Turf growers have been farming the Ladner soil in the Boundary Bay area for the last decade. At each harvest, approximately a 2cm layer from the A horizon is taken out with grass. Consequently, the cultivation layer is becoming thinner year after year and the growers are already cultivating the B horizon. The possible improvement of the B horizon structure through sewage sludge application will benefit the fanners in the area. A greenhouse experiment was conducted using a Ladner subsoil. Treatments included application rates of 0, 33, and 100 t/ha of composted sewage sludge. The effect of sludge application on the soil structural stability in relation to the destructive action of water was evaluated. Soil columns were subjected to periodic 24-hour simulated ponding events. Adding sewage sludge increased the ponding tolerance of the soil. This was reflected by statistically significant differences in satiated hydraulic conductivity ('Ks') between the sludge-amended columns and the control columns. The significant decrease of 'Ks' of the control treatment as a result of ponding was responsible for widening the gap between 'Ks' of the control columns and 'Ks' of the sludge-treated columns. The incorporation of sewage sludge slowed down the decrease of 'Ks' but could not stop it. The most plausible explanation is that the addition of sewage sludge was effective in increasing the resistance of aggregates to breakdown when subjected to ponding. Fifty days after the last ponding event, the percent stable aggregates averaged 13.7, 26.9, and 48.1% for the 0, 33, and 100 t/ha treatments respectively. In no case was a significant difference in bulk density observed between the treatments. The soil structure deterioration as a result of ponding was not reflected by the bulk density measurements. Thus, it was concluded that hydraulic conductivity and aggregate stability are better idices of soil structural deterioration than bulk density. A side investigation was carried out to illustrate trends of essential nutrient and heavy metal uptake by bermuda grass. Sludge incorporation at 33 t/ha did not seem to increase nutrient and metal uptake by bermuda grass. However N, Cd, and Zn uptake appeared to increase at 100 t/ha. / Land and Food Systems, Faculty of / Graduate

An investigation of the trend over time of the concentration of selected soil leachate constituents contained in domestic effluent applied to a ferro-humic podzol forest soil was undertaken. From July 15, 1976 to November 12, 1976, 2 cm of domestic effluent, selectively supplemented with commercial fertilizer, was sprayed twice weekly to a 900 m² plot situated on a mountain slope. Ten porous plate tension lysimeters installed at various depths and locations in the forest soil continuously extracted the resulting soil leachate. The soil leachate samples collected twice per week over the duration of the study, as well as the applied effluent samples, were analysed for chloride, nitrate and total Kjeldahl nitrogen and total and orthophosphorus. Based on. the concentrations of nitrate nitrogen, total Kjeldahl nitrogen, and total phosphate in the applied effluent as well as the average volume of effluent applied over the total irrigation plot, k8A kg/ha (^3.2 lb/acre) nitrate nitrogen, 93-7 kg/ha (83-6 lb/acre) total Kjeldahl nitrogen, and ^3.5 kg/ha (38.6 lb/acre) of total phosphate were applied to the plot during the project period. The chloride ion gradually increased in concentration over the duration of the study until it eventually equalled the value of the chloride in the domestic effluent. This gradual increase was a possible result of the retention of the initial amounts of applied chloride on the anion exchange sites in the soil, which when satisfied, allowed subsequent amounts of applied chloride to move through the soil with the applied effluent. No ortho or total phosphorus was detected in the soil leachate samples collected over the duration of the study. While recognizing the possibility of microbiological immobilization of a portion of the applied phosphorus, the most likely retention mechanism was the adsorption of the phosphorus by the amorphous iron and aluminum compounds in the soil. Nitrate and total Kjeldahl nitrogen were detected in low concentrations in the soil leachate samples only in the time interval following the application of domestic effluent containing greatly increased effluent concentrations of nitrate and total Kjeldahl nitrogen. The increased concentrations resulted from the addition of commercial fertilizers to the treatment lagoon. Such trends suggest microbiological immobilization was playing a role in the removal of the nitrogen compounds. The retention of ammonia, the major component of total Kjeldahl nitrogen, on the cation exchange sites and the retention of nitrate nitrogen on the anion exchange sites would also be occurring. In order to investigate the magnitude of the reaction between phosphorus and the iron and aluminum compounds in the podzol soil, batch scale laboratory tests were undertaken. The time-phosphorus adsorption results indicate that the phosphorus reacts very quickly with the amorphous iron and aluminum compounds in the soil on the plot. The Langmuir and Freundlich isotherms were calculated as was the phosphorus adsorption maximum based on the Langmuir isotherm. The calculated phosphorus adsorption would probably give a conservative estimate of the phosphorus removal potential since the isotherm is based only on the initial and not the long term phosphorus adsorption reactions. Despite the fact that the soil water content was continually above the soil water content at the field capacity, no phosphorus and very little nitrogen was detected in the soil leachate samples. Such results suggest that a phosphorus or nitrogen balance may be a useful irrigation operating criterion rather than the commonly accepted water balance criterion. In such a situation the phosphorus or nitrogen requirements over the growing season of the crop would be evaluated and met by the application of domestic effluent. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

One of the problems associated with the disposal of solid wastes in landfills, particularly in high precipitation areas, is the pollution caused by the production of the often highly contaminated leachate. This study was initiated to investigate the treatability of a low-strength municipal landfill leachate using aerobic digestion followed by activated carbon polishing, so that the most cost effective treatment system could be determined. Sludge desorption and leachate toxicity assessment were also included in the study. The aerated lagoon process alone was very effective in treating the leachate to a quality that is nearly acceptable for discharge to a receiving water. Only SO₄ and Fe in the settled effluent significantly exceeded the local requlatory standards for specific discharges. Carbon adsorption greatly improved the settled effluent quality in terms of color, Fe and COD. However, the addition of this polishing process for combined treatment may not be cost effective. For an influent COD of 1,600 mg/1 and with MLVSS concentrations ranging between 360 and 560 mg/1, the settled effluent COD removal increased from 82.6% to as high as 90.1% when 9C was increased from 2 to 10 days. For the corresponding influent BOD5 of about 1,000 mg/1 and with θ[sub c] greater than 3 days, the BOD5 removal efficiencies averaged 99.1% and the settled effluent BOD5's were no greater than 10 mg/1. This indicates that the raw leachate can be almost completely biodegraded by aerobic digestion. The metal removal efficiency in aerobic treatment was greater than 95% for Fe and Mn, better than 90% for Zn and Pb, and about 80% for Al. Metals expected to be mainly or significantly removed by chemical precipitation due to pH change during treatment included Ca, Fe, Mn, Zn and Pb. Analysis of the kinetic parameters associated with the biological treatment indicated that the concentrations of pollutants, such as heavy metals, in the leachate were not great enough to cause significant inhibition of biological growth. It also showed that this leachate could very likely be added to a domestic sewage, in a high percentage, for aerobic treatment without producing adverse effects. From a treatment efficiency point of view, the optimum solids detention time was found to be 7 to 10 days for leachate BOD₅ ranging from 1,000 to 3,000 mg/1. However, since the predicted θ[sub c] for failure was 0.42 day at 22°C for a 1,000 mg/1 BOD₅ leachate, a θ[sub c] of 2 to 4 days seems possible in the field. On the other hand, the effects of winter temperature on BOD₅ removal and sludge settleability, as well as many other unknown factors on the overall biological treatment efficiency must be considered. It was, therefore, felt that a solids detention time of 5 days or more would be the more realistic approach for a full-scale treatment system, despite the fact that an economic analysis favored a shorter θ[sub c]. / Applied Science, Faculty of / Civil Engineering, Department of / Unknown

No description available.

Squirrels appear to be unique among sub-primate mammals in being able to see at least some colors. A readily available Oregon squirrel species, golden mantled ground squirrels (Citellus lateralis), which has not previously been tested under laboratory conditions for color vision, was subjected to color discrimination testing in a Skinner box. On the basis of recent physiological tests of color reception capacity and behavioral tests of color discrimination response in closely related species, it was predicted that this species should be able to discriminate blue, green and possibly yellow, but not red. Three experiments were conducted. The first, a pilot study, checked for discrimination of blue from green and blue from gray; subjects were rewarded for pressing on one color, shocked for pressing on the other color. The second experiment, the main part of the study, used one subject tor each of three discriminations: green from gray, yellow from gray, and red from gray. Here, a choice approach was employed: two bars were used, with subjects having to choose the correct one tor each stimulus, receiving a food reward for correct choices and no reward for incorrect choices. Third, a series of tests was devised to check for use of cues other than color as a possible basis for discrimination in the main experiment. These squirrels succeeded in discriminating all four colors, and results of the series of cue tests indicate they were not making significant use of non-color cues. Despite past results, therefore, it was concluded that this species is capable of seeing all colors in the visible spectrum. This result should be of interest to evolutionary theorists and may have important implications for current theories of color vision processes.

A research report submitted to the Faculty of Engineering and Built Environment, University of the Witwatersrand, Johannesburg, in the partial fulfilment of the requirements for the degree of Master of Science in Engineering, January 2018 / The higher quality virgin coal resources in the Witbank Coalfield are near completion, hence new methods of mining the underground coal pillars that have been left insitu as primary support becomes attractive to mine using opencast methods. Up until 2006 more than three million pillars have been created (van der Merwe, 2006) and have been growing since. There are various challenges associated with pillar extraction via opencast mining method. These challenges relate to spontaneous combustion, underground water and the exact spatial location of underground pillars that have been mined in the early to mid-1900. The reliability of old underground mine plans pre-1960, before the Coalbrook disaster, saw underground pillars not being offset which resulted in unreliable survey plans (van der Merwe, 2006). This report focuses on possible techniques that can be used to identify underground pillars where no water and no spontaneous combustion are evident. The following two methods have been tested: Ground Penetrating Radar (GPR) technique which is based on geophysics and a down the hole 3D laser method using the Cavity, Auto-scanning, Laser System (CALS Tool) which uses reflectorless principles to measure the geometries of the underground pillars. The GPR did not provide any conclusive data, whilst the CALS Tool provides detailed information of the workings. The CALS Tool is not practical to identify every single pillar in a reserve but can be used on a larger extent as a short term mine planning mechanism. The CALS Tool proved to have the ability to identify the spatial location of the underground workings as confirmed by the test done at TOC. / XL2018

No description available.

Bees are a diverse group of insects responsible for pollinating plants in agricultural and ecological landscapes. Wild bees are impacted by anthropogenic activity and associated habitat loss. Although 75% of bee species nest underground, this nesting strategy has been overlooked. In my thesis, I explored the nesting habitat requirements of ground-nesting bees by studying the relation between bees and edaphic factors. First, I reviewed existing literature about ground-nesting bee nesting characteristics (Chapter 2). I found that certain abiotic factors (e.g., soil texture, temperature, moisture, compaction, slope, and soil surface features), as well as biotic factors (e.g., floral resources, conspecifics, predators), could be key in nest-site selection. I also discuss possible explanations for the choice of these nesting characteristics, particularly edaphic factors. Secondly, in Chapter 3, I assessed relationships between specific soil factors (soil texture, compaction, slope and ground cover) and the wild local ground-nesting bee communities on 35 farms around Ottawa throughout 2018 and 2019. I found that higher percentages of sand and bare ground were linked to increased total ground-nesting bee abundance and species richness, whilst slope and diversity (Simpson’s index) were negatively correlated. Furthermore, associations with soil factors were found to be species-specific, especially for associations with sand content, which were either positive, negative, or non-significant. Ground-nesting bee community’s composition was influenced by sand content, slope, soil compaction and bare ground in sampled agroecosystems. Finally, in Chapter 4, I experimentally tested nesting preferences of ground-nesting bee species for soil texture. Based on one season of sampling, there was no association between bee abundance or species richness and soil texture. Together, my research sheds light on the influence of soil characteristics on species-specific nesting-habitat associations for ground-nesting bees. Along with floral resources which have received far more study, nesting habitat is vital for the well-being and persistence of bee populations, and therefore for their conservation.

Researchers and GIS analysts have used Aerial Laser Scanning (ALS) data to generate Digital Terrain Models (DTM) since the 1990s, and various algorithms developed for ground point extraction have been proposed based on the characteristics of ALS data. However, Terrestrial Laser Scanning (TLS) data, which might be a better indicator of ground morphological features under dense tree canopies and more accessible for small areas, have been long ignored. In this research, the aim was to evaluate if TLS data were as qualified as ALS to serve as a source of a DTM. To achieve this goal, there were three steps: acquiring and aligning ALS and TLS of the same region, applying ground filters on both of the data sets, and comparing the results. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble's Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a DTM generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid. / Master of Science / Elevation is one of the most basic data for researches such as flood prediction and land planning in the field of geography, agriculture, forestry, etc. The most common elevation data that could be downloaded from the internet were acquired from field measurements or satellites. However, the finest grained of that kind of data is 1/3m and errors can be introduced by ground objects such as trees and buildings. To acquire more accurate and pure-ground elevation data (also called Digital Terrain Models (DTM)), Researchers and GIS analysts introduced laser scanners for small area geographical research. For land surface data collection, researchers usually fly a drone with laser scanner (ALS) to derive the data underneath, which could be blocked by ground objects. An alternative way is to place the laser scanner on a tripod on the ground (TLS), which provides more data for ground morphological features under dense tree canopies and better precision. As ALS and TLS collect data from different perspectives, the coverage of a ground area can be different. As most of the ground extraction algorithm were designed for ALS data, their performance on TLS data hasn’t been fully tested yet. Our research area was a 100m by 140m region of grass, weeds and small trees along Strouble’s Creek on the Virginia Tech campus. Four popular ground filter tools (ArcGIS, LASTools, PDAL, MCC) were applied to both ALS and TLS data. The output ground point clouds were then compared with a ground surface generated from ALS data of the same region. Among the four ground filter tools employed in this research, the distances from TLS ground points to the ALS ground surface were no more than 0.06m with standard deviations less than 0.3m. The results indicated that the differences between the ground extracted from TLS and that extracted from ALS were subtle. The conclusion is that Digital Terrain Models (DTM) generated from TLS data are valid.

No description available.