Degradation of the drug diclofenac in water by sonolysis in presence of catalysts

Diclofenac, as one of the most popular antiphlogistics, is produced in great quantities. Nowadays this drug is ubiquitously present in the aquatic environment due to its resistance to biodegradation. Degradation by ultrasonic irradiation is a possibility to eliminate diclofenac from water without the addition of chemicals. The sonolysis of diclofenac in water was investigated at ultrasound frequencies of 24 kHz, 216 kHz, 617 kHz, and 850 kHz and in the presence of various catalysts (TiO2, SiO2, SnO2, and titanosilicate). The degradation of diclofenac by sonolysis of an aqueous solution at 617 kHz followed first-order kinetics. Catalysts, especially TiO2 increased the rate of degradation. Within 30 min of irradiation, the relative concentration of diclofenac decreased from 100% to 16%. By HPLC and GC-MS methods, chlorinated anilines, phenols and carboxylic acid derivatives were detected as a result of the sonolysis. About 35% of organic chlorine was transformed into inorganic chloride. Most of the identified degradation products in the sonolysis of diclofenac were the same compounds that were detected during photo-oxidation experiments with this anti-inflammatory drug.     

Organochlorine contaminants in cormorant, darter, egret, and ibis eggs from South Africa

During the last 15 years, no research has been published on the levels of pesticides in bird eggs from South Africa, despite the high levels found previously. We analysed eggs from African darter, cattle egret, reed cormorant, African sacred ibis, as well as single eggs from some other species, and found HCB, DDTs, HCHs, chlordanes and PCBs at detectable levels. The presence of mirex in all species was unexpected, since this compound was never registered in South Africa. It also seemed as if terrestrial feeding birds had higher DDE:PCB ratios when compared with aquatic feeding birds. Except for chlordane, the African darter eggs had the highest levels of all other compounds (mean 370 and 300 ng g(-1) ww Sigma pesticides and Sigma PCBs, respectively). Multivariate analysis clearly distinguished the aquatic and terrestrially feeding birds on pollution profile. The African darter (aquatic feeding) and the cattle egret (terrestrial feeding) would be good indicator candidates. Eggshell thinning was detected in the African darter, and was associated with most of the compounds, including DDE and PCBs. We raise a concern that generally longer living birds in warmer climates, laying fewer eggs per clutch, might be at increased risk when compared with trophically similar birds exposed to equivalent levels of pollution in colder climates. Given the scarcity of water and the high biodiversity in Southern Africa, climate change will exert strong pressure, and any additional anthropogenic contamination at levels that can cause subtle behavioural, developmental and reproductive changes, can have serious effects.     

Characterization of alkylphenol metabolites in fish bile by enzymatic treatment and HPLC-fluorescence analysis

Alkylphenol (AP) metabolites were characterized in the bile of Atlantic cod (Gadus morhua L.) after exposure to nine individual compounds (10mg/kg fish), 2-methylphenol (2-MP), 4-methylphenol (4-MP), 3,5-dimethylphenol (3,5-DMP), 2,4,6-trimethylphenol (2,4,6-TMP), 4-tert-butylphenol (4-t-BP), 4-tert-butyl-2-methylphenol (4-t-B-2-MP), 4-n-pentylphenol (4-n-PP), 4-n-hexylphenol (4-n-HexP) and 4-n-heptylphenol (4-n-HepP), and a mixture (total dose; 13.5 mg/kg fish) of the nine APs by inter-muscular injection. The degree of alkylation ranged from methyl (C1) to heptyl (C7) and represents the types of APs present in produced water. Fish bile was collected on day 4 and 16 (exposure groups 2-MP, 3,5-DMP, 2,4,6-TMP and 4-t-B-2-MP) following exposure. Characterization of major metabolites was accomplished by enzymatic de-conjugation and analysis by high performance liquid chromatography connected to a fluorescence detector (HPLC-F) acquiring at ex/em 222/306 nm. Two solid phase extraction (SPE) columns were evaluated for clean-up of samples prior to analysis. Independent of alkyl homologue, the glucuronide conjugated APs were the most abundant metabolites (73-100%), whereas sulfates, glucosides and unchanged compounds were excreted in amounts of 0-21%, 0-6.1% and 0-6.3%, respectively. The total concentration of measured metabolites in the bile, determined as their respective APs after de-conjugation, increased with increasing degree of alkylation (3.2+/-2.6 microg/g bile for 2-MP and 571+/-81 microg/g bile for 4-n-HepP) after exposure to an equal dose of AP. Comparison of metabolite concentrations in bile sampled 4 and 16 days after exposure, showed that the levels of 2-MP, 2,4,6-TMP and 4-t-B-2-MP were reduced by 55%, 30% and 45%, respectively whereas 3,5-DMP increased by 25% (not significant). This study suggests that analysis of de-conjugated metabolites in fish bile can be used to monitor AP exposure to fish, due to the relatively high and persistent level of these compounds. However, although HPLC-F is suitable for laboratory exposures, it might not be sufficient selective for field studies.     

用TM影像进行湖泊水色反演研究的人工神经网络模型

利用人工神经网络技术进行了湖泊水色遥感的反演研究,在同步实验的基础上了构造了包含一个隐含层的BP神经网络模型,利用TM卫星影像反演悬浮物、COD_Mn、溶解氧、总磷、总氮和叶绿素浓度反演精度较高,相对误差基本在25%以下,同时分析了该人工神经网络反演模型的误差来源,改进措施以及应用前景.研究表明,在进行小规模的同步监测的基础上,此模型可用于湖泊水质调查、分析和评价.     

Evaluation of a respirometric test method to determine the heterotrophic yield coefficient of activated sludge bacteria

The heterotrophic yield coefficient of activated sludge bacteria is an important parameter in the field of wastewater degradation kinetics and the determination of degradation kinetics of defined chemicals. With the help of easily biodegradable organic compounds like glucose and acetate the respiration kinetics of degrading activated sludge bacteria was studied. The results of the respiration analysis were transformed to examine the degradation and respiration kinetics of municipal wastewaters at different food to microorganism ratios (F/M ratios). It was proved that the heterotrophic yield coefficient of aerobically degrading activated sludge bacteria could reliably be determined and that the heterotrophic yield coefficient was independent of the F/M ratio over a wide range.     

Inhibition of Na+/K+-ATPase and of active ion-transport functions in the gills of the shore crab Carcinus maenas induced by cadmium

Inhibition of Na⁺/K⁺-ATPase from gill plasma membranes of the shore crab Carcinus maenas by cadmium was investigated and compared with inhibitory effects by known antagonists (ouabain and Ca²⁺). For comparative considerations the Cd²⁺-inhibition of the enzyme from dog kidney was also tested. Na⁺/K⁺-ATPase from dog kidney and from crab gill differed greatly in sensitivity against ouabain. The inhibition constant K _i of the dog enzyme amounted to 9.1 × 10⁻⁷ mol l⁻¹, i.e. more than 300-fold smaller than the K _i of 2.9 × 10⁻⁴ mol l⁻¹ determined for the crab enzyme. Ca²⁺ inhibited the activity of Na⁺/K⁺-ATPase from crab gill plasma membranes with a K _i of 4.3 × 10⁻⁴ mol l⁻¹. The Na⁺/K⁺-ATPase from crab gill was inhibited by Cd²⁺ with a K _i of 9.1 × 10⁻⁵ mol l⁻¹. Cd²⁺ inhibited the Na⁺/K⁺-ATPase from dog kidney with a K _i (6.4 × 10⁻⁵ mol l⁻¹) comparable to that observed in the crab gill enzyme. Under experimental conditions Cd²⁺-inhibition of Na⁺/K⁺-ATPase was irreversible. Repeated washing, centrifugation and homogenization of the plasma membranes (four times) with Cd²⁺-free buffer did not restore any activity lost in the presence of 1 × 10⁻³ mol l⁻¹ Cd²⁺. Since ouabain-insensitive (nonspecific) ATPases in the plasma membrane fraction of crab gills were inhibited by Cd²⁺ in the same way as Na⁺/K⁺-ATPase, the heavy metal is considered as an unspecific ATPase inhibitor. Comparing these results with literature data on Cd²⁺-binding to electrophoretically separated proteins suggests that Na⁺/K⁺-ATPase is a Cd²⁺-binding enzyme. The results obtained on Na⁺/K⁺-ATPase were reflected by Cd²⁺-inhibition of the branchial ion-transport functions depending on this enzyme. The transepithelial short-circuit current of isolated gill half lamellae, a direct measure of area-specific active ion uptake, and the transepithelial potential difference of isolated, perfused whole gills, also indicative of active ion uptake, were inhibited by the heavy metal in a time- and dose-dependent mode. Remarkably these inhibitions were also irreversible. These findings are ecologically and biomedically significant: even when the actual environmental or tissue concentrations measured are low, biological microstructures such as Na⁺/K⁺-ATPase may accumulate the heavy metal by tight binding over prolonged periods until the first inhibitory effects occur. Received: 25 June 1997 / Accepted: 25 August 1997     

Polybrominated diphenyl ethers (PBDEs) and their methoxylated derivatives in pike from Swedish waters with emphasis on temporal trends, 1967-2000

Temporal trends of five tetra- to hexabromodiphenyl ethers [BDE47, BDE99, BDE100, BDE153 and BDE154) and two methoxy-tetraBDEs [6-methoxy-2,2',4,4'- tetraBDE (6-MeO-BDE47) and 2'-methoxy-2,3',4,5'- tetraBDE (2'-MeO-BDE68)] in pike from Lake Bolmen for the years 1967-2000, are presented. All BDE congeners show increasing trends up to the mid-1980s (Sigma5PBDE from 60 to 1600 pg/g wet weight in 1989, i.e. a more than 25-fold increase), and then decrease or level off. The decreasing trends of PBDEs after the 1980s were considerably slower in the present study than was found in a study of an environmental matrix from the Baltic Proper covering the same time period. This difference suggests local sources near Lake Bolmen. The MeO-BDEs show initially decreasing concentrations, which for 6-MeO-BDE47 continues until the early 1990s. The concentrations of 6-MeO-BDE47 in herring from five locations along the Swedish coast increased from south to north in the Baltic Sea. No correlation between the concentrations of the BDE congeners and the MeO-BDEs was observed, indicating sources other than PBDEs for these compounds. The presence of MeO-BDEs in fish from lakes with different characteristics suggests a natural production not favoured by eutrophication, or dependent on sampling season and geographical location.     

Reductive Dechlorination of Tetrachloroethylene by Soil Sulfate-Reducing Microbes under Various Electron Donor Conditions

Biotransformation of tetrachloroethylene (PCE) by soil sulfate-reducing bacteria was investigated using acetate, lactate and methanol as electron donors. Results show that the effectiveness of biotransformation of PCE by soil sulfate-reducing bacterial is dependent upon the type of electron donor used.     

Sustainability: definition and five core principles,a systems perspective

A systems perspective is used to discuss the concept of sustainability. From this perspective, it is argued, sustainability can be regarded as a system state that is mediated by specific structures. This is fundamentally different from regarding sustainability merely as a normative goal, as it is presently regarded by most. Insight into the kinds of structures which mediate a system’s state open the door to proactive design of new structures and mechanisms, which are necessary for yielding effective change: in this case, promoting the sustainability agenda. The kind of change required to transform the prevailing trajectory of human affairs is presented as a second order change: a change that requires a major shift, and a complete transformation of the system itself, not only in a few aspects of its behavior. A new definition of sustainability is offered, anchored in the interaction of a population and the carrying capacity of its environment. From this definition, five core sustainability principles are derived, along with their respective policy and operational implications. Together, these principles prescribe the conditions that must be met to attain sustainability as an enduring state. The principles themselves form an integrated, systemic set, which requires them to be acted on simultaneously. A piecemeal approach—focusing on one aspect while neglecting others—is not likely to yield effective results for the whole.     

Male white-handed gibbons flexibly time duet contributions

Behavioral Ecology and Sociobiology - In recent years, research on insect motor behaviour―locomotion in particular―has provided a number of important new insights, many of which became...