archives@tulane.edu / Over the past two centuries, coastal wetlands have become increasingly threatened by accelerated relative sea-level rise and anthropogenic modification. Engineered structures such as sea walls, levees, and drainage systems prevent natural processes of sediment distribution, reducing the resilience of coastal ecosystems. Land subsidence and shoreline erosion combine with global sea-level rise to make low-elevation coastal zones increasingly vulnerable to submergence. This dissertation examines processes of sediment accumulation, compaction, and relative sea-level rise in coastal wetlands and assesses strategies for restoration. I find that organic content strongly controls sediment compaction in wetland sediments. At least 80% of compaction happens quickly, largely within the first 100 years after deposition and in the top 1 m of the subsurface. This rapid shallow compaction is generally not recorded by traditional methods of measuring relative sea-level rise in low-elevation coastal zones (i.e., tide gauges and global navigation satellite systems). As a result, tide gauges generally underestimate rates of relative sea-level rise in low-elevation coastal zones and these areas may be at a greater risk of flooding than previously realized. However, despite accelerated rates of relative sea-level rise and rapid sediment compaction, coastal restoration efforts such as river diversions can be successful in building new land in some areas. I find that sediment deposition responds non-linearly to water discharge, reaching a maximum at moderate discharge. Wetlands are more likely to keep up with relative sea-level rise if hydrodynamic conditions are optimized to retain mineral sediment in targeted restoration areas. / 1 / Margaret Keogh

The Pariette Wetlands was constructed to provide wildlife habitat in an arid environment. Elevated levels of selenium (Se) have been detected in water, soil, and biota. Selenium concentrations have ranged from below detection limit to four times the water quality criterium limit. Here we report on three interrelated research topics: 1) selenium mass balance and flux in water, 2) selenium accumulation, concentration and volatilization of water and plant tissues; and 3) selenium sorption by upland and wetlands soils. 1) Mass balance and mass water flux of selenium for the Pariette Wetlands were studied. A comparison of inlet and outlet Se fluxes was used to determine the mass of Se stored. Selenium concentrations were higher at the inlet (2.1-16.3 μg L-1) than at the outlet (2.0-14.0 μg L-1). The average amount of Se retention and/or loss was 75%. 2) Elevated levels of selenium (Se) in water, soil, and biota of the Pariette Wetlands, Utah. Twelve sample sites were selected to determine the spatial and temporal variation of Se accumulation, concentration and volatilization. At the inlet, concentrations of waterborne Se during low-flow period (winter) were significantly higher than concentrations during high-flow irrigation season (summer). Se concentrations in water at the outlet were lower during the high-flow period ranging from. In contrast, plant tissue Se concentration was lower at the inlet and higher at the outlet. Selenium volatilization results indicated that there were spatial and temporal differences among samples sites. 3) The physical and chemical properties were compared for two soils in the Pariette Draw of Utah. It appears that Se mobility is associated with the distribution of soluble salts. We surmise that soluble Se is regulated by the solubility of a sodium selenate sulfate coprecipitate.. Knowledge gained about the mass balance, storage of Se, and the associated biogeochemical processes in water, plants, and soils that contribute to the accumulation or loss of Se in the wetlands will be beneficial to future land management decisions to minimize the impact of Se exposure to wildlife.

The phosphorus removal characteristics of several gravel-based constructed wetland systems (CWSs) in the treatment of secondary sewage effluent was studied.Investigations were conducted on water quality parameters (redox potential, pH, dissolved oxygen and temperature) which affect phosphorus adsorption to substrata.Laboratory phosphorus adsorption experiments on Richmond CWS gravel substrata, a gravel used in Griffith CWS trials and a locally available soil, Hawkesbury sandstone, involved ion-exchange experiments and calculation of Langmuir and Freundlich adsorption isotherms and column adsorption/desorption trials.Six steelworks by-products were investigated in laboratory studies, to determine their potential for use as phosphorus adsorbers in a CWS: granulated blast furnace slag(GBF), blast furnace slag(BF), steel slag(SS), fly ash(FA), bottom ash(BA) and coal wash(CW).The ability to adsorb phosphorus was then correlated to the chemical attributes of each substratum.Of the six steelworks by-products screened in laboratory-based studies as substrata for P removal in a CWS, BF and SS slags showed the most potential due to their high phosphorus adsorption capacity and useable matrix size.Further research is recommended to evaluate the sustainability of using slags for P removal (as well as other contaminants present in wastewater), using full scale CWSs, which should include an evaluation of any likely environmental impacts using leachability and toxicity studies. / Doctor of Philosophy (PhD)(Environmental Science)

Thesis (M. L. A.)--University of Hong Kong, 2007. / Includes special report study entitled: Water level control technology in constructed wetland. Title proper from title frame. Also available in printed format.

Five unique but related studies were conducted at the Oregon State University Dairy Wetland Treatment System (OSUDWTS), Corvallis, OR. The research site consisted of six parallel wetland cells, which were built in 1992 and began receiving concentrated dairy wastewater in the fall of 1993. Hydrologic, hydraulic, and water quality data were collected at the site for three years. The five resulting studies were: 1. the prediction of evapotranspiration (ET) from wetlands; 2. the development of a hydrologic model and water budget for the OSUDWTS; 3. a preliminary investigation of the hydraulics of the OSUDWTS; 4. an overall evaluation of the treatment performance of the OSUDWTS and applicability of current constructed wetland design methods to livestock wastewater wetlands; and 5. the development of a conceptual model for nitrogen removal in constructed wetlands. Average ET rates for the wetland cells were found to be 1.6 times as great as the Penman- Monteith alfalfa reference ET. Specific crop coefficients were 1.72, 2.32, and 0.57 for bulrush, cattails, and floating grass mats. The detailed hydrology model predicted daily water levels very accurately (R��=0.95) and showed seasonal rainfall and ET could increase or decrease the average detention time by as much as 18%. Tracer studies indicated that non ideal flow existed in the wetlands. Actual detention times were found to be an average of 43% shorter than theoretical detention times. Tank-in-series and plug flow modified by dispersion models were inadequate at describing the observed tracer response. Constructed wetlands were shown to be able to reduce a high percentage of most waste constituents in concentrated livestock wastewaters. Average reductions for COD, BOD, TS, TSS, TP, TKN, NH��� and fecal coliforms were 45, 52, 27, 55, 42, 41, 37 and 80%, respectively. Rate constants for volumetric and areal first-order plug flow models were found for each wastewater constituent. Overall, both models were fair at predicting wastewater reduction at the OSUDWTS. A conceptual model of nitrogen cycling showed denitrification to be the most important process for nitrogen removal in constructed wetlands. However, low dissolved oxygen in constructed wetlands limits nitrification, which in turn limits denitrification. / Graduation date: 1997

Contains reprint of author's professional report (Master of Landscape Architecture)--University of California, Berkeley, 2005. / Title from cover. "May 2006." Each report also has separate t.p. Includes bibliographical references. Also available in PDF via the Internet.

Thesis (M.S.)--University of Delaware, 2007. / Principal faculty advisor: Jacob L. Bowman, Dept. of Entomology & Wildlife Ecology. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2006. / Title from first page of PDF file. Includes bibliographical references (p. 169-180).

No description available.

The impacts of oil sands processed materials (OSPM) on phytoplankton and periphyton community growth and stable carbon and nitrogen isotopes were examined. Estimates of plankton and periphyton community growth, measured as chl a and dry weight, were low and similar in reference and OSPM reclamation wetlands. The use of stable isotope analyses revealed higher δ15N of plankton and periphyton in OSPM wetlands than reference wetlands, possibly due to increased TN concentrations in some OSPM wetlands. In the laboratory, water-soluble fractions (WSF) of two types of OSPM (mature fine tailings, MFT and consolidated tailings, CT) and an amendment material (peat-mineral mixture), potential fill materials in wetland or end pit lake reclamation, were examined for phytoplankton community growth and stable carbon and nitrogen isotopes. All WSF treatments had higher chl a compared to reference water and maximum growth was observed at a 50:50 ratio of peat:CT or peat:MFT. In general, WSFs of peat had the highest concentration of total nitrogen (TN) whereas WSFs of MFT had the highest total phosphorus (TP; 3x higher). The results suggested that the addition of peat as an amendment to OSPM (particularly for MFT), contributing additional TN, could improve phytoplankton community growth in oil sands reclamation. At higher percentages of MFT WSF, there was increased turbidity due to fine clay particles that likely contributed to reduced phytoplankton growth. Turbidity could be an important factor limiting phytoplankton growth and thus reducing dietary resources and biological detritus (via sedimentation) in the initial development of an end pit lake. The WSFs also promoted the unfavourable growth of filamentous algae, highest at intermediate concentrations of peat and CT WSFs and inhibited in MFT WSFs due to light limitation. Stable N isotopes of plankton and filamentous algae suggests that 15N enrichment of algae could be a useful indicator of nutrient inputs, including OSPM seepage into natural aquatic systems, for oil sands regional monitoring programs.