Dissolved organic matter (DOM) is comprised of a complex array of molecular constituents that are linked to many globally-relevant processes and yet this material is still largely molecularly uncharacterized. Research presented here attempted to probe the molecular complexity of this material from both Arctic and temperate climates via multifaceted and novel approaches. DOM collected from remote Arctic watersheds provided evidence to suggest that permafrost-disturbed systems contain more photochemically- and biologically-labile material than undisturbed systems. These results have large implications for predicted increasing temperatures where widespread permafrost melt would significantly impact stores of organic carbon in polar environments. In attempting to address the complexities and reactivity of DOM within global environments, more information at the molecular-level is necessary. Further research sought to unravel the molecularly uncharacterized fraction via use of nuclear magnetic resonance (NMR) spectroscopy in conjunction with hyphenated and varied analytical techniques. Directly hyphenated high performance size exclusion chromatography (HPSEC) with NMR was explored. This hyphenation was found to separate DOM into structurally distinct fractions but proved limited at reducing DOM heterogeneity. Of the many high performance liquid chromatography (HPLC) techniques tested, hydrophilic interaction chromatography (HILIC) was found the most effective at simplifying DOM. HILIC separations utilizing a sample from Florida resulted in fractions with highly resolved NMR signals and substantial reduction in heterogeneity. Further development with a 2D-HILIC/HILIC system to achieve additional fractionation was employed. This method produced fractions of DOM that were homogenous enough to produce excellent resolution and spectral dispersion, permitting 2D and 3D NMR experiments to be performed. Extensive NMR analyses of these fractions demonstrated strong evidence for the presence of highly oxidized sterols. All fractions, however, provided 2D NMR spectra consistent with oxidized polycyclic structures and support emerging data and hypotheses suggesting that cyclic structures, likely derived from terpenoids, are an abundant, refractory and major component of DOM. Research presented within this thesis demonstrates that HILIC and NMR are excellent co-techniques for the analysis of DOM as well as that oxidized sterols and other cyclic components with significant hydroxyl and carboxyl substituents are major constituents in DOM.

In aquatic ecosystems, dissolved organic matter (DOM) is an important source of detrital energy on which microorganisms rely. However, its dynamics are not well understood in an ecological context. By isolating watershed sources, the work reported in this thesis has attempted to characterize the seasonal patterns of DOM in the hyporheic zone of a temperate stream and to find the likely sources that contribute to this pool of organic carbon. Hyporheic DOM characteristics described by UV spectroscopy indicated temporal rather than spatial dependence. Excitation-emission matrices (EEMs) showed that hyporheic DOM was mainly comprised of fulvic- and humic-like fluorescence with small amounts of protein-like fluorescence. Increases in dissolved organic carbon (DOC) concentrations from birch litter isolates were greater than those from cedar litter in early autumn, but less in late autumn. Although streambed biofilm was not significant in increasing DOC concentrations, it was also a source of protein-like fluorescence.

The effects of different types and amounts of dissolved organic matter (DOM) on the isotope fractionation of Hg isotopes during aqueous photo-reduction of monomethylmercury (MMHg) were investigated to assess whether mass-independent fractionation (MIF) signatures can be used to track photo-degradation of MMHg in natural waters. From experiments conducted with different amounts of reduced organic sulfur (Sred-DOM), it appears that MIF during photo-reduction may be dependent on whether MMHg is dominantly bound to Sred-DOM. Similar fractionation factors were observed for experiments where Sred-DOM was in far excess of MMHg, while significantly lower fractionation factors were observed with lower Sred-DOM. We also characterized the signature of MIF (i.e. Δ199Hg/Δ201Hg) during MMHg photo-degradation to assess if it was similar in different matrices. The experimental Δ199Hg/Δ201Hg was very similar for different matrices. However, the experimental slope is slightly but statistically different than the slope observed in freshwater fish, which preserve MMHg in nature.

Previous research indicates that pharmaceutically active compounds (PhACs) and endocrine-disrupting compounds (EDCs) are poorly removed during conventional drinking water treatment processes including coagulation; however, removal efficiency increases in the presence of natural organic matter (NOM). Therefore, this project investigates the link between various NOM types with EDC/PhAC removal. Bench-scale coagulation tests were conducted on three different source waters spiked with environmentally relevant levels (nominally 1000 ng/L) of EDCs/PhACs. Two different coagulants were used: polyaluminum chloride (PACl) and aluminum sulphate (alum). NOM was characterized using size exclusion liquid chromatography-organic carbon detection (LC-OCD). Results for Lake Ontario, Otonabee and Grand River water indicate that certain EDCs/PhACs are significantly removed during coagulation while others increase in concentration. Concurrently, particular NOM fractions (biopolymers and humic substances) are also being removed. Solvents used for EDC/PhAC spiking (acetone and acetonitrile) did not affect coagulation, but contributed to low molecular weight neutral and hydrophobic NOM fractions.

The effects of different types and amounts of dissolved organic matter (DOM) on the isotope fractionation of Hg isotopes during aqueous photo-reduction of monomethylmercury (MMHg) were investigated to assess whether mass-independent fractionation (MIF) signatures can be used to track photo-degradation of MMHg in natural waters. From experiments conducted with different amounts of reduced organic sulfur (Sred-DOM), it appears that MIF during photo-reduction may be dependent on whether MMHg is dominantly bound to Sred-DOM. Similar fractionation factors were observed for experiments where Sred-DOM was in far excess of MMHg, while significantly lower fractionation factors were observed with lower Sred-DOM. We also characterized the signature of MIF (i.e. Δ199Hg/Δ201Hg) during MMHg photo-degradation to assess if it was similar in different matrices. The experimental Δ199Hg/Δ201Hg was very similar for different matrices. However, the experimental slope is slightly but statistically different than the slope observed in freshwater fish, which preserve MMHg in nature.

Previous research indicates that pharmaceutically active compounds (PhACs) and endocrine-disrupting compounds (EDCs) are poorly removed during conventional drinking water treatment processes including coagulation; however, removal efficiency increases in the presence of natural organic matter (NOM). Therefore, this project investigates the link between various NOM types with EDC/PhAC removal. Bench-scale coagulation tests were conducted on three different source waters spiked with environmentally relevant levels (nominally 1000 ng/L) of EDCs/PhACs. Two different coagulants were used: polyaluminum chloride (PACl) and aluminum sulphate (alum). NOM was characterized using size exclusion liquid chromatography-organic carbon detection (LC-OCD). Results for Lake Ontario, Otonabee and Grand River water indicate that certain EDCs/PhACs are significantly removed during coagulation while others increase in concentration. Concurrently, particular NOM fractions (biopolymers and humic substances) are also being removed. Solvents used for EDC/PhAC spiking (acetone and acetonitrile) did not affect coagulation, but contributed to low molecular weight neutral and hydrophobic NOM fractions.

In aquatic ecosystems, dissolved organic matter (DOM) is an important source of detrital energy on which microorganisms rely. However, its dynamics are not well understood in an ecological context. By isolating watershed sources, the work reported in this thesis has attempted to characterize the seasonal patterns of DOM in the hyporheic zone of a temperate stream and to find the likely sources that contribute to this pool of organic carbon. Hyporheic DOM characteristics described by UV spectroscopy indicated temporal rather than spatial dependence. Excitation-emission matrices (EEMs) showed that hyporheic DOM was mainly comprised of fulvic- and humic-like fluorescence with small amounts of protein-like fluorescence. Increases in dissolved organic carbon (DOC) concentrations from birch litter isolates were greater than those from cedar litter in early autumn, but less in late autumn. Although streambed biofilm was not significant in increasing DOC concentrations, it was also a source of protein-like fluorescence.

Allochthonous carbon can be a large proportion of the carbon budget in northern temperate and boreal lakes. This thesis uses stable carbon and oxygen isotopes to examine the fate of allochthonous dissolved organic matter (DOM) in northern temperate lakes, and to determine the importance of dissolved organic carbon (DOC) in lake carbon mass balances and in the δ¹³C of lake sediments. To use stable isotopes as a tool for studying DOC loss and sedimentation within lakes requires an understanding of processes that affect the δ¹³C and δ¹⁸O in aquatic systems. Photolysis is one mechanism that can account for the large allochthonous DOC loss within northern temperate lakes. There is, however, little research examining the effects of photolysis on stable isotopes (e.g. δ¹³C and δ¹⁸O) in aquatic systems, or how photodegradation of DOM affects the δ¹³C of lake sediments. To study the effects of DOM photodegradation on carbon and oxygen isotopes, stream waters from catchments with varying peatland coverage were incubated in Tedlar bags placed in water baths under natural sunlight. Results from three streams flowing into two oligotrophic headwater lakes (Harp and Dickie Lakes) indicate that O₂ consumption rates and dissolved inorganic carbon (DIC) production rates were an order of magnitude greater in light exposed treatments than in dark treatments, suggesting that light mediated processes control O₂ consumption and DIC production in incubations. The similarity between filtered, inoculated, and sterile treatments, indicate that photolysis was the dominant O₂ consuming and DIC producing process in the incubations, while the contribution of respiration to these processes was not detectable. Differences in both O₂ consumption rates and DIC production rates (normalized to DOC loss) among streams suggest that DOM photolability was an important factor in both O₂ loss and DIC production on a volumetric basis. A concomitant increase in δ¹⁸O-O₂ was observed with O₂ loss indicating that during the photo-oxidation of DOM, the lighter ¹⁶O isotopomer was preferentially consumed in the oxidation of DOC to CO₂. Fractionation factors for respiration, photolysis and other abiotic reactions were not a function of O₂ consumption rates and ranged between 0.988 and 0.995, which lies outside the range published for respiration (0.975-0.982). These are the first published photolytic fractionation factors. The δ¹³C-DIC produced collectively by photolysis, respiration, and other abiotic reactions in incubations exposed to natural sunlight ranged between –23‰ and –31‰, and were similar in the light incubations for each treatment, but different among streams. Together, the light and dark incubation data suggest that photolysis and other abiotic reactions were largely responsible for the DIC concentration and δ¹³C-DIC changes observed, while respiration is a relatively minor contributor. During the incubations, as DOC photodegraded to CO₂, the lighter ¹²C isotope was preferentially mineralized (or the moieties cleaved were depleted in ¹³C) leaving the residual δ¹³C-DOC 1‰ to 4‰ enriched, creating enrichment (ε) values up to ~–3‰. The change in final δ¹³C-DOC after DOM photodegradation was different for each inflow, ranging from ~1 ‰ to 8.0 ‰, and provides an average enrichment of –2.1‰ (Harp Inflows ε: –1.2‰; Dickie Inflows ε: –3.4‰). These ε values are in agreement with the average ε from previous incubations on 3 of the inflows and 3 published studies based on UV exposed bog water (Osburn et al., 2001), riverine waters (Opsahl and Zepp, 2001), and lyophilized Juncus leachate dissolved in lake water (Vähätalo and Wetzel, 2008) (average ε = –2.9‰). The structure of DOM changed during photolysis. Absorbance data indicated that the aromaticity, colour, UV absorption and the average molecular size of the DOC decreased. Additionally, after exposure to sunlight, C/N ratios of the DOC changed from high values (24-55), indicative of terrestrial inputs, to lower values (4-13) traditionally thought to be representative of algal or microbial inputs. This contradicts the conventional view that terrestrial DOC has C/N ratios >20, and shows that abiotic processes can alter allochthonous carbon structure and the residual allochthonous carbon can have C/N values similar to, or overlapping with, C/N ratios expected from algal or microbial carbon. With the loss of 61-90% of the DOC, the particulate organic carbon (POC) created accounted for 20-90% of the DOC lost. Values of δ¹³C-POC ranged from –25.7‰ to –27.7‰, with 80% of the samples within 1‰ of the initial δ¹³C-DOC indicating that the particulate carbon created from the photodegradation of DOM that settles to the lake sediments could be isotopically similar to the source DOC. Overall, these incubations indicate that the photodegradation of DOM can affect both concentrations and isotopes of O₂, DIC, DOC, and POC of the stream waters flowing into Harp and Dickie Lakes and are important to consider in lake dynamics of high DOC retention lakes. Two independent methods were used to examine the importance of allochthonous DOC to lake sediments. The first method used a two end-member mixing model to estimate the proportion of allochthonous and autochthonous carbon within the lake sediments. Inflow δ¹³C-POC data, δ¹³C-leaf litter measurements, and DOC photodegradation experiments were used to calculate average annual δ¹³C-POC values for the allochthonous end member. The average annual δ¹³C-POC values for the autochthonous end member were calculated using estimates of productivity, surface δ¹³C-CO₂ values and estimated average annual fractionation factors. Average annual δ¹³C-POC values from allochthonous and autochthonous sources for these lakes were distinct. Using the end members to calculate the relative contributions of allochthonous and autochthonous carbon to lake sediments revealed that the δ¹³C of the lake sediment can be significantly affected by the ratio of autochthonous and allochthonous contributions. Furthermore, peaks in the allochthonous contributions of carbon accompany the δ¹³C peaks in the sediment records to the lake sediments. This suggests that climate change and/or anthropogenic changes to the landscape, and the concomitant changes in DOC inputs to lakes, can be recorded in the sediment record indicating that sediment records are not just productivity signals, but also mass balance signals in high DOC retention lakes. In the second method carbon isotope budgets were completed to accompany the carbon mass budgets for Harp and Dickie Lakes. Mass-weighted average annual δ¹³C-DOC values from the inflows and outflows and δ¹³C-DIC values from the inflows varied by 0.2‰ to 1.3‰, suggesting the values are well constrained. Conversely, the range of weighted δ¹³C-DIC values from the outflows were larger (2.2‰) than those of the inflows. Calculated δ¹³C values of the lake sediment were not equal to the measured δ13C values of the lake sediments for either Harp or Dickie Lakes suggesting a problem lies within the mass balances, or the weighted average annual δ¹³C values used in the isotope budgets. To examine the sensitivity of the average annual weighted δ¹³C values for the carbon entering and exiting the lakes, and the mass of carbon entering the lakes δ¹³C of the lake sediments, a mass and isotope budget model was created. The model indicated that the δ¹³C of the lake sediments is sensitive to a number of parameters including the amount of DOC entering the lake, the δ13C-CO2 evaded from the lake, the areal water discharge rate (qs), the gas exchange coefficient (k), and pH. Many of these parameters required adjustments for the masses of carbon to match those presented in the mass balances suggesting that the mass balances averaged over 8 years have errors associated with them. However, changing the DOC load to the lakes in the model by the variability observed over all the years of the mass balances) indicates that the isotopic signature of the lake sediment could change by up to 2.5‰. This isotope change is large enough to account for the historical δ¹³C changes observed in the δ¹³C sediment record, suggesting that allochthonous DOC can drive the sediment record.

Environmental sustainability in Sweden is challenged by rising greenhouse gas emissions from transportation, input-intensive agriculture and potentially unsustainable removal of organic material from forests and farmland. The Swedish government is working towards sixteen environmental quality objectives in order to overcome these problems, among others.  The past decade gave rise to an international research community dedicated to investigate the age-old practice of applying charcoal to soil, practiced most notably by ancient civilisations in the Amazon region of South America. The high level of interest and controversy around this subject inspired this investigation of biochar’s potential benefits in Sweden.  A scientific study was conducted to examine the potential of biochar to enhance environmental sustainability in Sweden. This was largely a desk study, supplemented by expert interviews, GIS map work, an experiment and mathematical analysis.  It was found that there was insufficient research to date to prove the agronomic benefits of biochar in Sweden. More field studies are required to build up the evidence of its potential. Furthermore, as the rate of mineralization of the carbon content is dependent on numerous factors, including the composition of the soil to which the biochar is applied, it is difficult to conclusively define biochar’s carbon storage potential.  This study adds to the existing body of knowledge on the subject by integrating the conclusions from a variety of studies and expert opinions, as well as by providing maps indicating land areas in Sweden that would be likely to benefit from biochar application.

ABSTRACT Modeling of bark-, sand- and activated carbon filters for treatment of greywater Susanna Ciuk Karlsson   The part of the waste water produced in a household, originating from showers, dish - and wash water, is called greywater. It is possible to treat the greywater separately from the black water (toilet water) as it is less polluted and then use it for purposes such as garden irrigation. There are various methods for purifying greywater. Here, the possibility to purify greywater using three column filters with different materials (activated carbon, pine bark and sand) was examined through modeling in the computer program HYDRUS. A set-up with physical filters was available, where flow measurements were performed. These measurements were used to validate the model that was developed in HYDRUS. When a flow model had been produced that could replicate the measured flow, a module of HYDRUS was used to also model the reactive transport of nutrients and organic matter in the filters. The complete model was used for evaluation of the treatment performance of the filters during a default scenario where they were loaded with 1 liter of water per day containing pollutant concentration corresponding to typical greywater. / REFERAT Modellering av bark-, sand- och kolfilter för rening av BDT-vatten Susanna Ciuk Karlsson I ett hushåll används vatten som då blir till avloppsvatten. Detta avloppsvatten består till stor del av bad, disk och tvättvatten (BDT-vatten). Det är möjligt att behandla BDT-vattnet separat från klosettvattnet då det är mindre förorenat, låta det genomgå rening och sedan använda det för till exempel bevattning av trädgårdar. Det finns olika metoder för att rena BDT-vatten. Här studerades möjligheterna att rena BDT-vatten med hjälp av tre filter av olika material; aktivt kol, tallbark och sand, genom modellering i datorprogrammet HYDRUS. En praktisk experimentuppsättning med filterkolonner fanns att tillgå, där ett experiment med flödesmätningar genomfördes. Mätningarna användes för att validera modellen som utvecklades i HYDRUS. Efter att en flödesmodell som stämde överrens med uppmätta värden utvecklats, modellerades reaktiv transport av näringsämnen och organiskt material i filtren med en modul tillhörandes HYDRUS. Med hjälp av modelleringen kunde filtertypernas reningsförmåga utvärderas för ett iscensatt standardscenario där filtrena belastades med 1 l vatten/dag innehållandes föroreningar motsvarandes ett typiskt gråvatten.