• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 780
  • 271
  • 229
  • 97
  • 36
  • 30
  • 30
  • 30
  • 30
  • 30
  • 30
  • 24
  • 17
  • 16
  • 14
  • Tagged with
  • 1918
  • 807
  • 350
  • 287
  • 172
  • 148
  • 147
  • 142
  • 136
  • 132
  • 128
  • 112
  • 100
  • 96
  • 89
  • 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.
171

Dynamics of Dissolved and Particulate Trace Metals in a Snowmelt-Dominated Stream, Provo River, Utah, USA

Caskey, Kendra Louise 15 August 2024 (has links) (PDF)
Trace element concentrations vary substantially during snowmelt runoff, with changes in the dissolved versus particulate fractions potentially impacting their movement at the catchment scale. To investigate trace element behavior in a snowmelt dominated stream, we measured concentrations in different size fractions in the Provo River (northern Utah, USA). We sampled the river at three locations during water years 2016-2018 and 2021-2023 for trace metal and major ion concentrations. During the final year, we collected three fractions (unfiltered, <0.45 µm filtered, and <0.22 µm filtered) for trace metal chemistry and calculated the particulate concentration as the difference between the unfiltered and 0.45 µm fraction. Stream measurements included pH, discharge, turbidity, and fluorescent dissolved organic matter (fDOM). We also sampled water sources (soil water, ephemeral streams, and snowpack) to compare trace metal concentrations across the watershed with the stream. Trace metal (Al, Be, Fe, Pb) and rare earth element (REE +Y) concentrations had the highest particulate and dissolved concentrations during snowmelt runoff. In contrast, major cations were primarily found in the dissolved fraction with lowest concentrations during snowmelt runoff. Major cation and particulate metal concentrations increased from upstream to downstream. The increased trace metal and REE + Y concentrations during snowmelt relative to baseflow may be explained by increased discharge and associated increased turbidity and fDOM. A comparison with water sources suggests that dissolved and particulate trace metals in the stream are sourced from flushed soil water, as trace metal transport through the watershed is facilitated by suspended sediment and dissolved organic matter. For most of the trace metals and REE +Y, concentrations were similar in the <0.45 µm and <0.22 µm fractions. Yet Al tended to have higher concentrations in the <0.45 µm fraction, suggesting a colloidal form of Al between 0.22 µm and 0.45 µm may exist. Differences from upstream to downstream may be related to changes in pH, from ~7 at the upper site to ~8 at the lower sites, which would change sorption capacity, saturation indices, or speciation. Our study demonstrates that trace metal concentrations are variable during snowmelt as the metals interact with suspended particles or dissolved organic matter and are influenced by changing water chemistry, with implications for understanding water quality impairments in snowmelt-dominated streams.
172

Contamination by lead and other trace metals in roadside soil and vegetation in Hong Kong

Tai, Keen-man., 戴健文. January 1982 (has links)
published_or_final_version / Botany / Master / Master of Philosophy
173

Trace metal speciation and bioavailability in urban contaminated soils

Ge, Ying, 1974- January 1999 (has links)
Urban soils are often contaminated with trace metals and the toxicity of the metals depends, in part, on their speciation in soil solutions. The objectives of this project were to estimate the metal speciation in urban soils and to evaluate the predictability of soil metal pools on plant uptake. The chemical speciation of Cd, Cu, Ni, Pb and Zn was estimated by using the Windermere Humic Aqueous Model (WHAM). In soil solutions, Cd, Ni and Zn were present mainly as free ions when the solutions were acidic and their organic complexes were dominant as the pH was over 7.5. The other two metals mostly formed complexes with organic ligands. The activities of Cd2+, Cu2+, Ni2+, Pb2+ and Zn 2+ were affected by soil pH and total soil metal burdens. All five metals were under-saturated with respect to the minerals which could potentially control the metal solubility. / Metal uptake by plants in the contaminated railway yards was generally not correlated with free, dissolved and total soil metal pools. A pot experiment demonstrated better correlations between the metal pools and the metal content in wild chicory. Multiple regression analysis showed that the metals in the leaves and roots of wild chicory could be adequately predicted by the soil total metals and soil properties such as pH and exchangeable Ca.
174

History and the Natchez Trace Parkway

Gidcomb, Barry D. Drake, Frederick D., January 2000 (has links)
Thesis (D.A.)--Illinois State University, 2000. / Title from title page screen, viewed May 4, 2006. Dissertation Committee: Frederick D. Drake (chair), Lawrence W. McBride, M. Paul Holsinger, L. Moody Simms. Includes bibliographical references (leaves 245-254) and abstract. Also available in print.
175

Trace Visualization of Distributed and Centralized Applications / Trace-visualisering av distribuerade och centraliserade applikationer

Zhang, Siwei January 2023 (has links)
The Radio Access Network (RAN) plays a vital role in enabling mobile network connectivity using radio waves. Gaining a comprehensive understanding of RAN applications is crucial, and trace analysis provides valuable insights into their operations. Modern RAN applications can be deployed on different platforms and this can lead to the generation of different trace formats, which complicates the analysis process. Trace analysis and visualization tools, such as Trace Compass, can be used to ease the process, but for each new trace format the user often needs to create new code and visualizations. This is needed also when different trace formats generated by the same application contain similar information. To overcome this limitation, this thesis introduces an innovative approach to generalize the interpretation of traces, enabling to reuse existing analysis and visualization independently of the trace format. Moreover, a Domain Specific Language (DSL) is introduced to simplify the trace analysis procedure. The proposed thesis contributes to a generic approach for analyzing different trace formats, thereby facilitating the analysis of RAN applications deployed across diverse platforms. / Radio Access Network (RAN) spelar en viktig roll när det gäller att möjliggöra anslutning till mobilnät med hjälp av radiovågor. Att få en omfattande förståelse för RAN-applikationer är avgörande, och trace-analys ger värdefulla insikter i deras verksamhet. Moderna RAN-applikationer kan driftsättas på olika plattformar, vilket kan leda till att olika trace-format genereras, vilket komplicerar analysprocessen. Verktyg för trace-analys och visualisering, som Trace Compass, kan användas för att underlätta processen, men för varje nytt trace-format måste användaren ofta skapa ny kod och nya visualiseringar. Detta behövs även när olika traceformat som genereras av samma applikation innehåller liknande information. För att övervinna denna begränsning introducerar denna avhandling en innovativ metod för att generalisera tolkningen av trace-data, vilket gör det möjligt att återanvända befintlig analys och visualisering oberoende av traceformatet. Dessutom introduceras ett domänspecifikt språk (DSL) för att förenkla trace-analysförfarandet. Den föreslagna avhandlingen bidrar till en generisk metod för analys av olika trace-format, vilket underlättar analysen av RANapplikationer somanvänds på olika plattformar.
176

Trace metal speciation and bioavailability in urban contaminated soils

Ge, Ying, 1974- January 1999 (has links)
No description available.
177

ESTABLISHMENT OF THE BACKGROUND CONCENTRATION IN ARABLE SOILS, WOOD COUNTY, OHIO

Kawatsura, Asako January 2010 (has links)
No description available.
178

The effects of orally administered meloxicam and injectable trace mineral supplementation on weight gain, morbidity and mortality in newly-received, high-risk stocker calves and on serum trace mineral status before and after injectable trace mineral application

Hartschuh, Hattie E. January 1900 (has links)
Master of Science / Department of Animal Sciences and Industry / Christopher Reinhardt / Crossbred bull calves at high risk for morbidity (n = 190; BW = 159 ± 68 kg) were received at a commercial stocker operation to evaluate the effects of meloxicam administered at the time of castration on performance and health through d 30 post-arrival. Calves were assigned randomly to receive either a whey-powder placebo (CON), 0.5 mg/kg BW meloxicam (LOW), or 1.0 mg/kg BW meloxicam (HIGH) administered orally. Calves were vaccinated, knife-castrated, and received experimental treatments on d 0. Meloxicam had no effect on ADG (P ≥ 0.63), morbidity (P = 0.66), or mortality (P = 0.62). A second study was conducted using crossbred calves from the southeastern US and Mexico (n = 472; BW = 227 ± 45 kg) to evaluate effects of an injectable trace-mineral solution administered at time of arrival at a commercial stocker operation on animal performance, health, and serum concentrations of Cu, Mn, Se, and Zn on d 0 and d 45. Calves were assigned randomly to receive saline (CON; 1.0 mL/45 kg BW) or injectable trace mineral (ITM; 1.0 mL/45 kg BW) on d 0. Average daily gain from d 0 to d 42, overall ADG from d 0 to d 139, mortality, and morbidity were not different (P ≥ 0.31) between treatments. Calves originating from the Southeastern US had greater (P < 0.01) overall ADG from d 0 to 139. There were no source effects (P ≥ 0.21) on initial serum mineral concentrations for Mn or Zn; however, cattle originating in Mexico had lesser serum Cu (P < 0.01) and cattle originating in the Southeastern US tended to have lesser serum Se (P = 0.06). On d 45, there were no treatment differences (P ≥ 0.20) in serum concentrations of Cu, Mn, or Zn but cattle that received ITM tended (P = 0.09) to have elevated serum Se concentrations compared to those that received CON.
179

Varietal response and effects of different sources of zinc on soybean growth and yield

Bello, Adetunji B January 2011 (has links)
Typescript. / Digitized by Kansas Correctional Industries
180

Development and comparison of spectrographic methods for determination of zinc in plant material: survey of the zinc content of Kansas grown alfalfa

Hawley, Justin Eugene. January 1948 (has links)
Call number: LD2668 .T4 1948 H38 / Master of Science

Page generated in 0.0253 seconds