خيارات البحث
النتائج 731 - 740 من 783
Acute toxicity of 353-nonylphenol and its metabolites for zebrafish embryos النص الكامل
2009
Kammann, Ulrike | Vobach, Michael | Wosniok, Werner | Schäffer, Andreas | Telscher, Martin
Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere النص الكامل
2009
Schrader, Stefan | Bender, Jürgen | Weigel, Hans-Joachim
Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere النص الكامل
2009
Schrader, Stefan | Bender, Jürgen | Weigel, Hans-Joachim
A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O3: nonfiltered (NF) ambient air or NFþ 40 ppb O3 (NFþ). During O3 exposure, soil sampling was performed at two dates according to different plant growth stages. O3 exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O3 concentrations may influence the dynamic of decomposition processes and the turnover of nutrients.
اظهر المزيد [+] اقل [-]Ozone exposure of field-grown winter wheat affects soil mesofauna in the rhizosphere النص الكامل
2009
Schrader, Stefan | Bender, Jürgen | Weigel, Hans-Joachim
A 2-year open-top chamber experiment with field-grown winter wheat (Triticum aestivum L. cv. Astron) was conducted to examine the effects of ozone on plant growth and selected groups of soil mesofauna in the rhizosphere. From May through June in each year, plants were exposed to two levels of O3: non-filtered (NF) ambient air or NF+ 40 ppb O3 (NF+). During O3 exposure, soil sampling was performed at two dates according to different plant growth stages. O3 exposure reduced above- and below-ground plant biomass in the first year, but had little effect in the second year. The individual density of enchytraeids, collembolans and soil mites decreased significantly in the rhizosphere of plants exposed to NF+ in both years. Differences were highest around anthesis, i.e. when plants are physiologically most active. The results suggest that elevated O3 concentrations may influence the dynamic of decomposition processes and the turnover of nutrients. Ozone reduced the individual densities of enchytraeids, collembolans and soil mites in the rhizosphere of winter wheat indirectly via the plant–soil-system.
اظهر المزيد [+] اقل [-]Tradable permits under threat to manage nonpoint source pollution النص الكامل
2009
Ali, Mourad | Rio, Patrick
In this article we treat the problemof nonpoint source pollution as a problem of moral hazard in group. To solve this kind of problemwe consider a group performance based tax coupled to tradable permits market. The tax is activated if the group fails to meet the ambient standard. So the role of the tax is to provide an incitation to ensure that the agents provide the abatement level necessary to achieve the standard. The role of the tradable permits market is to distribute effectively this abatement level through the price of the permits which rises with the exchange of the permits.
اظهر المزيد [+] اقل [-]Model investigationss [i.e. investigations] of ejector for dosage of ozone into water | Modelska ispitivanja ejektora za doziranje ozona pri mesanju sa vodom
2009
Batinic, B., Univerzitet u Beogradu, Beograd (Serbia). Gradjevinski fakultet | Prodanovic, D., Univerzitet u Beogradu, Beograd (Serbia). Gradjevinski fakultet | Randelovic, A., Univerzitet u Beogradu, Beograd (Serbia). Gradjevinski fakultet
A series of measurements has been conducted with various combinations of ejector dimensions. Variables were diameter of the nozzle and the distance between the end of the nozzle and the beginning of the pipe. Vacuum head in function of water flow was measured when there was no air flow, and when there was air flow (from a reservoir with constant volume). The results are presented in this paper.
اظهر المزيد [+] اقل [-]Removal of Cu++ ions from aqueous solution by bisorbent based on Lagenaria vulgaris shell | Uklanjanje Cu++ jona iz vodenih rastvora biosorbentom na bazi kore Lagenaria vulgaris
2009
Bojic, A., Univerzitet u Nisu, Nis (Serbia). Prirodno-matematicki fakultet, Odsek za hemiju | Mitic-Stojanovic, D.L., JP Vodovod, Vranje (Serbia) | Bojic, d., Univerzitet u Nisu, Nis (Serbia). Prirodno-matematicki fakultet, Odsek za hemiju | Andjelkovic, T., Univerzitet u Nisu, Nis (Serbia). Prirodno-matematicki fakultet, Odsek za hemiju
This study investigates the effect of pH, temperature, contact time and initial metal concentration on Cu++ ions removal from water solutions, using biomass of Lagenaria vulgaris skin (LV). With higher pH, the efficiency of copper sorption increases and reaches its maximum at pH 7.0. Temperature has negative effect on sorption process due to its exothermic properties. Biosorption efficiency increases with time and reaches equilibium after 40 min. Increasing initial copper concentration gives an increase in biosorbent sorption capacity, and a proportional decrease in treatment efficiency. Obtained results have shown that LV based biosorbent is an efficient and available mean for toxic metal removal from natural and waste waters.
اظهر المزيد [+] اقل [-]Characterization of surface water and groundwater at Belgrade area using stable isotopes | Karakterizacija povrsinskih i podzemnih voda u okolini Beograda koriscenjem stabilnih izotopa
2009
Miljevic, N. | Obradovic, V. | Arezanovic-Eminovic, T. | Boreli-Zdravkovic, Dj., Institut za vodoprivredu Jaroslav Cerni, Beograd (Serbia) | Golobocanin, D., Institut za nuklearne nauke Vinca, Beograd (Serbia) | Ogrinc, N., Institut Jozef Stefan, Ljubljana (Slovenia)
The stable isotope content of hydrogen (2H/1H), carbon (13C/12C), nitrogen (15N/14N), and oxygen (18O/16O) in surface water (the Sava river and channels) and groundwater (Ranney wells) were determined in Belgrade (Serbia) during July 2008. Detailed evaporation calculation has estimated that fraction of water loss to be between 10 and 20% in the channels using the local meteoric water line and the local evaporation line. Carbon-13 content in dissolved inorganic carbon is distinguished between surface water and groundwater indicating different evolution pathways of carbon. Based on carbon and nitrogen isotopic composition and C/N ratios, sources of inorganic carbon and of organic matter in analyzed waters are discussed.
اظهر المزيد [+] اقل [-]Analysis of Cystoseira corniculata (Phaeophyceae) populations in the Boka Kotorska Bay [Adriatic sea, Montenegro] | Analiza naselja Cystoseira corniculata (Phaeophyceae) u Bokokotorskom zalivu [Jadransko more, Crna Gora]
2009
Macic, V., Institut za biologiju mora, Kotor (Montenegro)
New locations for the distribution of algae C. corniculata (Phaeophyceae) are presented, with a scope to improve scarce knowledge on phytobenthos of the Montenegrian coast. In the Bay of Boka Kotorska this algae is found on 10 locations and on 3 locations, on depth of 3 m and 5 m, measurements of wet weight and length of primary branches are done. Differences between biomass of algae are note between different depths and different seasons, but between different locations there are no significant differences.
اظهر المزيد [+] اقل [-]Chlorophyll a and eutrophication in Kotor Bay [Adriatic sea, Montenegro] | Hlorofil a i eutrofikacija u Kotorskom zalivu [Jadransko more, Crna Gora]
2009
Krivokapic, S., Prirodno-matematicki fakultet, Podgorica (Montenegro). Studijski program za biologiju | Pestoric, B., Institut za biologiju mora, Kotor (Montenegro) | Drakulovic, D., Institut za biologiju mora, Kotor (Montenegro)
The weekly measurement of physico-chemical and biological parameters was done during the spring of 2008 in order to assess the level of eutrophication in the Kotor Bay. Chlorophyll a was used as trophic level indicator and its values varied from minimal 1.00 mg/cubic meter in June on the depth of 10 m to maximal 3.71 mg/cubic meter on the sea surface in May. According to Nixon criteria during investigation period it can be concluded that the area in question is oligotrophic. On the other hand, according to UNEP criteria which are somewhat stricter when the concentration of chlorophyll a is in question, Kotor Bay was mesoeutrophic area.
اظهر المزيد [+] اقل [-]Spring and summer (2007) mesozooplankton communities of Boka Kotorska bay [Adriatic sea, Montenegro] | Prolecno-letnja (2007) mezozooplanktonska zajednica Bokokotorskog zaliva [Jadransko more, Crna Gora]
2009
Vukanic, V., Drzavni Univerzitet u Novom Pazaru, Novi Pazar (Serbia). Departman za bio-hemijske i medicinske nauke, Biologija | Hadzibrahimovic, M., Drzavni Univerzitet u Novom Pazaru, Novi Pazar (Serbia). Departman za bio-hemijske i medicinske nauke, Biologija
Zooplankton community analysis was conducted for spring (April - 07) and summer (August - 07) in Boka Kotorska Bay. Analyses included determination of biomass and qualitative composition. Data are given on the number of specimens per cubic meter as well as on the volume organisms. Qualitative composition showed domination Copepoda of zooplanktons groups.
اظهر المزيد [+] اقل [-]