x, 166 leaves : ill. ; 25 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.1973) from the Dept. of Agronomy, Waite Agricultural Research Institute, University of Adelaide

<p>One of the environmental problems today in seas, lakes and streams is eutrophication. This is often caused by nutrients such as phosphorus (P) and nitrogen (N) that leak from agricultural areas. A measure to partly prevent the nutrient discharge is to construct or restore wetlands.</p><p>In order to control the efficiency of nutrient reduction of existing wetlands in the county, the administrative board in Västra Götaland wants to find different criterias for reference wetlands. These reference wetlands should represent other wetlands and be used in future evaluations of reduction of nutrients and design of constructed wetlands.</p><p> </p><p>According to the administrative board in Västra Götaland the reference wetlands should have a catchment area of about 50 hectare consisting of at least 70 % arable land, to represent wetlands created to remove nutrients. The surface area should exceed 0,5 hectare and the inlet-nitrogen concentration should be around 5 mg N-1.</p><p>This report investigates nitrogen and phosphorus retention in two wetlands, Härstad and Åmot in the county of Västra Götaland, and if they fulfill the criteria of being a reference wetlands. In addition to this, a tracer study was performed in one of these wetlands with the purpose to study the hydraulic efficency.</p><p> </p><p>Neither the wetland in Åmot or Härstad achieves the guidelines of about 5 mg N l-1 in the incoming water. Therefore, they can be seen as inappropriate as reference wetlands according to their nitrogen retention. The wetland of Härstad, however, has significantly better N retention than the wetland of Åmot. Results from the report shows that N retention in the wetland of Härstad was relatively high not only due a higher N load, but also due to that N was largely in the form of NO3- facilitating efficient transformation of NO3- to N2 by denitrification bacteria. Nitrogen removal was much lower in the wetland in Åmot due to that N in incoming water was not in the form of NO3- and could therefore not be efficiently transformed to N2 by denitrification.</p><p>Incoming total phosphorus to the Härstad and Åmot wetlands exceeded 100 µg P l-1, which means "extremely high" tot-P concentrations according to environmental quality criteria from the Swedish Environment Protection Agency. Phosphorus load per wetland area was slightly higher in the wetland in Åmot than in the Härstad wetland. In spite of this, P retention per wetland area as well as relative P retention was clearly higher in the Härstad wetland. This can be explained by that P in incoming water to the Härstad wetland was to a larger degree than in the Åmot wetland bound to particles, facilitating P retention through sedimentation.</p><p>According to the tracer study, the Härstad wetland has a hydraulic efficency (λ) of about 0,13 which means it has a low hydraulic efficiency. The effective volume ratio (e) in Härstad was calculated to 18 % which means that the water has an inadequate spreading in the wetland, which is not good for the nutrient elimination in this wetland.</p><p>This study illustrates the difficulties in finding representative reference wetlands due to potential differences between wetlands in nutrient concentrations in incoming water, the degree that incoming P is bound to particles, the degree that incoming N is in the form of NO3-, and hydraulic efficiency.</p>

Graduation date: 1970

A numerical model has been developed to study the temporal and spatial variations of Phosphorus mass and fluxes around the tree islands of Shark River Slough in the Everglades. The developed model is based on a conceptualization of physical, chemical and biological processes that consider advective and diffusive transport of dissolved Phosphorus, adsorption on to soil, input from rainfall and external sources, and Phosphorus cycling in biomass. The biomass related processes are Phosphorus uptake, release as litter, transport as suspended litter and release from the decomposition of the deposited litter. The water flow and transport of dissolved Phosphorus in the numerical model are implemented originally in the simulator MODHMS. However, the transport equations for dissolved Phosphorus were also coded separately, as well as the balance equation for suspended litter particles and deposited litter. The parameterization of the model was conducted by using the data collected by Ross et al. [2004] in three tree islands of Shark River Slough, as well as other parameters reported among the literature. The model was calibrated in three phases. Initially, Manning coefficients were adjusted from surface water velocity data collected by Bazante et al. [2004]. Then the calibration of several groundwater flow parameters was performed from water table data collected at wells by Ross et al. [2004]. In the third phase, the Phosphorus input rate from external sources and the initial concentration of Phosphorus were calibrated by assuming that the average surveyed Phosphorus concentration in soil pore water remains approximately constant over a 10 year period. The quantitative assessment of the spatial distribution and temporal variations of Phosphorus mass and fluxes around tree islands obtained from the developed model corroborate the negative effect of the rainfall events on Phosphorus accumulation in the head of the tree island. However, the possible positive effect of the ET driven water flows on Phosphorous accumulation was found not as relevant as hypothesed by other authors in the literature. According to the model results, most of the Phosphorus transport in the tree islands occurs as suspended particles in surface water, even though the transport of dissolved Phosphorus in pore water cannot be neglected around the head of the island. The model results also suggest that an input of Phosphorus from external sources (e.g., animal activity such as bird guano and other sources) is needed to preserve the average Phosphorus levels in the head and in the whole tree island. Finally, Phosphorus accumulation and losses in certain areas of the tree island suggest changes in vegetation that need to be investigated in future work. The developed model can be used as a predicting tool to gain insight into the potential effects of restoration scenarios in tree islands environments. The model could be run for hypothetical future conditions and contribute to provide quantitative information for conservation and restoration efforts in the Everglades and similar wetlands.

Cultural eutrophication is caused by the excess addition of phosphorus to aquatic ecosystems, and has long been a water quality management issue in Lake Erie. Despite successful reductions in external loading of phosphorus in Lake Erie the in lake total phosphorus (TP) concentrations are increasing recently and symptoms of eutrophication are apparent. In this study I examined the sedimentation velocity of particulate phosphorus and how it is affected by stratification and plankton community composition over the growing season. Diatoms had the highest sedimentation velocities and a shift to slower settling species with greater form resistance (Synedra sp. and Fragilaria sp.) was observed during the stratified period possibly in response to the shallower mixed layer. No significant variation in sedimentation velocity was found with trap depth, plankton size or temperature; hence the individual plankton cells were employing methods to change their sedimentation velocity in accordance with changing environmental conditions. Phosphorus sedimentation was most closely related to silica sedimentation, which largely represents the sedimentation of the diatoms. Thus any shifts in community composition will affect phosphorus-settling rates. The sedimentation rate of phosphorus decreased from June 2nd until August 26th during the stratified period at station84 and from June 2nd to August 5th at station 452. The decline of total phosphorus was less than the sedimentation rate, hence, sediment resuspension and redistribution from the littoral sediments along with atmospheric deposition are important sources of phosphorus to the central and eastern basins of Lake Erie. The sedimentation rates of P, N and C did not follow the Redfield ratio. The sedimentation velocity of P was much less than that of C and N, indicating that P is conserved in the epilimnion and possibly that C and sedimentation contains more non-living material. Therefore, modelling phosphorus sedimentation after carbon and nitrogen sedimentation is inappropriate. Laboratory sedimentation towers can be used to measure phytoplankton sedimentation velocity including net upward movement, which traditional sedimentation traps are unable to do. Determination of the sedimentation velocity of the phytoplankton community to variables such as light, temperature and nutrient status, using this method, may eventually lead to a dynamic phosphorus model that could more effectively reduce eutrophication effects in Lake Erie.

One of the environmental problems today in seas, lakes and streams is eutrophication. This is often caused by nutrients such as phosphorus (P) and nitrogen (N) that leak from agricultural areas. A measure to partly prevent the nutrient discharge is to construct or restore wetlands. In order to control the efficiency of nutrient reduction of existing wetlands in the county, the administrative board in Västra Götaland wants to find different criterias for reference wetlands. These reference wetlands should represent other wetlands and be used in future evaluations of reduction of nutrients and design of constructed wetlands. According to the administrative board in Västra Götaland the reference wetlands should have a catchment area of about 50 hectare consisting of at least 70 % arable land, to represent wetlands created to remove nutrients. The surface area should exceed 0,5 hectare and the inlet-nitrogen concentration should be around 5 mg N-1. This report investigates nitrogen and phosphorus retention in two wetlands, Härstad and Åmot in the county of Västra Götaland, and if they fulfill the criteria of being a reference wetlands. In addition to this, a tracer study was performed in one of these wetlands with the purpose to study the hydraulic efficency. Neither the wetland in Åmot or Härstad achieves the guidelines of about 5 mg N l-1 in the incoming water. Therefore, they can be seen as inappropriate as reference wetlands according to their nitrogen retention. The wetland of Härstad, however, has significantly better N retention than the wetland of Åmot. Results from the report shows that N retention in the wetland of Härstad was relatively high not only due a higher N load, but also due to that N was largely in the form of NO3- facilitating efficient transformation of NO3- to N2 by denitrification bacteria. Nitrogen removal was much lower in the wetland in Åmot due to that N in incoming water was not in the form of NO3- and could therefore not be efficiently transformed to N2 by denitrification. Incoming total phosphorus to the Härstad and Åmot wetlands exceeded 100 µg P l-1, which means "extremely high" tot-P concentrations according to environmental quality criteria from the Swedish Environment Protection Agency. Phosphorus load per wetland area was slightly higher in the wetland in Åmot than in the Härstad wetland. In spite of this, P retention per wetland area as well as relative P retention was clearly higher in the Härstad wetland. This can be explained by that P in incoming water to the Härstad wetland was to a larger degree than in the Åmot wetland bound to particles, facilitating P retention through sedimentation. According to the tracer study, the Härstad wetland has a hydraulic efficency (λ) of about 0,13 which means it has a low hydraulic efficiency. The effective volume ratio (e) in Härstad was calculated to 18 % which means that the water has an inadequate spreading in the wetland, which is not good for the nutrient elimination in this wetland. This study illustrates the difficulties in finding representative reference wetlands due to potential differences between wetlands in nutrient concentrations in incoming water, the degree that incoming P is bound to particles, the degree that incoming N is in the form of NO3-, and hydraulic efficiency.

Cultural eutrophication is caused by the excess addition of phosphorus to aquatic ecosystems, and has long been a water quality management issue in Lake Erie. Despite successful reductions in external loading of phosphorus in Lake Erie the in lake total phosphorus (TP) concentrations are increasing recently and symptoms of eutrophication are apparent. In this study I examined the sedimentation velocity of particulate phosphorus and how it is affected by stratification and plankton community composition over the growing season. Diatoms had the highest sedimentation velocities and a shift to slower settling species with greater form resistance (Synedra sp. and Fragilaria sp.) was observed during the stratified period possibly in response to the shallower mixed layer. No significant variation in sedimentation velocity was found with trap depth, plankton size or temperature; hence the individual plankton cells were employing methods to change their sedimentation velocity in accordance with changing environmental conditions. Phosphorus sedimentation was most closely related to silica sedimentation, which largely represents the sedimentation of the diatoms. Thus any shifts in community composition will affect phosphorus-settling rates. The sedimentation rate of phosphorus decreased from June 2nd until August 26th during the stratified period at station84 and from June 2nd to August 5th at station 452. The decline of total phosphorus was less than the sedimentation rate, hence, sediment resuspension and redistribution from the littoral sediments along with atmospheric deposition are important sources of phosphorus to the central and eastern basins of Lake Erie. The sedimentation rates of P, N and C did not follow the Redfield ratio. The sedimentation velocity of P was much less than that of C and N, indicating that P is conserved in the epilimnion and possibly that C and sedimentation contains more non-living material. Therefore, modelling phosphorus sedimentation after carbon and nitrogen sedimentation is inappropriate. Laboratory sedimentation towers can be used to measure phytoplankton sedimentation velocity including net upward movement, which traditional sedimentation traps are unable to do. Determination of the sedimentation velocity of the phytoplankton community to variables such as light, temperature and nutrient status, using this method, may eventually lead to a dynamic phosphorus model that could more effectively reduce eutrophication effects in Lake Erie.

Greenroofs are increasingly being recognized as an effective site level best management practice (BMP) to reduce the volume of stormwater runoff in urban environments. For some water quality constituents, greenroofs can improve runoff water quality but recent studies demonstrate greenroofs are sources rather than sinks of phosphorus (P). Accordingly, further research is required to evaluate treatment technologies that improve the performance of these BMPs. This study examined the use of two engineered media types to reduce phosphorus loadings from a greenroof located on the Archetype Sustainable House at Kortright in Vaughan, Ontario. A treatment system was installed to capture and remove P in stormwater runoff using sorptive properties of an engineered media. A mass balance approach was used to evaluate pre and post-treatment water quality. Pre and post-treatment water samples were collected for 25 rainfall events from July 11, 2009 to August 22, 2010 and analyzed for soluble reactive phosphorus (SRP), total phosphorus (TP), suspended solids (SS) and total dissolved solids (TDS). Storm events ranged in return frequencies from < 2 years to 35 year periods. The results show that the greenroof was a consistent source of P. The volume weighted mean concentrations were 0.769 mg/L and 0.630 mg/L for 2009 and 2010 events, respectively. The media used in 2009 reduced SRP loadings by 32.0% and TP loadings by 25.4%. The media evaluated in 2010, reduced SRP loadings by 82.4% and TP loadings by 86.6%. The greater P removal demonstrated by the 2010 media is attributed to a higher specific surface area and increased P sorptive capacity. Results of this study will help inform the use of sorptive materials in greenroof applications and a wider range of best management practices for stormwater quality treatment.

Forest soil phosphorus (P) chemical behavior was evaluated in some mid-rotation fertilized loblolly pine (Pinus taeda L.) plantations in East Texas, that differed in their site drainage characteristics. Forest floor mass and carbon content in the forest floor were determined. Total P (PT) in the forest floor, and total and Mehlich-1 P and citratedithionite (CD) and acid ammonium-oxalate (AAO) extractable P, Al, Fe, and Mn within the mineral soil upper 100 cm were determined. Colorimetric determination of AAOand CD-extractable P by the molybdenum blue ascorbic acid method, without the use of pre-digestion, was assessed by an automated continuous flow injection system. Phosphorus distribution between different operationally defined solid phases and its relationships with CD and AAO extractable Mn, Al, Fe among depth, site, drainage class and treatment were evaluated. Soil P forms were highly correlated with iron oxides across sites, drainage classes, treatments, and depth intervals with significant differences in P content and distribution in the soil profile and solid phases among drainage classes. Soil P distribution patterns differed among drainage classes, yet it followed the distribution of the iron oxides. Iron oxide’s role as a sink for soil P was higher in the well-drained compared to the poorly drained sites. Amorphous phases of iron oxides were higher in the poorly drained sites and dominated the role of iron oxides as a sink for P under the poor drainage conditions. Fertilization resulted in significantly higher forest floor mass, P content in the forest floor, and total P (PT) and CD-extractable P (Pd) in the soils’ upper 10 cm. The treatment effect on P in the forest floor, and on PT and Pd in the upper 10 cm of the mineral soil was equivalent to 6, 19, and 11% of the applied P, respectively. AAO-extractable P was highly correlated with Mehlich-1 P in the fertilized plots. Treatment and site drainage class effects on P accumulation in the different solid phases in the mineral soil and in the forest floor and the potential contribution of these pools to P availability in subsequent rotations, following clearcutting, are discussed.

Mineral nutrients imported in composted dairy manure (CDM) and municipal biosolid (CMB) amendments for highway-rights-of-way and urban landscapes can pose a threat to surface water quality. Treatments were developed to evaluate recommendations for amending roadside and urban soils with compost at large volumebased rates. Texas Department of Transportation (TxDOT) recommendations were evaluated in 2002 and 2003. Municipal recommendations were evaluated in 2004. Treatments were imposed on 4 by 1.5-m field plots on a constructed soil with an 8.5% slope. Three TxDOT compost application methods were tested; incorporation at 25% by volume (CMT), topdressing over vegetation (GUC), and topdressing a 5-cm compost woodchip mix over bare soil (ECC). In 2003, a 12.5% CMT treatment was substituted for the GUC, and two contrasting composts were compared. In 2002, soil test phosphorus (STP) concentrations (mg kg-1) were 291, 360, 410, and 1921 mg kg-1 in the 0 to 5-cm layer of a course textured CMT, fine textured CMT, GUC, and ECC treatments, respectively using CDM. In 2003, STP concentrations were 264, 439, 496,623, 1115, and 2203 mg kg-1, in the 0 to 5-cm layer after incorporation of CDM and CMB at the 12.5 and 25% volume-based rates, and topdressing the 5-cm CDM- or CMB-woodchip mix over bare soil, respectively. In 2004, contrasting CMB products, relatively low or high in total phosphorus (TP) were incorporated into the soil at 12.5 and 25% by volume, or imported in transplanted sod at the 25% by volume rate. The STP concentrations were 87, 147, 180, 301, 322, and 544 mg kg-1, respective to the previously defined treatments. Runoff water from 14, 10, and 8 natural rain events was used to characterize nutrient and sediment transport in 2002, 2003, and 2004, respectively. Concentration of TDP in runoff water was highly variable for roadside treatments across rain events. Mass losses of TDP were similar after CDM or CMB were incorporated into the soil at 12.5 and 25% by volume. Compost incorporation was the most effective method for limiting TP loss in runoff. Roadway and urban soils are expected to contribute greater TP losses as P concentration increases in soils.