<p> The forms of phosphorus in sediments of acid and non-acid shield lakes were determined in order to assess the effects of lake acidification on the mobility of sediment phosphorus. Sediment phosphorus is conveniently classified into three categories: non-apatite inorganic phosphorus (NAI-P), apatite-P and organic P. The distribution of P between different categories was found to be dependent on the lithology of the lake basin, the pH in the water column, and the redox conditions.</p> <p> More than 90% of inorganic P in shield lake sediments was in the NAI-P category, associated presumably with hydrated Fe and Al oxides. Organic P accounted for more than 40% of total P in sediments of acid lakes, which is proportionally higher than that found in sediments of neutral lakes. Bioavailable P, a measure of the fraction of sediment inorganic P readily available for biological utilization, amounted to ~70% of NAI-P, similar to that found in hard water lakes.</p> <p> A series of experiments was designed to investigate the immobilization of P from solution. The uptake of P by solid phase was explained by an adsorption mechanism. The quantitative estimates of phosphate sorption parameters for sediments of acid and non-acid lakes show that mineralogical and chemical characteristics of sediments are more important than the pH of water in determining their efficiency of P removal. Therefore, acidification of lakes does not significantly influence the uptake of P by sediments.</p> / Thesis / Master of Science (MSc)

Various porous media were tested with biosurfactant solutions (rhamnolipid or Emulsan) at concentrations ranging from 0 ppm to 1000 ppm. The biosurfactant solutions in the presence of porous media often showed substantial gas hydrate catalyzation, localization on selected surfaces, and/or specific hydrate form (massive, stratified, dispersed.) At 1000-ppm concentrations of rhamnolipid, all porous media surfaces exhibited the same hydrate formation rate increase of 187% over the control. The curves generated for rhamnolipid or Emulsan concentration versus peak hydrate formation rate resembled certain classical adsorption curves. Bentonite and aragonite showed hydrate catalyzation properties with or without biosurfactants. The preference for hydrate formation on porous media surfaces (no surfactant) was: Bentonite/nontronite > aragonite/stainless steel > Ottawa sand/kaolinite. Porous media/biosurfactant concentration combinations play marked roles in the types of gas hydrates formed: massive, dendritic, or needle-like. The research helps to explain the vast occurrence of gas hydrates in ocean sediments.

Groundwater conditions beneath 11 hectares property owned by HydroOne near the southeastern edge of the Oak Ridges Moraine were assessed for contamination susceptibility using groundwater and geological information from HydroOne monitoring on-site and within one kilometre. Geological information was obtained from preexisting well records and a deep cored hole through dense glacial deposits (Newmarket Till) and through two deep regional sand aquifers (Thorncliffe and Scarborough Aquifers) into shale at 130 mbgs. The multiple data types included water levels, Tritium-Helium groundwater dating, oxygen-18 and deuterium, and major and minor ions. The water table is close to surface (<3m) and wells above 22 m depth in the highly active shallow zone show chemicals and Coliform Bacteria from human activities including roads, septics and agriculture. Shallow groundwater flows downward towards the Thorncliffe aquifer; the bottom of this most active zone is unknown due to insufficient data from deeper wells. Two private wells (100 mbgs) thought to be in the Thorncliffe aquifer contain constituents indicative of human influence. Seven of eight homeowner wells show tritium from nuclear power stations, one at detection limit. Three hypotheses are proposed to explain the susceptibility of wells in the Thorncliffe Aquifer to contamination: 1) the Newmarket aquitard is contains preferential pathways due to fractures connected to sand layers allowing deep penetration of contamination, 2) recharge can occur directly into the Thorncliffe aquifer in areas where Newmarket Till is non-existent, and 3) wells have faulty construction allowing short-circuiting to depth of contaminated shallow water down and along well casings. Based on the current data preferential pathways through the Newmarket is the most plausible hypothesis. However, additional work to define groundwater flow paths both on and off-site as well as additional geochemical and isotopic analyses from existing and new deep wells is needed to better determine risk to residential wells. / Thesis / Master of Science (MSc) / A groundwater study was conducted in an eight square kilometre area at the southeast edge of the Oak Ridges Moraine near Oshawa, ON. It included: geology from a 130m hole through overburden (including Newmarket Till) to bedrock, groundwater age determinations and water chemistry obtained by Hydro One from 16 monitoring wells on HydroOne property (11 hectares) and 25 nearby homeowner wells, most less than 22m deep. Wells above 22m show salt and other constituents from roads, septics or agriculture and show young groundwater age. Two deep wells (100m) in the Thorncliffe Aquifer beneath the Newmarket Till also show these chemicals; one of them sampled for tritium-helium showed young age, as do some intermediate -depth wells. The pathways for young water migrating so deep are undetermined.

<p> This work focuses on the advanced physical analysis of stormwater sediments using laser diffraction particle size analyzer and scanning electron microscope and chemical characterization using neutron activation analysis. Since previous studies of sediments from stormwater ponds in the Greater Toronto Area indicated a marginal-to-significant level of pollution by most of the regulated heavy metals, the characteristics of the storm water sediment samples obtained in this study were compared to the sediment quality guidelines of the Ontario Ministry of the Environment. The images from optical microscope showed that the particles in the dried sediment were irregular, and the sizes of each particle vary greatly. Using scanning electron microscope, it was shown that two different structures of particles were present in the storm water sediment. It was also observed that the main compositions (above 1000ppm) of the dried sediment included, in descending order of concentration, Ca >AI> Fe> K > Mg > Na >Ti > Mn. The trace compositions (below 1000ppm) included, also in descending order of concentration, Cl > Zn > Ba > Sr > Cr > V > La > Nd > As > Br > Co > Sc > Th > Sb > Sm > Eu. The concentrations of regulated elements such as Cr, Fe Zn, As and Mn were above the lowest effect level, suggesting that treatment of stormwater sediment may be necessary. A preliminary stormwater sediment treatment experiment using thermal plasma technology was therefore conducted. After the thermal plasma treatment, the percentage of total organic carbon decreased and eight gas compounds including CO, COz, NO, NOz, NOx, SOz, H2S and CxHy emitted during the process. Enrichments of Mg, Cl and Na were observed in the treated sludge while the concentrations of K and Ca decreased. The potential of thermal plasma technology for the treatment of contaminated stormwater sediment was demonstrated. </p> / Thesis / Master of Applied Science (MASc)

No description available.

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Science, 1982. / Microfiche copy available in Archives and Science / Vita. / Includes bibliographies. / by Daniel James Repeta. / Ph.D.

The purpose of this investigation was to study the sediment in the upper reaches of Claytor Lake. The lake is a manmade impoundment on the New River near Radford, Virginia. Eleven core samples, varying in length from 66 cm. to 141 cm, were taken from the lake. The concentration of various water quality parameters were determined for segments of the entire length of each core. An in vitro assay was performed in the laboratory to determine the productivity potential of the nutrients contained in the sediments. Results of this investigation showed that sufficient nutrients are contained in the sediments to sustain algae growth. These nutrients, when released under controlled conditions, were found to sustain abundant growth of three algal genera: <u>S. capricornutum, A. flosaguae, and M. aeruginosa</u>. Several nutrients were found to exhibit trends with sediment depth and also to correlate with each other. Particle size distributions were also determined on several of the sediment samples. Several nutrients were found to correlate with particle size of the sediment. / Master of Science

We investigated variations in resource availability (nitrate and labile organic carbon, LOC) as determinants of denitrification in sediments of streams in the southern Appalachian Mountains, USA. Stream water and sediments were sampled seasonally in two streams of contrasting nitrate availability, Noland Creek (high NO₃-N) and Walker Branch (low NO3-N). Eight additional streams with varying nitrate levels were sampled once during summer. Stream sediments were incubated at ambient stream temperatures, and nitrous oxide accumulation was quantified following acetylene inhibition of nitrous oxide reduction. Denitrification potential was greater in Noland Creek than Walker Branch and was generally greater in sediments from the higher-nitrate streams. In autumn and spring, nitrate and LOC amendments indicated that denitrification potential in Walker Branch sediments was nitrate limited, with temperature having no effect on rates. Denitrification potential in Noland Creek sediments was not limited by nitrate, but temperature had a significant effect. When Noland Creek seasonal data were corrected to a common temperature, no seasonal differences in denitrification potential were detected. Nitrate-N in the 10 surveyed streams ranged from 10 to 549 mg/L, with the highest NO₃-N levels and denitrification rates generally occurring in the higher elevation streams in the GSMNP. We found that nitrate availability, more than LOC availability, controls potential denitrification in these streams. / Master of Science

The mass of carbon trapped in methane hydrates exceeds that in conventional fossil fuel reservoirs. While methane in coarse-grained hydrate-bearing sediments is technically recoverable, most methane hydrates are found in fine-grained marine sediments where gas recovery is inherently impeded by very low gas permeability. Using experimental methods and analyses, this thesis advances the understanding of fine-grained sediments in view of gas production from methane hydrates. The research scope includes: a new approach for the classification of fines in terms of electrical sensitivity, the estimation of the sediment volume contraction during hydrate dissociation, a pore-scale study of gas migration in sediments and the self-regulation effect of surfactants, the formation of preferential gas migration pathways at interfaces during gas production, pressure core technology for the characterization of hydrate bearing sediments without causing hydrate dissociation, and the deployment of a bio-sub-sampling chamber in Japan.

published_or_final_version / Applied Geosciences / Master / Master of Science