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181.
182.
砖红壤中Al和Pb的竞争吸附 总被引:3,自引:1,他引:3
从pH值和离子加入量两个角度研究了砖红壤中Al和Pb的竞争吸附 .结果表明 ,当低数量的Al和Pb共存时 ,离子的吸附量与其单独存在下的情形相比都有所下降 ,该现象在低pH值的条件下较为明显 ,而随着pH值升高则逐渐减弱 ;若Al和Pb共存时的初始浓度均为 1 0mmol·l- 1 ,两者之间的竞争吸附在pH 3 5至 5 5范围内都较为显著 ;此外 ,当0 1mmol·l- 1 的Pb与 1 0mmol·l- 1 的Al共存时 ,Al的吸附没有受到Pb的影响 ,此时尽管Al和Pb的浓度比为 1 0∶1 ,但土壤对Pb的吸附并没有被Al完全抑制 ,反映出土壤表面某些吸附位对Pb具有高度的选择性 相似文献
183.
Robert C. Lee James R. Fricke William E. Wright Walt Haerer 《Environmental geochemistry and health》1995,17(4):169-181
A partially probabilistic blood lead prediction model has been developed, based on the US Environmental Protection Agency integrated exposure-uptake-biokinetic blood lead model (IEUBK model). This study translated the IEUBK model into a spreadsheet format. The uptake submodel incorporates uncertainty distributions for exposure and bioavailability parameters. The biokinetic submodel is duplicated with a table incorporating partitioning and decay of lead levels in the body. As a case study, the probabilistic model is applied to a lead exposure scenario involving a former smelter site in Sandy, Utah. The probabilistic model produces less biased estimates of means and standard deviations than the deterministic model. Parameter uncertainty is propagated in the model by the use of Monte Carlo simulation. Thus, sensitivity analysis is possible, and driving variables can be determined. 相似文献
184.
Twenty Henna samples were collected and analysed for lead by electrothermal atomic absorption spectrophotometry after a microwave acid digestion procedure. The mean lead concentration was 5.50 g g–1, with a range from 1.29 g g–1 to 16.48 g g–1. The data did not show a high concentration of lead in these samples. However, if we take into account the popular use of henna, the cumulative effects of prolonged exposure to low lead especially in children cannot be ruled out. 相似文献
185.
186.
J. Preston B. Engel G. C. Lalor M. K. Vutchkov 《Environmental geochemistry and health》1996,18(3):99-104
The Centre for Nuclear Sciences (CNS) uses a raster based geographic information system (GIS), integrated with a relational database to store information on point sampled data, including concentrations of over 50 elements and/or ions in a variety of sample materials. These data are filtered in the GIS to create surface layers and are assigned colours according to percentile ranges allowing visual inspection to be used to identify significant features and trends. The database currently contains raster map layers for soils and geologic features, point site data for water and air, and vector data for roads, rivers and streams. While data are still being added to the database interesting results are already being obtained and a few instances where the GIS was used to assist in the data interpretation are reported. 相似文献
187.
L. Viverette H. W. Mielke M. Brisco A. Dixon J. Schaefer K. Pierre 《Environmental geochemistry and health》1996,18(1):41-45
This study tests the hypothesis that exterior sources of lead dust are more important than interior sources in the route of exposure of children. Benign field methods were used to distinguish between potential and actual lead exposure problems. Utilising hand wipe and surface wipe techniques, hand and environmental samples were obtained from selected day care centres at different locations within New Orleans. Previous research has shown that soil lead is determined by location within the city. Private and public day care centres were selected from inner and outer city areas to estimate the extent of hand lead exposure. To measure and identify the extent of environmental lead exposure, hand wipes were taken before and after playing outdoors. Results of preliminary findings show that outdoor lead dust is a more potent contaminant of hands than indoor lead dust. An association was found between the amount of lead on children's hands after playing outdoors and the lead content in the exterior dust and soil. Although two girls out of forty children had exceptionally high hand lead quantities after playing outdoors, in general, boys have higher hand lead levels than girls. The private inner-city day care centre had a severe contamination problem in its outdoor play area. By contrast, the outdoor play area of the public inner city day care centre is of such a high quality that the quantity of lead dust is independent of location in the city. 相似文献
188.
189.
A geo-referenced data set of 12 228 first-time blood lead screening values for Syracuse, NY, children was established for the 4-year period 1992–1996. Soil lead values were measured in a 600 m by 600 m tessellation grid covering the city. The two data sets were merged for evaluation of relationships between them. Strong seasonal variation in blood lead levels suggests the importance of contaminated soils as an exposure source. When the data were aggregated at a large geographic scale (3 km2), a logarithmic model showed an R2 of > 0.65 for the regression of geometric mean blood lead on median soil lead values. Results showed a striking similarity to those obtained by Mielke et al. (1999) for a study in New Orleans, LA, USA. 相似文献
190.