There has been a dramatic expansion of dairying in New Zealand in the last two decades. This has been accompanied by a series of environmental issues around water use and water pollution. This thesis looks at the issue of excess nitrogen and phosphorus lost off dairy farms to waterways using a mixed method approach. Qualitative interviews with dairy farmers and GIS based water quality modelling are employed to explore whether the introduction of nutrient benchmarks would achieve sustainable milk production systems. Two Best Practice Dairy Catchments, Waikakahi in South Canterbury and Inchbonnie on the West Coast, were investigated as the study areas. These catchments are part of an established DairyNZ program. Findings show that nutrient benchmarks do have the ability to achieve sustainable milk production systems in the catchments. It presents the implications and recommendations for the benchmarking project.

The water quality in the United States has greatly improved since the implementation of the Clean Water Act (CWA) in the early 1970s. Unfortunately, the Clean Water Act only addresses one kind of water pollution, point source pollution. The major problem that is present in the degradation of todays water quality has to deal with nonpoint source pollution. Agriculture is commonly regarded as the leading contributor to nonpoint source pollution in the United States. This study uses two analytical tools to try to determine the significant factors in the transport of pollutants in the Lower Kentucky Watershed, located in central Kentucky. Spatial analysis (GIS) coupled with the statistical analysis (SAS), allowed for significant factors to be identified within a small proximity of sampling sites throughout the watershed. The results suggest that although agriculture is commonly regarded as the largest contributor to nonpoint source pollution, other factors outside of agriculture were also found to be significant, such as resident land use and rainfall. The results generated from this study suggest that land managers in communities throughout the watershed should analyze agricultural factors, as well as, factors outside of agriculture, in an effort to protect their communities water quality.

The western Antarctic Peninsula (WAP) is a hotspot of climatic and oceanographic change, with a 6°C rise in winter atmospheric temperatures and >1°C warming of the surface ocean since the 1950s. These trends are having a profound impact on the physical environment at the WAP, with widespread glacial retreat, a 40% decline in sea ice coverage and intensification of deep water upwelling. The main objective of this study is to assess the response of phytoplankton productivity to these changes, and implications for the marine carbon and nitrogen cycles in the WAP coastal zone. An extensive suite of biogeochemical and physical oceanographic data was collected over five austral summer growing seasons in northern Marguerite Bay between 2004 and 2010. Concentrations and isotopic compositions ( 15N, 13C, 14C) of dissolved nitrate, dissolved inorganic carbon species, particulate nitrogen, organic carbon and chlorophyll a are used in the context of a substantial ancillary dataset to investigate nutrient supply, phytoplankton productivity and nutrient uptake, export flux and the fate of organic material, and the factors underpinning pronounced seasonal and interannual variability. High-resolution biogeochemical time-series data for surface and underlying seawater, sea ice brine, sediment trap material and coretop sediments allow detailed examination of carbon and nitrogen cycle processes under contrasting oceanographic conditions and the interaction between these marine processes and air-sea exchange of climate-relevant CO2. This study shows that the WAP marine environment is currently a summertime sink for atmospheric CO2 in most years due to high productivity and biological carbon uptake sufficient to offset the CO2 supply from circumpolar deep waters, which act as a persistent source of heat, nutrients and CO2 across the shelf. For the first time, CO2 sink/source behaviour is parameterised in terms of nitrate utilisation, by exploiting the relationship between CO2 and nitrate concentrations, and deriving the nitrate depletion at which surface ocean CO2 is undersaturated relative to atmosphere and carbon sink behaviour is achieved. This could have vast utility in examining CO2 sink/source dynamics over greater spatial and temporal scales than by direct CO2 measurements, of which availability is more limited. This study documents abrupt changes in phytoplankton productivity, nitrate utilisation and biological CO2 uptake during a period of rapid sea ice decline. In fact, nitrate utilisation, particulate organic matter production and biological CO2 uptake all decrease by at least 50 % between a sea ice-influenced, high productivity season and one of low sea ice and low productivity. The key driver of interannual variability in production and export of organic material is found to be upper ocean stratification and its regulation of light availability to phytoplankton. Productivity, CO2 uptake and export are maximal when stratification is sufficient to provide a stable well-lit surface environment for phytoplankton growth, but with some degree of mixing to promote export of suspended organic matter. Strong stratification causes intense initial production, but retention of suspended organic particles in the surface ocean induces a self-shading effect, and overall productivity, CO2 uptake and export fluxes are low. When stratification is weak, mixing of phytoplankton over a larger depth range exposes cells to a wider range of light levels and reduces photosynthetic efficiency, thus total productivity and CO2 uptake. A conceptual model is developed here, which attempts to describe the mechanism by which sea ice dynamics exert the principal control on stratification and therefore productivity and CO2 uptake at the WAP, with potential application to other regions of the Antarctic continental shelf. Although meteoric waters (glacial melt and precipitation) are more prevalent in surface waters throughout the study, sea ice meltwater variability is driven by large and rapid spring/early summer pulses, which stabilise the upper ocean and initiate phytoplankton growth. The timing and magnitude of these sea ice melt pulses then exert the key control on stratification and seasonal productivity. In a low sea ice year of this study, the sea ice trigger mechanism was absent and productivity was low. This strongly suggests that ongoing sea ice decline at the WAP and greater frequency of such low sea ice years is likely to drive a dramatic reduction in productivity and export, which would substantially reduce the capacity of the summertime CO2 sink in this region. Ongoing warming and ecosystem change are thus likely to have severe impacts on net CO2 sink/source behaviour at the WAP over the annual cycle, and the role of the Southern Ocean in regulating atmospheric CO2 and global climate. Finally, factors influencing the stable isotopic signature of particulate organic carbon ( 13CPOC), a common paleo-proxy, are assessed. 13CPOC is greatly influenced by seasonal shifts in diatom assemblages and isotopically heavy sea ice material, so cannot be used as a robust proxy for ambient CO2 in the coastal Southern Ocean.

High levels of phosphorus loading in Lake Winnipeg, Manitoba, Canada are causing eutrophication and algal blooms of increasing intensity and frequency. Phosphorus is also a strategic and limited natural resource critical for plant growth, and essential for agriculture and global food security. This research study demonstrated an innovative environmental engineering approach to address multiple sustainable development challenges. Cattail (Typha spp.), a large competitive emergent aquatic plant, was harvested to capture and remove nutrients that would otherwise cause eutrophication in aquatic systems, and utilized as a biomass material for industry. Cattail reaches maturity in less than 90 days, and late summer/early fall harvests yielded average 15 to 20 t DM/ha, and captured 30 to 60 kg/ha/year of phosphorus. Once harvested, nutrients locked in plant tissue are prevented from being released into the environment via natural decomposition. Utilizing harvested biomass as a bioenergy feedstock provided a further benefit displacing fossil fuels for heating, and generated valuable carbon offsets. Cattail was compressed into densified fuel products, and combustion trials revealed an average calorific heat value of 17 MJ/kg to 20 MJ/kg, comparable to commercial wood pellets. Average ash content was 5 to 6%, and no major concerns identified regarding combustion emissions and ash. Estimated greenhouse gas (GHG) mitigation potential from coal displacement was one tonne of cattail biomass generated 1.05 tonnes of CO2 offsets. Additionally, up to 88 % of total phosphorus was recovered in ash following combustion in solid fuel burners. Harvesting cattail biomass offers greatest feasibility if combined for multiple purposes: nutrient capture, habitat, bioenergy, carbon offsets, water quality credits, and higher value end products and biomaterials (i.e. biochar). Economics of harvesting need to be further explored at the pilot and commercial scale for this novel renewable and sustainable ecological biomass feedstock. From an agricultural context, this biomass resource is presently undeveloped. It is a plant species prized for its nutrient capture and water quality benefits, and a biomass feedstock for bioenergy and high value end-products that grows on marginal agricultural land, not competing with prime land and food crops.

I investigated the usefulness of phytoplankton for the removal of surface water contaminants. Three experiments, consisting of nine large mesocosms (92.2 m3) were suspended in the flooded DJX uranium pit at Cluff Lake (Saskatchewan, Canada), and filled with contaminated mine water. During the summer of 2003, each mesocosm was fertilized with a different amount of phosphorus throughout the 35 day experiment to stimulate phytoplankton growth, and to create a range in phosphorus load (g) to examine how contaminants may be affected by different nutrient regimes. Algal growth was rapid in fertilized mesocosms as demonstrated by chlorophyll a profiles. As phosphorus loads increased there were significant declines in the surface water concentrations of As, Co, Cu, Mn, Ni, and Zn. This decline was near significant for uranium. The surface water concentrations of Ra226, Mo, and Se showed no relationship to phosphorus load. Contaminant concentrations in sediment traps suspended at the bottom of each mesocosm generally showed the opposite trend to that observed in the surface water, with most contaminants (As, Co, Cu, Mn, Ni, Ra226, U, and Zn) exhibiting a significant positive relationship (P < 0.05) with phosphorus load. Sediment trap concentration of Se and Mo did not respond to nutrient treatments. Similar experiments were repeated during the mid- and late-summer of 2004, with 5 mesocosms being fertilized with phosphorus, and another 4 with both phosphorus and ammonium to create different nutrient gradients. Results from these experiments were much more variable than those seen in the experiment conducted in 2003, and small samples (n = 5 for phosphorus treatments and n = 4 for both phosphorus and ammonium treatments) yielded insufficient statistical power to effectively determine statistically significant trends. However, contaminant sedimentation tended to respond to phosphorus treatments in a similar manner as results from 2003; phosphorus-with-ammonium treatments had little positive effect on contaminant sedimentation rates. My results suggest that phytoremediation has the potential to lower many surface water contaminants through the sedimentation of phytoplankton. Based on our results from 2003, we estimate that the Saskatchewan Surface Water Quality Objectives (SSWQO) for the DJX pit would be met in approximately 45 weeks for Co, 65 weeks for Ni, 15 weeks for U, and 5 weeks for Zn if treated using phytoremediation.Note:Appendix A content (pages 92-95) contains copyrighted material which has been removed. It can be viewed in the original thesis upon request.

We examined the physical and chemical soil characteristics in the cleared riparian areas at the Sooke Lake Reservoir, where the growing population has necessitated the expansion of the drinking water reservoir in Victoria, British Columbia. Additionally, hydrologic functioning was studied to establish the pathways riparian nutrients followed to the reservoir. In order to understand the potential release of nitrogen and phosphorous following inundation, both saturated riparian and upland areas were chosen as part of 17 transects encompassing the entire reservoir in four major soil types (Morainal, Colluvial, Fluvial and Organic). Various nutrient concentrations (TDP, TP. PO43- DOC, TC, IC, NO3-, NO2, NH4+, TN, TDN) were measured in relation to geomorphic features. Areal analyses confirm the hypotheses that nutrient concentrations differ with soil type, depth (0-10 cm, 10-30 cm, 30-60 cm) and hill slope. Hydrologic data established that seasonality and therefore transect connectivity is an important aspect for nutrient transport in the riparian areas via leaching and preferential flowpaths.

Dendrochronological techniques are currently limited to the identification of visible fire scars. However, through the development of new dendrochemical techniques, the potential exists to provide insight into a broader array of pyric ecosystems. In addition, the ability to identify historic climate-growth responses provides a better understanding of the conditions under which historic fire regimes occurred. This study provides the groundwork for the identification of a dendrochemical nutrient fire signature in xylem and identifies the climate-radial growth responses of loblolly pine (Pinus taeda L.) on five sites in the Piedmont of South Carolina. Changes in N, P, K, Ca, Mg, Zn, Cu, Mn, Fe, S, and Na concentrations in xylem as a result of a single fire were examined. The influences of monthly mean temperature, monthly total precipitation, Palmer Drought Severity Index (PDSI), Palmer Hydrological Drought Index (PHDI), and selected ocean-atmospheric oscillations such as El Nino-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), and Southern Oscillation Index (SOI) on radial growth using univariate and multivariate techniques were also assessed. Soil and duff analyses indicated sites were similar, but nutrient poor. Xylem mobile and immobile nutrient concentration analyses differed significantly through time for N, P, K, Ca, Mg, Zn, Cu, Mn, and S. No interactions were significant, thus identification of a nutrient fire signature was unsuccessful. The lack of significant interactions is attributed to the methodology used to collect the xylem nutrient samples; however, immobile nutrients indicate the most potential for future research. Climate-tree growth analyses indicate climate plays a role in the growth of mature loblolly pine in the South Carolina Piedmont. Temperature, precipitation, PDSI, positive phase NAO, and positive phase PDO are the primary drivers of loblolly pine radial growth. Temporal consistency results suggest drought sensitivity increases with tree age. Unlike the climate variables, the relationships between ocean-atmospheric oscillations and radial growth appear to be more cyclical in nature and only influence growth in positive phases.

Humans impact rivers in many ways that modify ecological processes yielding ecosystem services. In order to mitigate anthropogenic impacts, scientists are challenged to understand interactions among physicochemical factors affecting large river food webs. An understanding of socioeconomic factors also is critical for ecosystem management. In this dissertation, I explore spatiotemporal patterns in floodplain river food webs and political barriers to management of environmental flows, an important factor influencing river ecology. In Chapter II, I reviewed the scientific literature to test conceptual models of river food webs and predictions of environmental factors that might produce variation in basal production sources supporting consumer biomass. My review indicates that algae are the predominant production source for large rivers worldwide, but consumers assimilate C3 plants in rivers 1) with high sediment loads and low transparency during high flow pulses, 2) with high dissolved organic matter concentrations, and 3) following periods of high discharge or leaf litter fall that increase the amount of terrestrial material in the particulate organic matter pool. In Chapter III, I descrobe field research conducted to examine relationships among hydrology, nutrient concentrations, turbidity, and algal primary production and biomass in the littoral zone of five rivers in Texas, Peru, and Venezuela differing in physicochemical conditions. I used stable isotope signatures to estimate contributions of algal-versus terrestrial-based production sources to consumers during different hydrologic periods. My research indicates that during flow pulses in floodplain rivers, a decrease in algal biomass and productivity, combined with increased inputs of terrestrial organic matter, can result in increased terrestrial support of metazoan consumers in the aquatic food web. In 2007, Texas Senate Bill 3 directed that environmental flow recommendations be developed for river basins. Despite emphasis on use of the "best available science" to develop environmental flow regimes and "stakeholder involvement" to address needs of all water users, for the first two basins to complete the SB3 process, final environmental flow rules did not mimic a natural flow regime. In Chapter IV, I reviewed this process, concluding that incentives for river authorities to increase compromise with diverse stakeholders should result in more sustainable management of freshwater.

Syftet med denna studie har varit att utvärdera och granska den första tidsperioden av det unika projektet Enskilda avlopp i kretslopp samt åtgärder som genomförts inom jordbruket för minskad näringsbelastning i Stavbofjärden tillrinningsområde i Södertälje kommun. Utmaningar med projektet redovisas också för att undersöka möjligheten för andra kommuner att ta efter initiativet. För att uppnå syftet har litteraturstudier och semistrukturerade intervjuer genomförts. Arbetet är en fallstudie av utvärderande karaktär och har genomförts i Stavbofjärdens tillrinningsområde. Problemen med övergödning är stora i Stavbofjärdens tillrinningsområde och idag arbetar man aktivt för att minska näringsbelastningen. Sedan tre år tillbaka pågår projektet Enskilda avlopp i kretslopp för att försöka minska övergödningsproblematiken och möjliggöra återföring av näringsämnen till åkermark. Att avlopp kretsloppsanpassas innebär att klosettvatten samlas i en sluten tank skilt från bad, disk och tvättvatten (BDT- vatten). Därefter behandlas fraktionen för att göra den fri från smittämnen, bearbetad näring sprids slutligen på åkermark. I anslutning till detta har aktörer inom jordbruket arbetat med att försöka sluta kretsloppet och minska näringsutsläppen till Stavbofjärden. Flertalet åtgärder har genomförts under projektets första fas, bland annat har en kretsloppspolicy antagits, en lokal behandlingsanläggning har byggts och näringsämnen har börjat återföras till åkermark. Tydliga strukturella förändringar har skett under de första åren av projektet, framförallt har samarbetet mellan olika aktörer i tillrinningsområdet stärkts. Förutsättningarna för att nå en förbättrad vattenkvalitet i Stavbofjärden förbättras i och med genomförda och planerade åtgärder. Däremot uppstår en rad utmaningar i och med att avloppsfraktioner sprids på åkermark. Intervjuer och litteraturstudier har visat att användning av slam från reningsverk på åkermark inte är en helt okontroversiell fråga, mestadels på grund av en oro för eventuella effekter av de hormoner och läkemedel som kan förekomma i fraktionerna. Andra utmaningar är att byte av avloppssystem innebär en hög investeringskostnad och att människor ofta känner sig otrygga vid stora förändringar. Alla deltagande aktörer i projektet hänvisar till det faktum att människans avfall måste hamna någonstans och att det är betydligt bättre att lägga avfallet på jorden än att det läcker ut i vattnet eftersom det finns betydligt fler nedbrytande bakterier i jorden än i vatten. / The purpose of this study was to evaluate and examine the first period of the unique project Enskilda avlopp i kretslopp and actions implemented in the agriculture sector to reduce nutrient loading in Stavbofjärden. The idea was to provide an overall assessment of the current situation and discuss the possible future effects of the work. Challenges of the project are also discussed to examine the possibility for other communities to follow the initiative. To achieve the purpose, a study of literature and semi-structured interviews were conducted. The work is a case study of the evaluative nature and has been implemented in Stavbofjärdens catchment area.  Today several actors in Södertälje kommun are working actively to reduce nutrient loading in Stavbofjärdens catchment area. For the past three years, the project has been carried out in order to reduce eutrophication and enable recycling of nutrients to cropland. Within the project framework toilet water is collected in a closed tank separate from the bath, sink and wash water, the fraction is then processed in a facility and spread on farmland. In connection with this, the agriculture sector tries to close the cycle and reduce nutrient discharges to Stavbofjärden. Several measures have been implemented during the project's first phase, a recycling policy has been adopted, a local treatment facility has been built and nutrients have begun return to arable land. Distinct structural changes have occurred in the first years of the project, in particular, cooperation between different actors in the catchment area strengthened. The prospects for achieving improved water quality in Stavbofjärden increasing with the implemented and planned measures. The project also raises a number of challenges. Interviews and literature studies have shown that the use of sludge on farmland is not an entirely uncontroversial issue, mostly because of a concern about the possible effects of hormones and medicine which may occur in factions. Other challenges are that the replacement of sewer means a high investment cost and that people feel insecure when major changes happens. All actors involved in the project refers to the fact that human waste has to end up somewhere, and that it is much better to put the waste on soil than it leaks out in the water because there are far more degrading bacteria in the soil than in water.

The exotic Pinus plantations of southeast Queensland occupy approximately 130 000 ha and are prominent in catchments which drain to estuarine and marine waters that are economically, socially, and environmentally important. Recently, the deterioration of estuarine and marine water quality has raised concerns about the possible off-site impacts from the intensive management of the Pinus estate in southeast Queensland. Additionally, forest managers have raised questions over the effects of the currently adopted management practices on soil, water, and nutrient resources within plantations. A paucity of information regarding the impacts of these plantations in the humid sub-tropics of southeast Queensland initiated the research presented here. The objectives of this study were to: (i) determine the influence specific Pinus management techniques (harvesting, site-preparation, prescribed burning and forest roads) have on runoff generation; (ii) quantify fluxes of some nutrients (nitrogen (N), phosphorus (P), dissolved organic carbon (DOC) and iron (Fe)) and suspended solids (SS) in runoff from these management treatments; and, (iii) assess the overall effectiveness of the currently adopted Best Management Practices (BMP's) in protecting on-site soil, water and nutrient resources, as well as protecting off-site waters from pollution. The study site was located in an intensively managed sub-catchment within the Beerburrum State Forest Pinus plantation on the coastal plain of the Pumicestone region, southeast Queensland. This study was established in October 2001 and consisted of a 141 ha catchment based investigation into water quality and hydrology, which received a 50 ha harvest treatment in February and March 2002. Water was monitored for two water years (October 2001 - September 2003), and incorporated site-preparation and the establishment of the subsequent rotation. The influence of a forest road stream crossing was also monitored in this component of the investigation. Two discrete forest road plots were monitored for the same period to measure the response of runoff, nutrient and sediment fluxes to different road surface materials (gravelled and ungravelled), road maintenance and traffic intensity. Rainfall simulation was used on small plots covering specific management treatments (clearfall harvest, cultivation, fertilised cultivation, prescribed fire and established trees) within the general plantation area to determine their influence on water, sediment and nutrient fluxes. The investigation in the catchment receiving inter-rotation management revealed that that there was very little difference in water quality indices up and downstream of the forest road stream crossing, which suggests that road borne runoff contributed only minor amounts of N, P, Fe and SS to the stream. Perched groundwater quality within the general plantation area was similar to that observed in the adjacent stream. Water quality monitoring within the Coochin-Mellum and Coonowrin Creek catchments showed that the mean annual concentrations of N and P in surface waters were highest from catchments hosting agriculture and residential areas, respectively. Mean annual DOC and Fe concentrations were highest from the catchment hosting native Wallum vegetation. The mean annual concentration of SS was highest from an unmanaged native forest catchment. The rainfall simulation on specific management treatments revealed that mean losses of N and P from unfertilised and unburnt treatments were comparable to loads reported from catchment scale studies in the Pinus plantations of south-east Queensland. Mean SS loads from all treatments were considerably higher than stream loads reported in the literature from catchment scale investigations, and suggest that the currently adopted mitigation practices between the general plantation area and streams are effective in promoting the deposition of entrained solids. The investigation into gravelled and ungravelled forest roads revealed that the mean runoff coefficient (runoff depth / rainfall depth) was consistently higher from the gravelled road plot with 0.57, as compared to the ungravelled road with 0.38. Total sediment loss over the two year period was greatest from the gravelled road plot. Suspended solids contributed 86% of the total sediment loss from the gravelled road and 72% from the ungravelled road over the two years. When road and drain maintenance (grading) was performed runoff and sediment loss was increased from both road types. It should be noted that the results presented herein were based on only two water years, and both years experienced below average rainfall. As such it is important that future research in a catchment prone to waterlogging be conducted over a longer term so as to increase the chance of quantifying water, nutrient and sediment fluxes in response to average and above average rainfall years. It is likely that in above average rainfall years the results for nutrient and sediment fluxes from the general plantation area would be significantly different as runoff would be more readily generated and sustained for longer periods. Overall, the research presented suggests that the management of an exotic Pinus plantation during the inter-rotation period results in relatively low fluxes of N, P, SS Fe and DOC in stream water and vindicates the use of the current practices in protecting on-site water, soil and nutrient resources.