Imazaquin degradation and metabolism in a sandy loam soil amended with farm litters

Irnazaquin applied in legume crops has a long residual time in soil, which often impacts safety of the susceptible crops. To increase safety of imazaquin application, two composted litters, bovine manure （BM） and chicken manure （CM）, were used to determine their effects on imazaquin environmental behavior by incorporating each kind of manure into the tested sandy loam soil at 10% （w/w）. The degradation of imazaquin in BM- and CM-amended soil was about 2.4 and 1.5 times, respectively, faster than that in unamended soil. The half-lives of imazaquin in BM-amended soil varied between 6.7 and 15.4 d over the temperature range of 20 to 40℃, and the degradation rate constant （k） increased by a factor of about 1.5 for every 10℃ change. Higher mix ratio did not significantly increase the degradation, and the optimal active degradation of imazaquin was observed approximately at the mix ratio of 10：1 of soil to BM. The different moisture levels had negligible effect on imazaquin degradation. In both unamended and BM-amended treatments, two metabolites were observed at 5, 10 and 30 d after treatment. One metabolite at retention time （RT） of 8.4 rain was identified as 2-（4- hydroxyl-5-oxo-2-imidazolin-2-yl） quinoline acid, originating from the loss of isopropyl group and hydroxylation at the 4-position of imidazolinone ring. The other at RT of 12.9 rain was identified as quinoline-2,3-dicarboxylic anhydride, resulting from detachment of imidazolinone ring and the forming of dicarboxylic anhydride. This finding suggested that the addition of farm litters into soil might be a good management option since it can not only increase soil fertility but also contribute to increase safety of imazaquin application to the following susceptible crops.     

十溴联苯醚在单次暴露的孕和非孕SD大鼠血液内的吸收分布

五溴联苯醚、八溴联苯醚被禁以后,十溴联苯醚（BDE-209〉97%）是现在唯一仍在全球范围内广泛使用的多溴联苯醚阻燃剂。BDE-209在环境介质和生物体,甚至人体的血液、母乳中普遍存在,而且BDE-209的环境含量呈上升趋势。在实验室条件下,BDE-209可以通过生物代谢,或光降解、热降解转换形成毒性更强的低溴代PBDEs、羟基甲氧基PBDEs、致癌物多溴二苯并二噁英/呋喃（PBDD/DFs）。所以BDE-209的环境行为及生物效应成为环境污染物领域研究的热点之一。目前,关于BDE-209对妊娠期生物体的暴露研究还是很少。研究了十溴联苯醚在单次暴露的孕和非孕SD大鼠血液内的吸收代谢。结果表明,BDE-209可以被孕和非孕SD大鼠吸收,孕和非孕SD大鼠血液中吸收的BDE-209都可以快速的排出。BDE209在孕和非孕SD大鼠体内存在脱溴代谢,主要的脱溴代谢物是3种nona-BDE（sBDE-206,-207,-208）和五种octa-BDEs（BDE-196,-197/204,-198/203）,其中3种nona-BDEs是主要的代谢物,而BDE-207是nona-BDEs中含量最大的单体。BDE-209及其脱溴代谢物nona-BDEs的清除速率,在SD孕鼠的体内快于SD非孕鼠,而且在暴露实验的后期还存在统计意义的显著差异性。     

垂直流-水平潜流组合湿地对磺胺类抗生素的去除

利用垂直流串联水平潜流的组合人工湿地处理污水处理厂尾水,比较有植物和无植物组合湿地对磺胺类抗生素母体及N4乙酰代谢物的去除效果。结果表明:有植物组合湿地的去除效率为72.31%,高于无植物组合湿地的59.71%;不同种类湿地植物对磺胺类抗生素的吸收累积能力存在差异,美人蕉积累量最大,其次为风车草,花叶芦竹最低;植物各部位对磺胺类抗生素的积累为地下组织(根)大于地上组织(叶和茎);基质对磺胺类抗生素的吸附能力表现为有植物基质吸附量大于无植物基质,变化范围为0.34~1.59 ng/g dw,表明湿地植物的存在更有利于磺胺类抗生素的降解。垂直流-潜流组合湿地能较好地降解磺胺类抗生素,但其降解机理及植物在其中的作用有待进一步研究。     

铜绿微囊藻与藻际细菌Ma-B1菌株的相互作用

藻与细菌通常共生于淡水生境,形成藻-菌共生体系,藻际细菌是水体生态系统中的重要组成部分,对藻的消长起重要的调控作用,但有关藻际微环境中藻与细菌的互作机制还不清楚. 采用传统的细菌平板培养方法,从太湖优势水华藻——铜绿微囊藻(Microcystis aeruginosa)细胞表面分离出一株藻际细菌Ma-B1,基于生理、生化试验和16S rRNA基因序列分析,初步鉴定为甲基营养芽孢杆菌(Bacillus methylotrophicus). 通过测定细胞生长,分析藻-菌相互作用机理. 结果表明:一定浓度(＞60 μg/mL)的Ma-B1的胞外代谢物可显著抑制铜绿微囊藻的生长(培养基为BG11,28 ℃/日,22 ℃/夜,3 000 lx,光暗比为14 h∶10 h);铜绿微囊藻的胞外滤液(500 μL/mL)对Ma-B1的生长有一定的促进作用,但其总滤液(500 μL/mL)显著促进Ma-B1的生长;Ma-B1细胞对铜绿微囊藻的生长没有显著影响,而高浓度(藻菌比10∶1)的铜绿微囊藻细胞则可显著抑制Ma-B1的生长. 铜绿微囊藻与Ma-B1之间存在复杂的相互抑制或促进关系,共同影响着藻、菌在自然水体生态系统中的消长.      

Relation of hepatic EROD activity and cytochrome P4501A level in Sebastiscus marmoratus exposed to benzo[a]pyrene

This study was designed to investigate the in vivo effects of benzo[a]pyrene （BaP） on hepatic ethoxyresorufin-O-deethylase （EROD） activity and its correlation with cytochrome P4501A （CYP1A） protein levels in Sebastiscus marmoratus, which were exposed through a water column to BaP （10, 100, 1000 ng/L, respectively） or were treated with intraperitoneal injections of BaP （0.5, 1, 5, 10 mg/kg, respectively） every 7 d. The results showed that after 25 d of waterborne exposure to 1000 ng/L BaP, fish hepatic CYP1A levels and EROD activity were significantly induced. In contrast, EROD activity was not altered 7 d after second intraperitoneal injections, whereas, CYP1A protein levels were increased. Dose-dependent increase of biliary BaP metabolites demonstrated that the catalytic activity of CYP1A was induced by treatment with BaP. The lowest observable effect concentration with regard to biliary BaP metabolites （100 ng/L） was much lower than that with reference to EROD activity （1000 ng/L）. The results suggest that biliary polycyclic aromatic hydrocarbon （PAH） metabolites were shown to better reflect the contamination gradients of PAHs than EROD activity. It appeared to be necessary to measure CYP1A protein levels to complement the EROD activity in relevant toxicological assessments.     

人体接触多环芳烃的指标—尿中1—羟基芘的研究进展

本文对尿中１－羟基芘的研究意义，方法，在不同环境领域中开展研究的最新动向和所取得的成果做了系统介绍，尿中１－羟基芘是人体接触中多环芳烃的一个灵敏和有实用价值的指标，它在工业卫生，工业污染地区，城市环境和关系到多环芳烃污染的职业人群中有广泛的研究和应用价值，为多环芳烃的环境健康风险评价提供了有效的手段和依据，展望了未来的研究发展。     

Degradation of metabolites accumulated of benzo[a]pyrene by coupling Penicillium Chrysogenum with KMnO4

Several main metabolites of benzo[a]pyrene （BaP） formed by Penicillium chrysogenum, Benzo[a]pyrene-1,6-quinone （BP 1,6- quinone）, trans-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene （BP 7,8-diol）, 3-hydroxybenzo[a]pyrene （3-OHBP）, were identified by high-performance liquid chromatography （HPLC）. The three metabolites were liable to be accumulated and were hardly further metabolized because of their toxicity to microorganisms. However, their further degradation was essential for the complete degradation of BaP. To enhance their degradation, two methods, degradation by coupling Penicillium chrysogenum with KMnO4 and degradation only by Penicillium chrysogenum, were compared; Meanwhile, the parameters of degradation in the superior method were optimized. The results showed that （1） the method of coupling Penicillium chrysogenum with KMnO4 was better and was the first method to be used in the degradation of BaP and its metabolites; （2） the metabolite, BP 1,6-quinone was the most liable to be accumulated in pure cultures; （3） the effect of degradation was the best when the concentration of KMnO4 in the cultures was 0.01% （w/v）, concentration of the three compounds was 5 mg/L and pH was 6.2. Based on the experimental results, a novel concept with regard to the bioremediation of BaP-contaminated environment was discussed, considering the influence on environmental toxicity of the accumulated metabolites.     

吸烟及吸二手烟对人体多环芳烃内暴露的影响

采用快速液相色谱-三重四级杆串联质谱仪对吸烟、吸二手烟和不吸烟的居民的尿样进行抽检,分析了10种多环芳烃羟基代谢物(OH-PAHs)的组成和含量,评估了吸烟及吸二手烟对人体OH-PAHs内暴露水平的影响.结果表明,吸烟及吸二手烟对居民尿液中OH-PAHs的浓度水平和组成特征均有影响,对萘和芴的代谢产物影响最为显著.OH-PAHs的浓度水平按照吸烟组>吸二手烟组>不吸烟组的顺序递减,吸烟组和吸二手烟组人群尿液中萘的代谢产物2-羟基萘和1-羟基萘所占的比例分别是不吸烟组人群的1.5、1.2倍和1.7、1.9倍;吸烟、吸二手烟和不吸烟人群体内各OH-PAHs之间的相关性分析表明,吸二手烟人群体内OH-PAHs来源最为复杂,受环境空气和香烟烟雾的双重影响.与同类研究结果相比,本研究吸二手烟人群体内OH-PAHs明显偏低,这可能与吸二手烟人群受到烟气的暴露时间和暴露量有关.     

β-Proteobacteria菌降解甲基叔丁基醚的条件及中间代谢产物研究

采用可利用甲基叔丁基醚(methyl tert-butyl ether,MTBE)为唯一碳源和能源生长的1株β-Proteobacteria菌进行MTBE在密闭系统中的降解试验,确定了该菌降解MTBE的最适条件为:培养液初始pH值7.2,初始细胞浓度107 cells/mL,初始MTBE浓度为25mg/L.考察了密封培养系统内培养液溶解氧对降解效果的影响,结果表明,在培养系统密闭前充入氧气可提高菌体对MTBE的降解速率.以气相色谱-质谱联用法检测到MTBE降解主要中间代谢产物是叔丁基醇、异丙醇、丙酮.在选择离子扫描模式下定量分析,得到降解过程中主要中间代谢产物的浓度变化曲线,据此推断MTBE的降解途径属于"丙酮途径".