Arsenic is a notorious poison due to its high toxicity, worldwide distribution, and lack of any taste and colour once dissolved. The abundance of arsenic in Earth’s crust makes that it can naturally find its way into food and drinking water. Rapid and reliable detection of arsenic, directly in the field, is critical to support evidence-based decision-making in choosing irrigation or drinking water sources. Current cost-effective colourimetric techniques are associated with poor accuracy, health risks, and unacceptable levels of false negatives. Arsenic-specific cellular sensors, or biosensors, may present an inexpensive, safe, and renewable alternative, yet they have long been criticized for unsatisfactory sensing performance, and inconsistency of the outcome. This, in addition to the lack of suitable instruments capable of measuring the signals produced by these biosensors, has led to very few solutions reaching market. The goal of my thesis research was to test hypotheses that improve our fundamental understanding of As species biogeochemistry in simple and complex environmental matrices to then develop a new arsenic monitoring interface, one that would be both simple and accessible to the general public. Using a combination of wild-type and mutant strains, I managed to detail both the internal regulation of arsenic, and the external drivers of arsenic bioavailability. I started by designing a defined exposure protocol that achieved, for the first time, equimolar uptake of over 94% of the added As(III) and As(V) into the cells. By developing this control early into my thesis, I then worked to reintroduce commonly found constituents of environmental waters that are thought to impact arsenic uptake. This direct testing approach uncovered fundamentals of environmental arsenic redox chemistry such as As(III) photooxidation in solution, environmental ligand exchanges, and biological transport pathways. Simplifying a complex exposure protocol for use by the general public required automation of the data analysis steps. This consists of several hundred lines of code, capable of analyzing, normalizing and stabilizing biosensor output to improve the consistency and robustness of this system. These algorithms were then integrated into a new arsenic monitoring interface, one that was built and designed specifically for dehydrated biosensors. This portable, low-cost spectrometer achieved a fluorescent detection range that rivals expensive and sophisticated laboratory equipment at a fraction of the price, and without the need for a computer to compile the measurements. In contrast to highly criticized colorimetric techniques, the biosensor exposure protocol exceeds in operational use, reliability and detection limit. At its core, my thesis research provides a new and complete arsenic testing solution, one capable of measuring both As(III) and As(V) at levels relevant to the World Health Organization and Canadian guidelines for arsenic content in water (10 µg/L). It also provides a new method capable of selectively discriminating between arsenic species, thereby providing an inexpensive and high-throughput arsenic speciation method. I hope this work will help kickstart development of a marketable solution that empowers individuals to test and to monitor the quality of their water sources.

The case study investigated was the 208 water quality planning conducted in the Ashley Valley, around Vernal, Utah. The region is expected to urbanize rapidly due to energy development on adjacent state and federal land. The water quality planning was being conducted in the absence of substantial prior land use planning. A method is developed in the thesis for evaluating plans and methodologies. The method utilizes preformulated evaluation criteria to analyze structure and function of the methdology, political context, informational inputs, limiting factors, trigger factors, causeeffect relationships, and impacts of methodology on planning recommendations. The criteria collected from the literature and agency guidelines are consolidated into an evaluation model. Data were collected through field interviews, on-site inspection, and examination of workplans, critical path charts and plan documents. The planning was well conducted overall. However, the water quality planning methodology did not maximize the utilization of land use information, nor did it integrate the available land use information into the analysis as fully as possible. Utilization of land use information could have been increased through greater emphasis on land use in the original workplan, more guidance to staff through specification of land use analysis subtasks, tighter coordination of staff, and consideration of a broader range of alternative scenarios. The cursory nature of the land use analysis limited the number of alternative land use patterns identified. This in turn limited the number of potential pollution sources identified. The local political context discouraged serious consideration of some alternative land use patterns, and the use of land use controls as a management strategy.

No description available.

Twenty springs in the central parts of Vallentuna municipality have been studied to determine their present water qualities and suggest actions that could be taken to improve the water quality and availability of the springs. The measured parameters are the water volume, the water flow, the water temperature, the pH-value, the electrical conductivity, the chloride concentration, the alkalinity and the CODMn. The sensory properties of the springs were also examined, which include odour, colour, clarity and precipitation. Measurements of the water flows, the water temperatures, the pH-values and the electrical conductivities were performed during a field trip in Vallentuna. During this field trip, two water samples were taken from each spring. Thereafter, the alkalinity, the chloride concentration, the CODMn and the sensory properties were determined in the laboratory. Four of the springs, which were wells, have water of high quality and can easily be restored. Some of the twenty springs have not been cared for or have even disappeared. The water from the spring horizon near Arkels tingstad is unfortunately mixed with stormwater, which runs off the nearby roads. This contamination is examined by measuring the chloride flows of the different streams.  The roads also contribute with metal pollution, with metals such as cadmium. Therefore, metal speciations of cadmium were examined. A simple solution is suggested to remove the metal pollution. The measured water flows of all of the spring waters in Vallentuna were quite small. The results of the measurements of the spring waters were compared with the values recommended by Livsmedelsverket and Socialstyrelsen. Most of the values were between the recommended limits for drinking water. Suggestions are given to improve the springs concerning water quality and availability. / Tjugo källor i centrala Vallentuna studerades för att bestämma deras vattenkvalitet och för att föreslå åtgärder i avsikt att förbättra vattenkvaliteten och tillgängligheten av källorna. De mätta parametrarna är vattenvolym, flödeshastighet, vattentemperatur, pH-värde, elektrisk konduktivitet, kloridkoncentration, alkalinitet och CODMn. Dessutom undersöktes källvattnens sensoriska egenskaper, vilka innefattar lukt, färg, klarhet och utfällning. Mätningar av flödeshastigheterna, vattentemperaturerna, pH-värdena och elektriska konduktiviteterna gjordes under en exkursion i Vallentuna. Två vattenprover togs från varje källa. Därefter undersöktes kloridkoncentrationen, alkaliniteten, CODMn och de sensoriska egenskaperna på laboratoriet. Fyra av källorna, vilka var brunnar, har vatten av hög kvalitet och kan relativt enkelt restaureras. En del av de tjugo källorna har inte vårdats under lång tid och har till och med försvunnit. Vattnet från källhorisonten vid Arkels tingstad har olyckligtvis blandats med dagvatten, vilket rinner från de närliggande vägarna. Denna förorening analyseras genom att mäta kloridflödet i olika strömmar. Vägarna bidrar också med metallföroreningar, t.ex. kadmium. Därför har också metallförekomstformer för kadmium modellerats. En enkel metod föreslås för att avlägsna metallföroreningarna. Vattenflödena från källorna i centrala Vallentuna är relativt små.  Resultatet av mätningarna av källvattnen jämfördes med de rekommenderade värdena för dricksvatten enligt Livsmedelsverket och Socialstyrelsen. De flesta värdena låg inom gränserna för de rekommenderade värdena för dricksvatten. Förslag ges till förbättring av källorna med avseende på vattenkvalitet och tillgänglighet.

This study was conducted on two Mississippi watersheds. The SWAT model was applied to the Upper Pearl River Watershed (UPRW) to evaluate flow, sediment, nutrients, and fecal coliform bacteria (FCB) transport. The model was further applied to evaluate crop and sediment yields from three tillage systems (Conventional, Reduce 1, and Reduce 2) of the Big Sunflower River Watershed (BSRW). In the UPRW, flow and sediment simulations showed good to very good model performances (for flow R2 up to 0.76 and NSE up to 0.75; and for sediment R2 up to 0.72 and NSE up to 0.54). Both total nitrogen (TN) and total phosphorous (TP) simulations showed fair to good model performances (R2 up to 0.71 and NSE up to 0.63 for TN; R2 up to 0.70 and NSE up to 0.59 for TP). The FCB simulation showed good model performance (R2 up to 0.59 and NSE up to 0.58). In the BSRW, crop simulations showed good to very good model performances (for corn yield R2 up to 0.5 and NSE up to 0.9; and for soybean yield R2 and NSE up to 0.6). Furthermore, modeling outputs of the BSRW explained 64% of the water table fluctuations in the Mississippi alluvial aquifer. The future climates of the UPRW and the BSRW were evaluated for three emission scenarios (A1B, A2, and B1) from the Intergovernmental Panel on Climate Change (IPCC) with the help of the general circulation model, CCSM3. Simulations predict future sediment yields will increase as much as 25% in the UPRW. Both TN and TP yields will also be elevated as much as 7.3% and 14.3% respectively in future climates of the UPRW. Four best management practices (BMPs) were applied to the current and future climates in the UPRW and results showed that BMPs were able to reduce 51% of flow, 55% of sediment, 44% of TN, and 88% of TP in the baseline climate. Moreover, the effectiveness of TN removal will increase in future climates, while the effectiveness of TP removal will remain unchanged. The effects of climate variability on corn and soybean yield were insignificant in the BSRW.

Studies have shown wetlands act as filters for nutrient rich waters, in part due to macrophyte properties. Differences have been found in nitrogen removal rates among plant species in studies of monocultures grown in mesocosms mimicking wastewater treatment constructed wetlands, but little research has been done on assemblages in natural or restored wetlands. This study aims to identify differences in water quality among plant assemblages in natural and restored wetlands. Thirty natural and restored wetlands in the Mississippi portion of the Mississippi Alluvial Valley were sampled four times. Water quality was measured and plant assemblages identified. Significant differences in pH, conductivity, and turbidity were found among four different plant growth forms, but nutrient concentrations were not significantly different among growth forms. Because nutrient concentrations were low, data collected may not have adequately captured potential differences in nutrient concentrations among plant assemblages.

Sediment oxygen demand (SOD) and nutrients releases from the bottom sediments of a water body are important parameters to be included in studies of water quality processes. Two methods to measure SOD, in situ and at laboratory, were applied at Eckie’s Pond on late spring of 2015. Based upon preliminary results, which showed greater values for the in situ method, some modifications of procedures and equipment were made to improve the measurements. Another set of measurements were made on June of 2016, however their results were not conclusive to establish a correlation between these methodologies. As a result of this research, three standard operating procedures (SOP) have been established to measure SOD at shallow waters, first in situ, second at laboratory, and a third SOP to analyze nutrients and metals by using a spectrophotometer.

Shade is defined as the coolness and darkness caused by shelter from solar radiation. In freshwater, shade is most commonly provided by riparian vegetation, which can affect water quality through its effects on temperature and light. The purpose of this research was to explore riparian shade influences on (1) fish distribution along reservoir littorals and (2) diel water quality patterns. Sampling was conducted in shaded and non-shaded paired sites in Columbus Lake, Mississippi, U.S.A. Differences in species distribution revealed that, in general, clupeids and most centrarchids were better represented in unshaded sites, while percids were better represented in shaded sites. Diel cycles of water quality variables were measured in situ over 24-h periods with auto-samplers and assessed using trigonometric polynomial regression to describe daily cycles. Analysis of covariance revealed all water quality variables differed between sites and most also varied between shaded and unshaded sites and exhibited daily cycles.

Water contaminations are currently threatening ecosystems and human health on a world-wide scale. Monitoring the water quality is one of the most essential steps to provide better understanding and mitigation of water contamination. Among the water quality monitoring techniques, optofluidic technologies have created a burgeoning number of novel devices designed to test water quality in an efficient and portable format. However, current optofluidic devices have yet to be successfully translated to onsite monitoring applications due to their high cost, high maintenance and dependence on delicate laboratory instruments or bulky instruments. In this work, we developed two optofluidic platforms for onsite water quality monitoring: a fluorescence-based optofluidic platform for chemical analysis and an imaging-based optofluidic platform for microbe detection. Several technologies associated to optical sensing modules were developed to overcome the above challenges, making the optofluidic platforms compatible with onsite monitoring applications. First, excitation coupling mechanism and frequency domain time-resolved fluorescence (TRF) were developed on the fluorescence-based optofluidic platform to improve sensing sensitivity and stability, while reducing dependence on costly instruments. Their effectiveness was demonstrated by dissolved oxygen (DO) measurements and ray-tracing simulation. Second, a low-cost and portable imaging system with dual modalities were developed on the imaging-based optofluidic platform. Thus, both morphological features and fluorescent features can be observed for microbe detection without using bulky microscope setups. The effectiveness of dual-modality imaging was demonstrated by experimental results of phytoplankton analysis. Third, a fluorescence lifetime imaging (FLIM) approach was developed under a low-cost (Complementary metal–oxide–semiconductor) CMOS format. This approach enables integrating FLIM module in portable optofluidic platforms for onsite monitoring. These advances bring optofluidic platforms closer to realizing the requirements of onsite water quality monitoring and provide a clear picture for future improvements and research directions. / Thesis / Doctor of Philosophy (PhD)

The stress protein response (SPR) is a conserved and ubiquitous mechanism that enables cells to tolerate a wide variety of environmental insults. This response involves the preferential synthesis of an array of proteins with different molecular weights. These proteins perform a variety of functions, such as protein folding, multimeric protein assembly, steroid receptor binding, and heme catabolism. To evaluate the potential use of the SPR as a biomonitoring tool, a stepwise plan was utilized that proceeded through various physical and chemical laboratory exposures and culminated with a field validation study. The goals of the laboratory exposures were threefold: (1) determine the time required for induction of the SPR; (2) determine the dose-responsiveness of the SPR; and (3) compare the increased syntheses and accumulations of stress proteins to classical toxicological endpoints (i.e. percent mortality, LC50, LC1, etc).