Tracing organic matter composition and distribution and its role on arsenic release in shallow Cambodian groundwaters

Biogeochemical processes that utilize dissolved organic carbon are widely thought to be responsible for the liberation of arsenic from sediments to shallow groundwater in south and southeast Asia. The accumulation of this known carcinogen to hazardously high concentrations has occurred in the primary source of drinking water in large parts of densely populated countries in this region. Both surface and sedimentary sources of organic matter have been suggested to contribute dissolved organic carbon in these aquifers. However, identification of the source of organic carbon responsible for driving arsenic release remains enigmatic and even controversial. Here, we provide the most extensive interrogation to date of the isotopic signature of ground and surface waters at a known arsenic hotspot in Cambodia. We present tritium and radiocarbon data that demonstrates that recharge through ponds and/or clay windows can transport young, surface derived organic matter in to groundwater to depths of 44 m under natural flow conditions. Young organic matter dominates the dissolved organic carbon pool in groundwater that is in close proximity to these surface water sources and we suggest this is likely a regional relationship. In locations distal to surface water contact, dissolved organic carbon represents a mixture of both young surface and older sedimentary derived organic matter. Ground-surface water interaction therefore strongly influences the average dissolved organic carbon age and how this is distributed spatially across the field site. Arsenic mobilization rates appear to be controlled by the age of dissolved organic matter present in these groundwaters. Arsenic concentrations in shallow groundwaters (< 20 m) increase by 1 μg/l for every year increase in dissolved organic carbon age compared to only 0.25 μg/l for every year increase in dissolved organic carbon age in deeper (> 20 m) groundwaters. We suggest that, while the rate of arsenic release is greatest in shallow aquifer sediments, arsenic release also occurs in deeper aquifer sediments and as such remains an important process in controlling the spatial distribution of arsenic in the groundwaters of SE Asia. Our findings suggest that any anthropogenic activities that alter the source of groundwater recharge or the timescales over which recharge takes place may also drive changes in the natural composition of dissolved organic carbon in these groundwaters. Such changes have the potential to influence both the spatial and temporal evolution of the current groundwater arsenic hazard in this region

'Tell me what you eat' : representations of food in nineteenth century culture

Drawing upon the poststructuralist theories of Barthes, Derrida, Foucault and Lacan, this thesis analyses the multiple significations attached to food in nineteenth-century culture, and the art and literature of the Victorian bourgeoisie in particular. Chapter one utilises Lacanian theories of vision and desire in order to suggest that nineteenth-century representations of food are frequently caught up in a politics of display, constituting a feast for the eyes as well as the palate. It goes on to argue that the preoccupation with display in the middle-class dining room reveals something of the nature of bourgeois desire, as well as the fundamental instability of subjectivity. Chapter two examines the class-specific locations in which food was consumed, focusing on the special status accorded to the dining room in bourgeois culture. It also suggests that the picnic - a phenomenon which transported the middle classes outside of the security of the domestic realm - holds a disruptive, disorderly potential in representation, which ultimately undoes the inside/outside binary used to order Victorian eating spaces. Chapter three considers the relationship between food and nation in nineteenth-century art and literature, arguing that racial and cultural others are often portrayed in terms of food, functioning simultaneously as objects of desire - appetising dishes to enhance the white, British palate - and sources of anxiety, having a destabilising effect upon the hegemonic cultural identity when 'consumed'. Considered collectively, these chapters demonstrate that the act of eating is by no means an innocent one. Freighted with cultural significations both manifest and covert, caught up in complex networks of meaning relating to hierarchies of gender, race and class, food and its associated practices work to construct, as well as to nourish, the consuming subject.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

'Tell me what you eat' : representations of food in nineteenth century culture

Drawing upon the poststructuralist theories of Barthes, Derrida, Foucault and Lacan, this thesis analyses the multiple significations attached to food in nineteenth-century culture, and the art and literature of the Victorian bourgeoisie in particular. Chapter one utilises Lacanian theories of vision and desire in order to suggest that nineteenth-century representations of food are frequently caught up in a politics of display, constituting a feast for the eyes as well as the palate. It goes on to argue that the preoccupation with display in the middle-class dining room reveals something of the nature of bourgeois desire, as well as the fundamental instability of subjectivity. Chapter two examines the class-specific locations in which food was consumed, focusing on the special status accorded to the dining room in bourgeois culture. It also suggests that the picnic - a phenomenon which transported the middle classes outside of the security of the domestic realm - holds a disruptive, disorderly potential in representation, which ultimately undoes the inside/outside binary used to order Victorian eating spaces. Chapter three considers the relationship between food and nation in nineteenth-century art and literature, arguing that racial and cultural others are often portrayed in terms of food, functioning simultaneously as objects of desire - appetising dishes to enhance the white, British palate - and sources of anxiety, having a destabilising effect upon the hegemonic cultural identity when 'consumed'. Considered collectively, these chapters demonstrate that the act of eating is by no means an innocent one. Freighted with cultural significations both manifest and covert, caught up in complex networks of meaning relating to hierarchies of gender, race and class, food and its associated practices work to construct, as well as to nourish, the consuming subject.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

'Tell me what you eat': Representations of food in nineteenth century culture

Drawing upon the poststructuralist theories of Barthes, Derrida, Foucault and Lacan, this thesis analyses the multiple significations attached to food in nineteenth-century culture, and the art and literature of the Victorian bourgeoisie in particular. Chapter one utilises Lacanian theories of vision and desire in order to suggest that nineteenth-century representations of food are frequently caught up in a politics of display, constituting a feast for the eyes as well as the palate. It goes on to argue that the preoccupation with display in the middle-class dining room reveals something of the nature of bourgeois desire, as well as the fundamental instability of subjectivity. Chapter two examines the class-specific locations in which food was consumed, focusing on the special status accorded to the dining room in bourgeois culture. It also suggests that the picnic - a phenomenon which transported the middle classes outside of the security of the domestic realm - holds a disruptive, disorderly potential in representation, which ultimately undoes the inside/outside binary used to order Victorian eating spaces. Chapter three considers the relationship between food and nation in nineteenth-century art and literature, arguing that racial and cultural others are often portrayed in terms of food, functioning simultaneously as objects of desire - appetising dishes to enhance the white, British palate - and sources of anxiety, having a destabilising effect upon the hegemonic cultural identity when 'consumed'. Considered collectively, these chapters demonstrate that the act of eating is by no means an innocent one. Freighted with cultural significations both manifest and covert, caught up in complex networks of meaning relating to hierarchies of gender, race and class, food and its associated practices work to construct, as well as to nourish, the consuming subject

Dual in-aquifer and near surface processes drive arsenic mobilization in Cambodian groundwaters

Millions of people globally, and particularly in South and Southeast Asia, face chronic exposure to arsenic from reducing groundwater in which arsenic release is widely attributed to the reductive dissolution of arsenic-bearing iron minerals, driven by metal reducing bacteria using bioavailable organic matter as an electron donor. However, the nature of the organic matter implicated in arsenic mobilization, and the location within the subsurface where these processes occur, remains debated. In a high resolution study of a largely pristine, shallow aquifer in Kandal Province, Cambodia, we have used a complementary suite of geochemical tracers (including 14C, 3H, 3He, 4He, Ne, δ18O, δD, CFCs and SF6) to study the evolution in arsenic-prone shallow reducing groundwaters along dominant flow paths. The observation of widespread apparent 3H-3He ages of 30 m, and the relationships between age-related tracers and arsenic suggest that this surface-derived organic matter is likely to contribute to in-aquifer arsenic mobilization. A strong relationship between 3H-3He age and depth suggests the dominance of a vertical hydrological control with an overall vertical flow velocity of ~0.4 ± 0.1 m·yr−1 across the field area. A calculated overall groundwater arsenic accumulation rate of ~0.08 ± 0.03 μM·yr−1 is broadly comparable to previous estimates from other researchers for similar reducing aquifers in Bangladesh. Although apparent arsenic groundwater accumulation rates varied significantly with site (e.g. between sand versus clay dominated sequences), rates are generally highest near the surface, perhaps reflecting the proximity to the redox cline and/or depth-dependent characteristics of the OM pool, and confounded by localized processes such as continued in-aquifer mobilization, sorption/desorption, and methanogenesis

Roadmap on Li-ion battery manufacturing research

Growth in the Li-ion battery market continues to accelerate, driven primarily by the increasing need for economic energy storage for electric vehicles. Electrode manufacture by slurry casting is the first main step in cell production but much of the manufacturing optimisation is based on trial and error, know-how and individual expertise. Advancing manufacturing science that underpins Li-ion battery electrode production is critical to adding to the electrode manufacturing value chain. Overcoming the current barriers in electrode manufacturing requires advances in materials, manufacturing technology, in-line process metrology and data analytics, and can enable improvements in cell performance, quality, safety and process sustainability. In this roadmap we explore the research opportunities to improve each stage of the electrode manufacturing process, from materials synthesis through to electrode calendering. We highlight the role of new process technology, such as dry processing, and advanced electrode design supported through electrode level, physics-based modelling. Progress in data driven models of electrode manufacturing processes is also considered. We conclude there is a growing need for innovations in process metrology to aid fundamental understanding and to enable feedback control, an opportunity for electrode design to reduce trial and error, and an urgent imperative to improve the sustainability of manufacture