That proportion of the total zinc (Zn) in the soil that is available to plants is variable, and little is known about the various forms of Zn or even the extent to which it occurs. Because of the complexity of the problem, most workers have approached the problem of availability of Zn to plants from the opposite point of view, that is, the forms in which the added or available Zn becomes unavailable.

Indiana University-Purdue University Indianapolis (IUPUI) / Phosphorus (P) is essential for aquatic life; cycling between both inorganic and organic forms to maintain an ecological balance. Its addition into P-scarce freshwaters, either through terrestrial (external) or sedimentary (internal) loading, may disrupt this balance causing blooms of phytoplankton to flourish, often resulting in harmful environmental and anthropogenic consequences. Accordingly, reduction of external P loading has been commonly implemented with a recent focus on sediment-bound legacy P that is mobilized into the water column during dynamic redox conditions. Mobile P species have been identified as both inorganic and organic, with the former representing the most bioavailable fraction, and the latter serving as a source for labile P in freshwaters when in high demand, particularly during blooms. Missisquoi Bay in Lake Champlain, VT experiences harmful cyanobacterial blooms driven by internal P loading and has been the target of numerous geochemical and hydrological studies. This thesis describes a high-resolution investigation of both the organic P and organic matter compositions of the bay with respect to mobility, reactivity, and bioavailability using Fourier Transform-Ion Cyclotron Mass Spectrometry (FT-ICR MS). Sediment from Missisquoi Bay was extracted with a diverse set of reagents, resulting in fractionation of both organic matter and organic P, and illustrating the distribution of various labile and recalcitrant compounds. Many of these molecules are associated with porewater or easily extractable mineral surfaces providing a link to the benthic organic matter and phosphorus fractions available to microorganisms. Additionally, the organic chemistry of the bay was investigated seasonally from May 2017 to January 2018 revealing biological processing from the spring runoff season through the post-bloom summer season. The transition from late summer to under ice conditions in winter was less severe with a higher commonality between both organic matter and organic P compounds, suggesting reduced biological and abiotic degradation. Moreover, short-term anoxic incubations of sediment cores from each season revealed the presence of diverse organic signatures from sorption processes, and a significant contribution of benthic microbial activity to the benthic organic geochemistry.

This study examined the effect of manipulating forest floor and harvest residue inputs on nutrient availability and carbon content in the context of intensive forest management. Treatments were removal and addition of forest floor and slash, and a reference. Tree volume, litterfall, and root biomass were measured to assess aboveground productivity and soil moisture and temperature, available nitrogen and phosphorus, O-horizon, and mineral soil for below ground processes. Organic matter additions increased stand bole volume, carbon at 20-60cm, and total nitrogen in the mineral soil. Severely removing the floor and harvest residues did not result in any large differences in below or above ground productivity, soil carbon or nitrogen pools. Removing a potential nutrient pool did not severely affect stand productivity through mid-rotation but could be a concern in subsequent rotations.

The microbial origin of methane produced from sedimentary basins is a subject of great interest, with implications for the global cycling of carbon as well as natural gas exploration. Despite the growing body of research in sedimentary basin methanogenesis, few studies have sought to understand the subsurface microbial communities that produce methane, the metabolic pathways involved in the decomposition of ancient organic matter, or the components of ancient organic matter that are consumed. This research examined shale-derived dissolved organic matter (DOM) as a potential substrate to support a subsurface methanogenic community in a known microbial shale gas reserve, the Antrim Shale in the Michigan Basin, USA. Experiments were conducted that enriched fermentative and sulfate-reducing microbial communities from Antrim Shale formation waters. Additionally, 1H NMR spectroscopy was used to characterize shale-derived DOM solutions before and after they were used as growth media for fermentative and sulfate-reducing microbial communities, and to characterize the DOM of the Antrim Shale formation waters. The results of the enrichment studies demonstrate that both fermentative and sulfate-reducing microbial communities from the Antrim Shale are capable of growth using shale-derived DOM as their only source of organic carbon; further, the production of methane in a fermentative enrichment demonstrates that methanogenesis can be supported by shale-derived DOM alone. The 1H NMR characterization studies of the shale-derived DOM solutions before and after growth revealed subtle but detectable differences in DOM compositions, indicating the production and consumption of DOM components by the fermentative and sulfate-reducing microbial communities. Characterization analyses of Antrim Shale formation waters suggest that salinity and microbiological activity may influence the liberation of aliphatic and aromatic compounds from shale. The DOM characterization studies also suggest that carboxylic acids may be consumed by methanogenic communities in the Antrim Shale, and aromatic compounds may be produced by the enriched microbial communities and the communities present in the Antrim Shale.

Yes / Characterising the organic and microbial matrix of water are key issues in ensuring a safe potable water supply. Current techniques only confirm water quality retrospectively via laboratory analysis of discrete samples. Whilst such analysis is required for regulatory purposes, it would be highly beneficial to monitor water quality in-situ in real time, enabling rapid water quality assessment and facilitating proactive management of water supply systems. A novel LED-based instrument, detecting fluorescence peaks C and T (surrogates for organic and microbial matter, respectively), was constructed and performance assessed. Results from over 200 samples taken from source waters through to customer tap from three UK water companies are presented. Excellent correlation was observed between the new device and a research grade spectrophotometer (r2 = 0.98 and 0.77 for peak C and peak T respectively), demonstrating the potential of providing a low cost, portable alternative fluorimeter. The peak C/TOC correlation was very good (r 2 = 0.75) at low TOC levels found in drinking water. However, correlations between peak T and regulatory measures of microbial matter (2 day/3 day heterotrophic plate counts (HPC), E. coli, and total coliforms) were poor, due to the specific nature of these regulatory measures and the general measure of peak T. A more promising correlation was obtained between peak T and total bacteria using flow cytometry. Assessment of the fluorescence of four individual bacteria isolated from drinking water was also considered and excellent correlations found with peak T (Sphingobium sp. (r 2 = 0.83); Methylobacterium sp. (r 2 = 1.0); Rhodococcus sp. (r 2 = 0.86); Xenophilus sp. (r 2 = 0.96)). It is notable that each of the bacteria studied exhibited different levels of fluorescence as a function of their number. The scope for LED based instrumentation for insitu, real time assessment of the organic and microbial matrix of potable water is clearly demonstrated. / The research reported here was sponsored by the Engineering and Physical Sciences Research Council under grants EP/I001379/1, EP/I001468/1 and EP/I029346/1.

Yes / Wastewater treatment is an energy-intensive operation. Energy consumption is forecast to increase by 60% in the forthcoming decade due to tightened legislation surrounding the discharge of final effluent to watercourses. Treatment plants rely on the time-consuming and unreliable biochemical oxygen demand to assess the quality of final effluent, leading to process inefficiencies. Here, the authors show that fluorescence spectroscopy is a robust technique for real-time monitoring of changes in effluent quality. Three portable fluorimeters were installed for one month at the final effluent discharge point of a large municipal wastewater treatment plant. The authors show that organic matter composition of the wastewater varies diurnally depending on the flow rate and antecedent rainfall. High fluorescence intensity and ammonia are attributed to sewage sludge liquor, which is regularly discharged to the treatment plant. Moreover, elevated fluorescence intensities were recorded as a result of process failure following a power outage. The study shows that online fluorescence analysis is capable of detecting both minor changes in effluent quality and issues with treatment process performance. / European Commission Framework Programme 7, Marie Curie IEF (PIEF-GA-2012-329962) and the Core Program, ANCS (PN 16.40.01.01).

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Intensely managed and modified catchments in the Great Lakes are linked to eutrophication and hypoxia of receiving water bodies downstream, resulting in water quality impairment, and adverse impacts on aquatic ecology. While much focus has been on the role of phosphorous and nitrogen, dissolved organic carbon (DOC) plays a complex and critical role in lake biogeochemical cycles, as it influences the interations between nutrients and contaminants in water and soil through processes of mobilization, transport, biological uptake, and deposition. Human-dominated landscapes have a range of consequences on DOC dynamics as catchment hydrology, plant cover, and nutrient inputs are altered in these environments. As such, the objectives of this study were to identify the controls and drivers of DOC quantity and DOM quality in the Spencer Creek watershed, which is the largest contributor of water to Cootes Paradise that ultimately drains into Lake Ontario. The 159 km2 study area of the catchment is complex, as the present landscape is composed of a mosaic of various land uses including agriculture, forest, wetland, urban, and industrial regions. Flow alterations contribute to the complexity of the watershed as there are managed reservoirs and alterations in water courses. From 2016- 2018, hydrometric data was collected across 9 monitoring sites, along with surface water samples that were analyzed for DOC concentration and optical properties. Results indicate differences in flow magnitudes and stream DOC between dry and wet conditions, where concentrations during wet conditions were significantly higher compared to dry. Additionally, there was substantial variation in DOC concentration and quality across the Spencer Creek watershed. DOC concentrations were found to be the lowest at groundwater influenced sites in the headwaters of the watershed, and the highest in the mid-catchment region where DOC quality was strongly influenced by wetland sources. The reservoir-influenced sites showed relatively intermediate concentrations of DOC, with quality that exhibited strong microbial signatures. At the outlet, DOC concentrations were attenuated and DOC quality was intermediate between allochthonous and autochthonous end members, reflecting upstream mixing processes. These processes were presented as a conceptual model of water and DOC movement through the Spencer Creek watershed. The implications of this research suggest that with anticipated wetter and warmer conditions DOC concentrations would increase in the watershed. The repercussions of increased DOC concentrations overall imply a decrease of terrestrial carbon storage, and greater input into more reactive and susceptible pools, which may result in further water quality degradation. Overall, the findings from this research provide insight into the fate and transport of water and DOC in a complex, managed catchment in the Great Lakes region, with the aims of providing key information for local stakeholders. / Thesis / Master of Science (MSc)