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141.
Occurrence and behaviour of 4-nonylphenol in river water of Germany   总被引:1,自引:0,他引:1  
An analytical method composed of solid-phase-extraction (SPE) followed by gas chromatography-mass spectrometry (GC-MS) has been developed to investigate the occurrence and the behaviour of the endocrine disruptor 4-nonylphenol (4-NP) in river water of Germany. 16 Para-isomers of the complex mixture of 4-NP isomers have been resolved in the SPE-extracts of river water samples. The mass spectra indicate the presence of four distinct groups of isomers. The different groups are characterised by different base peaks of the mass spectra dependent on the substitution of the alpha-carbon on the alkyl chain. The different isomers show (i) alpha-methyl, alpha-ethyl (base peak 149), (ii) alpha-dimethyl (base peak 135), (iii) alpha-methyl, alpha-propyl, alpha-butyl (base peak 121) and (iv) alpha-methyl, alpha-propyl, alpha-butyl (base peak 107) configuration of the alkyl chain. The recovery of the unbranched compound 4-n-NP was > or = 90%. Detection limit and determination limit of the whole analytical procedure were 6 ng L(-1) and 25 ng L(-1), respectively with a relative standard deviation of 11.7%. The concentration of the sum of the 4-NP isomers in all samples of river water ranged from 28 ng L(-1) (Elbe River) to 1220 ng L(-1)(Oder River). In a period of a higher river water level, a higher amount of 4-NP was detected in the Oder River than in a period of a lower water level. Therefore dilution was not the determinant factor of the 4-NP concentration in river water. The diurnal dynamics of the sewage treatment works (STWs) have to be considered as an influencing factor for the presence of 4-NP in river water.  相似文献   
142.
We investigated the accumulation of PCB and DDT in crayfish populations in 10 streams in southern Sweden. The results were compared with an earlier study on crayfish in lakes from the same area. We found that the concentration of pollutants in crayfish did not differ between the two types of systems. Variation in body burden was higher in stream living crayfish probably because of the higher influence from pollutants deposited in the catchment area and the more dynamic transport in streams. In streams, p,p'-DDE concentrations were positively correlated to trophic status (total phosphorous) while PCB did not show any correlation with the nutrient regime. Further, mean SigmaPCB and p,p'-DDE concentrations in crayfish did not correlate in streams. We suggest that the sources of the two pollutants differ for stream living crayfish. The results indicate that crayfish in streams are affected to a higher degree to pollutants in the catchment area and the precipitation regime. In lakes, internal processes govern uptake of pollutants in crayfish.  相似文献   
143.
Four small river systems in Hesse, Germany, were investigated with respect to seasonal and spatial concentrations of the herbicide terbutryn [2-(t-butylamino)-4-(ethylamino)-6-(methylthio)-s-triazine]. Despite introduction of a ban on its use as a herbicide in July 2003, terbutryn was still present in the rivers during the whole sampling period from September 2003 to September 2006, and there was no trend of decreasing concentration during this time. In the Weschnitz and Modau river systems the mean terbutryn concentration exceeded the German drinking water ordinance threshold value for single biocides. Maximum concentrations of up to 5.6 microg l(-1) were determined in the Weschnitz River. Higher terbutryn concentrations in summer are suggested to originate from agricultural sources, as well as from sediment redissolution. Effluents of two sewage treatment plants had high terbutryn concentrations, indicating that terbutryn enters the rivers from this source. Sources other than agriculture must explain terbutryn occurrence in the rivers during winter, when farm pesticide application typically ceases. The potential for mobilization of terbutryn from sediments and leaching from soils are discussed.  相似文献   
144.
145.
Summary. Larvae of the chrysomelid beetles Phaedon cochleariae and Gastrophysa viridula use iridoid monoterpenes for defense. The compounds are synthesized de novo in the glandular tissue and the reservoir. However, larvae feeding on leaves impregnated with thioglycosides of early precursors of iridoid biosynthesis such as the thioglycosides of 8-hydroxygeraniol, 8 and 9, rapidly accumulate in their defensive secretion. Thioglycosides combine a unique structural similarity to natural substrates with an exceptional chemical and biological stability against hydrolytic enzymes and can be, therefore, used to study transport phenomena of glycosides. The successful import suggests that the larvae possess, in addition to the de novo biosynthesis, the capability to sequester appropriate glycoside precursors that are transformed to iridoid monoterpenes in the reservoir. The uptake process displays a remarkable substrate selectivity, since the thioglycoside of geraniol 10 is not imported. From the two isomeric thioglycosides of 8-hydroxygeraniol, 8 and 9, the isomer 8 is preferred by a factor of ten. The data clearly support the existence of a highly selective transport system which enables the larvae to utilize plant derived terpenoid precursors in addition to their own de novo biosynthesis of iridoids.  相似文献   
146.
Human bocavirus (HBoV) is predominantly found in the respiratory tract infections and in the stool of patients with gastroenteritis symptoms. However, data on the prevalence of HBoV genotypes in environmental samples are limited. Here we addressed the prevalence of HBoV in sewage collected from three different wastewater treatment plants in Egypt. HBoV-1, HBoV-2, and HBoV-3 were detected, whereas none of the samples were positive for HBoV-4. The median concentration of HBoV in influent samples was 8.5 × 103 GC/l for HBoV-1, 3.0 × 104 GC/l for HBoV-2, and 2.5 × 104 GC/l for HBoV-3. The concentration was reduced but not completely removed in the effluent samples. The median concentration in the outlet samples was 2.9 × 103 GC/l for HBoV-1, 4.1 × 103 GC/l for HBoV-2, and 2.1 × 103 GC/l for HBoV-3. Moreover, no seasonality pattern of HBoVs was found. The high incidence of HBoV in sewage samples provided an evidence of its circulation in the local population. Although the role of HBoV in respiratory or gastro-intestinal infections still remains to be fully elucidated, the risk of infection via contaminated water should be taken into consideration.  相似文献   
147.
Chorionic villus samples from a healthy pregnant female were obtained for first-trimester prenatal diagnosis. A translocation trisomy 21 was diagnosed. A consecutive amniocentesis revealed a normal male karyotype. At term a healthy boy was born. Cytogenetic analysis from cord blood showed a regular karyotype of 46,XY, whereas in term placenta a pathological karyotype of 47,XY,+mar was found.  相似文献   
148.
149.
Habitat Assessment of Non-Wadeable Rivers in Michigan   总被引:1,自引:0,他引:1  
Habitat evaluation of wadeable streams based on accepted protocols provides a rapid and widely used adjunct to biological assessment. However, little effort has been devoted to habitat evaluation in non-wadeable rivers, where it is likely that protocols will differ and field logistics will be more challenging. We developed and tested a non-wadeable habitat index (NWHI) for rivers of Michigan, where non-wadeable rivers were defined as those of order ≥5, drainage area ≥1600 km2, mainstem lengths ≥100 km, and mean annual discharge ≥15 m3/s. This identified 22 candidate rivers that ranged in length from 103 to 825 km and in drainage area from 1620 to 16,860 km2. We measured 171 individual habitat variables over 2-km reaches at 35 locations on 14 rivers during 2000–2002, where mean wetted width was found to range from 32 to 185 m and mean thalweg depth from 0.8 to 8.3 m. We used correlation and principal components analysis to reduce the number of variables, and examined the spatial pattern of retained variables to exclude any that appeared to reflect spatial location rather than reach condition, resulting in 12 variables to be considered in the habitat index. The proposed NWHI included seven variables: riparian width, large woody debris, aquatic vegetation, bottom deposition, bank stability, thalweg substrate, and off-channel habitat. These variables were included because of their statistical association with independently derived measures of human disturbance in the riparian zone and the catchment, and because they are considered important in other habitat protocols or to the ecology of large rivers. Five variables were excluded because they were primarily related to river size rather than anthropogenic disturbance. This index correlated strongly with indices of disturbance based on the riparian (adjusted R2 = 0.62) and the catchment (adjusted R2 = 0.50), and distinguished the 35 river reaches into the categories of poor (2), fair (19), good (13), and excellent (1). Habitat variables retained in the NWHI differ from several used in wadeable streams, and place greater emphasis on known characteristic features of larger rivers.  相似文献   
150.
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