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The reduction of pathogenic microorganisms is essential to minimize human health risks associated with the reuse, reclamation, and recycling of wastewater and the land application of biosolids (sewage sludge). The most advanced treatment technologies, as well as, the most representative methods and indicator organisms are necessary to ensure public safety. The goal of this dissertation is to assess advanced Bardenpho wastewater treatment technologies in regards to virus removal, suggest the most appropriate viral indicators of human fecal contamination and/or treatment process controls, and develop an updated method for enumerating Ascaris ova viability in land applied biosolids. Appendix A evaluates the incidence of 11 different virus types in sewage throughout a 12-month time period, and their subsequent reduction via advanced Bardenpho treatment processes. This study showed that wastewater treatment facilities utilizing advanced Bardenpho for secondary treatment are more effective at reducing viruses in wastewater than facilities utilizing conventional aeration basin and trickling filter processes. Appendix B develops a new method for determining the viability of Ascaris ova in land applied biosolids. In this method, early development stages prior to larval-development, are included in the estimation of potential viability. Comparisons between viability enumerations suggests that the conventional microscopy method, in which only ova containing motile larva are considered viable, underestimates the number of eggs that may progress to an infectious stage. Whereas, the method based on early-to-late stage development, considers the potential viability of all eggs, providing a more conservative approach.

Mobile technologies now afford unprecedented opportunities, resources, and possibilities for learning. Among them, is the opportunity for students to engage in hands-on, out-of-classroom learning activities such as Adventure Learning. Since 2007, Adventure Learning has developed as an educational framework for using information and communication technologies to connect learners with expeditionary teams where video-based communication provides a sense of adventure for learners. The study was conducted in a public high school where an Environmental Science teacher used mobile learning technologies to create Adventure Learning projects where students participated both fin the classroom and as members of an “expeditionary team.” It was also intended to examine both the benefits and challenges in implementing ubiquitous mobile technologies in the field, combined with the use of student-centered pedagogies in their classrooms. The major questions of the study asked how did a teacher leverage mobilized Adventure Learning to design learning activities? And how did active participation in a mobilized Adventure Learning project affect student interest in the subject of Environmental Science? The study involved examining the ways the teacher leveraged the affordances of mobile technologies to create a hands-on, collaborative, and Adventure Learning environments outside of the classroom. The hands-on learning activities were designed to enable students to gather first-hand information related to environmental science. Subjects in the study included a high school Environmental Science teacher along with 104 participating students. Using a mixed methods approach, qualitative data were gathered through observations of learning activities, interviews and focus groups and artifacts. Quantitative data were gathered through surveys administered to the students before and after the treatment. The results indicated that, contrary to the teacher’s expectations, students indicated a preference for learning through book and lecture rather than hands-on discovery of information in both pre and post treatment surveys. Results of the study also demonstrated differences in learning preference relating to percentage of students participating in field-based, hands-on learning activities or in lecture-book classroom learning activities. Recommendations for future research and for educational practice are offered. Limitations of the study include the small sample size and short time duration of the study. / text

<p>While much is known about the abundance and genetic diversity of environmental microbial communities, little is known about their taxon-specific activity. In this thesis I address this gap using a model marine microbe, the cyanobacterium <italic>Prochlorococcus spp.</italic>, which numerically dominates tropical and subtropical open oceans and encompasses a group of genetically defined clades that are ecologically distinct. Ribosomal RNA is a promising indicator of in situ activity because of its essential role in protein synthesis as well as its phylogenetic information, which could be used to distinguish clades among mixed populations. Here I show that, in a laboratory system the specific growth rate of representative <italic>Prochlorococcus</italic> strains could be quantitative predicted from cellular rRNA content (assessed by RT-qPCR), cell size (assessed by flow cytometry) and temperature. Applying this approach in the field, I show unique clade-specific activity patterns for <italic>Prochlorococcus</italic>. For example, vertically within the euphotic zone, eHL-II activity is strongly impacted by light and is consistent with patterns of photosynthesis and on a horizontal transect from Hawaii to San Diego, eHL-I and eHL-II activities exhibit significant transitions and appear to be regulated by temperature, nutrient and vertical mixing gradients. Using ribosomal tag pyrosequencing of DNA and RNA, I have extended our observation to the Eubacterial community and described the biomass distribution (rDNA) and activity (rRNA) patterns from two representative depths (25 and 100 m) at a well-studied oligotrophic ocean station. These results show that for some populations the abundances and activities are significantly uncoupled, which suggests substantial top-down controls or physical transport processes. Further exploring the taxon-specific activity patterns along with abundances and environmental variables across time and space is essential to better understanding the dynamics of a complex microbial system as well as predicting the consequences of environmental change.</p> / Dissertation

Acidification of surface waters has been recognised as the major water quality problem in the UK uplands. The adverse effects of conifer afforestation on streamwater chemistry and ecology are well documented in acid-sensitive catchments and have mainly been attributed to the enhanced deposition of atmospheric pollutants onto conifer canopies (the “scavenging effect”). Currently, international and national policies promote the expansion of native broadleaf woodland in the UK. Pollutant deposition onto broadleaf canopies is considered less than onto the more aerodynamically rough conifers, but there is concern that largescale broadleaf planting could delay the recovery of acidified waters or lead to further acidification in most sensitive areas. However, there has been limited investigation of the influence of broadleaf woodland cover on streamwater chemistry in the UK. To investigate the effect of woodland cover 14 catchments with different (0-78%) percentages of broadleaf woodland cover were identified in representative acidsensitive areas in north-western and central Scotland (Glen Arnisdale and Loch Katrine area) and northern and south-western England (Ullswater area and Devon) using spatial datasets in a GIS. Streamwater was sampled at high flow from the catchment outlets in winter and spring 2005 and 2006 and was analysed for major cations, anions and trace metals using standard methods. The number of samples ranged from two in the Glen Arnisdale catchments to 10 in the Loch Katrine area catchments which were sampled more intensively. Significant positive correlations were found between percentage broadleaf woodland cover and streamwater NO3 (rs = 0.51) and soluble Al (rs = 0.64) concentrations. The greater NO3 leaching to streamwater in the three most forested catchments (> 50%) was probably due to enhanced N deposition onto woodland canopies and nitrification by alder in the Ullswater area forested catchments. Streamwater NO3 concentrations equalled or exceeded non-marine SO4 in the above catchments indicating that NO3 was the principal excess acidifying ion in catchments with greater woodland cover. The woodland effect on streamwater chemistry in the study catchments was masked to some extent by variability in acid deposition climate and soil type composition. Seasalt inputs were found to be a more important control than woodland cover for streamwater chemistry in the maritime Glen Arnisdale catchments. A risk assessment of acid-sensitivity in the study catchments was conducted by calculating streamwater critical load exceedances using the Steady-State Water Chemistry (SSWC) and First-order Acidity Balance (FAB) models and modelled pollutant deposition for 1995-97 and 2002. Critical loads were exceeded by 0.01 to 1.74 keq H ha-1 yr-1 in two catchments which had woodland covers > 50% and in the Devon control catchment. The remaining 11 study catchments were assessed to be not at risk of acidification, probably due to significantly reduced non-marine S deposition from 1986 to 2001, but seasalt inputs to the Glen Arnisdale catchments might cause acidic streamwater episodes. Acid-sensitivity was also assessed using macroinvertebrates sampled in 11 of the study catchments and the results generally agreed with the critical load assessments. More detailed estimates of the enhancement of dry S and N deposition onto birchwoods in the Loch Katrine area catchments using calculated roughness length within FRAME showed that it posed no risk for streamwater acidification in these catchments because of the high rainfall environment. However, in acid-sensitive areas of the UK with lower rainfall and closer to major pollution sources, enhanced pollutant scavenging by broadleaf woodland canopies could pose a greater risk of acidification to freshwaters. The finding that almost all study catchments with woodland covers less than 30% are well protected from acidification suggests that this is a sensible threshold value for use in risk assessments of the effects of broadleaf woodland planting conducted within the Forests and Water Guidelines. The results of a sensitivity analysis of the Guidelines’ methodology, conducted using parameters such as numbers and timing of streamwater sampling, different runoff estimates and critical acid neutralising capacity values, showed that the Guidelines should be able to protect sensitive freshwaters from acidification in areas where broadleaf woodland is expanding.

Global sustainable energy and environmental policies have increased the need to understand how new energy innovations diffuse into the market. The transport sector is currently a major source of unsustainable energy use contributing ~20-25% global CO2 emissions. Although the potential benefits of alternative fuel vehicle (AFV) technologies to reduce CO2 emissions and fossil fuel dependency have been demonstrated, many uncertainties exist in their market diffusion. It is also not well understood how policy can influence rapid diffusion of AFVs. To transition to a more sustainable energy-transport system, we need to understand the market conditions and factors necessary for triggering widespread adoption of new energy innovations such as AFVs. Modelling the diffusion of innovations is one way to explain why some ideas and technologies spread through society successfully, while others do not. These diffusion processes are characterized by non-linear interactions between heterogeneous agents in complex networked systems. Diffusion theory has typically been applied to consumer durable goods but has found less application to new energy and environmental innovations. There is much scope for advanced diffusion methods to inform energy policy. This depends upon understanding how consumer behaviour and technologies interact and can influence each other over time. There is also need to understand the underlying mechanisms that influence adoption behaviour among heterogeneous agents. This thesis tackles the above issues using a combination of empirical data analysis, scenarios, and simulation modelling as follows: 1) We first develop the empirical basis for assessing innovation diffusion from a technology-behavioural perspective, where we explicitly account for interactions between consumer preferences and technological performance across different spatial and temporal scales; 2) Scenarios are then used to disaggregate consumer markets and analyze the technological and behavioural factors that might trigger large-scale adoption of AFVs; 3) We then case-analyze the UK transport sector and develop a model of the dynamics between how vehicle technologies and consumer preferences can change and influence the diffusion process; 4) Finally, we develop exploratory simulations to assess how social network effects can influence individual adoption behaviour; 5) We close with policy implications of our findings, contributions and limitations of the thesis, and possible avenues for taking the research forward.

<p>Wetland ecosystems provide many valuable ecosystem services, including carbon (C) storage and improvement of water quality. Yet, restored and managed wetlands are not frequently evaluated for their capacity to function in order to deliver on these values. Specific restoration or management practices designed to meet one set of criteria may yield unrecognized biogeochemical costs or co-benefits. The goal of this dissertation is to improve scientific understanding of how wetland restoration practices and waterfowl habitat management affect critical wetland biogeochemical processes related to greenhouse gas emissions and nutrient cycling. I met this goal through field and laboratory research experiments in which I tested for relationships between management factors and the biogeochemical responses of wetland soil, water, plants and trace gas emissions. Specifically, I quantified: (1) the effect of organic matter amendments on the carbon balance of a restored wetland; (2) the effectiveness of two static chamber designs in measuring methane (CH4) emissions from wetlands; (3) the impact of waterfowl herbivory on the oxygen-sensitive processes of methane emission and coupled nitrification-denitrification; and (4) nitrogen (N) exports caused by prescribed draw down of a waterfowl impoundment.</p><p>The potency of CH4 emissions from wetlands raises the concern that widespread restoration and/or creation of freshwater wetlands may present a radiative forcing hazard. Yet data on greenhouse gas emissions from restored wetlands are sparse and there has been little investigation into the greenhouse gas effects of amending wetland soils with organic matter, a recent practice used to improve function of mitigation wetlands in the Eastern United States. I measured trace gas emissions across an organic matter gradient at a restored wetland in the coastal plain of Virginia to test the hypothesis that added C substrate would increase the emission of CH4. I found soils heavily loaded with organic matter emitted significantly more carbon dioxide than those that have received little or no organic matter. CH4 emissions from the wetland were low compared to reference wetlands and contrary to my hypothesis, showed no relationship with the loading rate of added organic matter or total soil C. The addition of moderate amounts of organic matter (< 11.2 kg m-2) to the wetland did not greatly increase greenhouse gas emissions, while the addition of high amounts produced additional carbon dioxide, but not CH4. </p><p>I found that the static chambers I used for sampling CH4 in wetlands were highly sensitive to soil disturbance. Temporary compression around chambers during sampling inflated the initial chamber CH4 headspace concentration and/or lead to generation of nonlinear, unreliable flux estimates that had to be discarded. I tested an often-used rubber-gasket sealed static chamber against a water-filled-gutter seal chamber I designed that could be set up and sampled from a distance of 2 m with a remote rod sampling system to reduce soil disturbance. Compared to the conventional design, the remotely-sampled static chambers reduced the chance of detecting inflated initial CH4 concentrations from 66 to 6%, and nearly doubled the proportion of robust linear regressions from 45 to 86%. The new system I developed allows for more accurate and reliable CH4 sampling without costly boardwalk construction. </p><p>I explored the relationship between CH4 emissions and aquatic herbivores, which are recognized for imposing top-down control on the structure of wetland ecosystems. The biogeochemical consequences of herbivore-driven disruption of plant growth, and in turn, mediated oxygen transport into wetland sediments, were not previously known. Two growing seasons of herbivore exclusion experiments in a major waterfowl overwintering wetland in the Southeastern U.S. demonstrate that waterfowl herbivory had a strong impact on the oxygen-sensitive processes of CH4 emission and nitrification. Denudation by herbivorous birds increased cumulative CH4 flux by 233% (a mean of 63 g CH4 m-2 y-1) and inhibited coupled nitrification-denitrification, as indicated by nitrate availability and emissions of nitrous oxide. The recognition that large populations of aquatic herbivores may influence the capacity for wetlands to emit greenhouse gases and cycle nitrogen is particularly salient in the context of climate change and nutrient pollution mitigation goals. For example, our results suggest that annual emissions of 23 Gg of CH4 y-1 from ~55,000 ha of publicly owned waterfowl impoundments in the Southeastern U.S. could be tripled by overgrazing. </p><p>Hydrologically controlled moist-soil impoundment wetlands provide critical habitat for high densities of migratory bird populations, thus their potential to export nitrogen (N) to downstream waters may contribute to the eutrophication of aquatic ecosystems. To investigate the relative importance of N export from these built and managed habitats, I conducted a field study at an impoundment wetland that drains into hypereutrophic Lake Mattamuskeet. I found that prescribed hydrologic drawdowns of the impoundment exported roughly the same amount of N (14 to 22 kg ha-1) as adjacent fertilized agricultural fields (16 to 31 kg ha-1), and contributed approximately one-fifth of total N load (~45 Mg N y-1) to Lake Mattamuskeet. Ironically, the prescribed drawdown regime, designed to maximize waterfowl production in impoundments, may be exacerbating the degradation of habitat quality in the downstream lake. Few studies of wetland N dynamics have targeted impoundments managed to provide wildlife habitat, but a similar phenomenon may occur in some of the 36,000 ha of similarly-managed moist-soil impoundments on National Wildlife Refuges in the southeastern U.S. I suggest early drawdown as a potential method to mitigate impoundment N pollution and estimate it could reduce N export from our study impoundment by more than 70%.</p><p>In this dissertation research I found direct relationships between wetland restoration and impoundment management practices, and biogeochemical responses of greenhouse gas emission and nutrient cycling. Elevated soil C at a restored wetland increased CO2 losses even ten years after the organic matter was originally added and intensive herbivory impact on emergent aquatic vegetation resulted in a ~230% increase in CH4 emissions and impaired N cycling and removal. These findings have important implications for the basic understanding of the biogeochemical functioning of wetlands and practical importance for wetland restoration and impoundment management in the face of pressure to mitigate the environmental challenges of global warming and aquatic eutrophication.</p> / Dissertation

Large areas of mesotidal estuaries become subaerial during low tide. Here we study the effect of nutrient enrichment and several meteorological and hydrodynamic parameters on the erodability of mudflat substrates when they are emergent. We tested the impact of nutrient fertilization on tidal flat sediments over a two week period in September 2011 in Plum Island Sound, Massachusetts (USA). High resolution measurements from our experiment indicate that daily nutrient enrichment at 70 μM NO3‾ using our experimental approach does not change the critical shear stress of the muddy substrate, nor affect the concentration of chlorophyll a at the surface. Sediment erodability is instead directly related to the potential evaporation rate and to the duration of the subaerial period. Chlorophyll a concentration decreases when evaporation is high, possibly due to the downward migration of diatoms. Sediment concentrations in the water column during submergence strongly depend on bottom shear stresses triggered by tidal currents. Surprisingly, they are also related to the total evaporation that occurred in the previous emergence period. We conclude that subaerial desiccation at low tide decreases the erodability of mudflat sediments. This strengthening effect is not lost during the following submerged period, thus limiting the erosive effect of tidal currents. For the first time we show that not only subaqueous but also subaerial processes control the erodability of mudflats. Global warming and other climatic variations regulating long-term evaporation rates can therefore directly affect the stability of mudflats in mesotidal environments.

Salt marshes are some of the most productive and valuable landscapes on earth, but they are vulnerable to the effects of sea-level rise, erosion and eutrophication. These processes act on a wide range of temporal and spatial scales, which complicate assessments of the health and stability of marsh ecosystems. High-frequency monitoring using in situ sensors captures the complete range of these dynamics, but extracting meaningful physical and ecological information from these signals requires process-based models coupled with statistical techniques. I develop and apply such methods to study two coastal landscapes, a coastal pine forest on the Eastern Shore of Virginia and a mesotidal salt marsh complex in the Plum Island Estuary, Massachusetts. Observations from groundwater wells in the Virginia pine forest indicate that storms are the dominant controls on the hydrology of the forest and that tidal influence is nonexistent. This forest exhibits a distinct spatial pattern in age structure in which young trees do not grow at low elevations. This pattern can be explained by a model that includes the interaction of sea-level rise, storms and the age-dependent variation in tree stress response, which predicts that the long-term evolution of the boundary is an ecological ratchet. Stresses due to sea-level rise slowly push the boundary at which young trees can survive upslope. Powerful storms then kill the mature, persistent forest at low elevations, which quickly pushes the forest boundary up to the regeneration boundary. Salt marshes need to accumulate sediment to replenish material lost as sea-level rises and creek banks erode. Fluxes of sediment can be monitored with simultaneous high-frequency observations of flow from acoustic Doppler current profilers and turbidity from optical backscattering sensors. I first investigate the relationship between water level and flow in marsh channels and develop predictive stage-discharge models to simplify the monitoring of fluxes. I then construct sediment budgets for eleven salt marshes in the Plum Island Estuary. The observed budgets depend strongly on the unique hydrodynamic conditions of each marsh channel. Variability in these conditions leads to the observed spatial and temporal variability in sediment fluxes from these marshes.