187 research outputs found
Levels of organochlorine pesticides in five species of fish from Lake Ziway, Ethiopia
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Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird and fish species from Lake Hawassa, Ethiopia
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Organochlorine pesticides and polychlorinated biphenyls in carnivorous waterbird species from Lake Ziway, Ethiopia
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Pesticide residue levels in surface water, using a passive sampler and in the sediment along the littoral zone of Lake Ziway at selected sites
Abstract DiaionÂŽ HP-20 resin passive samplers deployed in water and sediment samples collected from Lake Ziway were analyzed for 30 organochlorine, organophosphorus, carboxamide, and pyrethroid pesticide residues. The samples were collected from purposely selected sampling stations in five sites on Lake Ziway. Levels of selected pesticides were determined by GCâMS/MS in all samples. p,pâ˛DDE and boscalid residues were the only detected pesticides in sediment samples. Similarly, only metalaxyl and boscalid residues were recovered from HP-20 resins. The concentration of p,pâ˛DDE and boscalid in sediment ranged from 0.66â7.23 and 0.1â15.26 ng gâ1 dry weight respectively. The presence of p,pâ˛DDE but no other metabolites of DDT in all sediment samples indicated that DDT residues in Ziway Lake were aged and probably originated from the weathered agricultural soils of the surrounding region. The highest level of boscalid was recorded at Site 2 (near the floriculture enterprises) both in sediment and in HP-20 resins with a mean concentration of 11.8 ng gâ1 dw and 39.6 ng gâ 1 disk respectively. However, the concertation of metalaxyl was the highest in the HP-20 resins deployed at Site1 and Site 4 (near the intensive small-scale vegetable farm) with a mean concentration of 54.7 ng gâ1 disk and 54.3 ng gâ 1 disk respectively. Generally, most sampling sites of p,pâ˛DDE were found to have a moderate ecological risk based on levels specified in the sediment quality standards. Moreover, the relatively high boscalid and metalaxyl levels in HP-20 deployed in Lake Ziway would be the result of recent intensive pesticide use by floriculture enterprises and small-scale vegetable farmers in the region. A spatial variation on the accumulation of detected pesticides among the sampling sites depends on the anthropogenic activities, around the lake from the point and non-point sources. Although most of the analyzed pesticides were below the detectable limit, further studies and continued monitoring of currently used pesticide residues in the Lake are highly recommended.Pesticide residue levels in surface water, using a passive sampler and in the sediment along the littoral zone of Lake Ziway at selected sitespublishedVersio
Effect of tillage frequency, seed rate, and glyphosate application on teff and weeds in Tigray, Ethiopia
Field experiments were conducted in 2015 and 2016 to study the effect of tillage frequency, seed rate, and glyphosate on teff and weeds. The experiments were arranged in a split plot design with three replications consisting of tillage frequency (conventional, minimum, and zero tillage) as the main plot and the combination of seed rate (5, 15, and 25 kg haâ1) and glyphosate (with and without) as subplots. Results showed that zero tillage reduced teff biomass yield by 15% compared to minimum tillage and by 26% compared to conventional tillage. Zero tillage and minimum tillage also diminished grain yield by 21% and 13%, respectively, compared to conventional tillage. Lowering the seed rate to 5 kg haâ1 reduced biomass yield by 22% and 26% compared to 15 and 25 kg haâ1, respectively. It also reduced the grain yield by around 21% compared to 15 and 25 kg haâ1 seed rates. Conventional tillage significantly diminished weed density, dry weight, and cover by 19%, 29%, and 33%, respectively, compared to zero tillage. The highest seed rate significantly reduced total weed density, dry weight, and cover by 18%, 19%, and 15%, respectively, compared to the lowest seed rate. Glyphosate did not affect weed density but reduced weed dry weight by 14% and cover by 15%. Generally, sowing teff using minimum tillage combined with glyphosate application and seed rate of 15 kg haâ1 enhanced its productivity and minimized weed effects.publishedVersio
Kjelle avrenningsforsøk. Ă rsrapport 2016â2017 for jordarbeidingsforsøk pĂĽ lav erosjonsrisiko
Redusert og endret jordarbeiding har vÌrt et av de viktigste tiltakene mot erosjon og tap av nÌringsstoffer fra jordbruksarealer siden begynnelsen pü 1990-tallet. Redusert jordarbeiding betyr bare harving i stedet for pløying, mens endret jordarbeiding betyr pløying om vüren i stedet for høsten. Avrenningsforsøk som startet pü 1980-tallet viser stor effekten av redusert og endret jordarbeiding pü erosjon og nÌringsstofftap pü forholdsvis bratte jordbruksarealer. Det eksisterer derimot kun fü undersøkelser av jordarbeidingseffekter pü arealer med liten helling, pü tross av at slike arealer utgjør størsteparten av jordbruksarealene der det dyrkes korn.....publishedVersio
Surveillance of antimicrobial resistance in the environment - Scientific Opinion of the Panel on Microbial Ecology, Norwegian Scientific Committee for Food and Environment
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