Environmental Research Institute - Doctoral Theses

Smallholder agriculture and food and nutrition security: a study from south-eastern Tigray, Ethiopia

Sun, 01 Jan 2017 00:00:00 GMT

Smallholder agriculture and food and nutrition security: a study from south-eastern Tigray, Ethiopia Kahsay, Zenebe Abraha Smallholder agriculture is the mainstay of the economy of Tigray, northern Ethiopia. Households located in the food insecure south-eastern zone rely on agriculture for their livelihood. Supplementary income is obtained from a range of off/non-farm activities. Households in the area consume a restricted diet, dominated by cereals. This study examines smallholder agriculture and food and nutrition security of rural households using mainly survey data collected in the post- and pre-harvest seasons from 400 randomly selected households across four villages in Enderta and Hintalo-Wajerat districts. Quantitative and qualitative analyses were used. Households in the study area own small areas of land (average size only 0.8 ha), but with important differences across study villages and between gender of household heads, thereby influencing food availability. Ownership of livestock has also similar patterns. Wealthier households (generally correlated with higher income groups) both produce and consume more nutrient-rich food items. Off-farm income comprises 74% of female-headed households’ income (47% for male-headed households). A number of food security indicators were calculated by village, season and gender of household head. These indicators generally showed that food insecurity is higher in the preharvest season and amongst female-headed households. Location, livestock ownership and household income were significantly associated with the main food security indicators. Education level of mothers was associated with better food security in the pre-harvest season, supporting women’s empowerment to improved nutrition. Farming practices influence dietary diversity through a combination of production for ownconsumption and income effects. The study concludes that there is a need to develop policy and specific agricultural interventions to promote more nutrition-sensitive agriculture. This implies a range of actions, including promoting women’s empowerment. There is a need for enhanced promotion of information and knowledge at household level to encourage greater dietary diversity. Multisectoral policy making and implementation need to be strengthened.

Building resilience for social-ecological sustainability in Atlantic Europe

Fri, 01 Jan 2016 00:00:00 GMT

Building resilience for social-ecological sustainability in Atlantic Europe Scollick, Andrew Dale This thesis argues that complex adaptive social–ecological systems (SES) theory has important implications for the design of integrated ocean and coastal governance in the EU. Traditional systems of governance have struggled to deal with the global changes, complexity and uncertainties that challenge a transition towards sustainability in Europe’s maritime macro-regions. There is an apparent disconnect between governance strategies for sustainability in Europe’s maritime macro-regions and a sound theoretical basis for them. My premise is that the design of governance architecture for maritime regional sustainability should be informed by SES theory. Therefore, the aim of this research was to gain insight into a multilevel adaptive governance architecture that combines notions of sustainability and development in the context of the Atlantic Europe maritime macro-region. The central research question asked whether it is possible to achieve this insight by using a SES as a framework and analytical tool. This research adopted social ecology and sustainability science as a foundation for understanding society–nature relations. Concepts from complex adaptive systems, SES and resilience theories were integrated into a conceptual framework that guided the investigation and analysis. A study was conducted to conceptualise the European Atlantic social–ecological system (EASES). This was used to represent and understand the Atlantic Europe macro-region as a SES. The study examined the proposition that governance can be focused on building SES resilience to help achieve maritime regional sustainability. A workbook method was developed and used to elicit expert opinion regarding EASES. The study identified sources of resilience and resilience dynamics that require management in the context of multilevel adaptive governance. This research found that the Atlantic Europe macro-region is a key focal level for multilevel adaptive governance architecture. The majority of the findings are specific to Atlantic Europe and not generalisable to other maritime macro-regions in Europe.

Biomethane production from macroalgae

Fri, 01 Jan 2016 00:00:00 GMT

Biomethane production from macroalgae Tabassum, Muhammad Rizwan Irish brown seaweeds have been identified as a potential bio-resource with potentially high specific methane yields. Anaerobic digestion is deemed the most feasible technology due to its commercial viability for handling such wet feedstock. However, the biomethane potential of seaweed is highly dependent on its chemical composition which can vary by species type, cultivation method, and time of harvest. This study aims to investigate and optimize the process for the production of biomethane from Irish brown seaweeds focusing on the key technology bottlenecks including for seaweed characterization, biomethane potential assessment, optimization of long-term anaerobic digestion and suitable pre-treatment technologies to enhance potential gas yields. Laminaria digitata and Ascophyllum nodosum were tested for seasonal variation. From the characterization and batch digestion of L. digitata, August was found to be the optimal month for harvest due to high organic matter content, low level of ash and ultimately highest biomethane yield. The specific methane yield of 53 m3 CH4 t-1 wwt in August was 4.5 times higher than the yield in December (12 m3 CH4 t-1 wwt), with ash content the key factor in seasonal variation. For A. nodosum, the optimal harvest month was October with polyphenol content found to be a more influential factor than ash. The gross energy yields from both species were evaluated in the range of 116-200 GJ ha-1 yr-1. Continuous digestion trials were subsequently designed for S. latissima and L. digitata to optimize the key digestion parameters. Results from mono-digestion and co-digestion with dairy slurry revealed that both seaweeds could be digested at maximum biomethane efficiency to a loading rate of 4 kg VS m-3 d-1. Accumulation of salt in the digesters was a concern for long term digestion and it was reasoned that suitable pretreatment may be required prior to digestion. Various pre-treatments were subsequently tested on L. digitata to enhance the gas yield. It was found that maceration after hot water washing yielded 25% more specific methane and up to 54% salt removal as compared to untreated L. digitata. The experiments undertaken aim to assist in providing a basic guideline for feasible design and operation of seaweed digesters in Ireland.

Chamber investigations of atmospheric mercury oxidation chemistry

Thu, 01 Jan 2015 00:00:00 GMT

Chamber investigations of atmospheric mercury oxidation chemistry Darby, Steven B. Mercury is a potent neurotoxin even at low concentrations. The unoxidised metal has a high vapour pressure and can circulate through the atmosphere, but when oxidised can deposit and be accumulated through the food chain. This work aims to investigate the oxidation processes of atmospheric Hg0(g). The first part describes efforts to make a portable Hg sensor based on Cavity Enhanced Absorption Spectroscopy (CEAS). The detection limit achieved was 66 ngm−3 for a 10 second averaging time. The second part of this work describes experiments carried out in a temperature controlled atmospheric simulation chamber in the Desert Research Institute, Reno, Nevada, USA. The chamber was built around an existing Hg CRDS system that could measure Hg concentrations in the chamber of<100 ngm−3 at 1 Hz enabling reactions to be followed. The main oxidant studied was bromine, which was quantified with a LED based CEAS system across the chamber. Hg oxidation in the chamber was found to be mostly too slow for current models to explain. A seven reaction model was developed and tested to find which parameters were capable of explaining the deviation. The model was overdetermined and no unique solution could be found. The most likely possibility was that the first oxidation step Hg + Br →HgBr was slower than the preferred literature value by a factor of two. However, if the more uncertain data at low [Br2] was included then the only parameter that could explain the experiments was a fast, temperature independent dissociation of HgBr some hundreds of times faster than predicted thermolysis or photolysis rates. Overall this work concluded that to quantitatively understand the reaction of Hg with Br2, the intermediates HgBr and Br must be measured. This conclusion will help to guide the planning of future studies of atmospheric Hg chemistry.