物质的复杂性

ODP 184航次 114 4孔位于南海北部陆缘 (2 0°3.18′N ,117°2 5 .14′E ,水深 2 0 37m) ,在岩心样品中发现的微玻璃陨石主要赋存于 386 .17～ 386 .2 7mcd处 ,这些玻璃陨石主要以球形和椭球形为主 ,可见泪滴状、马鞍形、扁豆形、圆盘形、哑铃形、翼形、异形等形态和不规则状碎片。通过微玻璃陨石主量元素电子探针分析 ,并用Harker图解讨论了主量元素氧化物之间的相关性 ,同时结合Niggli参数进一步深入探讨微玻璃陨石的母源物质特征。研究结果表明 ,ODP114 4孔微玻璃陨石属于澳亚散落区内的普通型微玻璃陨石 ,其母源物质成分复杂 ,可能有两种或两种以上的物质组成 ,一种可能是化学成分没有太大变化的碎屑沉积岩 ,另一种可能是粘土及杂砂岩等。