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991.
Brown JE Iospje M Kolstad KE Lind B Rudjord AL Strand P 《Journal of environmental radioactivity》2002,60(1-2):49-60
The objective of this study was to reassess 99Tc transit times and transfer factors, from Sellafield to northern Norway, and to determine the extent of 99Tc migration to the Barents Sea. Filtered seawater samples were collected on a monthly basis from Hilles?y, northern Norway, and in February 1999 from the Barents Sea. Results showed an increase in levels of 99Tc at Hilles?y where activity concentrations have increased from a baseline of 0.2-0.4Bq m(-3) to a maximum of 1.6 Bq m(-3). A transit time of 42 months and a transfer factor of 6Bq m(-3) per PBq a(-1) have been derived, using cross-correlation analysis. The current study predicts that future levels are unlikely to increase dramatically over the levels observed in 1998. Levels of 99Tc in the Barents Sea ranged from 0.2 Bq m(-3) to 1.1 Bq m(-3) showing the influence of new 99Tc inputs by early 1999. 相似文献
992.
Volpe AM Bandong BB Esser BK Bianchini GM 《Journal of environmental radioactivity》2002,60(3):365-380
Radiocesium, 137Cs, and rare earth elements (REEs) were determined in suspended material and dissolved fractions of waters across the salinity gradient in North San Francisco Bay (estuary). We describe the variation of this conservative isotope tracer with salinity and sediment load. REE data are used to differentiate marine and terrigenous source terrains for suspended material and dissolved fractions. We estimate that about 1-4 x 10(10) Bq of 137Cs migrates annually on suspended material through the North Bay. In addition, 137Cs concentrations were measured in surface waters off Baja California. Combined in situ water density (sigma(t)) and 137Cs data distinguish between California Current and Gulf of California water, and delineate areas of upwelling, where nutrient-rich, deep Pacific Intermediate water, with little or no 137Cs, is brought to the surface off promontories along Baja California. 相似文献
993.
Recent investigations in Russia have emphasised the significance of dose contributions from contamination on urban streets and roof pavings, and, typically to a lesser extent, walls in the urban environment. The crucial factor determining the magnitude of these contributions is the retention of the contamination by the different types of urban surface. Since the Chernobyl accident, a series of long-term field studies has been carried out on urban streets, walls and roofs, to examine the weathering processes of 137Cs on the various surface types. The derived time-functions are applied to estimate resultant long-term doses to inhabitants of an urban centre. The paper highlights the effect on caesium retention of surface material characteristics. 相似文献
994.
Barman SC Kisku GC Salve PR Misra D Sahu RK Ramteke PW Bhargava SK 《Journal of environmental biology / Academy of Environmental Biology, India》2001,22(4):251-256
The present study deals with the assessment of industrial water of an electronic component manufacturing unit with electroplating and its subsequent effects on soil and plants receiving the effluent. The physico-chemical parameters of the effluent samples showed higher value than that of ground water. The treated effluent was within the permissible limit. Microtox test was conducted and determined the degree of toxicity of untreated, treated effluents as well as the water sample collected at effluent discharge point of receiving river (confluence point). The physico- mechanical parameters of the soil samples were not changed due to irrigation of the treated effluent, but the concentration of metals were comparatively higher than the control soil. Higher accumulation of metals was found in the plant parts in naturally growing weeds and cultivated crop plant irrigated with treated effluent. Elevated accumulation of metals in Eichhornia crassipes and Marsilea sp. growing along the effluent channel has been identified as a potential source of biomonitoring of metals particularly for Cu and Ca and can be utilised for the removal of heavy metal from wastewater. 相似文献
995.
Shetty PK Magu SP 《Journal of environmental biology / Academy of Environmental Biology, India》2001,22(2):79-81
In an experiment, application of different levels of metalaxyl to a sandy loam soil significantly affected the nodulation and nitrogenase activity of mungbean. In both the compost amended and unamended soils, 0.5 mg kg(-1) of metalaxyl enhanced acetylene reduction activity and yield of mungbean, where as higher concentrations (1 mg and 2.5 mg kg(-1) of fungicide) inhibited the nodulation traits as well as economic traits of mungbean. 相似文献
996.
Gupta R Mukerji KG 《Journal of environmental biology / Academy of Environmental Biology, India》2001,22(2):83-86
Trianthema portulacastrum is a noxious weed which spreads rapidly in the field. Pathogen Alternaria alternata was observed on this host for three years continuously i.e. 1997 to 1999. The incidence of the pathogen depended on rainfall and temperature. 相似文献
997.
Acidification in developing countries: ecosystem sensitivity and the critical load approach on a global scale 总被引:1,自引:0,他引:1
Acidification represents a growing threat to certain developing country ecosystems in tropical and subtropical climates. A methodology investigating the extent of acidification risks from sulfur emissions on a global scale is presented. Atmospheric transfer models have been used to calculate transfer and deposition of sulfur (using emissions for 1990 and a projection for 2050) and alkaline soil dust. A method to derive the relative sensitivity of terrestrial ecosystems is explained and preliminary critical load values are assigned. A range of values for critical loads and base cation deposition have been used to investigate uncertainty in maps depicting the excess of deposition above critical loads. These show an increasing risk of acidification in 2050 in extended regions of southern and eastern Asia, as well as parts of southern Africa, in comparison to 1990. Certain areas, especially in Asia, are shown at risk even when high values of critical load and base cation deposition are used. 相似文献
998.
Synthetic hydrotalcite-like layered materials are known for their ability to remove anions, like the chromates. These sorbents usually exist in powder form, thereby exhibiting high surface area and rapid kinetics for adsorption, but presenting appreciable problems in the subsequent solid/liquid separation process. Almost complete removals were obtained in this paper, from batchwork dispersed-air flotation in presence of a flocculant. Due to the experienced difficulty of flotation of thermally activated (at 500 degrees C) hydrotalcite metal-loaded particles, the application of various surfactants was studied. Continuous-flow laboratory runs certified also the effectiveness of this combined process of sorptive flotation, a promising innovative treatment technology. 相似文献
999.
Enzymatic treatment of sanitary landfill leachate 总被引:2,自引:0,他引:2
The objective of this investigation was to study the effectiveness of applying enzymes (bioaugmentation) for enhancement of biological treatability of leachates generated in a typical municipal solid waste sanitary landfill. The basic purpose of enzyme use is to enforce the biodecomposition of organic constituents, as well as to reduce nitrogen content. A laboratory-scale sequencing batch (bio)reactor (SBR) was used for the examination of enzymatic application. The effect of different operation strategies on the efficiency of this biological treatment process was studied to optimize performance, especially for the removal of nitrogen compounds and of biodegradable organic matter. It was found that the enzymatic process was able to remove organic matter effectively (expressed as BOD5 and COD) and nitrogen content, color and turbidity. 相似文献
1000.
14C-carbofuran underwent considerable mineralization (approximately 30% of the applied activity) in Vertisol soil under moist and flooded conditions during 60 days incubation. Bound residues were formed under both the conditions, the extent being more in moist soils (approximately 55% of the applied activity) than under flooded conditions (approximately 41% of the applied activity). 3-Keto carbofuran was the only significant metabolite observed under flooded conditions. 相似文献