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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Bioaccumulation of Heavy Metals from Soils to Plants in Watersheds Contaminated by Acid Mine Drainage in SE Arizona

Eddleman, Katherine January 2012 (has links)
Current concerns about inorganic contaminants in food products have raised consumer awareness of anthropogenic sources of heavy metal contamination in ecosystems and their potential threat to human health. Mining and exploration of mineralized zones is a major source of such contamination. Mining throughout the Patagonia Mountains, Arizona, has left a legacy of surface water contamination by acid mine drainage (AMD). This study assessed the impacts of AMD on soils and plants throughout the study area. Concentrations, transport, and loading of heavy metals (Ag, As, Cd, Co, Cr, Cu, Fe, Mn, Mo, Ni, Pb, Sb, and Zn) in soils and plants was quantified using total concentrations, suggested toxic levels, and plant and soil pollution indices. Pollution indices were modified to include antimony and molybdenum. Pollution indices greater than 100 were found in areas disturbed by mining, remediation sites and beyond. Cattle grazing on grasses contaminated by metals were documented.
2

Goatsrue (Galega officinalis) Seed Biology, Control, and Toxicity

Oldham, Michelle 01 May 2009 (has links)
Goatsrue is an introduced perennial plant that has proven to have great invasive potential, leading to its classification as a noxious weed in many states and at the federal level. This research focused on seed biology, herbicide control, and toxic dynamics of goatsrue. Physical dormancy of mature goatsrue seed was tested through scarification using sulfuric acid with exposures of up to 60 minutes resulting in 100% germination. Comparison of dormancy for 26-year-old and 6-month-old goatsrue seed indicated aged seeds had reduced dormancy levels compared to newly harvested seeds, but had similar viability. Goatsrue seedling emergence was inversely related to burial depth; emergence was greatest at 0.5 cm soil depth (93%), and no emergence occurred from 12 and 14 cm. Goatsrue seed density ranged from 14,832 seeds m-2 to 74,609 seeds m-2 in the soil seed bank of five goatsrue-infested areas. Viability and dormancy of seeds recovered from the soil seed bank survey ranged from 91 to 100% and 80 to 93%, respectively. Goatsrue was most sensitive to the ALS inhibitor herbicides chlorsulfuron and imazapyr in greenhouse trials. Field studies showed that plots treated with dicamba, chlorsulfuron, metsulfuron, aminopyralid, triclopyr, and picloram provided at least 93% control of goatsrue 12 months after treatment at two field sites and increased perennial grass cover at one site. All treatments at one site decreased seedling goatsrue cover 11 months after treatment. The concentration and pools (dry weight x concentration) of the toxin galegine, found in goatsrue, vary over plant tissues and phenological growth stages. Galegine concentration is significantly different among plant tissues; reproductive tissues have the highest levels of galegine (7 mg/g), followed by leaf (4 mg/g), and then stem (1 mg/g) tissues. Galegine pools or the total amount of galegine per stalk was lowest at the vegetative growth stage and increased until reaching a maximum at the immature pod stage, but decreased nearly in half at the mature seed stage. Average galegine concentration also peaked at the immature pod stage and decreased by half at the mature seed stage. Thus, goatsrue is most toxic in its phenological development at the immature pod stage.
3

Efeitos da exposição gestacional a fração aquosa da Ipomoea carnea no desenvolvimento físico e neurocomportamental da prole de ratos. / Ipomoea carnea aqueous fraction intake effects during gestation on physical and neurobehavior development of rats offspring.

Schwarz, Aline 16 May 2002 (has links)
A lpomoea carnea, planta amplamente distribuída no Brasil, quando ingerida pelos animais provoca efeitos neurotóxicos. Não há relatos a respeito de seus efeitos sobre a prole de animais expostos durante a gestação. Assim, no presente trabalho estudou-se os efeitos da exposição à planta durante a gestação de ratas. Os animais receberam, por gavage, a partir do 5° dia de gestação, diferentes concentrações da fração aquosa da planta (0,7; 3,0 ou 15,0 mg/kg/dia). Os filhotes foram analisados quanto ao desenvolvimento físico e reflexológico; quando adultos avaliou-se aspectos comportamentais e níveis de neurotransmissores cerebrais. Os resultados mostraram alta mortalidade dos filhotes expostos à maior dose, que nasceram com menor comprimento. Os sobreviventes apresentaram retardo na abertura dos ouvidos e na geotaxia negativa. Não foram observadas alterações nos vários comportamentos avaliados e nos níveis de neurotransmissores cerebrais destes animais quando adultos. Estes resultados mostram que a exposição de ratos durante a gestação à Ipomoea carnea produz alguns efeitos tóxicos nos recém-nascidos, porém não afeta o desenvolvimento e os parâmetros comportamentais avaliados nos animais já adultos. / Ipomoea carnea, plant Iargely distributed in Brazil, when ingested by animais causes neurotoxic effects. No relates about it\'s effects upon offspring of animais exposed during gestation period appears in the literature. So, in this work, the effects of the exposure of rats, during the gestation period, to the plant were studied. The rats received, by gavage, since the fifth day of gestation, diferent concentrations of the aqueous fraction of the plant (0.7, 3.0 or 15.0 mg/kg/day). The pups were evaluated by physical and reflexological development; when adults, behavior and cerebral neurotransmitters leveis were analised. The results demonstrated that the pups exposed to the higher dose presented high mortality and smaller size at birth. The survivors showed delay in both ears opening and negative geotaxis. No alterations were observed in ali the behaviors evaluated and in the leveis of cerebral neurotransmitters of the animais when adults. This results shows that exposition of rats during gestation to Ipomoea carnea produce some toxic effects in their offspring that don\'t changes the development and the behaviors parameters evaluated in the rats in adult age.
4

Efeitos da exposição gestacional a fração aquosa da Ipomoea carnea no desenvolvimento físico e neurocomportamental da prole de ratos. / Ipomoea carnea aqueous fraction intake effects during gestation on physical and neurobehavior development of rats offspring.

Aline Schwarz 16 May 2002 (has links)
A lpomoea carnea, planta amplamente distribuída no Brasil, quando ingerida pelos animais provoca efeitos neurotóxicos. Não há relatos a respeito de seus efeitos sobre a prole de animais expostos durante a gestação. Assim, no presente trabalho estudou-se os efeitos da exposição à planta durante a gestação de ratas. Os animais receberam, por gavage, a partir do 5° dia de gestação, diferentes concentrações da fração aquosa da planta (0,7; 3,0 ou 15,0 mg/kg/dia). Os filhotes foram analisados quanto ao desenvolvimento físico e reflexológico; quando adultos avaliou-se aspectos comportamentais e níveis de neurotransmissores cerebrais. Os resultados mostraram alta mortalidade dos filhotes expostos à maior dose, que nasceram com menor comprimento. Os sobreviventes apresentaram retardo na abertura dos ouvidos e na geotaxia negativa. Não foram observadas alterações nos vários comportamentos avaliados e nos níveis de neurotransmissores cerebrais destes animais quando adultos. Estes resultados mostram que a exposição de ratos durante a gestação à Ipomoea carnea produz alguns efeitos tóxicos nos recém-nascidos, porém não afeta o desenvolvimento e os parâmetros comportamentais avaliados nos animais já adultos. / Ipomoea carnea, plant Iargely distributed in Brazil, when ingested by animais causes neurotoxic effects. No relates about it\'s effects upon offspring of animais exposed during gestation period appears in the literature. So, in this work, the effects of the exposure of rats, during the gestation period, to the plant were studied. The rats received, by gavage, since the fifth day of gestation, diferent concentrations of the aqueous fraction of the plant (0.7, 3.0 or 15.0 mg/kg/day). The pups were evaluated by physical and reflexological development; when adults, behavior and cerebral neurotransmitters leveis were analised. The results demonstrated that the pups exposed to the higher dose presented high mortality and smaller size at birth. The survivors showed delay in both ears opening and negative geotaxis. No alterations were observed in ali the behaviors evaluated and in the leveis of cerebral neurotransmitters of the animais when adults. This results shows that exposition of rats during gestation to Ipomoea carnea produce some toxic effects in their offspring that don\'t changes the development and the behaviors parameters evaluated in the rats in adult age.

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