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101.
Temporal variation of RNA: weight, RNA: protein, RNA: DNA, and protein: DNA ratios in Stenonema femoratum (Say) was assessed by monitoring at the same site in a small midwestern stream over a two-year period. Variation components were estimated using a two-way mixed model analysis of variance with weight class and collection date as main effects. About 30% of the variation in RNA concentration was within-cell variation associated with differences among individuals and analytical error. Temporal variation accounted for about 50% of the total variability in RNA concentration data. RNA: weight had 11% and RNA: protein had 17% variation attributed to weight class effects indicating that these ratios were dependent on the size of the mayfly. RNA: DNA ratios were not influenced by mayfly weight, suggesting that this ratio would be the most appropriate for comparing populations based on means of mixed individual sizes. Comparison of mean RNA: DNA ratios among collection dates yielded significant increases in the ratio during late fall in two consecutive years. Spatial variations in RNA: DNA ratios of S. femoratum collected from sites of similar habitats were not significantly different. These data encourage the future development of RNA concentration as an in situ biochemical indicator of growth rate and possibly of stress related effects on growth rate. 相似文献
102.
In this study, the composition of vinasse was first analysed. It was found to contain 8.43% dry matter, 3.3% total ash, 4% crude protein and 0.95% total carbohydrates; BOD load was determined as 63 g litre(-1). Subsequently, the effects of vinasse in various concentrations (1, 2.5, 5, 10, 25, 50, 75 and 100%) on the activity of cellulase and pectin methyl esterase and the chlorophyll and protein contents of Pisum sativum and Helianthus annuus were investigated. The activity of these enzymes and the protein and chlorophyll contents in potted plants showed a gradual increase from the control up to 2.5% concentration of vinasse, but decreased at higher concentrations. These different effects of the effluent may be due to the high BOD load and the presence of cell wall cations in it. 相似文献
103.
The catalytic effects of copper and iron compounds were examined for their behavior in promoting formation of chlorine (Cl2), the major chlorinating agent of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), in an environment simulating that of municipal waste fly ash. Formation of Cl2 occurred as a result of a metal-catalyzed reaction of HCl with O2. Catalytic activity was greatest at a temperature of approximately 400 °C, supporting a theory of de novo synthesis of PCDDs and PCDFs on fly ash particles downstream of waste combustion. 相似文献
104.
Viskari EL Rekilä R Roy S Lehto O Ruuskanen J Kärenlampi L 《Environmental pollution (Barking, Essex : 1987)》1997,97(1-2):153-160
Vertical snow sampling and moss bag transplants were used to estimate the local inorganic and organic pollutant load deposited from traffic along a major highway in Finland. The pH and concentrations of Cl(-), NO(3)(-), SO(4)(2-), Ca(2+), Na(+) and polyaromatic hydrocarbons (PAHs) were determined from snow samples collected in winter at different sites along the highway. In summer, moss bags containing 20 g of fresh red-stemmed feather moss (Pleurozium schreberi) were transplanted at the same sites. The moss bag transplants remained exposed to roadside traffic for a period of one month following which the samples were collected and the PAH profiles and concentrations were analysed. The deposition of inorganic and organic pollutants from road traffic was observed up to 60 m from the road. The prevailing winds had a significant effect on the dispersion of pollutants. Snow appears to be a good collector of inorganic pollutants from the atmosphere and can be used to monitor local airborne pollution from road traffic. Snow packs can also be used as passive collectors of organic pollutant loads from road traffic on a local scale. To monitor organic PAH deposition from the road traffic, moss bags appeared to be better indicators compared to snow sampling. The efficiency of moss bags in accumulating PAH compounds indicate that vegetation may be an important sink for traffic pollution. 相似文献
105.
Accidental releases of waste water from the first Czechoslovak nuclear power plant, A1, caused contamination of sediments of the Dudváh river, flowing into the Vah river, in Slovakia. Rather high concentrations of 137Cs and 90Sr (2150Bq dm−3 and 215Bq dm−3, respectively) were found in bottom sediments of a former channel of the re-engineered river body at a distance of about 250 m from a village, Siladice, with water-supply wells. In order to assess the possibility of contamination of the wells, underground migration of both radionuclides from the contaminated area was simulated using an original layered convection-diffusion model. Kd values determined in laboratory experiments were used. The analysis of the hydrological situation in the area reveals that the critical condition is a dominant horizontal groundwater flow near the water table in the direction from the Váh bank to Siladice, in the periods when the contaminated body lies under the water table. The simulation calculated under conservative conditions showed that the contamination of water-supply wells would not exceed permissible concentration limits. 相似文献
106.
ELECTRE or Concordance Analysis is a French system of multicriteria analysis which is used in economics.The application of ELECTRE for hazard evaluation and risk assessment of chemical substances is suggested, and a first attempt in adapting it for this purpose is presented. 相似文献
107.
François Mermoud Fazil O. Gülaçar Samuel Siles Bernard Chassaing Armand Buchs 《Chemosphere》1982,11(6):557-567
Sediment cores from oxygen depleted zones of lake Léman (lake of Geneva) and from anoxic surface sediment from Voua de la Motte (France) were analyzed for their sterol compositions. 4-methylstanols were found to be major sterols in Motte lake sediment, which is rich in organic matter. In lake Léman, the relative abundances of the same 4-methylstanols increase with the depth in the core, but they remain always minor compounds. An extensive search for a possible external source for these compounds included the analysis of water, of the plankton and of the surrounding soil material. All these results, along with those of an in situ incubation experiment, give strong evidence in favor of their in situ bacterial biosynthesis. 相似文献
108.
Peter Orris M.D. John R. Kominsky M.S. Daniel Hryhorczuk M.D. James Melius M.D. 《Chemosphere》1986,15(9-12):1305-1311
A Polychlorinated Biphenyl (PCB) containing transformer released approximately 50 gallons of askarel oil. No polychlorinated dibenzofurans (PCDF) or polychlorinated dibenzodioxins (PCDD) were detected in a sample of the askarel (analytical limit of detection of 40 parts per billion per isomer group). Skin irritation, unusual tiredness, and headaches occurred in approximately 20% of the individuals at the scene of the incident. Serum PCB levels, and mean values for blood and urine tests were within normal ranges. 相似文献
109.
Koh CH Khim JS Villeneuve DL Kannan K Giesy JP 《Environmental pollution (Barking, Essex : 1987)》2006,142(1):48-57
This study employed mechanism-specific in vitro bioassays to help characterize the occurrence and distribution of dioxin-like and estrogenic contaminants in sediment from Yeongil Bay, Korea. Approximately 85% of the sediments tested induced significant dioxin-like activity in the H4IIE-luc bioassay, while approximately 50% induced significant estrogenic activity in the MVLN bioassay. Instrumentally-derived estimates of 2,3,7,8-tetrachlorodibenzo-p-dioxin and 17beta-estradiol equivalents tended to underestimate the magnitude of response observed in the bioassays, suggesting that compounds detected by chemical analysis did not account for all the activity associated with Yeongil Bay sediments, or that non-additive interactions were occurring. The greatest dioxin-like and estrogenic activity was associated with the mid-polarity Florisil fractions (F2) expected to contain polycyclic aromatic hydrocarbons (PAHs) as well as chlorinated dioxins and furans. As in previous studies of Korean coastal sediment, more polar fractions (F3) generated more modest responses both in terms of magnitude and the number of samples responding. 相似文献
110.
Leaves of Eucalyptus sp., Prunus domestica (plum), and Anacardium occidentale (cashew), as well as roots and leaves of Manihot esculenta (cassava) were used to study the local distribution of pesticides and metabolites from a point source, an old storage site at Vikuge farm in Tanzania. The GPC-cleaned extracts were analyzed by GC-ECD and GC/MS. Eleven organochlorine pesticide residues namely pentachloroanisole, p,p'-DDT, o,p'-DDT, p,p'-DDE, o,p'-DDE, p,p'-DDD, o,p'-DDD, alpha-HCH, beta-HCH, delta-HCH and epsilon-HCH were detected in the samples. The concentrations of total DDT were 818 ng/g fw in Eucalyptus sp., 16 ng/g fw in A. occidentale and 4 ng/g fw in P. domestica. In M. esculenta, total DDT ranged from 191 to 586 ng/g fw in roots and 7 to 425 ng/g fw in leaves. The concentrations of total HCH were up to 15 ng/g fw in Eucalyptus sp., while the concentrations of pentachloroanisole were up to 2 ng/g fw in leaves of M. esculenta. There are very strong positive correlations in the concentrations of the detected compounds, suggesting that they have a common source. The low DDE/DDT ratios (0.02-0.07) in all samples indicate input of non-degraded DDT from the source. The high alpha-HCH/gamma-HCH ratios in some samples (>3.1-10) indicate input of technical HCH. The concentrations of total DDT in cassava roots were either very close to, or greater than, the FAO/WHO limit, indicating risks and concern to public health. 相似文献