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231.
232.
Ian Colbeck Zaheer Ahmad Nasir Zulfiqar Ali 《Environmental science and pollution research international》2010,17(6):1187-1196
Background and purpose
In Pakistan, almost 70% of the population lives in rural areas. Ninety-four percent of households in rural areas and 58% in urban areas depend on biomass fuels (wood, dung, and agricultural waste). These solid fuels have poor combustion efficiency. Due to incomplete combustion of the biomass fuels, the resulting smoke contains a range of health-deteriorating substances that, at varying concentrations, can pose a serious threat to human health. Indoor air pollution accounts for 28,000 deaths a year and 40 million cases of acute respiratory illness. It places a significant economic burden on Pakistan with an annual cost of 1% of GDP. Despite the mounting evidence of an association between indoor air pollution and ill health, policy makers have paid little attention to it. This review analyzes the existing information on levels of indoor air pollution in Pakistan and suggests suitable intervention methods. 相似文献233.
The aim of the present study was to assess the sonographic contour of the increased nuchal translucency (NT) and to correlate this with pregnancy outcome. Fifty sonographic images of fetuses with increased NT [>95th centile thickness of the normal range for crown–rump length (CRL) between 38 and 84 mm] were retrospectively assessed. In all the cases a complete pregnancy and even infancy follow-up (<36 months) was available. The NT appearances were subdivided into two forms: a ‘notched’ or ‘uniform’ appearance. The images were correlated with karyotype results [trisomy 21 (DS) vs euploid cases] and pregnancy outcome. Complicated outcomes were classified as being either DS fetuses, miscarriage or termination of pregnancy because of structural anomaly. Thus 30/35 (86%) of the euploid fetuses had a ‘uniformly’ increased NT, whereas 8/13 DS cases (62%) had a ‘notched’ appearance (Fisher's exact test, p=0.004). Additionally, 27/29 fetuses (93%) which had an uneventful pregnancy outcome had a ‘uniform’ increased NT, whereas 12/26 (57%) of the fetuses which had adverse pregnancy outcome had a ‘notched’ appearance of their NT (Fisher's exact test, p<0.001). Although it was not possible to correlate the sonographic data with post-evacuation microdissection findings, it is possible that a uniformly shaped, increased NT may be more representative of a developmental delay in a normal fetus. Conversely, a ‘notched’ nuchal surface may represent abnormal lymphatic or cardiovascular development more commonly seen in DS fetuses. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
234.
Ian Boustead 《Journal of Cleaner Production》1993,1(3-4)
This paper examines the minimum essential requirements that must be satisfied when a database is established for life cycle inventory calculations. It shows that the format of the database is governed by the physical requirements of the system being examined, by the need to include iterative calculations within the analysis and by the demands of the final data presentation. 相似文献
235.
Individual particle analysis by scanning electron microscopy is a high resolution analytical technique which can provide the detail necessary to solve many particulate pollution problems. In an electron microscope a beam of electrons is focused on a specimen resulting in a number of signals which are used to collect chemical and morphological information from individual features either manually or automatically. Case studies are presented which illustrate the applications of the technique to three paniculate pollution problems of differing complexity. 相似文献
236.
237.
Newcombe AC Gustafson DI Fuhrman JD van Wesenbeeck IJ Simmons ND Klein AJ Travis KZ Harradine KJ 《Journal of environmental quality》2005,34(3):1004-1015
The Acetochlor Registration Partnership conducted a prospective ground water (PGW) monitoring program to investigate acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)-acetamide] transport to ground water at eight sites. The distribution of soil textures among these sites was weighted toward coarser soil types, while also including finer-textured soils that dominate most corn (Zea mays L.)-growing areas of the United States. Each site consisted of a 1.2-ha test plot adjacent to a 0.2-ha control plot. Suction lysimeters and monitoring wells were installed at multiple depths within each test and control plot to sample soil-pore water and near-surface ground water. Irrigation was applied to each site during the growing season to ensure water input of 110 to 200% of average historical rainfall. Acetochlor dissipated rapidly from surface soils at all sites with a DT(50) (time for 50% of the initial residues to dissipate) of only 3 to 9 d, but leaching was not an important loss mechanism, with only 0.25% of the 15,312 soil-pore water and ground water samples analyzed containing parent acetochlor at or above 0.05 microg L(-1). However, quantifiable residues of a soil degradation product, acetochlor ethanesulfonic acid, were more common, with approximately 16% of water samples containing concentrations at or above 1.0 microg L(-1). A second soil degradation product, acetochlor oxanilic acid, was present at concentrations at or above 1.0 microg L(-1) in only 0.15% of water samples analyzed. The acetochlor PGW program demonstrated that acetochlor lacks the potential to leach to ground water at detectable concentrations, and when applied in accordance with label restrictions, is unlikely to move to ground water at concentrations hazardous to human health. 相似文献
238.
Stratification and Circulation in a Shallow Turbid Waterbody 总被引:1,自引:0,他引:1
Shallow waterbodies are often assumed to be well mixed in the vertical. However, when they are characterised by high turbidity levels, absoption of solar heating within a relatively thin surface layer can produce thermal stratification. Results from an intensive monitoring program have been combined with three-dimensional circulation modelling to examine the diurnal stratification cycles in a small turbid waterbody. The waterbody, known as Rushy Billabong, is located in southeastern Australia and its high turbidity coupled with forcing by wind and solar radiation resulted in regular diurnal cycles of stratification and overturning. Under conditions of light wind and high solar radiation, the model results were generally consistent with the observed temperature field. However, under stronger winds, preferential cooling and sinking of shallow water around the edge of the lake began to contribute significantly to the interior stratification. Model estimates then became more sensitive to the detailed bathymetry and the choice of turbulence parameterisation. The level of stratification is also shown to influence the circulation in the billabong by trapping the wind-driven flow near the surface. Insights provided by the observations and modelling may have broader implications for the management of small turbid systems such as settling ponds, aquaculture ponds, and some natural wetlands. 相似文献
239.
240.
Ian D. Leith Lucy J. Sheppard David Fowler J. Neil Cape Matt Jones Alan Crossley Ken J. Hargreaves Y. Sim Tang Mark Theobald Mark R. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):207-218
Providing an accurate estimate of the dry component of N deposition to low N background, semi-natural habitats, such as bogs and upland moors dominated by Calluna vulgaris is difficult, but essential to relate nitrogen deposition to effects in these communities. To quantify the effects of NH3 inputs to moorland vegetation growing on a bog at a field scale, a field release NH3 fumigation system was established at Whim Moss (Scottish Borders) in 2002. Gaseous NH3 from a line source was released along of a 60 m transect, when meteorological conditions (wind speed >2.5 m s–1 and wind direction in the sector 180–215°) were met, thereby providing a profile of decreasing NH3 concentration with distance from the source. In a complementary study, using a NH3 flux chamber system, the relationships between NH3 concentrations and cuticular resistances were quantified for a range of NH3 concentrations and micrometeorological conditions for moorland vegetation. Cuticular resistances increased with NH3 concentration from 11 s m–1 at 3.0 g m–3 to 30 s m–1 at 30 g m–3. The NH3 concentration data and the concentration-dependent canopy resistance are used to calculate NH3 deposition taking into account leaf surface wetness. The implications of using an NH3 concentration-dependent cuticular resistance and the importance for refining critical loads are discussed. 相似文献