Thesis (Ph. D.)--Ohio State University, 2004. / Title from first page of PDF file. Document formatted into pages; contains xv, 214 p.; also includes graphics (some col.). Includes bibliographical references (p. 194-206). Available online via OhioLINK's ETD Center

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis - Amsterdam.

Dissolved organic matter (DOM) is found in all freshwaters globally, by dissolving in rainwaterduring its path through soil and on to oceans via. rivers and streams. To provide potable water fit for human consumption, selected streams and rivers are used by either direct abstraction, or by diversion into reservoirs prior to treatment. For ca.100 years, chlorine and its compounds have been used by water treatment companies to disinfect water. However, research has shown that reactions between chlorine and DOM can produce compounds (disinfection by-products, or DBPs) which may be hazardous to human health. This thesis explores the relationship between catchment character, organic matter concentration, and the potential formation of DBPs. In particular, trihalomethanes (THMs) were measured as these are currently the only regulated DBPs in the UK. To achieve this, water samples were collected quarterly over one year from two contrasting catchments, to study seasonal variations in DOM concentration and character. A third catchment was also sampled, with similar catchment characters to the first two catchments, to determine whether geographical location and land use types affected the data. Each catchment was studied to see if catchment characteristics (e.g. class of vegetation, soil type or bedrock) could be mapped using a Geographical Information Systems (GIS) approach), to observe any effects on DOM and/or the DBPs found in treated water, with the aim of producing a risk assessment map to aid the choice of future abstraction locations for drinking water. Hence, samples were chlorinated and chloraminatedin the laboratory before being analysed for DBP formation and residual chlorine concentrations were measured. Catchment specific GIS derived data were statistically analysed with water chemistry data, and detected relationships were explored statistically. Major findings include medium to strong positive correlations between the standardised THM4 (STHM4 - the concentration of THM4 formed from 1 mg L-1 dissolved organic carbon (DOC)) concentration and geology, where an increase of the area of inland rock in a catchment increases STHM4 concentration. Medium strength positive correlations were found between STHM4 and vegetation classes, where, as the area of acid grassland, and heather increase, so does the concentration of STHM4. Negative relationships were discovered showing the obverse, where, as loamy and clayey floodplain soils with naturally high groundwater increased in area, STHM4 concentration dropped (at the Hampshire Avon ii and Conwy catchments combined). The occurrence of coniferous woodland in a catchment was found to correlate with the CHCl3 formation potential of waters (Pearsons, f=0.530, p= < 0.05, n=20), supporting findings in published literature. Laboratory based chlorination and chloramination of sample waters, followed by gas chromatography provided DBP data, specifically THM4. These data show that more chloroform was formed after chlorination than chloramination, and that chloramination formed 3 times more CHBr3 (another THM4 compound) than chlorination, under laboratory formation potential conditions. Results showed that the chlorination of water prior to DOM removal could result in a THM4 concentrations 5 times greater than the current UK regulatory limit, per mg L-1 dissolved organic carbon (DOC), whereas chloramination forms ca.5 times less than the current UK regulation per 1 mg L-1 DOC. However, chlorination of water prior to DOM removal is never done in practice, so this data provides information on the composition of the organic matter and whether DOM from a specific catchment contains specific components that are responsible for an increase in a specific DBP. Data also show that increasing organic nitrogen or organic carbon does not necessarily increase nitrogenous or carbonaceousDBPs (N-DBPs or C-DBPs). However, importantly, data shows that an increase in the area of land use classed as 'urban', results in an increase in DON (likely due to human influences) in the water draining from them, posing potential issues for eutrophication in downstream water bodies and the formation of N-DBPs at water treatment works. Whilst N-DBP detection was explored from several different angles, the development of a definitive method was not possible due to very low N-DBP concentrations, time and financial constraints. However, various methods were adapted to aid in the detection of them, showing promising initial results, providing the background for future projects into the discovery of a suite of N-DBPs such as haloacetonitriles and halonitromethanes. Finally, the data in this thesis have been inputted into maps for each major catchment to present data with a high visual impact, but also to illustrate land use types that have been found to correlate with increases in DBPs and specific nutrients in the water draining from them. However, the high variation in DOM concentration and character from site to site make extrapolation of these risk assessment data, to other catchments, unsafe. Nevertheless, collection of data from a catchment (similar to the work presented here) where a new water abstraction location is desired can prove advantageous in providing information to utility companies of what difficulties they may encounter when treating the water. Though this can be done by grab sampling at each site of interest, this can prove costly and timely and involves both field and laboratory based work aspects, wheras the method presented here requires less cost and time, once the method is initialised, to derive data of similar value. Despite the fact that disinfection performance would always trump DBP minimalisation, this is likely to be a vital tool in ensuring the provision of safe and healthy water fit for the consumption of an ever increasing human population.

Pulse crops grown in prairie crop rotations can provide greater carbon (C) inputs than non-pulse crops in rotation and reduce nitrogen (N) fertilizer requirements. The aim of this research was to estimate the aboveground (ABG) and belowground (BG) partitioning of C and N inputs to soil from continuous (three year) chickpea (CP), lentil (L) and pea (P) systems and from CP, L and P grown in rotation with mustard (M) or wheat (W). Stable isotope techniques were used to label plants grown in a greenhouse and track residue C and N inputs to the bulk soil, heavy fraction organic matter (HF), light fraction organic matter (LF), very light fraction organic matter (VLF), water extractable organic matter (WEOM), the soil microbial biomass (SMB) and the inorganic N pool. Repeat-pulse 13CO2-labeling and shoot 15N-labeling techniques revealed rhizodeposition of C and N was higher in non-continuous pulse crop systems (P-M-CP, P-W-CP, CP-W-CP, L-W-L, P-M-P and P-W-P), than in continuous CP, L and P. Belowground residue (roots and rhizodeposits) C made up 35%, 30% and 33% of total residue C in the continuous CP, L and P, respectively. Belowground residue C made up 50%, 43% and 25% of total residue C in CP, L and P in rotation with M or W, respectively. Belowground-N made up a greater proportion of total residue N than ABG-N in the continuous CP (56%), L (53%) and P (68%) systems, and in the non-continuous CP (76%), L (70%) and P (62%) rotations. Soil pool C and N did not differ between continuous CP, L or P, nor did it differ between the non-continuous CP, L or P rotations. There were no differences between M and W, as the ABG and BG residue C and N in the M pulse crop rotations did not differ from that of the W pulse crop rotations. There was a greater amount of C derived from rhizodeposition (CdfR) and N derived from rhizodeposition (NdfR) in the bulk soil and in the very light fraction organic matter (VLF) of the non-continuous pulse crop rotations, than in the continuous pulse crop systems. This research demonstrates the importance of BG inputs of C and N to soils from CP, L and P grown in rotation with M and W.

No description available.

River networks act as a link between components of the terrestrial landscape, such as soils and groundwater, with the atmosphere and oceans, and are now believed to contribute significantly to global budgets of carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The idea of rivers being an inert conduit for carbon and nitrogen to reach the coast has been challenged recently, with considerable processing of carbon and nitrogen occurring in both the water column and bed sediments in the various aquatic components that make up a river network, including lakes, streams, rivers and estuaries. Although understanding of the cycling of carbon and nitrogen has improved markedly in the last 20 years, there is still much uncertainty regarding the production and emission of greenhouse gases (GHGs) linked to this processing across river catchments and few studies have quantified GHG fluxes from source to sea. Therefore this study aimed to a) understand the spatial and temporal saturations and fluxes of GHGs from both the freshwater River Tay catchment (Scotland) and the River Tay estuary, and b) understand what controls the production of GHGs within both a freshwater lake and across multiple sites in the freshwater river using laboratory incubations of sediment. Hotspots of in-stream production and emission were evident both in the freshwater catchment and the estuary, with significant temporal and spatial variability in saturation and emission (density) for CH4, CO2 and N2O. CH4 emission densities, across the freshwater river sites, ranged from 1720 to 15500 μg C m-2 d-1 with a freshwater catchment wide mean of 4640 μg C m-2 d-1, and in general decreased from upland to lowland sites along the main river stem, with notable peaks of emission in a lowland tributary and at the outflow of a lowland loch. This corresponds well with the main drivers of spatial variability which include allochthonous inputs from gas rich soil waters and in-situ production in fine grained organic rich sediments. CH4 production was observed to be higher in the lowland tributaries (R. Isla 4500 μg C m-2 d- 1) compared to main-stem river sites both in the lowland river (129 μg C m-2 d-1) and upland river which displayed an uptake of CH4 (-1210 μg C m-2 d-1). The main driver of spatial variability in CH4 production rates was the quality of the sediment, as production was higher in fine grained sediments rich in carbon compared to sand and gravels with a low carbon content. CH4 production also varied seasonally, with temperature and seasonal variation in sediment quality as the predominant driving factors. CO2 emission densities across the freshwater catchment ranged from 517 to 2550 mg C m-2 d-1 with a catchment mean flux density of 1500 mg C m-2 d-1. Flux densities on the whole increased along the main river stem from upland sites to lowland sites, with higher fluxes in lowland tributaries. Seasonally, CO2 flux density was highest in late summer and autumn and lowest in winter at most sites, highlighting the importance in seasonal environmental controls such as temperature, light, and substrate availability. Production rates in the sediment increased from upland to lowland sites with highest production rates evident in the lowland tributaries, and in autumn sediment samples. N2O emission density also showed considerable spatial and seasonal variation across the catchment with flux densities ranging from 176 to 1850 μg N m-2 d-1 with a mean flux of 780 μg N m-2 d-1. Mean fluxes were highest in the lowland tributaries and lowest in the upland river with sediment experiments finding similar spatial variation in N2O production. On the whole, in-stream N2O production and emission across the freshwater catchment was driven by increases in nutrient concentration (NO3 -, NH4 +) which in turn was related to the proportion of agricultural landuse. The saturation and emission of GHGs also varied substantially both spatially and temporally in the River Tay estuary, with a mean emission density of 2790 μg CH4-C m-2 d-1, 990 mg CO2-C m-2 d-1 and 162 μg N2O-N m-2 d-1. The spatial variability of GHG concentrations and emission densities in the estuary were predominantly controlled by the balance between lateral inputs (from tidal flushing of surrounding intertidal areas), in-situ microbial production/consumption (both in the water column and bed sediments) and physical mixing/loss processes. Although emission densities of CH4, CO2 and N2O appear low compared to the freshwater river, this is because the estuary is emitting large quantities of gas in the middle and outer estuary, for example net annual emission of N2O increased from 84.7 kg N2O-N yr-1 in the upper freshwater section of the estuary to 888 kg N2O-N yr-1 in the middle estuary section, then decreased to 309 kg N2O-N yr-1 in the saltwater lower estuary. Overall, this study has shown that both dissolved and aerial fluxes of GHGs vary markedly both spatially and temporal from source to sea in a temperate river catchment, with hotspots of in-stream production and emission across the river catchment. The catchment (river, lake and estuary) was a smaller source of CO2, CH4 and N2O emission (total emission and by area) compared to other highly polluted aquatic systems both in the UK and globally.

This thesis explores the ecology of a pre-contact Western Alaskan faunal assemblage, through a combination of zooarchaeological and stable isotope techniques. The permafrost-preserved assemblage was excavated in 2009/10 at Nunalleq (c. AD 1350-1700) on the Yukon-Kuskokwim Delta by the University of Aberdeen, in collaboration with Qanirtuuq Inc. and the Native village of Quinhagak. Zooarchaeological analysis was conducted to identify the species present at Nunalleq. Analysis of butchery marks suggested patterns of human utilization of faunal resources and data on the age profile of the assemblage provided information on the seasonality of hunting and site occupation. A wide range of marine, freshwater and terrestrial species was observed, with pinnipeds, dogs and caribou particularly frequent. Subsequently, stable isotope analysis (δ13C, δ15N and δ34S) was carried out on 20 species identified at Nunalleq. The application of carbon and nitrogen isotope analysis enabled investigation of the diets and habitats of the various species and their relative positions in the food-web. These data were compared with data from contemporaneous Alaskan sites and modern studies, allowing investigation of diachronic and geographical variability. The dogs, as the only domestic species found in the prehistoric North American Arctic with a unique role between the domestic and the wild, were the focus of an in-depth zooarchaeological and isotopic case study. The comparison of stable isotope data from humans and dogs revealed a similarity in diet and, together with osteological evidence for butchery, indicated the complex role of dogs in human subsistence strategies. Sulphur isotope analysis provided a complementary tool with which to explore isotope variability, and facilitated a consideration of its potential benefits in enhancing the more commonly-used combination of carbon and nitrogen analysis in the interpretation of faunal isotope ecology. The advantages of integrating zooarchaeological and stable isotope data are discussed and future research directions are explored.

Dissertation (Ph.D.)--Auburn University, 2009. / Abstract. Vita. Includes bibliographic references (p.142-151).

Thesis (Ph.D.). / Written for the Dept. of Biochemistry. Title from title page of PDF (viewed 2009/06/08). Includes bibliographical references.