6-2氟调醇在活性污泥中的降解

为了解6-2氟调醇(6-2 FTOH)在城市污水处理厂活性污泥中的好氧降解规律,利用室内模拟实验装置,研究了6-2FTOH在未经稀释驯化的活性污泥中的降解动力学及降解产物分布.结果表明,6-2 FTOH能被活性污泥快速吸附并发生降解,降解反应符合一级动力学,半衰期为0.9d.降解产物包括6-2氟调酸(6-2 FTCA)、6-2不饱和氟调酸(6-2 FTUCA)、5-3氟调酸(5-3 FTCA)、5-2s氟调醇(5-2s FTOH)和全氟己酸(PFHxA).第28 d实验结束时,6-2 FTOH残留率为5.5％,6-2 FTCA和6-2 FTUCA的最终产率分别为0和1.2％.5-3FTCA、5-2s FTOH、PFHxA最终产率分别为23.4％、17.6％和1.3％.     

Leaching potential of some phenylureas and their main metabolites through laboratory studies

BACKGROUND, AIMS AND SCOPE: Laboratory studies were conducted with the aim of defining the leaching potential of some phenylureas and their metabolites. A first study was performed for calculating their leaching index (as GUS) on the base of intrinsic properties: persistence (as DT50) and mobility (as Koc) in soil. Another study consisted of aged column leaching experiments whose meaning was to semi-quantify the occurrence of the tested compounds in the leachates, so simulating in field conditions. METHODS: The tested compounds were: diuron, linuron and monolinuron (parents); 3,4-dichloroaniline (DCA), 4-chloroaniline (CLA), 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU), 1-(3,4-dichlorophenyl)urea (DCPU), 1-(4-chlorophenyl)urea (CPU) and monuron, this latter considered both as a metabolite and parent compound. The Koc values of the examined substances were determined by the HPLC screening methods, according to the OECD TG 121. DT50 determinations and aged column leaching experiments were carried out according to SETAC procedures. RESULTS AND DISCUSSION: The examined compounds showed a rather wide range of persistence in soil, with DT50 values less than 2 days for DCA and CLA, close to 8 days for DCPU and CPU and from 16 (diuron) up to 24.8 (DCPMU) days for the others. Their mobility was generally high, based on their Koc values, which ranged from 33 (CPU) to 406 (linuron). The GUS indices indicated that monuron has a clear potential to contaminate groundwater (> 2.8); DCPMU, monolinuron, CPU and diuron are intermediate contaminants (1.8-2.8). Linuron, DCPU, CLA and DCA exhibited a non-leaching behaviour (< 1.8). The aged leaching column experiments showed that parents were found in the leachates at very high percentages respect to the doses applied. The metabolites reached much less percentages, the highest values were observed for monuron from diuron (5.7), CPU (7.2) and DCPMU (8.2%). CONCLUSION: Diuron, Monuron, CPU and DCPMU on the basis of their intrinsic properties, formation from their parents and occurrence in leachates from aged column leaching studies, seem to possess the characteristics of groundwater contaminants. The methodological approach of this study is relatively easy and rapid, hence it can represent a tool for a first screening of compounds such as pesticide metabolites (generally available only in small quantities and for which a field study is not conceivable) or other compounds for which not adequate environmental data are available.     

铜绿假单胞菌降解菲的产物鉴定及代谢过程

研究了1株能快速降解疏水性化合物的铜绿假单胞菌NY3对菲的降解机理。GC-MS分析表明,该菌代谢菲的各个阶段,能够被检测到的主要酸性产物有1-羟基-2-萘甲酸、α-萘酚、邻羟基苯基羰基乙酸、水杨酸、苯甲酸等。铜绿假单胞菌NY3经过一系列氧化代谢将菲转化为1-羟基-2-萘甲酸,进一步反应生成α-萘酚。由菲到1-羟基-2-萘甲酸,未检测到其他产物,说明该阶段产物被继续代谢的速度快,产物含量低不易积累。1-羟基-2-萘甲酸为体系中积累的唯一的主要代谢产物。尽管继续代谢速度慢,但它可以按照α-萘酚、邻羟基苯基羰基乙酸、水杨酸、苯甲酸途径被继续转化。NY3降解菲的代谢产物中未检测到二羟基萘、苯二酚等多羟基化合物,但羟基和羧基处于邻位的化合物,如1-羟基-2-萘甲酸和水杨酸有非常明显积累的趋势,α-萘酚和苯甲酸积累速度次之。     

4种磺胺类药物及乙酰化代谢物在污水处理厂的去除及机制

乙酰化代谢物是磺胺类药物的重要代谢产物.为研究4种常见磺胺类药物及其乙酰化代谢物在污水厂中的去除机制,根据污水停留时间采集厦门某A2/O型工艺污水厂不同处理单元的污水和污泥样品,采用固相萃取-高效液相色谱串联质谱法检测目标化合物.结果显示,8种目标物中有6种在水体中被检测出,污泥中有5种目标物被检测出.计算总去除率及各个处理单元间的去除率,结果表明,磺胺二甲基嘧啶在污水厂中总去除率几乎为0,而其他5种化合物都有不同程度的去除,但不同目标物在各处理单元的去除率不同.利用质量平衡,分析各物质可能的去除机制,磺胺二甲基嘧啶可能去除机制为污泥吸附,磺胺嘧啶、磺胺甲基嘧啶和磺胺甲唑可能的去除机制均为生物降解.     

2, 4-二硝基甲苯在鲤鱼体内的代谢研究

应用水生生物体内实验方法，研究了２，４－二硝基甲苯在鲤鱼肝肠提取物中的生物浓缩及代谢转化过程。半静态条件下，采用３种不同的暴露浓度，测定肝，肠组织的生物浓缩曲线，并同步对肝提取物进行了ＨＰＬＣ检测。     

Assessment of bioavailable PAH, PCB and OCP concentrations in water, using semipermeable membrane devices (SPMDs), sediments and caged carp

Bioavailable water concentrations of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and organochlorine pesticides (OCPs) were assessed at several freshwater sites in and around the city of Amsterdam. Carp (Cyprinus carpio) were caged for 4 weeks at 10 sites, together with semipermeable membrane devices (SPMDs). In addition, sediment samples were taken at each site. SPMDs and sediments were analysed for PAHs, PCBs and OCPs. Carp muscle tissues were analysed for PCBs and OCP, while PAH metabolites were assessed in fish bile. Contaminant concentrations in the water phase were estimated using three different methods: 1. Using fish tissue concentrations and literature bioconcentration factors (BCFs), 2. Using SPMD levels and a kinetic SPMD uptake model, and 3. Using sediment levels and literature sorption coefficients (K_ocs). Since PAH accumulation in fish is not considered an accurate indicator of PAH exposure, calculated aqueous PAH concentrations from SPMD data were compared with semiquantitatively determined biliary PAH metabolite levels. Contaminant concentrations in the water phase estimated with fish data (Cw_fish) and SPMD data (Cw_spmd) were more in line for compounds with lower K_ow than for compounds with higher K_ow values. This indicates that the assumption of fish–water sorption equilibrium was not valid. At most sites, sediment-based water levels (Cw_sed) were comparable with the Cw_spmd, although large differences were observed at certain sites. A significant correlation was observed between biliary PAH metabolite levels in fish and aqueous PAH concentrations estimated with SPMD data, suggesting that both methods may be accurate indicators of PAH exposure in aquatic ecosystems.     

Chemical studies on Indopacific Ceratosoma nudibranchs illuminate the protective role of their dorsal horn

Summary. Two Ceratosoma species, C. trilobatum and C. gracillimum (Mollusca: Gastropoda: Opistobranchia), collected along the South China Sea coast, have been studied in order to investigate their defensive strategies. Both species contain four typical sponge furanosesquiterpenoids, probably with a dietary origin. The tissue distribution of these compounds has been studied by ¹H-NMR analysis and preliminary bioassays have been carried out in order to evaluate the ecological role of the isolated metabolites. The main sesquiterpene component in both species was (–)-furodysinin (2), which showed significant feeding-deterrent and ichthyotoxic properties in bioassays with freshwater organisms. The work has been performed studying a very limited number of molluscs that prevented the realization of ecologically relevant experiments. However, the almost exclusive presence of compound 2 in the crude extract of the mantle glands concentrated in the dorsal horn of C. gracillimum strongly supports the defensive role of that dorsal protuberance, which probably acts as a defensive lure attracting potential predators to the part of the animal that contains the distasteful chemicals.     

Glucosinolates and other metabolites in the leaves of <Emphasis Type="Italic">Arabidopsis thaliana</Emphasis> from natural populations and their effects on a generalist and a specialist herbivore

Because many secondary metabolites in plants act as defense against herbivores it has been postulated that these compounds have evolved under selective pressure by insect herbivores. One explanation for the within-species variation in metabolite patterns in a particular species is that different populations are under selection by different herbivores. We tested this hypothesis, using Arabidopsis thaliana plants that originated from dune and inland areas. We analyzed Arabidopsis thaliana leaves using NMR spectroscopy and multivariate data analysis. Major differences in chemical composition were found in water-methanol fractions and were due to higher concentrations of sinigrin and fumaric acid in dune plants. Inland plants showed lower levels of glucose. Quantitative analysis of glucosinolates was performed with HPLC. Individual plants and populations demonstrated differences in glucosinolate composition and concentration. In growth chamber experiments, the generalist herbivore, Spodoptera exigua grew significantly better on the inland plants, while the specialist herbivore Plutella xylostella performed equally well on plants of both origins. Aliphatic glucosinolate as well as total glucosinolate concentrations negatively correlated with larval mass of Spodoptera exigua. No significant correlations, however, were found between larval mass of Plutella xylostella and glucosinolates in the leaves. A specialist and a generalist herbivore were responding differently to plant secondary chemistry, as was also found in several other studies. This is an important indication that differences in glucosinolate concentrations among populations may result from differential selection by different guilds of herbivores.     

HCH residues in point-source contaminated samples of the Teltow Canal in Berlin,Germany

Contaminated groundwater and a riverine sediment core heavily affected by the same industrial point source were analysed for hexachlorocyclohexanes (HCH) and its degradation products. A detailed quantification by GC/MS revealed contamination levels up to 730 μg/L and 396 ng/g in sum for the water and sediment samples, respectively. The isomer pattern differed significantly in both compartments. The ground water samples were depleted in γ-HCH, whereas a significant loss of α-HCH was evident in the sediments as compared to the technical composition. The data obtained revealed interesting insights into the transformation behaviour and fate of HCH mixtures in anaerobic environmental compartments. In the affected groundwater system an ongoing microbial degradation was pointed out by the identification of indicative anaerobic metabolites. On the contrary in the sedimentary system a high environmental stability or rather a hindered degradation was observed as indicated by unaltered concentration levels as compared to production rates as well as by the absence of metabolites. Interestingly, the environmental fate of HCH in subaquatic sediments as well as in anaerobic ground water differs highly in contrast to the behaviour in anaerobic soil or surface water systems. Further on, it has to be stated, that the knowledge about the long-term behaviour of HCH residues in sedimentary material under anaerobic conditions is rather limited so far.     

Biodegradation of 1,1,1-trichloro-2,2-bis(4-chlorophenyl) ethane (DDT) by using Serratia marcescens NCIM 2919

A solvent tolerant bacterium Serratia marcescens NCIM 2919 has been evaluated for degradation of DDT (1,1,1-trichloro-2,2-bis (4-chlorophenyl) ethane). The bacterium was able to degrade up to 42% of initial 50 mg L^?1 of DDT within 10 days of incubation. The highlight of the work was the elucidation of DDT degradation pathway in S. marcescens. A total of four intermediates metabolites viz. 2,2-bis (chlorophenyl)-1,1-dichloroethane (DDD), 2,2-bis (chlorophenyl)-1,1-dichloroethylene (DDE), 2,2-bis (chlorophenyl)-1-chloroethylene (DDMU), and 4-chlorobenzoic acid (4-CBA) were identified by GC-Mass and FTIR. 4-CBA was found to be the stable product of DDT degradation. Metabolites preceding 4-CBA were not toxic to strain as reveled through luxuriant growth in presence of varying concentrations of exogenous DDD and DDE. However, 4-CBA was observed to inhibit the growth of bacterium. The DDT degrading efficiency of S. marcescens NCIM 2919 hence could be used in combination with 4-CBA utilizing strains either as binary culture or consortia for mineralization of DDT. Application of S. marcescens NCIM 2919 to DDT contaminated soil, showed 74.7% reduction of initial 12.0 mg kg^?1 of DDT after 18-days of treatment.