京津冀区域PM2.5中碳组分污染特征研究

为了解京津冀区域PM_(2.5)中碳组分污染特征,于2015年7月和10月及2016年1月和4月在北京、天津、保定、石家庄、沧州5个城市同步采集PM_(2.5)样品,采用热/光分析法分析样品中有机碳(OC)和元素碳(EC),使用OC/EC最小比值法估算二次有机碳(SOC).结果表明:京津冀区域主要城市OC、EC和SOC的年均浓度分别为12.9~28.5、4.1~7.9和3.3~10.4μg·m~(-3),OC/EC和SOC/OC的比值分别为2.4~3.0和0.26~0.32.OC和EC的浓度呈现保定石家庄沧州天津北京的空间分布特点和夏季春季秋季冬季的季节变化特点.OC/EC的比值及OC和EC的相关性在夏季最低,冬季最高,这可能与京津冀区域冬季采暖燃煤有关,冬季不利的气象条件也加剧了碳质气溶胶污染.冬季较高的SOC浓度主要与低温、气态前体物的增加以及频繁出现的逆温、小风和混合层高度降低等不利气象条件有关.京津冀区域碳质气溶胶的污染特征具有空间相似性.     

Characterization of volatile organic compounds in the urban area of Beijing from 2000 to 2007

Beijing is one of the most polluted cities in the world. In this study, the long-term and continuous measurements of volatile organic compounds (VOCs) in the urban area of Beijing, specifically at Beijing 325 m Meteorological Tower, were conducted from 2000 to 2007. The annual record of VOC trends exhibited in two different phases was separated in 2003. Records show that VOC concentrations increased from 2000 to 2003 due to the abrupt increase in vehicle number. Contrarily, since 2003, there had been a decrease in VOCs concentrations as the policy on gasoline and air pollution was implemented. Toluene, benzene, and i-pentane are the chemicals that abound in and are directly related to vehicle activity, such as in vehicle exhaust and gasoline evaporation. Furthermore, records indicate that there had been seasonal variation in VOCs levels in that VOCs level in summer is higher than that in winter. As such, temperature is considered to significantly contribute to VOCs in Beijing. Records also show that VOCs level was high in the morning and during rush hours in the evening. In contrast, VOCs level was low during midday due to photochemical destruction with OH radical and dilution effect. In this study, a particular benzene to toluene ratio range (0.4-1.0) was used as the indicator of air propelled by vehicular exhaust. We also applied the correlation coefficients between BTEX and i-pentane to evaluate evaporation influence to ambient BTEX in the Beijing urban area.     

Micropollutant removal and disinfection byproduct control by sequential peroxymonosulfate-UV treatment in water: A case study with sulfamethoxazole

UV/peroxymonosulfate (UV/PMS) advanced oxidation process has attracted significant attention for removal of micropollutants in water. However, during practical water treatment applications, the PMS treatment must be performed before the UV treatment to achieve full contact. In this study, sulfamethoxazole (SMX) was selected as the target micropollutant. Four different operational approaches, including UV alone, PMS alone, simultaneous UV/PMS and sequential PMS-UV, were compared for their differences in SMX removal and disinfection by-product (DBP) formation potentials during chlorine-driven disinfection. Among the four approaches, UV/PMS and PMS-UV achieved over 90% removal efficiencies for SMX without substantial differences. For raw water, the trichloronitromethane (TCNM) formation potential after treatment with PMS-UV was lower than that after UV/PMS treatment. The time interval over which the PMS-UV process was conducted had little effect on the final removal efficiency for SMX. However, a brief (5 min) pre-PMS treatment significantly reduced the TCNM formation potential and the genotoxicity from DBPs. The formation risk for TCNM during chlorination increased markedly with increasing PMS dosages, and the appropriate dosage under these experimental conditions was suggested to be 0.5–1.0 mmol/L. Under alkaline conditions, PMS-UV treatment can enhance SMX degradation as well as dramatically reduced the formation potentials for haloketones, haloacetonitriles and halonitromethanes. This study suggests that proper optimization of UV/PMS processes can remove SMX and reduce its DBP formation.     

水生和陆生生物体中卤系阻燃剂的差异性富集研究:以鲶鱼和家鸽为例

分析了水生(鲶鱼)和陆生(家鸽)生物体中卤系阻燃剂(HFRs)的组成和浓度。鲶鱼中短链氯化石蜡(SCCPs)浓度均值为30 800 ng·g~(-1)lw(脂肪归一化浓度),是最主要的HFRs,然后依次是多溴联苯醚(PBDEs)(2 300 ng·g~(-1)lw)、四溴双酚A(TBBPA)(37 ng·g~(-1)lw)、六溴环十二烷(HBCD)(21 ng·g~(-1)lw)、德克隆(DP)(14 ng·g~(-1)lw)、十溴二苯乙烷(DBDPE)(7.1 ng·g~(-1)lw)和六溴苯(HBB)(6.2 ng·g~(-1)lw);而家鸽中PBDEs含量最高(17 000 ng·g~(-1)lw),其次是SCCPs(7 600 ng·g~(-1)lw)DP(1 600 ng·g~(-1)lw)DBDPE(14 ng·g~(-1)lw)HBB、TBBPA和HBCDs(未检出)。鲶鱼和家鸽HFRs组成比较发现,鲶鱼中具有较高百分含量的低溴代PBDE单体和较低的fanti值,而家鸽中具有较高百分含量的高溴代PBDE单体和较高的fanti值。实验结果初步表明,水生生物较多地富集水溶性较大的化合物,陆生生物则较多地富集疏水性较强的化合物。研究认为以上水生和陆生生物体中污染物的差异性富集现象可能与化合物因不同物理化学性质导致的不同环境迁移行为有关。     

硫酸法制二氧化钛生产中废酸浓缩技术的述评

介绍和评价了国内外硫酸法制二氧化钛生产中废酸的浓缩技术,从工艺、设备及材质3方面分析了国内在二氧化钛废酸处理中存在的问题,指出最有效的解决措施是：以防为主,改善工艺条件;使硫完全参与反应,减少硫的损失和对环境的破坏;完善配套设施,提高设备质量;综合考虑废酸、新酸和钛铁矿的物料配比;选择耐腐蚀性较好的复合材料作为设备材质;最终使废酸少产生或无产生。     

过山车立环轨道设计方法

基于加速度研究过山车立环轨道曲线的设计方法.分别研究向心加速度恒定的立环曲线,加速度恒定的立环曲线和以欧拉螺线为基础的立环曲线.建立三种立环曲线的方程,通过数值方法进行求解,借助Matlab计算在给定初始条件和边界条件下的轨道曲线.以加速度为评判标准来分析三种曲线的优点和缺点,最终得到以加速度为基础的立环轨道曲线设计方...     

Fe2O3-Cr2O3/TiO2系列催化剂的结构和脱硝性能

研究以纳米TiO2为载体,浸渍负载过渡金属氧化物,以CO为还原剂的脱硝催化剂的脱硝性能。实验中以计算量的Ni（NO3）2和Fe（NO3）3混合溶液浸渍纳米TiO2粉末,室温下搅拌30 min至混合均匀,放入旋转蒸发器中,70℃下至水分蒸干为止;所得粉末在550℃下、空气气氛中焙烧4 h即得所需催化剂。用以上方法分别制备2%Fe2O3-10%Cr2O3/TiO2、4%Fe2O3-8%Cr2O3/TiO2、6%Fe2O3-6%Cr2O3/TiO2、8%Fe2O3-4%Cr2O3/TiO2与10%Fe2O3-2%Cr2O3/TiO2等5种催化剂样品。实验结果表明,制备的催化剂具有较好的结构,分散较为均匀。对于CO＋NO反应,Fe2O3-Cr2O3/TiO2系列催化剂具有较好的催化活性,NO的转化率都达到了100%。其中,10%Fe2O3-2%Cr2O3/TiO2样品具有最好的低温活性,H2-TPR结果表明,这是由于10%Fe2O3-2%Cr2O3/TiO2催化剂更易于被CO预还原。     

SBR处理高浓度养猪废水工艺条件

以养猪场废水作为研究对象,采用序列间歇式活性污泥法SBR,通过实验研究了供气量、pH、排泥量、原水稀释倍数、水力停留时间（HRT）对SBR出水水质的影响。结果表明,供气量为375 L/（min·m³）、pH为8.0,并添加排泥100 mL的操作,可使SBR处理效果明显提高,COD、磷和凯氏氮去除率最高分别可达96.37%、94.14%、99.38%。逐步降低进水稀释倍数有利于培养出处理高浓度有机养猪废水的活性污泥,可将平均COD、磷和凯氏氮含量高达9 161.24、33.41和1 502.77 mg/L的养猪废水处理至出水的490.11、5.35和17.84 mg/L。降低HRT对SBR去除率影响不大。     

全氟辛烷磺酸盐(PFOS)及替代品对两栖类蝌蚪的急性毒性

PFOS及其4种替代品对两栖动物非洲爪蟾和黑斑蛙蝌蚪的急性毒性结果为:用调聚法合成的织物三防整理剂对非洲爪蟾蝌蚪和黑斑蛙蝌蚪的96h-LC50分别为8和21mg·L-1,而PFOS对两种蝌蚪的96h-LC50分别为92和81mg·L-1。此实验结果说明织物三防整理剂的急性毒性高于PFOS。用电解氟化法合成的C4、C6织物三防整理剂和50%的全氟丁基有机铵盐阳离子表面活性剂浓度在100mg·L-1时,对两种蝌蚪都没有毒性。这说明,从急性毒性的角度,C4、C6织物三防整理剂和表面活性剂可作为PFOS的替代品使用,但是织物三防整理剂的急性毒性比PFOS大,作为替代品使用应慎重考虑。另外,PFOS和织物三防整理剂对黑斑蛙蝌蚪的急性毒性与对非洲爪蟾蝌蚪的急性毒性存在差异。出于保护我国本土两栖动物的目的,使用黑斑蛙开展毒性评价比使用非洲爪蟾更有现实意义。     

天津地区土壤中DDT的残留分布研究

采集了覆盖整个天津地区的188个土壤表层样品,并分析了样品中p,p′-DDE, p,p′-DDD, p,p′-DDT, o,p′-DDE, o,p′-DDD 和 o,p′-DDT等6种DDT代谢产物.结果表明p,p′-DDT 和 p,p′-DDE是表土中的主要污染物,其平均残留量分别为27 5和 18 8 ng@g -1.不同类型土壤∑DDT差异不显著.污灌区与非污灌区内的样品中 DDT及其代谢产物的差异不显著,但1970-1980年DDT施用量较高的地区如今土壤中的残留量均较高.土壤理化性质如pH以及TOC对DDTs的残留量有较显著的影响.禁用20年以来,DDT的总体残留量水平仍较高,是否依然有间或使用,有待探讨.