Accumulation of Geosmin and 2-methylisoborneol in European Whitefish Coregonus Lavaretus and Rainbow Trout Oncorhynchus Mykiss in RAS

Geosmin (GSM) and 2-methylisoborneol (MIB)-induced off-flavors can cause serious problems in a recirculating aquaculture system (RAS), such as delayed harvest and increased production costs, but also damage producers’ reputation. Traditionally, off-flavors have been removed by depuration before harvesting. Rainbow trout (Oncorhynchus mykiss) and European whitefish (Coregonus lavaretus) are commercially valuable species produced for consumers, both being suitable for rearing in RAS. In this study, European whitefish and rainbow trout were raised from juvenile up to 240 g (European whitefish) and 660 g (rainbow trout) to monitor the long-term accumulation of off-flavors. The concentrations in fillet of rainbow trout reached 3.6 ng·g-1 (MIB) and 5.6 ng∙g-1 (GSM) with lipid content of 22.5%, while for European whitefish up to 3.2 ng·g-1 (MIB) and 3.9 ng·g-1 (GSM) were found with 14.8% in lipid content. Concentrations up to 58 ng·L-1 (MIB) and 49 ng·L-1 (GSM) were found in the circulating water. Based on the results, the accumulation of MIB proceeds at similar pace for both species. In the case of GSM, the accumulation started similarly for both species but proceeded more quickly for rainbow trout after 140 days of the experiment, with a statistically significant difference (p < 0.05).202

Domestic Varieties

Tiedotteessa sama artikkeli suomeksi ja englanniksivokKirjasto Aj-

Pohjois-Suomen nurmituhotutkimuksen koetuloksia vuosina 1976-1979

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Kotimaiset lajikkeet

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Mathematical modeling of dissolved oxygen in fish ponds

A mathematical model was developed to predict the effects of wind speed, light, pH, Temperature, dissolved carbon dioxide and chemical oxygen demand (COD) on Dissolved Oxygen (DO) in fish ponds. The effects of organic feeds, aeration and fish activity were added to the model developed by Kayombo et al. for Waste Stabilization Ponds (Ecological Modelling 127(2000): 21 - 31) to reflect the situation in fish ponds. Model calibration and validation was done by use of average DO, pH, temperature, COD, CO2 and algae biomass data measured from RETCO fish ponds in Dar es Salaam; and light intensity data were adopted from Kayombo et al. (2000). Model results showed a linear relationship between simulated DO and measured DO in fish pond (r2 = 0. 87) for model calibration and (r2 = 0.88) for model validation. Simulation results also showed a general decrease of DO with time in 13 days by 28 and 38% for first and second batch, respectively. Thus, the model developed in this study could be used to predict the DO dynamics in fish ponds. Based on the model results, successful cultivation of healthy fish may require that retention time for water in the fish pond be 10 days.Key words: Calibration, light, pH, substrate, temperature, validation

Occurrence and Fate of Antibiotics as Trace Contaminants in Wastewater Collection and Disposal Systems - Case Study: University of Dar es Salaam Wastewater Stabilization Ponds, in Tanzania

Antibacterial agents (Antibiotics) are emerging micro-contaminants in institutional and municipal wastewater and the aquatic environment. These substances enter wastewater effluents via urine and faeces and by improper disposal of domestic and or medical waste. An environmental analytical study was conducted at the University of Dar es Salaam (UDSM) Waste Stabilization Ponds (WSP). These ponds  receives and treats influents from students’ halls of residence and staff quarters (domestic effluents) as well as hospital effluent sources. The study focused on seven (7) antibiotics commonly used in human therapy, which include Ciprofloxacin, Flucloxacillin, Erythromycin, Ampicillin, Penicillin-V, Amoxycillin and Cloxacillin. In hospital wastewater, the detected antibiotics ranged from 0.98 - 7.10 µg/l, while in student’s halls of residence, the range was 0.2- 1.47μg/l. In WSP influent and effluent concentrations ranged from 8.89 to 63.75µg/l and 1.51 to 28.01µg/l, respectively. The concentration in the sewage sludge was from 72.12 to 370µg/l. Results of this study indicated that significant amount of antibiotics remain in the treatment plants during wastewater treatment process, through sorption to sewage sludge. This suggests that wastewater treatment options currently applicable in Tanzania including different sanitation options should now be designed taking into account the presence of trace concentrations of antibiotics for the purpose of sanitation and environmental protection at large. Keywords: Antibacterial Agents and Wastewater Stabilization Ponds

Kalsiumnitraatin käyttömäärän vaikutus jääsalaatin satoon ja laatuun

Luken kirjat, raportit, oppaat ja esitteet. Loppuraportti 30.10.2015201

Molybdeeni- ja kuparilannoiteruiskutusten vaikutus tuorerehunurmilla

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Nurmien talvituhosienten torjuntakokeen tuloksia paikalliskokeissa

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