Concentrations of dissolved organic carbon (DOC) measured within water bodies have been increasing on a global scale over the last two decades. Changes in temperature and rainfall have been shown to increase the production and export of DOC from catchments with peat soils in the UK (Freeman et al., 2001). However it is not clear whether increases in DOC concentrations are caused by production increases induced by temperature changes or by a greater incidence of high flows induced by rainfall changes. Increases in both temperature and rainfall have been predicted in Scotland over the next few decades (Kerr et al., 1999) which may further increase current DOC concentrations and exports. The implications of this include both a decrease in water quality and an increase in mobility of metals in upland water bodies. The overall aim of the thesis is to determine if the relationship between dissolved organic carbon (DOC) concentrations and discharge has changed over a 20 year period in small stream catchments in Scotland, in order to better understand the role of hydrology, in driving changes in DOC concentration. To achieve this streams draining two coniferous forest sites and one moorland site were monitored intensively between June 2004 and February 2006. Analysis of the relationship between DOC and discharge, within the catchments, identified the importance of the amount of precipitation falling on the catchment, antecedent precipitation and season, on the concentration of DOC that was measured within the stream. Models were then developed using variables to represent these drivers in terms of both the production (seasonal sine values and 14 day average temperatures) and movement (log of discharge (log Q), days since previous storm event and rising or falling stage) of DOC. In the Ochil Hills catchment, the best predictive model, used 4 hour average discharge and 1 day average 30cm soil temperatures (R2= 0.88). In the Duchray and Elrig catchments, the best predictive models produced used discharge and seasonal sine values; the strength of the model was greater in the Elrig (R2= 0.80) than the Duchray (R2= 0.48) catchment. The strength of the regression models produced highlighted the importance of precipitation in the movement of DOC to the stream and temperature variables representing production in the surrounding catchment. To determine if dissolved organic carbon (DOC) concentrations had changed within the three study catchments, since previous research was conducted at the same sites in the early 1980s and 1990s (Grieve, 1984a; Grieve, 1994), then regression analysis conducted in the previous research was repeated, so changes in the DOC and discharge relationship could be identified. Analysis of the Ochil Hills regression equations identified higher log of discharge and lower temperature and seasonal sine values in the present study (2004-06), when compared to the previous study (1982-83). This suggests that more DOC is now available for movement from the soil, and that the difference between winter and summer DOC production has decreased, potentially because of increasing temperatures. This would explain the limited increase in DOC concentration within the Ochil Hills stream. In the Duchray and Elrig streams, a large increase in DOC was identified at all discharges when all the models produced were compared between the two sampling periods (1989-90 and 2004-06). The increasing trend in DOC concentrations is too large to have been produced by change in temperature alone and it is suggested that the measured reduction in acidic deposition has resulted in the increased DOC concentrations measured in the Duchray and Elrig. The results from this research have identified that concentrations of DOC have increased in Scottish streams over the last 20 years and that the increases in DOC have been induced, potentially by temperature changes in climate. However, changes in temperature are not the only driver of this change as the reduction in acidic deposition is potentially more important, specifically in areas with base poor geology such as the Duchray and Elrig catchments.

This research aimed to investigate an area of research that has largely been overlooked in the past, that is, the efficiency, profitability and sustainability of informal waste recycling in semi-urban areas. In exploring the research topic, a recycling buyback centre was used as a case study. The centre facilitates collection, sorting and selling of waste and is located in Senwabarwana, Northern Limpopo Province. Here the P.E.A.C.E (Planning, Education, Agriculture, Cooperatives and Environment) Foundation, an organisation looking at rural poverty alleviation in South Africa, initiated a flagship recycling buyback centre as a community project. This research picks up on prior research that was conducted on a similar project initiated by the same organisation in Ndumo, KwaZulu Natal. Even though the location is different from KwaZulu Natal, both Senwabarwana and Ndumo are faced with similar challenges affecting social, economic and environmental circumstances. Five objectives were identified to provide structure to this research. Through action research, the study assessed the sustainability of this recycling buyback centre with regard to the impact on social, economic and environmental factors within Senwabarwana. It also covered problems experienced in rolling out waste management initiatives within the semi-urban study location and assessed the municipal framework with regard to waste and how waste is managed and recycled. Furthermore, analyses of the waste data generated at the recycling centre was examined that culminated in offering solutions to the identified problems. Recommendations for acceptable practices in semi-urban waste management are made to enable further research and potentially up-scaling the project for application in other geographic areas. The study reports both qualitative and quantitative data collected through the investigation of the case study in the start-up phase. The data gathering was done through administering questionnaires to waste pickers associated with the case study centre. Telephonic and face-to-face interviews and secondary data were interchangeably used to address each of the five objectives. The results from the data gathered show that, if properly coordinated and structured, informal waste recycling in semi-urban communities is possible and can contribute positively to the socio-economic and environmental development of these areas. It is envisaged that this study would contribute to the body of knowledge already in existence, whilst also creating an opportunity for further academic research and input within this field to enable the scaling-up of such initiatives. / Environmental Sciences / M. Sc. (Environmental Science)