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Relationships between river sediment characteristics and trace metal concentrations in tubificid worms and chironomid larvae
1997
Bervoets, L. | Blust, R. | Wit, M. de | Verheyen, R. (Department of Biology, University of Antwerp (UIA), Universiteitsplein I, 2610, Wilrijk (Belgium))
Seasonal variability of total and easily leachable element contents in topsoils (0-5 cm) from eight catchments in the European Arctic (Finland, Norway and Russia)
1997
Niskavaara, H. | Reimann, C. | Chekushin, V. | Kashulina, G. (Geological Survey of Finland, PO Box 77, FIN-96101 Rovaniemi (Finland))
Biological nutrient removal in suspended growth system
1997
Wisjnurapto, IR.
A series of experiments on biological nutrient removal using suspended growth bioreactor with a various reactor configuration have been conducted during the last five years. The first configuration applied a contact stabilization flowed by a denitrification processes in two sludge system. The two sludge systems mean that the aerobic sludge is recirculated in the aerobic circuit, and the anaerobic sludge is recirculated in the anaerobic circuit. The second configuration was conducted in a contact stabilization and denitrification processes in a one sludge system. The one sludge system meant that there are no separation between aerobic and anaerobic sludge; the aerobic and anaerobic processes are in the same circuit and all sludge are recirculated in the same circuit. The third configuration was performed in anaerobic-aerobic-anaerobic reactors and ended by the clarifier to clarify the biosludge before recirculated to the head of the circuit. This configuration was also using a one sludge system. In those three configurations, the hydraulic detention time in the reactors were varied from 2 to 6 hours, and the sludge age from 2 to 15 days. The results showed that the first configuration gave a very high performance in carbon and nitrogen removal. In terms of TOC [total oxygen concentration], the carbon removal achieved up to 92 percent or in terms of total COD [carbon oxygen demand] up to 80 percent, and 97 percent for total nitrogen removal. On the other hand, the phosphorus removal was only limited to the amount required for cells metabolism. More carbon removal were observed in the second configuration (94 percent of total COD) but less total nitrogen were removed (93), however, phosphorus were removed significantly (up to five times of the cells metabolism requirement). The best results in those three nutrients removal was achieved in the third configuration. No less than 95 percent of total COD and 96 percent of nitrogen removal were noticed, and phosphorus were removed at the level of more than six times of the cells metabolism requirement. The experiments concluded that the phosphorus removal was conducted by the aerobic microorganisms which are alternately treated in aerobic-anaerobic conditions. The degree of removal depended on how long the microorganisms were put in the aerobic and anerobic conditions. If the anaerobic condition was too long, the microorganisms would die, and no phosphorus removal took place. If it was too short, the removal would be less. For carbon and nitrogen removals in the system, the hydraulic detention time in the reactors and sludge appeared as the essential parameters in the process
显示更多 [+] 显示较少 [-]highway stormwater runoff quality: development of surrogate parameter relationships
1997
Thomson, N. R. | McBean1, E. A. | Snodgrass, W. | Monstrenko, I. B.
The development of relationships for predicting the impact of highway stormwater runoff is described. The predictive relationships are regression-based equations reflecting variations in the magnitude of the constituents of interest. The objective is to identify a subset of constituents that can be used as surrogates for the remaining constituents as a means of decreasing the costs of collection and measurement of highway stormwater runoff quality data.The Minnesota highway stormwater quality database complied in the late 1970's and early 1980's is employed in identifying the set of surrogate parameters. The findings indicate that total suspended solids, total dissolved solids, total volatile solids, and total organic carbon are effective surrogate parameters for numerous metals, ionic species, and nutrients. The findings also indicated that the developed ionic species constituent relationships are portable, while the metal and nutrient constituent relationships were limited to urban sites with similar environmental conditions. The development of these relationships represents a step towards remediating and preventing the problem of nonpoint source highway pollution.
显示更多 [+] 显示较少 [-]Possibilities for increased carbon sequestration through the implementation of rational forest management in Russia
1997
Shvidenko, Anatoly | Nilsson, Sten | Roshkov, Vjacheslav
Huge areas of the Russian forests suffer from insufficient forest management. A scenario has been developed for an improved management program that would be implemented over the next 40 years. Possible options have been aggregated into three interlinked groups: increase in forest productivity through improvement of the forest conditions and the structure of the Forest Fund, decrease of carbon release by mitigation of disturbance regimes, and improvement of landscape management. One prerequisite in developing this scenario was that the cost of sequestering one ton of carbon should not exceed US$3 (1992 dollar value). In this article a simple model is described to illustrate the following possibilities for increased carbon fixation by improved forest management: large-scale reforestation and afforestation, replacement of stands with low productivity and replacement of so called soft deciduous species and “climax” stands, and implementation of rational silviculture (thinning). The results indicate a potential for an increase in carbon fixation in Russian forest ecosystems of 24.4 Pg over 100 years, after the first year that the actions discussed are implemented. The net sink of carbon was determined to be 16.5 Pg in the “low” estimate and 42.5 Pg in the “high” estimate. There are, however, many uncertainties in the data and there are difficulties in adequately modeling the possibilities for implementation under current conditions in Russia. In spite of these uncertainties, we conclude that there is great potential for economically justified increased carbon fixation through improved forest management in Russia.
显示更多 [+] 显示较少 [-]Possibilities for increased carbon sequestration through the implementation of rational forest management in Russia
1997
Shvidenko, A. (International Inst. for Applied Systems Analysis, Laxenburg (Austria).) | Nilsson, S. | Roshkov, V.