城市污水处理厂的挥发性恶臭有机物组成及来源

采用GDX-502采样管和二次热解吸与GC-MSD联用仪研究广州一个典型城市污水处理厂不同污水处理单元和周边环境空气中挥发性恶臭有机物(MVOC)的组成和含量,通过对源排放特征、分子标志物和大气化学活性分析,建立该污水处理厂的MVOC源成分谱.结果表明,该污水处理厂检出烷烃、卤代烃、烯烃、芳香烃、含氧有机物和硫醚等6类40种挥发性有机物(VOC),其中34种为MVOC成分,各处理单元排放的MVOC含量占其VOC总量的95%以上;苯系物、2-丁酮、乙酸乙酯、乙酸丁酯和甲硫醚等为该污水处理厂重要的MVOC分子标志物,其中苯系物的含量最高,占源排放MVOC总量的75.89%;经归一化和重整的MVOC源成分谱与环境受体点的MVOC组成之间具有显著相关性.     

夏季海河与渤海湾中壬基酚和辛基酚污染的状况

对夏季海河与渤海湾表层水中溶解态的壬基酚(NP)和辛基酚(OP)的污染状况进行了调查.结果表明,海河中NP和OP的浓度分别为160～429ng/L和18～56ng/L;渤海湾中NP和OP的浓度分别为33～132ng/L和n.d.～14ng/L.污水排放是海河中NP和OP的重要来源.渤海湾中NP和OP的浓度要远远低于海河,但是海水稀释不是造成其浓度降低的唯一原因.研究还发现该地区NP和OP与COD_Mn和TP具有显著的正相关.与珠江三角洲相比,该地区NP和OP污染情况较为严重,与国外其他类似区域相比则处于中等或较低水平.     

厌氧菌对化石燃料中有机硫的还原降解

对硫酸盐还原菌D.desulfuricansM6及模型化合物和原油的脱硫活性。苯并噻吩脱硫率高达96%,硫醇低于10%。一些模型化合物的降解受到正十二烷的抑制,石油重馏分的脱硫率高于原油和轻馏分。在微生物还原降解模式中,与脂肪族含硫化合物相比,芳香含硫化合物中的碳硫键易于受到攻击而降解,某些石油样品的低脱硫率源于样品中硫的赋存形态。介绍了DesulfomicrobiumescambiuK114和Desulfovibriolonggreachill213及其同生群在仅有氮气的环境中对模型物的还原降解。     

饮食业后堂噪声综合控制技术研究

分析了饮食业后堂噪声的频率特性,采取隔声、吸声、消声控制技术和防油雾措施,并独创设计了一种排油烟通风复合消声器,解决了同时排油烟和降噪的难题,得出了饮食业后堂噪声综合控制的有效工艺。经2年的实际应用证明,降噪能力强,可满足60dB(A)的区域环境标准的要求,效果稳定,是一项值得推广的技术。特别是排油烟通风复合消声器、通风消声窗及“声闸”的设计参数,可在同类噪声控制中推广应用。     

典型城市河流中嗅味物质和微生物菌落特征

对某城市河流沿程水质、典型嗅味物质以及微生物群落结构进行了调查分析. 结果表明:河水中2种嗅味物质〔二甲基异莰醇(2-MIB)和土臭素(Geosmin)〕的质量浓度均受到ρ(DO)的显著影响. 绝对厌氧条件〔ρ(DO)<0.2 mg/L〕水体中,ρ(二甲基异莰醇)和ρ(土臭素)的平均值分别为794.8和269.8 ng/L;好氧条件〔ρ(DO)>2.0 mg/L〕水体中,二者的平均值分别为91.6 和104.7 ng/L;而且ρ(DO)较低时,水体中的可疑致病菌含量升高,微生物安全性降低. 控制该河流水体ρ(DO)在2.0 mg/L以上,有利于抑制水体中嗅味物质的产生,可提高河流水体的微生物安全性.      

Fe/TiO2/ACF三元复合光催化材料联合脉冲放电降解甲基橙

采用溶胶-凝胶法制备了Fe/TiO₂/ACF三元复合光催化材料,将其投入到脉冲放电水处理反应器中降解甲基橙,考察该材料的光催化性能,以及它与脉冲放电的联合降解过程中操作因素的影响. 结果表明,Fe/TiO₂/ACF三元复合光催化材料与脉冲放电产生协同作用,大大提高了对甲基橙的去除率. 甲基橙的去除率与掺铁量〔以摩尔分数计〕、煅烧温度、溶液电导率和pH有关. 当掺铁量为0.07%,煅烧温度为900 ℃时,降解效果最佳;当溶液pH为6,电导率为300 μS/cm时,对Fe/TiO₂/ACF与脉冲放电的联合降解效果有利.      

典型医药活性物质在污水处理厂中的归趋及其风险评估

采用固相萃取、高效液相色谱/串联质谱法 (污泥样品先采用超声波萃取预处理方法提取) 检测分析了包括磺胺类、喹诺酮类、大环类酯类抗生素、心血管类、止痛剂类等8类医药活性物质在重庆某污水厂中的含量水平及其行为归趋.采用 EC/PNEC 综合评价体系评估环境中目标医药活性物质的生态风险,利用质量平衡分析的方法分析了其在水相及污泥相中的分布.结果表明,目标物质在水相中均可检出,其检出浓度在ng/L~μg/L,在污泥样品中可检测出18种目标物质,其浓度在ng/g (干重,下同).仅仅1.1%的目标物质被污泥吸附去除.污水处理厂初级处理及氯化消毒阶段对目标物质无明显去除效果,目标物质的去除主要发生在生物处理阶段,生物的降解或转化作用是目标物质的主要去除机制.EC/PNEC分析表明,磺胺嘧啶、磺胺甲恶唑、氧氟沙星与脱水红霉素在污水处理厂出水及其污泥中综合评价因子均大于1,它们的存在可能对环境产生不同程度的危害.本研究结果表明,污水处理厂并不能完全去除水相中微量的医药物质,为防止排放导致的潜在生态风险,出水及污泥中活性医药物质需采取措施进行进一步的处理.     

Dislodgeable residues of profenofos on jasmine and risk assessment of post application exposure to flower bud pickers

A field study was conducted to measure the dislodgeable residues of profenofos applied to jasmine (Jasminum sambac) and risk assessment was done for laborers engaged in picking of flower buds. Profenofos was applied at 0.10, 0.15, and 0.20% concentration and the jasmine bud samples were analysed for residues using GC. The initial deposit of 1.6–3.8, 3.8–7.1, and 5.2–7.6 µg cm^?2 was detected on jasmine buds at 0.10, 0.15, and 0.20% concentration, respectively. At the recommended dose of 0.10%, the half-life was 1–2 days and the dislodgeable residues disappeared within 7 days. The results indicate faster disappearance of dislodgeable residues on jasmine buds. Risk assessment was done based on dislodgeable foliar residues and exposure estimates based on surrogate data and expressed as Margin of Exposure (MOE). The entry restrictions for exposure of jasmine flower pickers to profenofos, would be at least, 1 day following application, for the recommended concentration of 0.10% (MOE = 106) and 3 days, at higher concentrations of 0.15% (MOE = 156) and 0.20% (MOE = 115).     

Persistence of oxyfluorfen in soil and detection of its residues in rice crop

Oxyfluorfen is a post-emergence herbicide used for control of annual and perennial broad-leaf weeds and sedges in rice. There is increasing concern about persistence of pesticide residues in soils, agricultural products and sub-sequent contamination of ground water through runoff, leaching and drift. Thus, persistence of oxyfluorfen was evaluated under field conditions in a rice cropping system. Oxyfluorfen was sprayed at 240 and 500 g ai ha^?1 application rates to the rice crop as post-emergence herbicide. Paddy grains, straw and soil samples were collected at harvest and analyzed for oxyfluorfen residues by HPLC. Straw samples contained 0.01 and 0.03 µg g^?1 oxyfluorfen residues at 240 and 500 g ha^?1 concentrations, respectively. In the soil, 0.028 and 0.03 µg g^?1 of oxyfluorfen residues were detected when applied at 240 and 500 g ai ha^?1, respectively. However, in rice grains, 0.018 and 0.106 µg g^?1 of oxyfluorfen residues were found in 240 and 500 g ai ha^?1 treated plots. In light of the potential adverse effects of oxyfluorfen, it is important to determine herbicide levels in these crops.     

Persistence of carbaryl and its risk assessment through consumption of treated grapes

The average initial deposits of carbaryl were observed to be 1.4 and 3.1?mg?kg^?1, respectively, following four applications of the insecticide at 4.95 and 9.9?kg active ingredient per hectare. Residues of carbaryl dissipated below its limit of quantification of 50?µg?kg^?1 after 7 and 10 days at single and double the application dosage, respectively. The half-life values (t _1/2) of carbaryl were worked out to be 1.3 and 0.7 days, respectively, at single and double dosages. The acceptable daily intake (ADI) for carbaryl has been fixed at 8?µg?kg^?1 body weight per day. Keeping in view the residues of carbaryl observed one day after the last application, a child of 10?kg and an adult of 60?kg will have an intake of 77 and 154?µg carbaryl after consumption of 100 and 200?g grapes, in comparison to its ADI of 80 and 480?µg; thus, no health risk is to be expected. Therefore, a waiting period of 1 day has been suggested for the safe consumption of carbaryl-treated grapes to avoid any health hazards.