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Full-Text Articles in Life Sciences

Stream Quality Improvement Through Watershed Wide Establishment Of Multi-Species Riparian Buffer Strips: An Economic Analysis, Christopher Joel Ball Jan 1996

Stream Quality Improvement Through Watershed Wide Establishment Of Multi-Species Riparian Buffer Strips: An Economic Analysis, Christopher Joel Ball

Retrospective Theses and Dissertations

No abstract provided.


Economic Feasibility Of Growing Herbaceous Biomass Energy Crops In Iowa , Young-Woo Park Jan 1996

Economic Feasibility Of Growing Herbaceous Biomass Energy Crops In Iowa , Young-Woo Park

Retrospective Theses and Dissertations

Depletion of natural energy resources and environmental degradation caused by current energy resources (fossil fuels) have rekindled interest in energy availability and developing environmentally benign and renewable alternative energy resources. In addition, the reduced productive capacity of soil and environmental problems in rural areas caused by the loss of topsoil has created interest in ways to conserve soil;These concerns have generated considerable attention on the production of herbaceous energy crops on marginal land as a possible solution to meeting future energy demands, addressing environmental concerns, and reducing soil erosion;This research suggests that herbaceous energy crops, especially switchgrass, can ...


Enhanced Degradation Of Pesticide Wastes In Soil: Implications For Bioremediation Of Agrochemical Dealer Sites , Ellen Louise Kruger Jan 1996

Enhanced Degradation Of Pesticide Wastes In Soil: Implications For Bioremediation Of Agrochemical Dealer Sites , Ellen Louise Kruger

Retrospective Theses and Dissertations

The fate of atrazine and metolachlor, applied as a mixture, in soils taken from pesticide-contaminated sites (Alpha and Bravo) was determined in laboratory studies. Mineralization of metolachlor (less than 1%) in the Bravo sites was minimal after a 30-d. Degradation of metolachlor was greater in the Kochia scoparia rhizosphere soil. The amount of mineralization of atrazine at the Alpha site was as high as 62% of the applied 14C. A mass balance of the 14C applied revealed significant differences (p < 0.05) between the two soil types in soil bound residues, 14CO2, and the extractable organic fraction. The half-life for atrazine was significantly less in the rhizosphere soil (p < 0.05) with a half-life of 50 d compared to 193 d in the nonvegetated soils. A 14C-most-probable-number procedure was also carried out on soils from the pesticide-contaminated sites to determine specific atrazine and metolachlor degraders;To determine the influence of the presence of plants on the degradation of aged herbicide contaminants, vegetated and nonvegetated soil studies were conducted. The percent of applied 14C-atrazine remaining as atrazine in soil which was nonvegetated, or planted with Brassica napus or Kochia scoparia was 9.3, 6.5, and 4.2%, respectively. Combustion of plants revealed that 11% of the applied radioactivity was taken up in Kochia scoparia, while less than 1% was taken up in Brassica napus plants;A screening study was conducted to determine if soils obtained from several pesticide-contaminated sites had enhanced degradative capability to degrade four freshly applied herbicides. Atrazine mineralization was extensive in four of the soils. Minimal mineralization of pendimethalin, alachlor, and metolachlor was seen in this study. Atrazine, metolachlor, and trifluralin were applied in all possible combinations at a rate of 200 [mu]g/g each to soils exhibiting enhanced atrazine degradation in order to determine if higher concentrations and mixtures would inhibit degradation. Only the atrazine was radiolabeled. Rapid mineralization of atrazine occurred in all soil treatments, with 60% to 80% mineralization after 9 weeks;Deethylatrazine degradation was enhanced in soils which had received long-term exposure to atrazine compared with soils that had not received long-term atrazine exposure.


Effects Of Emergent Vegetation On Wetland Microbial Processes , Charles Lee Rose Jan 1996

Effects Of Emergent Vegetation On Wetland Microbial Processes , Charles Lee Rose

Retrospective Theses and Dissertations

Wetland areas with varying amounts of emergent and free-floating vegetation may have very different microbial carbon and energy processing rates and and pathways. In Goose Lake Marsh, a natural prairie pothole wetland in central Iowa, transect measurements, continuous monitoring, and synoptic surveys were used to examine patterns light availability, temperature, dissolved O2 concentrations, dissolved CH4 concentrations, plant densities, litter densities, and CH4 flux due to diffusion and ebuliation within and outside emergent vegetation zones. Water column light availability was less than 2% of ambient light in emergent vegetated areas due to canopy cover, small floating plants (lemnids), and plant litter ...


The Fate Of Methyl Bromide, Ethylene Glycol, And Propylene Glycol In Soil And Surface Water: Influence Of Soil Variables And Vegetation On Degradation And Offsite Movement , Patricia Jane Rice Jan 1996

The Fate Of Methyl Bromide, Ethylene Glycol, And Propylene Glycol In Soil And Surface Water: Influence Of Soil Variables And Vegetation On Degradation And Offsite Movement , Patricia Jane Rice

Retrospective Theses and Dissertations

Within the last few years methyl bromide (MeBr), ethylene glycol (EG), and propylene glycol (PG) have become environmental concerns due to their adverse impact on the environment. The purpose of our research was to study each compound within the framework of where and how they are environmental concerns by (1) investigating the influence of soil environmental variables on the degradation and mobility of MeBr in soil and (2) evaluating the use of vegetation to reduce soil infiltration and remediate soil and surface waters contaminated with aircraft deicing agents (EG, PG). Our research indicates MeBr rapidly volatilized from fumigated soil and ...


Composition And Transport Of Sludge-Derived Organic Carbon In Soil And Aquifer Material , Nizhou Han Jan 1996

Composition And Transport Of Sludge-Derived Organic Carbon In Soil And Aquifer Material , Nizhou Han

Retrospective Theses and Dissertations

Land application of sewage sludge may introduce handful trace metals into soils and cause surface and ground water contamination. The mobilities of the metals are affected by dissolved organic carbon (DOC) in sludge or in soils. The major objective of the present study was to characterize the DOC in a digested sewage sludge and a sludge-amended soil and to examine the influence of DOC subcomponents on Cu mobility in an aquifer material collected near sludge application field;DOC from digested sewage sludge was fractionated according to its molecular weight (MW) and polarity. Investigations were performed on the mobilities and Cu-binding ...


Five-Year Survival And Growth Of Northern Red Oak (Quercus Rubra L) Seedlings In Upland Hardwood Stands In South Central Iowa , Robert Edward Bardon Jan 1996

Five-Year Survival And Growth Of Northern Red Oak (Quercus Rubra L) Seedlings In Upland Hardwood Stands In South Central Iowa , Robert Edward Bardon

Retrospective Theses and Dissertations

A major concern in the management of Quercus rubra is the the difficulty in regenerating stands that have developed dense understories of shade tolerant species. A study was conducted at two locations in south central Iowa to determine the impact over a five year period of using root graded seedlings, understory control, tree shelters, and overstory reduction on establishing underplanted, 1-0, Quercus rubra bare root stock. Relationships between growth or mortality, and photosynthetically active radiation, red to far red light ratio, basal area, average stand diameter, number of trees/hectare, percent stocking, and various combinations of these variables were tested ...


The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel Jan 1996

The Role Of Arbuscular Mycorrhizal Fungi In Prairie Wetlands , Paul Robert Wetzel

Retrospective Theses and Dissertations

Research on arbuscular mycorrhizal fungi (AMF) suggests that their effect on plant growth is a continuum that changes from positive to negative along environmental gradients as conditions for plant growth improve. Prairie wetlands were used to test this mycorrhizal continuum model. First, three saline and three freshwater wetlands were surveyed for AMF, to investigate the hypothesis that AMF colonization would be greater in wetlands with high soil salinity, lower nutrient levels, and during periods of drought. Second, a greenhouse experiment on Carex stricta and Calamagrostis canadensis tested whether AMF improved plant growth and nutrient uptake under five hydrologic regimes. Third ...


A Novel Mechanism For Resistance To Colorado Potato Beetle (Leptinotarsa Decemlineata) In Wild Solanum Species , Evans Olonyi Sikinyi Jan 1996

A Novel Mechanism For Resistance To Colorado Potato Beetle (Leptinotarsa Decemlineata) In Wild Solanum Species , Evans Olonyi Sikinyi

Retrospective Theses and Dissertations

The Colorado potato beetle (Leptinotarsa decemlineata Say) is the most destructive insect pest of the potato (Solanum tuberosum L.) worldwide and has shown remarkable adaptability to insecticides. In wild Solanum species, the best known host-plant resistance mechanisms are a high level of foliar glycoalkaloids and the presence of specialized, glandular trichomes. Through a preliminary field-test screen, three Solanum species, Solanum trifidum, S. raphanifolium, and S. circaeifolium, were identified with low foliar glycoalkaloid levels and no glandular trichomes, but still exhibiting substantial resistance to L. decemlineata. These three species along with two species, S. berthaultii and S. chacoense, representing the two ...


Evaluation Of Factors Affecting Avian Risk From Granular Pesticides , Tamara Rae Stafford Jan 1996

Evaluation Of Factors Affecting Avian Risk From Granular Pesticides , Tamara Rae Stafford

Retrospective Theses and Dissertations

The Environmental Protection Agency evaluates the risk of granular pesticides to birds using an LD50s/ft2-risk index. The index does not include avian response to granular characteristics, pesticide load per granule, or weather conditions, and it assumes that avian risk increases as granule availability increases. Fensulfothion was formulated on granular pesticide carriers to evaluate the effects of carrier type (silica, clay, and corncob), pesticide load per granule (1/2, 1/8, and 1/32 of the LD50), granule color (blue, white, and uncolored), and granule size (large and small) on captive house sparrows (Passer domesticus). In the initial experiments, silica ...


Environmental Ethics Made Explicit Through Situated Narrative: Implications For Agriculture And Environmental Education , Danielle Marie Wirth Jan 1996

Environmental Ethics Made Explicit Through Situated Narrative: Implications For Agriculture And Environmental Education , Danielle Marie Wirth

Retrospective Theses and Dissertations

This dissertation is about the meaning, relevancy, and effectiveness of situated narrative in contemporary Western culture, and particularly about how this mode of message transmission might expand environmentally sustainable behaviors. In-depth interviews with environmental educators and storytellers yielded descriptions of what constitutes ethical behavior and guidelines for how to conduct effective storytelling;Bioregionalism, deep ecology, and ecological feminism were studied to learn salient points and normative behaviors associated with each perspective. Similarities and differences among the three philosophical traditions were explained. Classic and contemporary narratives that promote one or more of these ethics were identified in the literature review;This ...


Bacterial Physiology And Enzymology Of The Membrane-Associated Methane Monooxygenase And Ammonia Oxidation System From Methylococcus Capsulatus Bath, 1992-1996 , James Allan Zahn Jan 1996

Bacterial Physiology And Enzymology Of The Membrane-Associated Methane Monooxygenase And Ammonia Oxidation System From Methylococcus Capsulatus Bath, 1992-1996 , James Allan Zahn

Retrospective Theses and Dissertations

The enzymology and microbial physiology of methane and ammonia oxidation by the membrane-associated methane monooxygenase (pMMO) from the obligate methylotroph, Methylococcus capsulatus Bath were studied. Conditions leading to the stabilization of the pMMO were defined, and an active preparation of the pMMO from M. capsulatus Bath was isolated by ion exchange and hydrophobic interaction chromatography using dodecyl-[beta]-D-maltoside as the detergent. The active preparation consisted of three major polypeptides with molecular masses of 47,000 and 27,000, and 25,000 Da and contained 2.5 iron and 14.5 copper atoms per mole of enzyme. The 27,000 ...


Preliminary Characterization Of The Transmission Of Porcine Reproductive And Respiratory Syndrome Virus , Robert William Wills Jan 1996

Preliminary Characterization Of The Transmission Of Porcine Reproductive And Respiratory Syndrome Virus , Robert William Wills

Retrospective Theses and Dissertations

The objective of this dissertation is to provide a more complete characterization of the transmission of porcine reproductive and respiratory syndrome virus (PRRSV). Three papers are presented within the dissertation. The first paper focuses on modes of transmission between infected and susceptible animals. Portals of exit and duration of shedding of virus from infected animals are investigated in the second paper. The final paper concentrates on the occurrence and duration of infection in swine;In the first study, five trials were conducted to study transmission of virus to pigs placed in different degrees of contact with inoculated pigs. The study ...


Assessment Of Coleomegilla Maculata (Coleoptera: Coccinellidae) Predation Of The Colorado Potato Beetle (Coleoptera: Chrysomelidae) , Joseph Munyaneza Jan 1996

Assessment Of Coleomegilla Maculata (Coleoptera: Coccinellidae) Predation Of The Colorado Potato Beetle (Coleoptera: Chrysomelidae) , Joseph Munyaneza

Retrospective Theses and Dissertations

The functional response, foraging behavior, and developmental and reproductive responses of fourth instars and adults of the predatory lady beetle Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae) were investigated under laboratory, greenhouse, and field conditions. Prey were eggs of Colorado potato beetle, Leptinotarsa decemlineata (Say) (Coleoptera: Chrysomelidae). Coleomegilla maculata fourth instars exhibited a type II functional response to L. decemlineata eggs under laboratory, greenhouse, and field conditions. The maximum attack rate in the field was about half of that observed in the laboratory or greenhouse. The differences in prey density and environmental conditions seem to be major contributing factors in determining the ...


The Persistence, Degradation, And Mobility Of Metolachlor In Soil And The Fate Of Metolachlor And Atrazine In Surface Water, Surface Water/Sediment, And Surface Water/Aquatic Plant Systems , Pamela Joan Rice Jan 1996

The Persistence, Degradation, And Mobility Of Metolachlor In Soil And The Fate Of Metolachlor And Atrazine In Surface Water, Surface Water/Sediment, And Surface Water/Aquatic Plant Systems , Pamela Joan Rice

Retrospective Theses and Dissertations

Metolachlor and atrazine are two of the most widely used herbicides in the Midwest. Detection of pesticides in drinking water resources has increased interest in the environmental fate of these compounds in soil, surface water, and groundwater. The persistence of a compound and its adsorption to soil are the two most important factors related to the off-site movement of pesticides from the soil to groundwater or surface water. The aim of my research was to (1) study the environmental fate of metolachlor in soil and evaluate its potential to become a groundwater contaminant and (2) investigate the persistence of metolachlor ...