No description available.

The Rideau River Waterway, also known as the Rideau Canal, is a constructed navigation channel that links Ottawa to Kingston, Ontario. Opened in 1832, it was designated a Canadian Heritage Site in 2003 and a UNESCO World Heritage Site in 2007. South of Smiths Falls, the Rideau Canal consists of a series of 14 interconnected lakes, primarily used for recreational purposes, as well as commercial fishing. The objectives of this study were to examine the spatial and temporal distributions of anthropogenic elements to three headwater lakes of the Rideau Canal system and to examine the relationship between sport fish Hg and historical sediment Hg concentrations. Utilizing paleolimnological techniques, historical records of As, Cd, Co, Cr, Cu, Hg, K, Ni, Pb, Rb, and Zns were analyzed from chronologically deposited lake sediments. Overall, Indian Lake, though the smallest of the three studied lakes, consistently had the highest overall As, Cd, Cu, Hg, Ni, Pb and Zn concentrations. While all peak concentrations were buried, recent surface sediment Hg, Cd, and Zn concentrations still remain above the federal interim sediment quality guideline and the concentration of Pb remains above the federal probable effect level within Indian Lake, leading to continued concern for human and ecosystem health. The general agreement between lake sediment profiles for Cd, Pb and Zn and then Cu and Ni suggest that each group of elements is primarily contributed from the same source. The similarity in trends and timing of peak concentrations between the study lakes and other Ontario lakes suggests large-scale, atmospheric contributions of elements to the freshwater systems in the area. Although only historical northern pike (Esox lucius) THg tissue concentration data was available for analysis, results indicate that concentrations in fish have decreased more than 60% since the late 1970’s, while sediment THg concentrations have decreased 35% within the same time period. Overall, this study has demonstrated that the headwater lakes to the Rideau Canal are presently impacted by elements, at concentrations which are of potential concern for human health. / Thesis (Master, Biology) -- Queen's University, 2009-09-26 00:02:42.317

No description available.

No description available.

The mixed sand and gravel barrier beaches located on the South Island's East Coast are formed predominantly of Greywacke, eroded from the mountains, and transported via the major river systems. These barriers act as the interface between the South Pacific Ocean and the surrounding hinterland. In times of high energy coastal events, breaching is common. This thesis examines the form and function of the Waihao-Wainono barrier, a section of the coastline situated north of the Waitaki River. Breaches along this part of the barrier are frequent and several have rendered the surrounding farmland unusable for several years due to the effects of saltwater inundation. There is some concern among the local community as to exactly why the barrier breaches at certain locations and not others, making land planning and management a difficult task for farmers. Several of the local landowners believe that since the construction of the Waitaki Dam in 1935, a significant decrease in sediment size along the barrier has occurred. It is also thought that the barrier form has experienced substantial change. Through the use of physical techniques used in the field of coastal science, 17 sites along the Waihao-Wainono barrier were studied. Excavations were carried out, surface and substrate profiles recorded and sediment samples collected from the surface. sub-surface and substrate of the barrier. Analysis of the barrier form and barrier volume concluded that the past breach sites consisted of steeper lower foreshore slopes than the non-breach sites, and at two sites, the substrate was not reached. Breach areas display the greatest barrier volume of all the study sites, which is contrary to belief. In relation to the surface sediments, the majority of barrier profiles displayed the distinct mean grain size cross shore zonation, characteristic of mixed sand and gravel beaches. The best and most consistent surface sorting was also identified as being a characteristic of the breach sites. The sediment size is not shown to have drastically reduced over the thirty year sampling period as was perceived by the local community. Within the sub-surface of the barrier, the sediments displayed chaotic sizes and generally poorly sorted material. Several of the breach sites contained a distinct change in sediment size between the coarser surface layer and the finer layer located immediately below. This layering of coarse and fine sized sediments leads to differences in permeability within the barrier, which is thought to be a major factor in why these sites have breached. Resulting from these findings, a group of characteristics of breach sites was formed and several predictions made as to where the barrier may breach in the near future.

Worldwide, estuaries are under increasing pressure from numerous contaminants. There is a need to develop reliable bioassay methodologies to assess the effects of these stressors on estuary health. This thesis aimed to develop and validate toxicity tests in a New Zealand marine harpacticoid copepod species for use in monitoring and evaluating the effects of estuarine pollution. A survey and toxicological assessment of a range of native copepod species resulted in the selection of Quinquelaophonte sp. as the ideal bioassay species. This selection was based on a broad regional distribution, ease of culture and high reproductive rate in the laboratory, sexual dimorphism, and sensitivity to contaminants. To validate the bioassay, spiked sediments were used to expose Quinquelaophonte sp. to three reference compounds representing important categories of estuarine chemical stressors: zinc (a metal), atrazine (a pesticide), and phenanthrene (a polyaromatic hydrocarbon). A method for spiking sediments that Quinquelaophonte sp. inhabit was developed to ensure even contaminant distribution in sediments. Two sediment bioassays using lethal and sublethal endpoints were validated, one acute (96 h) and one chronic (14 d). These assays incorporated both lethal and sublethal endpoints, which included reproductive output and mobility. Acute-to-chronic ratios were calculated for use in environmental risk assessment and to provide insight into the mode of action of the reference contaminants. The chronic sediment bioassay was used to assess sediment quality in three estuaries across New Zealand: Napier, Christchurch and Invercargill. This validated the bioassay for use with naturally-contaminated field sediments with varying mixtures of pollutants and sediment types (coarse sandy to fine silty organic rich sediments). Quinquelaophonte sp. was also tested to assess whether it can be used to characterise multi–generation impacts. After four generations of exposure to zinc, there were changes in acute sensitivity, indicating this species possesses mechanisms for acclimating or adapting to toxic stressors. Sediment bioassays in Quinquelaophonte sp. were successfully developed and validated, offering significant promise as a tool for monitoring effects of pollution in New Zealand estuaries.

The physical and biological characteristics of a stream are strongly influenced by its surrounding catchment. The riparian zone acts as a buffer between land and water ecosystems and can play an essential role to retain contaminants (e.g. sediment) from entering and affecting the receiving waterway. When the riparian zone is not managed, the consequence can be high amounts of sediment entering the waterway that negatively affects in-stream communities with a decline in native invertebrate and fish populations. I investigated three aspects of riparian management in the Canterbury region, South Island, New Zealand, by investigating the public perception using a questionnaire to determine what the public knows about riparian management and what practices are being done in the farming community. Results showed that riparian management varied across farm types, and there was some confusion about the roles of riparian management. Crop farmers were the least likely to do riparian management, in contrast to dairy farmers who were the most likely to do riparian management. A main concern is that the majority of respondents highlighted that filtering nutrients was the main goal for riparian management, and only 5% thought it was due to sediment, and 10% to decrease erosion. I then conducted a field survey to investigate riparian zone sediment retention in different land-uses (dairy farming, production forestry and urbanisation) compared to native forest. Surprisingly, dairy farms produced the least amount of sediment, and urban areas produced the most, and there was a marginal effect of season. However, generally there was no difference between the amounts of sediment passing through the riparian zone. Therefore, I was unable to distinguish if there were any vegetation effects occurring within the riparian zone. To complement the field survey, I tested sediment overflow by conducting multiple experiments using a rain simulator. The simulator controlled the intensity and amount of rainfall over differing percentages of riparian groundcover. My results were consistent with other studies showing that as groundcover increases, sediment runoff decreases. However, there was no relationship between rainfall intensity and the amount of sediment in runoff. My thesis indicated that riparian planting to reduce sediment flow into streams needs to focus on high amounts of groundcover (such as rank grass).

The structural framework of the northern Gulf of Mexico coastal zone is characterized by numerous growth fault systems. Neotectonic processes in coastal marshes in this region have been shown to be important drivers of relative sea-level rise as well as having significant influence on marsh accretion processes. One active growth fault has been identified at East Matagorda Peninsula, Texas. To characterize the Holocene behavior of this fault and the consequent sedimentary responses, a suite of fallout radionuclides (7Be, 137Cs, 210Pb) and radiocarbon, supplemented by sediment physical property data have been used to determine sediment mixing depths, rates of accumulation, and geochronology. Correlation of time-equivalent stratigraphic boundaries reveals a maximum total Holocene offset of ~1 meter. Determination of slip rates from these values reveals a linear trend of displacement as a function of distance along the fault trace with maximum slip occurring to the southwest and minimum slip to the northeast. Sediment accumulation rates from the downthrown station nearest to the fault trace display a dramatic increase over the last 30 years. Sediment bulk density and grain size data suggest an interaction between fault-driven geomorphic change and sedimentation where a migrating land-water interface has influenced the type of sediment accumulation here.

An understanding of the clogging of fine sediments within gravel substrates is advanced through the use of dimensional analysis and macro-analysis of clogging experiments in hydraulic flumes. Dimensional analysis is used to suggest that the dimensionless clogging depth can be collapsed using the original and adjusted bed-to-grain ratios, substrate porosity, roughness Reynolds number, and Peclet number. Macro-analysis followed by statistical analysis of 146 experimental test results of fine sediment deposition in gravel substrates suggests that the dimensionless clogging depth can be collapsed using the substrate porosity and roughness Reynolds number reflecting the processes of gravity settling and turbulence induced fluid pumping between substrate particles. In addition, a clear cutoff of fine sediment unimpeded static percolation and sediment clogging is found using the adjusted bed-to-grain ratio. Thereafter, a physics-based approach is used to predict the clogging depth of fine sediment in gravel and in turn approve upon the preliminary findings in the empirical analysis. A momentum-impulse model that accounts for the critical impulse of a particle bridge is balanced with a fluid pulse resulting from turbulent pumping. The momentum-impulse model reduces the number of unknown parameters in the clogging problem and increases the model predictability as quantified using k-fold validation and model comparison with the empirical approach. A nomograph derived from applying the momentum-impulse model is provided herein, which will be useful for stream restoration practitioners interested in estimating embeddedness. Also, prediction of the clogging profile is shown using the clogging depth predicted with the momentum-impulse model.

The sediment accumulation is an important characteristic in the ageing process of integrated constructed wetlands (ICW). Retained nutrient and other contaminants in wetland sediments have the potential to be remobilized and released to the overlying water column when environmental conditions change. In this study, mesocosms which filled with saturated sediments and planted with Phragmites australis and Agrostis stolonifera were set up to examine nutrient and other contaminants retention and/or release by wetland sediment and substrates. The effects of physico-chemical parameters on sediment-water contaminant exchange were also investigated through the application of multiple regression models, principal component analysis (PCA), redundancy analysis (RDA), and self-organizing map (SOM) model. The results demonstrated an average net release of chemical oxygen demand (COD), ammonianitrogen (NH3-N), nitrate-nitrogen (NO3-N) and molybdate reactive phosphorus (MRP) to the overlying water column, indicating that the ICW sediment and substrates acted as new contaminant sources. According to statistical analysis, electrical conductivity (EC) and redox potential (RP) values affected COD treatment efficiency. Chloride (Cl) concentration and RP value had an impact on NH3-N treatment performance. NO3-N removal was influenced by dissolved oxygen (DO) concentration and RP value. MRP treatment efficiency was related to DO concentration and EC value. The SOM model was selected as prediction tool to provide numerical estimations for the performance of ICW mesocosms. The model was validated, indicating that NH3-N, NO3-N, MRP, and COD treatment efficiencies could be predicted by input variables which are quick and cost-effective to measure. The SOM model can be seen as an appropriate method for monitoring the performance of mature ICWs. The type of vegetation played a minor role in releasing nutrients and other contaminants. However, the mesocosm planted with Phragmites australis outperformed the one planted with Agrostis stolonifera. No water reached bottom outlet of the mesocosm suggesting that there was little potential risk to contaminate groundwater. The clay liner and the biogeochemical processes taking place within sediments proved to be effective in preventing surface water from infiltration. Although no reduction in the overall performance has been observed for the full-scale ICW sites 7 and/or 11, this laboratory-scale study provided valuable warning signs regarding the loss of contaminant sequestration which may contribute to decline in wetland treatment performance over time. The impacts of hydraulic loading rate (HLR) and seasonal temperature fluctuations on contaminant removal efficiencies of a new ICW system receiving domestic wastewater were also assessed. The system showed good overall treatment performance in terms of effluent quality and removal efficiency. The influence of ICW removal efficiencies of the hydraulic loading rate, which was based on overall water balance, was negligible due to large footprint and multi-cellular configuration of the studied system. Relatively low temperature in autumns and winters resulted in decreased biological activities and lower contaminant removal efficiency. The long-term trends in nutrient removal have been investigated to five Wildfowl & Wetlands Trust constructed wetland systems. The results showed less effective removal even release of NO3-N, total oxidised nitrogen (TON), orthophosphate- phosphorus (PO4-P) and total phosphorus (TP) in many of the systems as a result of wetland aging and lack of sediment management.