表面活性剂Burkholderia xenovorans LB400体系对低氯代PCBs的好氧强化降解

增强多氯联苯(PCBs)的水溶性是强化PCBs微生物降解的主要控制因素之一,本研究选取了PCB5(2,3-CB)和PCB31(2,4’,5-CB)作为低氯代PCBs的典型代表,以曲拉通100(TX-100)、吐温80(Tween 80)、鼠李糖脂粗提物(RL crude)3种表面活性剂和β-环糊精(HPCD)联合Burkholderia xenovorans LB400构建PCBs好氧降解体系,测试了它们对PCB5和PCB31的溶出率及微生物生长的影响.结果表明,TX-100(CMC=194 mg·L-1)、Tween 80(CMC=13.1 mg·L-1)、RL crude(CMC=50mg·L-1)浓度在1~7 CMC时和HPCD浓度在500~1500 mg·L-1时对PCB5和PCB31溶出率分别达到54.7%~100%、59.8%~100%;10.5%~40.8%、6.8%~31.6%;10.3%~19.9%、3.3%~11.6%和19.5%~34.2%、4.2%~10.7%.TX-100浓度在1~7 CMC时对B.xenovorans LB400生长的抑制率达到30.3%~45.8%,而Tween 80浓度在0.1~1 CMC时对其生长的抑制率为10.0%~15.4%;RL crude本身能作为底物促进LB400的生长,而HPCD对其生长无明显影响.B.xenovorans LB400对PCB31(5 mg·L-1)的降解效率在添加表面活性剂后有不同程度的提高:TX-100,23.7%~65.5%;Tween80,14.6%~44.3%;RL crude,9.6%~27.2%;HPCD,15.3%~20.7%;而表面活性剂对PCB5(10 mg·L-1)的降解效率则无明显影响.表面活性剂主要通过增大溶液中PCBs-表面活性剂的胶束浓度来提高LB400对PCBs的降解效率,在水溶液培养体系中当设置TX-100和Tween 80浓度分别在1和7 CMC时,PCB31的降解效率达到100%和81.7%,而此时B.xenovorans LB400生长的抑制率为30.3%和5.4%.     

渗滤液反渗透浓缩液回灌出水水质变化规律的研究

为更科学合理地选择回灌填埋体提供一定的理论依据,对3个不同年份垃圾柱的回灌出水进行了水质变化规律的研究.采用成都某垃圾填埋场的渗滤液反渗透浓缩液,对装填了填埋龄为1、5和15 a垃圾的垃圾柱开展了回灌实验,研究了回灌出水中酸碱度、总有机碳、氨氮、硝态氮、重金属的变化规律.结果表明,1 a垃圾柱处于产甲烷化阶段,具有较好的去除硝态氮的能力,硝态氮的降解率达到了88%以上,但出水有机物、氨氮浓度较高,对指标的改变主要通过生物作用;5 a垃圾柱已接近稳定化,但还没有矿化垃圾的典型特征,吸附能力与生物作用均较差,对有机物、盐分、Cr、Ni的削减能力较小;15 a柱具有较好的吸附能力和络合能力,对有机物、盐分、Cr、Ni具有较好的削减能力,初期的去除率分别达到了90%、78%、93%、74%,但随着回灌进行会接近或达到吸附容量,需要控制回灌过程和进度.     

铅锌矿区蜈蚣草内生放线菌的多样性及群落结构

为了认识重金属累积对植物内生菌的影响,采用变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术及序列分析对四川汉源铅锌矿区蜈蚣草内生放线菌的多样性进行了研究,并分析了内生放线菌多样性与Pb、Zn、Cu和Cd等主要重金属之间的相互关系.结果表明,蜈蚣草不同部分内生放线菌的群落结构和多样性存在一定的差异,多样性指数在2.79~3.29之间,与其他非重金属污染环境植物内生放线菌的多样性指数相似,说明在重金属污染地区仍然存在较为多样的内生放线菌类群.相关分析表明,蜈蚣草内生放线菌多样性指数与Cu、Cd和Pb的含量之间存在显著负相关.DGGE条带序列系统发育显示,链霉菌(Streptomyces)、假诺卡氏菌(Pseudonocardia)、小单孢菌(Micromonospora)、Xianggella为蜈蚣草内生放线菌优势类群,拟诺卡氏菌(Nocardiopsis)、小双孢菌(Microbispora)、马杜拉放线菌(Actinomadura)、弗兰克氏菌(Frankia)以及一些未培养放线菌也在蜈蚣草中存在.研究表明铅锌矿区蜈蚣草内生放线菌存在丰富的多样性,重金属的累积影响了内生放线菌的分布.     

Effect of alkalinity on nitrite accumulation in treatment of coal chemical industry wastewater using moving bed biofilm reactor

Nitrogen removal via nitrite （the nitrite pathway） is more suitable for carbon-limited industrial wastewater. Partial nitrification to nitrite is the primary step to achieve nitrogen removal via nitrite. The effect of alkalinity on nitrite accumulation in a continuous process was investigated by progressively increasing the alkalinity dosage ratio （amount of alkalinity to ammonia ratio, mol/mol）. There is a close relationship among alkalinity, pH and the state of matter present in aqueous solution. When alkalinity was insufficient （compared to the theoretical alkalinity amount）, ammonia removal efficiency increased first and then decreased at each alkalinity dosage ratio, with an abrupt removal efficiency peak. Generally, ammonia removal efficiency rose with increasing alkalinity dosage ratio. Ammonia removal efficiency reached to 88% from 23% when alkalinity addition was sufficient. Nitrite accumulation could be achieved by inhibiting nitrite oxidizing bacteria （NOB） by free ammonia （FA） in the early period and free nitrous acid in the later period of nitrification when alkalinity was not adequate. Only FA worked to inhibit the activity of NOB when alkalinity addition was sufficient.     

Sources of nitrous and nitric oxides in paddy soils：Nitrification and denitrification

Rice-paddies are regarded as one of the main agricultural sources of N 2O and NO emissions. To date, however, specific N2O and NO production pathways are poorly understood in paddy soils. ^15N-tracing experiments were carded out to investigate the processes responsible for N2O and NO production in two paddy soils with substantially different soil properties. Laboratory incubation experiments were carried out under aerobic conditions at moisture contents corresponding to 60% of water holding capacity. The relative importance of nitrification and denitrification to the flux of NaO was quantified by periodically measuring and comparing the enrichments of the N2O, NH~-N and NO3-N pools. The results showed that both N2O and NO emission rates in an alkaline paddy soil with clayey texture were substantially higher than those in a neutral paddy soil with silty loamy texture. In accordance with most published results, the ammonium N pool was the main source of N2O emission across the soil profiles of the two paddy soils, being responsible for 59.7% to 97.7% of total N2O emissions. The NO3-N pool of N2O emission was relatively less important under the given aerobic conditions. The rates of N2O emission from nitrification （N2On） among different soil layers were significantly different, which could be attributed to both the differences in gross N nitrification rates and to the ratios of nitrified N emitted as NzO among soil layers. Furthermore, NO fluxes were positively correlated with the changes in gross nitrification rates and the ratios of NO/N2O in the two paddy soils were always greater than one （from 1.26 to 6.47）. We therefore deduce that, similar to N2O, nitrification was also the dominant source of NO in the tested paddy soils at water contents below 60% water holding capacity.     

Dry deposition of PM10 over the Yellow Sea during Asian dust events from 2001 to 2007

Dry deposition velocities and fluxes of PM10during Asian dust events over the Yellow Sea from 2001 to 2007 were investigated using observation data in Qingdao, China and Jeju, Korea. The dry deposition velocities of PM10 during dust events over the Yellow Sea ranged from 0.19 to 8.17 cm/sec, with an average of 3.38 cm/sec. Dry deposition fluxes of PM10during dust events over the Yellow Sea were in the range of 68.5–2647.1 mg/(m2·day), with an average of 545.4 mg/(m2·day), which is 2–10 times higher than those reported by other studies for both dust and non-dust periods. It was estimated that 2.6 × 1011–48.7 × 1011g dust particles deposit to the Yellow Sea during dust events through dry deposition every year. Compared with the results in previous studies, it was found that the dry deposition of PM10over the Yellow Sea during dust events in the years with high frequency of dust could account for a large or overwhelming fraction of the annual total dry deposition. Backward air mass trajectory analysis showed that dust events influenced Jeju mainly originated from the desert regions located in Mongolia and Inner Mongolia, China. There were 119 backward trajectories influenced both Qingdao and Jeju during 15 dust events from 2001 to 2007, accounting for 61.3% of the total trajectories of 194, indicating that Qingdao and Jeju were usually on the same pathway of dust transport downwind from source areas.     

Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides(HFOs) using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents(denoted as HFO-201 and IOCCS) were employed for Sb(V) removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb(V) removal by both composites, while increasing temperature from 293 to 313 K only improved Sb(V) uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb(V) than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for IOCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb(V) adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb(V) adsorption by both hybrids was attributed to the inner sphere complexation of Sb(V) and HFO, and Ca(II) induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb(V) in the synthetic water could be effectively removed from 30 μg/L to below 5 μg/L(the drinking water standard regulated by China), and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.     

Quantification of viable bacteria in wastewater treatment plants by using propidium monoazide combined with quantitative PCR (PMA-qPCR)

The detection of viable bacteria in wastewater treatment plants(WWTPs) is very important for public health, as WWTPs are a medium with a high potential for waterborne disease transmission. The aim of this study was to use propidium monoazide(PMA) combined with the quantitative polymerase chain reaction(PMA-qPCR) to selectively detect and quantify viable bacteria cells in full-scale WWTPs in China. PMA was added to the concentrated WWTP samples at a final concentration of 100 μmol/L and the samples were incubated in the dark for 5 min, and then lighted for 4 min prior to DNA extraction and qPCR with specific primers for Escherichia coli and Enterococci, respectively. The results showed that PMA treatment removed more than 99% of DNA from non-viable cells in all the WWTP samples, while matrices in sludge samples markedly reduced the effectiveness of PMA treatment. Compared to qPCR, PMA-qPCR results were similar and highly linearly correlated to those obtained by culture assay, indicating that DNA from non-viable cells present in WWTP samples can be eliminated by PMA treatment, and that PMA-qPCR is a reliable method for detection of viable bacteria in environmental samples. This study demonstrated that PMA-qPCR is a rapid and selective detection method for viable bacteria in WWTP samples, and that WWTPs have an obvious function in removing both viable and non-viable bacteria. The results proved that PMA-qPCR is a promising detection method that has a high potential for application as a complementary method to the standard culture-based method in the future.     

空调病房真菌气溶胶浓度及粒径分布特征

医院室内空气真菌污染会影响医护人员、病人及陪护人员的健康,其影响程度不仅与空气真菌的种类和浓度有关,还与真菌气溶胶粒径及分布特征有关,不同粒径的真菌气溶胶影响人体健康的作用机制不同.本研究对重庆某综合医院的普通病房进行空气真菌取样,系统分析了病房空气真菌浓度、种属及粒径分布特征.通过分析实验数据,发现病房空气真菌浓度与病人患病类型及人员密度无关,主要影响因素为温湿度与季节变化.冬夏各科室病房真菌粒径分布特征大致呈正态分布,粒径的百分比从Ⅰ级~Ⅲ级各级所占比例逐渐增大,Ⅲ级~Ⅴ级所占比例总体最大,Ⅴ级~Ⅵ级所占比例逐渐降低.冬夏不同科室病房的空气真菌孢子中值直径没有显著差异,真菌孢子的中值直径小于3.19μm.病房冬夏优势菌属基本相同,主要为青霉属、曲霉属及交链孢霉属,与其它建筑相比并无显著性差异.因此,病房空调系统设计应提高对粒径为1.1~4.7μm真菌孢子的过滤效率,病房的日常卫生维护与空调系统运行管理时应有针对性地选择适宜的抑菌除菌方法和设备.     

落叶燃烧排放的颗粒物及有机碳、元素碳的研究

为研究落叶燃烧排放的颗粒物(PM)及有机碳(OC)、元素碳(EC),采用明燃和闷燃两种形式对10种乔木的落叶进行燃烧实验,采集了排放的烟尘,并用元素碳/有机碳分析仪测定样品的OC和EC含量.结果表明,落叶在明燃状态下PM、OC、EC的排放因子范围分别为7.9~31.9、0.9~9.7、3.6~13.9 g·kg-1,平均值分别为19.7、5.2、6.8 g·kg-1.闷燃状态下PM、OC、EC的排放因子范围分别为61.3~128.9、31.7~60.4、1.9~6.0 g·kg-1,平均值分别为91.0、43.0、4.0 g·kg-1.明燃和闷燃的OC/EC变化范围分别为0.21~1.82和8.16~16.84.明燃状态下OC/PM、EC/PM的范围分别为0.11~0.41和0.18~0.56.闷燃状态下OC/PM、EC/PM的范围分别为0.43~0.53和0.03~0.06.OC和PM的排放因子在两种燃烧状态下均呈现显著的相关性.在不同的燃烧状态下,各组分之间的排放因子具有较大的差异,OC的排放因子在闷燃状态下高于明燃状态,而EC的排放因子则相反.不同燃烧状态下PM、OC、EC的排放因子及它们之间的比值分析,对建立森林生物质燃烧源排放清单以及来源解析具有重要意义.