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951.
Cleaner production (CP) working methods should facilitate the search for feasible CP options and contribute to their on-going implementation in a company. Over the past decade, numerous working methods have been developed in order to cater for specific segments of industry. This paper describes, compares and analyses the core components of six Dutch working methods to develop a framework for CP methodologies, to draft guidelines for the selection of an appropriate working method for a certain industry, and to identify areas which require additional methodology development. A division is proposed between four types of CP working methods: indicators, scan, pre-assessment and assessment. Each of these has its strengths and weaknesses, which calls for a careful selection of the working method, which in turn could be based on size of the company, material- and energy-intensity of the production, and complexity of the production processes. This comparative evaluation further proves that the working methods are still weak in stimulating the corporate transition process from ‘end-ofpipe’ to CP thinking and acting. It is tentatively concluded that an ‘assessment’ is superior in identifying comparatively radical environmental improvements (‘innovations’) as well as in fostering the integration of CP into the daily operation and management of a company. The use of simplified working methods in selected industries, is, however, justified given their ability to contribute to the implementation of relatively obvious CP options.  相似文献   
952.
953.
A microfluorimetric assay was designed to monitor β-glucuronidase (β-gluc) activity during the early development of mouse embryos and was also applied to measure β-gluc activity in human sperm cells and single human oocytes. Mouse oocytes and preimplantation embryos at different stages of development, failed fertilized human oocytes, and human sperm cells were collected, and β-gluc activity was analysed. In the mouse, β-gluc activity could be measured starting from the morula stage on in a pooled sample of 15 embryos and at blasto-cyst formation in one single embryo. β-Gluc activity was low in human sperm cells. The enzyme could be readily demonstrated in 87 per cent of non-fertilized human oocytes. Considerable variation in β-gluc activity was noticed between individual oocytes.  相似文献   
954.
Agroforestry is considered to be a promising alternative to short-fallow shifting cultivation or other monocropping systems. An on-farm experiment was established in 1996 in northern Viet Nam to examine the contribution of the leguminous bush Tephrosia candida (Roxb.) D.C. as a fallow or hedgerow species and as a mulch producer to improve nutrient cycling and prevent nutrient losses by erosion. The systems tested were upland rice monocropping (Mono), natural fallow (NaFa), fallow of Tephrosia (TepFa), hedgerow intercropping with upland rice (Oryza sativa L.) and internal mulching using pruned Tephrosia biomass (TepAl), and upland rice with external mulching using Tephrosia biomass (TepMu). Over two cropping seasons, from April 1996 to April 1998, nutrients recycled and inputs and exports were recorded, as well as changes in C-, N- and P-pools, and in pH in the 0–5 cm topsoil layer.The Tephrosia systems (TepFa, TepAl, TepMu) prevented nutrient losses by erosion effectively. Compared to the NaFa system, the TepFa system accumulated 34% more N in the above-ground plant parts and increased topsoil N by 20%, probably due to N-fixation. There was a trend that the less labile P-pools (NaOH-P) were reallocated into the more labile P-pools (Bicarb-P) in the soil of the TepFa system. Burning released significant amounts of the inorganic P-pools in both the NaFa and TepFa systems and this effect seemed to be more pronounced in the TepFa than in the NaFa. Organic input to crop export ratios for N and P were >1 in the TepAl and TepMu treatments. This was due to a sufficient quantity and quality of the Tephrosia mulching material. However, moderately labile NaOH-extractable organic P seemed to be depleted in the topsoil due to high P uptake in the TepMu treatment. Thus, nutrient cycling and nutrient balances were improved under the Tephrosia systems. But for long-term P sustainability, there is a belief that a combined use of mulching and mineral P fertiliser is needed.  相似文献   
955.
956.
957.
Elbe river flood peaks and postwar agricultural land use in East Germany   总被引:1,自引:0,他引:1  
Collectivization of farmland since the 1950s has changed the agricultural land use in former East Germany. Single fields on the collective farms became increasingly large and were cultivated with increasingly heavy farm equipment. This led to large-scale physical degradation of arable soils, enhancing the formation of surface runoff in periods with prolonged and excessive precipitation. The extent to which this development may have affected the discharge behavior of the main East German river, the Elbe, has so far not been studied. We analyzed the flood peaks of the Elbe during the past century (1900-2000). The flood discharge behavior of the Elbe has apparently changed significantly since the 1950s. Although climate changes may be involved, we conclude that the Elbe flood peaks, recorded since 1950, are related to the changes in postwar agricultural land use in former East Germany. To restore the degraded farmland soils, a change in agricultural land use may be necessary.  相似文献   
958.
959.
Wintering oystercatchers (Haematopus ostralegus), charadriid shorebirds that chiefly feed on intertidal bivalves, suffered mass mortality in The Netherlands during severe frosts in 1986 and 1987. PCBs were analysed in liver and (partially) brain lipids of 96 birds to examine the influence of age (three categories), sex and wintering area (the Oosterschelde estuary versus the westernmost Wadden Sea) on levels, and the risk of intoxication due to starvation. Victims had lost nearly 40% of their normal winter weight. PCB-structures were similar in all age/sex categories, and in both areas. Sex did not affect total PCB-concentrations. First-winter Wadden birds had lower levels than subadults and adults, but an age-difference was absent in the Oosterschelde birds. Some juvenile outliers possibly originated from polluted breeding areas. Individual variation was considerable in most categories. Relevant ecological factors are discussed. Although a dam has considerably reduced the direct transport of PCBs into the Oosterschelde since 1969, contamination of local birds was hardly lower than in Wadden winterers. Influx of riverine PCBs into the Oosterschelde from coastal water may have been underrated. Starvation increased liver concentrations by a factor of 35; factors for the brain were 56 for juveniles and approximately 120 for older birds. Considering published lethal levels for other species, it is doubtful if PCBs contributed to this winter mortality.  相似文献   
960.
For decades, trees have been exposed to atmospheric S pollution (acid rains). They can thus fulfil their S requirements not only via the roots, but also via their needles. However, whether leaf-absorbed S has a different fate from that of root-absorbed S, or may be toxic to the plant, remains uncertain. Norway spruce trees have been contaminated with (35)SO(4)(2-) either via a nutrient solution, or via a spray, and their (35)S distribution has been analysed. In the case of foliar contamination, a high percentage of (35)S(-) was present in the form of SO(4)(2-), both on the surface and inside the youngest needles. In the case of root contamination, the (35)S of the youngest leaves was mainly incorporated into insoluble organic compounds. Older needles showed a different S distribution.  相似文献   
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