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211.
Prior to a prospective application of amniotic fluid (AF) cell filtration to early amniocentesis, we tested the technique on a surplus from mid-trimester samples. By using the same sample size of 5 ml in experiments with a filter and in routine diagnostic procedures (control), we evaluated an optimal filter system. The prolonged culture time of filtered cells and the reduced number of clones are most probably due to mechanical stress (filtration pressure), whereas loss of the cells by adhesion to the filter system, and an AF-free culture medium (growth factors) are suggested to be less important. The AF cells are very sensitive to mechanical stress. Slow filtration (⩽3 ml AF/min) through filters with a high porosity and the largest possible pore size should be preferred. A mixed cellulose ester filter membrane with a pore size of 5·0 μm proved to be the most efficient, allowing harvest of the filtered cells after only a slight prolongation of the culture time (+2·4 days) compared with unfiltered aliquots. A filter set with a bypass connected by three-way taps allows cell filtration during either aspiration or reinjection of the AF. Cell filtration after amniocentesis and consecutive reverse flushing of the membrane with the appropriate amount of culture medium proved to be the best with regard to easy handling and reducing the risk of bacterial contamination. 相似文献
212.
Hans -Martin Mulisch Werner Winter Hermann H. Dieter 《Environmental Sciences Europe》2000,12(5):269-278
To include consequences emanating from former military sites on the drinking water supply, a catalog of criteria has been developed which permits the determination and assessment of the hazards in general and their impact on human health in particular. The assessment criteria correspond to the special requirements and standards for drinking water hygiene and protection in Germany. The criterion catalog is a completion module to the usual praxis and existing conceptions, and has proved its practical value in the initial assessment of military sites in the new federal states of Germany. The scheme is a control instrument suitable for obtaining an assessment concerning the extent to which drinking-water resources are and will be affected by former waste disposal and other contaminated sites at the present and in the future. 相似文献
213.
Dieter Schäfer Steffen Seibel Regina Hoffmann-Kroll 《Environmental Sciences Europe》2000,12(5):286-290
The quality of regionalizations can only be evaluated with regard to its specific purposes. In environmental monitoring, regionalizations, besides being an analysis tool, has a great importance on the selection of monitoring sites. The article describes the relationship between regionalization, selection procedure and representativeness using the example of Ecological Area Sampling (EAS) and presents the regionalization which was tested in an EAS pilot study. 相似文献
214.
Frank-Albert Pitten Gerald Müller Peter König Dieter Schmidt Axel Kramer 《Environmental Sciences Europe》1998,10(2):75-80
The risk assessment of former ammunition factories, where chemical weapons consisting of diphenylarsenic compounds have been produced or stored is difficult because of the lack of data concerning bioavailability and metabolism of the residues of these sternutators. In order to estimate the contamination of fodder plants by typical pollutants of the former Heeresmunitionsanstalt Löcknitz, the total concentration of arsenic was determined in 186 samples of wild plants. The total arsenic concentration in plants of high feed value did not exceed 1 ppm, whereas 15% of the samples of plants of middle and little value in regard to animal fodder showed arsenic concentrations above 1ppm. The uptake of arsenic by wild plants, however, appears to be comparably low taken the high-grade contamination of the soil into account. A final toxicological evaluation of the risk potential is not yet possible because it requires the characterization of the anorganic and organic arsenic compounds in these plants. 相似文献
215.
Different collector types for sampling deposition of polycyclic aromatic hydrocarbons--comparison of measurement results and their uncertainty 总被引:1,自引:0,他引:1
Gladtke D Bakker F Biaudet H Brennfleck A Coleman P Creutznacher H Van Egmond BF Hafkenscheid T Hahne F Houtzager MM Leoz-Garziandia E Menichini E Olschewski A Remesch T 《Journal of environmental monitoring : JEM》2012,14(8):2054-2062
Different collector types, sample workup procedures and analysis methods to measure the deposition of polycyclic aromatic hydrocarbons (PAH) were tested and compared. Whilst sample workup and analysis methods did not influence the results of PAH deposition measurements, using different collector types changed the measured deposition rates of PAH significantly. The results obtained with a funnel-bottle collector showed the highest deposition rates and a low measurement uncertainty. The deposition rates obtained with the wet-only collectors were the lowest at industrial sites and under dry weather conditions. For the open-jar collectors the measurement uncertainty was high. Only at an industrial site with extremely high PAH deposition rates the results of open-jar collectors were comparable to those obtained with funnel-bottle collectors. Thus, if bulk deposition of PAH has to be measured, funnel-bottle combinations are proved to be the collectors of choice. These collectors were the only ones always fulfilling the requirements of European legislation. 相似文献
216.
Dieter H. Ehhalt 《Journal of the Air & Waste Management Association (1995)》2013,63(8):518-519
Methane is present in the troposphere with a volume concentration of about 1.5 ppm. Estimates of Koyama (1963) indicate a predominantly biological origin with a total production rate of about 2.7 × 1014 g CH4/yr. From that he estimated the atmospheric lifetime of methane to be around 20 years. Measurements of the C-l4 in methane by Libby and later by Bainbridge, et al. (1961 ) gave a C-l4 content of 75% of recent wood and, therefore, confirm the predominant biological origin, the addition of inactive CH; from industrial sources being only about 25%. Much less is known about sinks of CH4. Cadle (1966) reported fairly high destruction rates by atomic O, a reaction which should be important at high altitude. Bainbridge (1966) indeed reports a decrease in the measured methane concentration above the tropopause. He, however, considers this decrease too small to account for the destruction rate of 20 years estimated by Koyama. Our measurements on air samples collected on aircraft flights at various altitudes show a high variability of the CH4 content both with time and altitude. 相似文献
217.
Spranger Till Kunze Frank Gauger Thomas Nagel Dieter Bleeker Albert Draaijers Geert 《Water, Air, & Soil Pollution: Focus》2001,1(1-2):335-351
Critical load exceedances have been used as an effects-related parameter for guiding international air emission control negotiations. High-resolution critical load data are combined with low-resolution deposition data.This article shows that doing so systematicallyunderestimates `true' critical load exceedances as obtainedfrom combining critical load and deposition data of identicalhigh spatial resolution. 95th percentile critical loadexceedances in EMEP grids based on high resolution depositiondata are 60 and 150% higher (mean values for nutrientnitrogen and acidity, respectively) than critical loadexceedances based on the low resolution EMEP depositionmodel. The latter are used in international negotiations. Differences in individual EMEP grid squares vary betweeninsignificantly different from zero and 340%, depending onregional deposition and critical load characteristics andcritical load types (nutrient nitrogen versus acidity).Exceedances based on high-resolution deposition values arealso compared to EMEP grid averages of these values forforests only. This comparison excludes the effect ofsystematically higher depositions to forests. Still, thescale difference of (averaged, low-resolution) deposition and(high-resolution) critical loads data yields underestimatesof the 95th percentiles by on average ca. 20%.These systematic errors due to the scale dependence should beborne in mind when interpreting effects of internationalemission control measures. 相似文献
218.
219.
The residues of 31 chlorinated hydrocarbons (CHCs), 25 chlorophenols (CPs), 30 organophosphorus (OP) and pyrethroid (PRT)
in two arable soils from the semi-arid and subtropical regions of China were assessed. Data obtained indicate that the main
compounds of CHC pesticide residues in the semi-arid soil were 4,4′-DDE (25.3 ng/g) and β-HCH (14.1 ng/g), which totally accounted
to about 90% of total CHC residues detected. The total content of CHC residues detected in the subtropical soil was only 3.1
ng/g, of which approximately 50% was β-HCH. However, the total content of CP residues in both of the soils was about 11 ng/g.
In the semi-arid soil, only parathion-methyl amongst the 30 compounds of OP and PRT residues was detected (32.5 ng/g), whilst
malathion and parathion-methyl (8.7 and 17.7 ng/g, respectively) detected in the subtropical soil. Based on these results,
it was suggested the environmental risk of pesticide residues ranked in an order as CHCs (mainly as 4,4′-DDE, β-HCH) > OP
(parathion-methyl) > CPs for the semi-arid soil, and as OPs (parathion-methyl and malathion) > CPs > CHCs (β-HCH) for the
subtropical soil. 相似文献
220.
In 1984, 115 samples of the starfish Asterias rubens L. collected in the south-eastern part of Cadet Trench (Mecklenburg Bay/Western Baltic Sea) were analyzed for their contents of a few major (calcium, magnesium) and trace elements (cadmium, copper, iron, mercury, manganese, nickel, lead, selenium and zinc). Distinct differences were found between starfish from different stations, and these are attributed to the composition of the sediments acting as a substrate for their prey (mussels, snails). Except for cadmium, the concentrations of the elements studied all correlated negatively with the diameter and weight of the starfish. Parallel analyses of starfish arms and the central discs of the same animals showed that iron, zinc, copper and mercury levels were 16 to 30% higher, and selenium, manganese, magnesium, calcium and lead were 4 to 9% higher in the arms. Cadmium concentrations were 20% higher in the central discs than in the arms. Stock estimations (about 52,000 tons fresh weight) show that starfish play a significant role in the benthic ecosystem of the western Baltic Sea. They can consume up to 200,000 tons of mussels and clams (Mytilus edulis, Macoma baltica) a year and may therefore represent a notable factor in the trace metal balance of the region. 相似文献