Photocatalytic degradation of 5-nitro-1,2,4-triazol-3-one NTO in aqueous suspension of TiO2. Comparison with Fenton oxidation

5-nitro-1,2,4-triazol-3-one (NTO) is a powerful insensitive explosive, present in industrial waste waters. A remediation method based on photochemical decomposition and Fenton oxidation of NTO has been evaluated by monitoring the mineralization of 14C-labelled NTO. The TiO2-catalyzed photodegradation (lambda > 290 nm, TiO2 0.4 g/l, NTO 150 mg/l)) leads to the complete mineralization of NTO in 3 hours. This degradation involves a simultaneous denitrification and ring scission of NTO leading to nitrites, nitrates and carbon dioxide. No significant photo-degradation of NTO was detected in the absence of the catalyst. Long term irradiation over one week, leads to a complete degradation of concentrated NTO (5 g/l), suggesting that this method could be useful to clean-up NTO wastes. Fenton oxidation offers an efficient cost-effective method for NTO remediation. This reaction is faster that the TiO2 catalyzed photolysis and find application on the mineralization of high concentrations of NTO (15 g/l). Fenton oxidation provokes ring cleavage and subsequent elimination of the two carbon atoms of NTO as CO2. During this reaction, the nitro group is completely transformed into nitrates.     

纳米氧化锌对羊角月牙藻毒性效应及其在藻细胞内外的分布

为研究纳米氧化锌(ZnO NP)的毒性效应及其在细胞内外分布,以羊角月牙藻(Selenastrum capricornutum)为模型藻类,研究了不同浓度ZnO NP对羊角月牙藻生长、叶绿素含量、可溶性蛋白含量、超氧化物岐化酶(SOD)及过氧化物酶(POD)活性、丙二醛(MDA)含量及细胞内外ZnO NP含量变化。结果表明,ZnO NP对羊角月牙藻的生长抑制与处理浓度呈现正相关。在45 mg·L^-1 ZnO NP暴露24 h后,其生长抑制率已达到95%。当ZnO NP处理藻细胞72 h后,羊角月牙藻细胞的叶绿素含量与处理浓度之间存在剂量-效应关系。低浓度(0.5 mg·L^-1)ZnO NP处理后藻细胞可溶性蛋白质含量、SOD和POD活性明显下降,MDA含量升高,其产生的毒性效应高于高浓度组(5 mg·L^-1、45 mg·L^-1)。细胞培养液溶出Zn²⁺量及藻细胞外吸附的ZnO NP量与ZnO NP处理浓度成正比,但是藻细胞内ZnO NP量与ZnO NP浓度没有相关性,胞内积累量基本维持不变。研究表明,各浓度组对藻细胞毒性的差异,不仅与细胞内Zn²⁺量有关,还与细胞外粘附的ZnO NP有关。     

转基因植物和食品保障

为了以可持续方式确保世界食品保障,必须解决许多与安全性、流通及其它因素有关的问题.然而,不应当忘记,生产足够的食品是至关重要的.与食品有关的世界贸易问题(包括涉及生物技术应用的问题)应当成为各国之间和各公司之间不断对话的课题.以共同商定的风险评价程序为基础的、国际和谐的质量和安全性标准,是此类讨论的最合理依据.     

Multivariate imputation in cross-sectional analysis of health effects associated with air pollution

We demonstrate a recently developed spatial interpolation methodology in a study of the chronic effects of air pollution on respiratory morbidity. Our study uses data from the Ontario Health Study, a large survey of households in Ontario conducted for the province by Statistics Canada. The interpolation procedure imputes unobserved vectors of air pollution concentrations for individual Public Health Units, from those observed at a few fixed air pollution monitoring sites. We use logistic regression methods to assess the significance of air pollution levels based on the imputed values after modelling the relationship between binary health responses and assorted covariates such as measures of life style. Our findings prove negative; no significant relationship between chronic respiratory morbidity and air pollution is found. The imputation methodology is seen to be promising and might well be used in other such analyses.     

市售植物源中药材的多环芳烃污染现状与评价

采用气相色谱-串联质谱法测定了79个市售植物源中药材中的16种多环芳烃化合物.所有样品均检出多环芳烃,16种多环芳烃之和（∑PAH）浓度范围为21.1—2856.0 μg·kg-1.检出单体以2—4环PAH为主,占总量的85%.花、叶、根和茎类样品中∑PAH浓度明显高于果实和种子类样品.24.1%的样品中苯并[a]芘含量超过5 μg·kg-1的国标限量要求,说明其对人体存在健康风险.     

Sexual selection for male parental care in the sand goby, Pomatoschistus minutus

Male parental care is typically thought to come at a cost to mate attraction and future mating success. However, it has also been hypothesized that paternal care may be under sexual, as well as natural, selection, such that good fathers actually attract more mates. Here we show experimentally that in the sand goby, Pomatoschistus minutus, females prefer to mate with males that provide higher levels of parental care. We manipulated male behavior using (1) different nest sizes and (2) an application of low-O₂ water in the nests, and found that females consistently preferred males with elevated levels of care in dichotomous mate choice tests. This complements our earlier study in which we showed that males increase the amount and quality of care they provide in the presence of females. Our results demonstrate that male care may have evolved as a result of sexual selection rather than natural selection alone, and furthermore, that male care may not necessarily be in conflict with mate attraction.     

Multivariate analysis of spatial patterns: a unified approach to local and global structures

We propose a new approach to the multivariate analysis of data sets with known sampling site spatial positions. A between-sites neighbouring relationship must be derived from site positions and this relationship is introduced into the multivariate analyses through neighbouring weights (number of neighbours at each site) and through the matrix of the neighbouring graph. Eigenvector analysis methods (e.g. principal component analysis, correspondence analysis) can then be used to detect total, local and global structures. The introduction of the D-centring (centring with respect to the neighbouring weights) allows us to write a total variance decomposition into local and global components, and to propose a unified view of several methods. After a brief review of the matrix approach to this problem, we present the results obtained on both simulated and real data sets, showing how spatial structure can be detected and analysed. Freely available computer programs to perform computations and graphical displays are proposed.     

Sorption and transport of iodine species in sediments from the Savannah River and Hanford Sites

Iodine is an important element in studies of environmental protection and human health, global-scale hydrologic processes and nuclear nonproliferation. Biogeochemical cycling of iodine is complex, because iodine occurs in multiple oxidation states and as inorganic and organic species that may be hydrophilic, atmophilic, and biophilic. In this study, we applied new analytical techniques to study the sorption and transport behavior of iodine species (iodide, iodate, and 4-iodoaniline) in sediments collected at the Savannah River and Hanford Sites, where anthropogenic (129)I from prior nuclear fuel processing activities poses an environmental risk. We conducted integrated column and batch experiments to investigate the interconversion, sorption and transport of iodine species, and the sediments we examined exhibit a wide range in organic matter, clay mineralogy, soil pH, and texture. The results of our experiments illustrate complex behavior with various processes occurring, including iodate reduction, irreversible retention or mass loss of iodide, and rate-limited and nonlinear sorption. There was an appreciable iodate reduction to iodide, presumably mediated by the structural Fe(II) in some clay minerals; therefore, careful attention must be given to potential interconversion among species when interpreting the biogeochemical behavior of iodine in the environment. The different iodine species exhibited dramatically different sorption and transport behavior in three sediment samples, possessing different physico-chemical properties, collected from different depths at the Savannah River Site. Our study yielded additional insight into processes and mechanisms affecting the geochemical cycling of iodine in the environment, and provided quantitative estimates of key parameters (e.g., extent and rate of sorption) for risk assessment at these sites.     

Estimation of vinyl chloride emissions from gasholders and validation of in situ emission reduction methods

Gasholders consist of a floating bell in a tank filled with water. Water provides a seal between the enclosed gas and ambient air. Gasholder emissions come from the contaminated water seal exposed to ambient air and the wet bell wall. The study objectives were to define parameters influencing gasholder emissions, determine the quantities of vinyl chloride (VC) emitted, generate a correlation equation between parameters of influence and mass emissions, and evaluate the efficiency of emission reduction methods. The research project was carried out on a laboratory-scale representation of a gasholder. The classic two-phase resistance model was used successfully to generate a correlation equation, which can be used to calculate the gasholder water seal emissions. A strictly empirical model was generated to estimate the wet wall emissions. Two in situ reduction methods were evaluated with the laboratory installations: floating objects and an oil layer. Both methods showed significant emission reductions, but the oil layer was the most effective. To reduce emissions even further, it is recommended that the water level of the gasholder be set to the lowest achievable level, that a windshield be placed around the water seal perimeter, and that hydrophobic paint be used on the bell wall.