Detection of polychlorinated biphenyls employing chemical dechlorination followed by biphenyl whole cell sensing system

Polychlorinated biphenyls (PCBs) are a mixture of 209 individual chlorinated compounds commonly known as PCB congeners. These compounds are hydrophobic and are persistent in the environment. Their use was banned in the US a few decades ago because of harmful health effects. Therefore, detection of PCBs in environmental samples is increasingly important. To that end, we have developed a two-step simple and sensitive method for the detection of total PCBs. Specifically, our method involves dechlorination of PCBs to biphenyl followed by detection of biphenyl using a whole cell sensing system as the detection system. The whole cell sensing system consists of cells of the strain Pseudomonas pseudoalcaligenes KF707 harboring plasmid pSD7000. Plasmid pSD7000 contains the gene of lacZ, a reporter protein under the control of the bph operon. The detection is achieved through the emission of light afforded by the expression of reporter protein triggered by the presence of biphenyl. Due to the fact that this operon is activated only by few PCB congeners, a chemical dechlorination method was employed to convert all PCBs to biphenyl, and thus all the PCBs present in a given sample are able to be detected. The results showed that PCB congeners were rapidly (30?min) and efficiently (>98.5%) dechlorinated to biphenyl using a Mg/K₂PdCl₆ catalyst, and the biphenyl could be subsequently quantified using the whole cell sensing system. This hybrid analytical method that combines classical dechlorination with novel biosensing methods may find applications in the on-site monitoring of PCBs contamination levels.     

我国主稻作区稻谷镉和铅含量及其分布特征

收集我国6个主稻作区代表性稻谷样品120份,采用原子吸收光谱法测定Cd、Pb含量,分析各地区各品种稻谷及其加工产物Cd、Pb含量差异,探讨Cd、Pb在稻谷、精米、米糠和米糠油中的分布规律.结果表明,我国主稻作区稻谷、精米、米糠和米糠油中Cd平均含量分别为(0.116 ±0.057)、(0.089 ±0.413)、(0.149±0.069)和(0.111±0.043) mg·kg-1,且华中稻作区、华南稻作区、华北稻作区、西北稻作区、东北稻作区和西南稻作区稻谷及其加工产物Cd平均含量依次降低;稻谷、精米、米糠和米糠油中Pb平均含量分别为(0.232±0.105)、(0.125±0.061)、(0.301±0.142)和(0.089±0.024) mg· kg-1,华中稻作区、华南稻作区、西北稻作区、华北稻作区、东北稻作区和西南稻作区稻谷及其加工产物Pb平均含量依次降低.米糠、稻谷、米糠油和精米中Cd平均含量依次降低,米糠、稻谷、精米和米糠油中Pb平均含量依次降低,稻谷加工为精米,Cd去除率为(9.40±1.46)％,Pb去除率为(36.03±1.15)％,米糠加工为米糠原油,其Cd和Pb残留率分别为(62.43±2.00)％和(31.24±0.63)％.     

Enhanced production of laccase by Coriolus hirsutus using molasses distillery wastewater

The effect of physical parameters of cultivation (load volume, temperature, pH, agitation, inoculum size, and incubation period) in the production of laccase by wood-rotting basidiomycete Coriolus hirsutus were studied using diluted molasses distillery wastewater (MDW) as a major composition. Using fractional factorial design, our study first identified load volume, agitation, and inoculum size as statistically significant factors. Optimal preferences and mutual interactions of the factors were then determined by the response surface method, which is based on the center composite design. A quadratic model was used to fit the experimental data. The optimized operational parameters for laccase production were determined to be the following: culture temperature of 25°C, pH 4, load volume of 40 mL diluted MDW in 150 mL flask, agitation rate of 183 r·min^?1, inoculation of 11.5% v/v, and cultivation time of 6 d. The experimental validation under these conditions (the maximum laccase production of 2198.2 U·mL^?1 was within the confidence interval) subsequently verified the accuracy of the constructed model. Moreover, the removal of chemical oxygen demand and nitrogen of MDW reached 62.85% and 48.00% respectively, and the decolorization ratio under the optimal condition was 41.85%. The enhanced production of laccase by C. hirsutus is a new recovery strategy for MDW.     

Gridded usage inventories of chlordane in China

Chlordane (1,2,4,5,6,7,8,8-octachloro-3a,4,7, 7a-tetra-hydro-4,7-methanoindane) is one of organochlorine pesticides (OCPs) which has been listed as one of the persistent organic pollutants (POPs) to be reduced and finally eliminated in the Stockholm Convention on Persistent Organic Pollutants, because of its great persistence, toxicity, bio-accumulation and long-range transport potential. It is critical to create a national chlordane usage inventories for China to compile chlordane emission inventories, which is helpful for carrying out risk assessments and other researches related to chlordane in China. The annual data of chlordane usage was calculated and modified in accordance with the reported annual production of chlordane which was caculated on the basis of the termite distribution, the data of chlordane usage rate and the annual new construction area (NCA).With the help of Geographic Information System, the usage data of this NCA were allocated to a grid system then, with a 1/4° longitude by 1/6° latitude resolution and a size for each grid cell of approximately 25 km by 25 km. Between 1988 and 2008, the total usage of chlordane in China was 2745 t, accounting for approximately 80% of the production in the same period. Zhejiang Province was the largest consumer of chlordane in China, whose usage adds up to 980 t, greatly exceeding other provinces/regions, followed by Jiangsu Province (534 t) and Sichuan Province (428 t). The region with the least usage of chlordane was Beijing. Provinces of Guizhou, Henan and Hebei did not use any chlordane, even though termites had occurred in these provinces. Gridded usage inventories showed that the intensive use of chlordane was concentrated in the southeast part of China, Yangtze River Delta and Pearl River Delta in particular. The satisfaction of the inventories was supported by the consistence between the estimated data of annual usage and the reported annual production of chlordane, and by the consistence between distribution pattern of chlordane’s usage and ambient air concentration.     

Fermentative hydrogen production from beet sugar factory wastewater treatment in a continuous stirred tank reactor using anaerobic mixed consortia

A low pH, ethanol-type fermentation process was evaluated for wastewater treatment and bio-hydrogen production from acidic beet sugar factory wastewater in a continuous stirred tank reactor (CSTR) with an effective volume of 9.6 L by anaerobic mixed cultures in this present study. After inoculating with aerobic activated sludge and operating at organic loading rate (OLR) of 12 kgCOD?m^-3·d^-1, HRT of 8h, and temperature of 35°C for 28 days, the CSTR achieved stable ethanol-type fermentation. When OLR was further increased to 18 kgCOD?m^-3·d^-1 on the 53rd day, ethanol-type fermentation dominant microflora was enhanced. The liquid fermentation products, including volatile fatty acids (VFAs) and ethanol, stabilized at 1493 mg·L^-1 in the bioreactor. Effluent pH, oxidation-reduction potential (ORP), and alkalinity ranged at 4.1–4.5, -250–(-290) mV, and 230–260 mgCaCO₃?L^-1. The specific hydrogen production rate of anaerobic activated sludge was 0.1 L?gMLVSS^-1·d^-1 and the COD removal efficiency was 45%. The experimental results showed that the CSTR system had good operation stability and microbial activity, which led to high substrate conversion rate and hydrogen production ability.     

Removal of sulfadiazine from aqueous solution on kaolinite

The adsorption of sulfadiazine onto kaolinite clay as an alternative adsorbent was examined in aqueous solution, hnpacts of the contact time, pH, temperature, ionic strength and coexistent surfactants on the adsorption process were evaluated. The pH significantly influenced the adsorption process, with adsorption being promoted at lower pH due to the cation exchange mechanism. Decreasing ionic strength in the solution was favorable for adsorption, and the addition of cationic and anionic surfactants had negative effects on the adsorption capacity of sulfadiazine on kaolinite. Kinetic experiments showed that the adsorption followed the pseudo-second-order model. The equilibrium adsorption was well described by both Freundlich and Dubinin-Radushkevich （DR） models. According to the DR model, the adsorption mechanism was determined by cationic exchange and weak physical forces. The thermodynamic study showed that sulfadiazine adsorption onto kaolinite was a sponta- neous and endothermic reaction.     

TCP的污泥减量效果及其对出水水质的长期影响

向倒置A2/O中试系统中投加2,4,5-三氯苯酚(TCP),研究TCP对污泥的减量效果及进入处理系统后对系统出水水质长期影响。研究结果表明:与参照组相比,加药组投加TCP 2 mg/L时,污泥减量达62.5%,出水TN比参照组平均高0.8 mg/L,137 d后出水TP超过0.5 mg/L。TCP对污泥的减量效果好,需要加除磷药剂进行辅助除磷。     

纳米Fe3O4对小鼠肺细胞的氧化损伤

纳米Fe3O4作为一种功能材料,在生物医药、生物靶向材料、微波吸收材料和高梯度磁分离器等方面应用前景广阔,其潜在的生物毒性也备受关注。为研究纳米Fe3O4对生物体可能造成的氧化损伤,以昆明小鼠为受试体,设置5、10、20和40mg·kg-14个染毒组,腹腔注射染毒7d后,测定小鼠肺组织中活性氧(reactive oxygen species,ROS)、还原型谷胱甘肽(glutathione,GSH)和丙二醛(malondialdehyde,MDA)的含量。结果显示,随着纳米Fe3O4染毒剂量的升高,肺组织ROS和MDA含量逐渐上升,GSH含量逐渐降低,各指标均呈一定的剂量-效应关系。剂量≥10mg·kg-1,肺组织ROS含量与对照组相比有显著差异(p<0.05);剂量≥20mg·kg-1,肺组织MDA含量与对照组相比有显著差异(p<0.05);剂量≥40mg·kg-1,肺组织GSH含量与对照组相比有显著差异(p<0.05)。研究表明,较高剂量(≥20mg·kg-1)的纳米Fe3O4颗粒材料会引起小鼠肺细胞的氧化损伤。     

全氟辛酸(PFOA)对蚯蚓的毒性作用

为考察全氟化合物的土壤生态毒性,以赤子爱胜蚓为模式生物,通过人工土壤染毒方法研究全氟辛酸(PFOA)对蚯蚓急性毒性、回避行为和SOD、CAT等抗氧化酶活性的影响。结果表明,PFOA对蚯蚓的急性毒性作用与染毒时间和染毒浓度相关,实验求得PFOA对蚯蚓毒性作用7和14d的LC50值分别为816.58和792.50mg·kg-1;蚯蚓在160mg·kg-1PFOA暴露浓度下表现出明显的回避反应。在10～120mg·kg-1PFOA长时间暴露下,蚯蚓体内SOD出现"低促高抑"的变化趋势,而GSH-Px则总体上被PFOA所抑制。     

全氟辛烷磺酸盐(PFOS)替代品对中华蜜蜂的毒性

选用中国蜂种中华蜜蜂工蜂作为受试生物,建立其环境危害评价毒性测试方法,用所建立的方法对全氟辛烷磺酸盐(PFOS)替代品进行了接触急性毒性及经口急性毒性风险评价,并比较了"小烧杯法"和"饲喂管法"两种经口毒性方法的优缺点及对毒性结果的影响。研究结果表明,"小烧杯法"实验中C4织物三防整理剂对中华蜜蜂的24h-LC50为1435mg·L~(-1),48h-LC_(50)为284.67mg·L~(-1);其余替代品在限度实验均未出现蜜蜂死亡,4种PFOS替代品对中华蜜蜂的接触毒性及经口毒性均为低毒,但"小烧杯法"测得的经口毒性结果比"饲喂管法"高。