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21.
Many diets employed in aquaculture are enriched with selenium to improve the diet quality and its conservation. The aim of the study was to investigate the effects of a diet enriched in selenium (1.21 mg kg(-1)) on the antioxidant response of Procambarus clarkii (Girard, 1852). Crayfish fed a diet with lower selenium content (0.30 mg kg(-1)) were the control. Selenium accumulation, enzymatic activities, and total glutathione were evaluated in hepatopancreas of adults of both sexes fed with both diets for 50 days at two experimental times (T(30), T(50) days). Treated females exhibited the highest selenium bioaccumulation during both experimental times, while treated males displayed the highest selenium concentration after 30 days, compared to control crayfish. A sex-related difference was found for the response of the analyzed enzymes in the selenium diet-treated specimens. In fact, superoxide dismutase, glutathione peroxidase and glyoxalase I activities in males were more sensitive compared with females, showing depleted activities in both experimental times. Catalase activity was induced in females (T(50)), while glutathione S-transferase activity was the highest in treated females and the lowest in treated males, compared with own controls. Only glutathione reductase activity and glutathione content showed the same trend in both sexes, which were both lowered in treated specimens, when compared with control crayfish. This result might be due to the effect of selenium toxicity on this freshwater species. Males and females of P. clarkii showed a different susceptibility to the prooxidant effects in a Se-enriched diet. 相似文献
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Jiří Pšeja Hana Charvátová Petr Hruzík Josef Hrnčiřík Jan Kupec 《Journal of Polymers and the Environment》2006,14(2):185-190
The presented work deals with blends composed of polyvinyl alcohol (PVA) and biopolymers (protein hydrolysate, starch, lignin). PVA does not belong to biologically inert plastics but its degradation rate (particularly under anaerobic conditions) is low. A potential solution to the issue problem lies in preparation of blends with readily degradable substrates. We studied degradation of blow-molded films made of commercial PVA and mentioned biopolymers in an aqueous anaerobic environment employing inoculation with digested activated sludge from the municipal wastewater treatment plant. Films prepared in the first experimental series were to be used for comparing biodegradation of blends modified with native or plasticized starch; in this case effect of plasticization was not proved. The degree of PVA degradation after modification with native or plasticized starch increases in a striking and practically same manner already at a starch level as low as approximately 5 wt.%. Films of the second experimental series were prepared as additionally modified with protein hydrolysate and lignin. Only lignin-modified samples exhibited a somewhat lower degree of biodegradation but regarding the measure of lignin present in blend this circumstance is not essential. Level of biodegradation with all discussed films differed only slightly—within range of experimental error. 相似文献
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Mest'ánková H Mailhot G Pilichowski JF Krýsa J Jirkovský J Bolte M 《Chemosphere》2004,57(10):1307-1315
The degradation of Monuron (3-(4-chlorophenyl)-1,1-dimethylurea) photoinduced by Fe(III) in aqueous solution has been investigated. The rate of degradation depends on the concentration of Fe(OH)2+, the most photoreactive species in terms of *OH radical formation. These *OH radicals are able to degrade Monuron until total mineralisation. The primordial role of the speciation of Fe(III)-hydroxy complex in aqueous solution, for the efficiency of the elimination of pollutant, was shown and explained in detail. The formation of Fe(II) in the irradiated solution was monitored and correlated with the total organic carbon evolution. Degradation photoproducts were identified and a mechanism of degradation is proposed. 相似文献
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Jeanger P Juanga Chettiyappen Visvanathan Josef Tr?nkler 《Waste management & research》2007,25(1):30-38
The optimization of anaerobic digestion aims to maximize organic waste stabilization after a short digestion period. This paper presents the optimization performance of the combined anaerobic digestion and sequential staging concept in a thermophilic, solid-state batch system as a treatment technology prior to landfill. The former involves enhanced pre-stage flushing with the addition of microaeration and inoculum in the methane phase. The latter involves leachate cross-recirculation between the mature and fresh waste reactors without conducting a pre-stage operation. The optimized process for combined anaerobic digestion showed that reducing the pre-stage operation with the maximum removal of organics from the waste bed is beneficial. Moreover, the sequential staging concept offers an improved process over the combined anaerobic digestion wherein the specific methane yield of 11.9 and 7.2 L CH4 kg(-1) volatile solids (VS) per day was achieved, respectively. After 28 days of operation, the sequential staging process showed an improved waste stabilization with 86 and 79% mass and volume reduction, respectively. A higher methane yield of 334 L CH4 kg(-1) VS with 86% VS reduction, which is equivalent to 84% process efficiency was obtained. 相似文献
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Josef Leitmann 《Journal of Environmental Planning and Management》1998,41(1):129-144
There is now a wealth of international experience and lessons about options for managing environmentallysensitive zones. This paper1 provides a brief guide to two sets of options, regulatory instruments and incentive measures, that are commonly used to manage special areas. Managementapproachesthat combine both sets of tools are then reviewed, including integrated coastal zone management, municipal-level programmes and efforts to promote sustainable local development such as eco-tourism. The paper concludes that, regardless of which approach is applied to a protected area, the key threats to an area's sustainability must be identified and addressed. Examples and case studies of both good and poor practice are included to illustrate the use of different options. In order to sustain our global environment and improve the quality of living in our human settlements, we commit ourselves to sustainable patterns of production, consumption, transportation and settlement development, pollution prevention, respect for the carrying capacity of eco-systems, and the preservation of opportunities for future generations. (Istanbul Declaration on Human Settlements, June 1996) 相似文献
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Josef Leitmann 《Local Environment》1999,4(2):169-180
The paper concludes its first section by answering the title question: no, QOL indicators cannot be purely objective but yes, they can be relevant while being subjective. The second section develops a framework for making measures of urban QOL more relevant. The objective is that such indicators can be a useful tool for sustaining urban development into the next millennium. The framework consists of three elements: (a) a process—QOL indicators should be locally developed through an approach that combines expertise with stakeholder consultation; (b) an output—developing, collecting and evaluating QOL measurements should be linked to implementation of policies, programmes and/or projects; and (c) a method—a series of tested guidelines should be applied to ensure that QOL indicators are realistic, both logistically (they can be collected) and analytically (they are appropriate measures). Real-world examples are used to illustrate points made in the paper. 相似文献
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