• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 445
  • 324
  • 36
  • 31
  • 25
  • 16
  • 16
  • 9
  • 7
  • 7
  • 6
  • 4
  • 3
  • 3
  • 2
  • Tagged with
  • 1109
  • 327
  • 158
  • 138
  • 116
  • 99
  • 92
  • 83
  • 82
  • 76
  • 76
  • 73
  • 71
  • 60
  • 59
  • 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.
11

Performance comparison of stormwater biofiltration designs

Limouzin, Maëlle 21 December 2010 (has links)
A biofiltration system is a stormwater Best Management Practice (BMP) that uses a biologically active filtration bed to remove contaminants. This type of BMP is preferred because it provides the opportunity for pollutant uptake (particularly nutrients) by vegetation in an aesthetically pleasing design. The goals of this research, proposed by the City of Austin, Texas, are to assess the role of plants in nutrient removal and to compare the pollutant removal effectiveness of biofiltration systems containing different media, plant species and designs. A laboratory column study was conducted with nineteen experiments using synthetic stormwater and one experiment using real stormwater. The results of this study show a significant improvement in nutrient removal with the presence of plants and a submerged zone with a carbon source in the filter. The columns without plants were found to export up to twice the nitrate/nitrite input, whereas the columns with plants showed significant removal of all nutrients (Nitrate 30-50%, Total Kjeldhal Nitrogen 65-85%, Total Phosphorus 80-90%). The difference between the two biofiltration media was not significant. Metals (Copper, Lead, Zinc) removal by all columns was very high (>95%) compared to similar field studies. Total Suspended Solids removal remained high through the whole set of experiments for all the columns (85- 95%). / text
12

Assessing nutrient and pharmaceutical removal efficiency from wastewater using shallow wetland treatment mesocosms

Cardinal, Pascal 13 March 2013 (has links)
Wastewaters from rural sewage lagoons in Manitoba contain pharmaceuticals that are potentially harmful to non-target organisms and reduce overall water quality when released. An option for reducing exposure to wastewater contaminants and potential toxicity is surface flow treatment wetlands. However, little is known of the fate of pharmaceuticals in these types of systems. The fate and effects of six pharmaceuticals (carbamazepine, clofibric acid, fluoxetine, naproxen, sulfamethoxazole, sulfapyridine) were assessed in mesocosms simulating treatment wetlands in two separate 28-day experiments in the summer and fall of 2011, respectively: with and without significant aquatic plant communities, and with additional nutrients and harvesting of biomass. The removal of pharmaceuticals had half-lives that ranged from 0.23 to 9.4 days and 1.4 to 18 days during the summer and fall, respectively, and were predicted to occur primarily through photolysis and sorption. No overt toxicity from pharmaceuticals was observed for the common wetland macrophytes Myriophyllum sibiricum and Typha spp., but there was partitioning and bioaccumulation into macrophyte biomass. Treatment wetlands appeared to reduce pharmaceuticals and nutrients adequately, and may be a cost-effective means of treating rural wastewater.
13

Sediment-associated nutrients and their contribution to the nutrient loads of Devon catchments

Thornton, R. C. January 1985 (has links)
No description available.
14

Long-chain fatty acid transport by the human placenta : the role of fatty acid-binding proteins

Campbell, Fiona M. January 1997 (has links)
The placenta is thought to play a vital role in the transfer of essential fatty (EFA) and their long-chain polyunsaturated derivatives (LCPUFA) from mother to the fetus. There is a preferential accumulation of these fatty acids from maternal to fetal tissues. However, little was known about the manner in which these nutrients preferentially traversed the placenta. This study investigated part of this placental transport mechanism. The results from these investigations demonstrated that the preferential transport of LCPUFA to the fetal circulation may at least be partially mediated by a preferential uptake system in the placenta involving a 40 kDa, placental membrane fatty acid binding protein (p-FABP<sub>pm</sub>). This protein was found exclusively in the maternal facing microvillous membranes. It was characterised as different from previously identified ubiquitous FABP<sub>pm</sub> by virtue of having a different pl value, different amino acid composition, no aspartate aminotransferase activity and a higher binding affinity for LCPUFA over non-essential fatty acids. The human choriocarcinoma cell line (BeWo) expressed a protein immunoreactive to anti-p-FABP<sub>pm </sub>anti-serum. This anti-serum inhibited the binding of LCPUFA to placental membranes and the uptake of LCPUFA by BeWo cells, to a greater degree than it inhibited the uptake and binding of non essential fatty acids. In addition to p-FABP<sub>pm </sub>the existence of multiple types of both cytosolic (L-FABP and H-FABP) and membrane (FAT and FATP) fatty acid-binding proteins was demonstrated in placental cells. These proteins could play important roles in both the uptake of fatty acids by the placenta and in controlling the fate of fatty acids inside placental cells.
15

Nutritional studies in the African catfish Clarias gariepinus (Burchell, 1822)

Pantazis, Panagiotis Aristeidis January 1999 (has links)
No description available.
16

Assessing nutrient and pharmaceutical removal efficiency from wastewater using shallow wetland treatment mesocosms

Cardinal, Pascal 13 March 2013 (has links)
Wastewaters from rural sewage lagoons in Manitoba contain pharmaceuticals that are potentially harmful to non-target organisms and reduce overall water quality when released. An option for reducing exposure to wastewater contaminants and potential toxicity is surface flow treatment wetlands. However, little is known of the fate of pharmaceuticals in these types of systems. The fate and effects of six pharmaceuticals (carbamazepine, clofibric acid, fluoxetine, naproxen, sulfamethoxazole, sulfapyridine) were assessed in mesocosms simulating treatment wetlands in two separate 28-day experiments in the summer and fall of 2011, respectively: with and without significant aquatic plant communities, and with additional nutrients and harvesting of biomass. The removal of pharmaceuticals had half-lives that ranged from 0.23 to 9.4 days and 1.4 to 18 days during the summer and fall, respectively, and were predicted to occur primarily through photolysis and sorption. No overt toxicity from pharmaceuticals was observed for the common wetland macrophytes Myriophyllum sibiricum and Typha spp., but there was partitioning and bioaccumulation into macrophyte biomass. Treatment wetlands appeared to reduce pharmaceuticals and nutrients adequately, and may be a cost-effective means of treating rural wastewater.
17

Biofiltration enhancement for the treatment of highway stormwater runoff

Caruso, Nicole Theresa 12 January 2015 (has links)
Highway stormwater runoff contains a number of contaminants including nutrients and heavy metals that can be detrimental to the health of lakes, rivers, and streams. Biofiltration is a common stormwater treatment mechanism that can reduce nutrients and heavy metals through physical, chemical, and biological processes. Vegetation type has been shown to impact the removal of nutrients from stormwater runoff (Barrett et al. 2013; Read et al. 2008). The inclusion of a permanent saturated layer underneath the surface of a biofilter has been investigated to enhance denitrification and thus nitrogen removal (Kim et al. 2003; Zinger et al. 2007). Six Georgia native grasses as well as one turf grass have been tested in a column study along with a permanent saturated zone for biofiltration enhancement. Synthetic stormwater was used in this study. Two months of dosages with an average synthetic stormwater were monitored followed by one event with a heavy metal spiked synthetic stormwater, one event with a nutrient spiked synthetic stormwater, and one event with an average synthetic stormwater after two weeks of drought conditions. Biomass fly ash was also added to columns to determine potential benefits to biofiltration applications. Results indicated that Big Bluestem, Indiangrass, and Switchgrass when paired with a permanent saturated zone remove the highest percentage of total nitrogen across all experiments (4%, 13%, and 18% respectively). These species contained think and dense root systems that spanned the entirety of the biofilter column. Removal of nitrate was enhanced with a saturated zone while ammonium removal decreased. Nitrogen leaching from the columns may be reduced by utilizing soil of low organic content. Phosphorus, copper, lead, and zinc removal was not correlated with plant species; however, a permanent saturated zone increased removal of phosphorus, copper, and zinc (removal of lead was >97% in all cases making differences in removal insignificant). These results support the impact of specific vegetation types on the removal extent of total nitrogen. Saturation provided benefits of total nitrogen, phosphorus, copper, and zinc removal in terms of removal extents as well as consistency of treatment across all experiments. Field experimentation is encouraged to determine long term effects at a large scale.
18

Effluent from the ensilage of grass as a source of nutrients for the pig

Patterson, D. C. January 1980 (has links)
No description available.
19

Modeling metal uptake by barley plants (Hordeum vulgare) in nutrient solution

Flores-Meza, Diego M. January 2008 (has links)
Thesis (M.A.S.)--University of Delaware, 2008. / Principal faculty advisor: Herbert E. Allen, Dept. of Civil & Environmental Engineering. Includes bibliographical references.
20

Sodium as a plant nutrient

Geraldson, C. M. January 1950 (has links)
Thesis (Ph. D.)--University of Wisconsin--Madison, 1950. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 53-56).

Page generated in 0.0446 seconds