The presence of organic micropollutants (OMPs) in water is of great environmental concern. OMPs such as endocrine disruptors and certain pharmaceuticals have shown alarming effects on aquatic life. OMPs are included in the priority list of contaminants in several government directorate frameworks. The low levels of OMPs concentration (ng/L to μg/L) force the use of sophisticated analytical instruments. Although, the techniques to detect OMPs are progressing, the focus of current research is only on limited, important OMPs due to the high amount of time, cost and effort involved in analyzing them. Alternatively, quantitative structure activity relationship (QSAR) models help to screen processes and propose appropriate options without considerable experimental effort. QSAR models are well-established in regulatory bodies as a method to screen toxic chemicals. The goal of the present thesis was to develop QSAR models for OMPs removal by oxidation. Apart from the QSAR models, a decision support system (DSS) based on multi-criteria analysis (MCA) involving socio-economic-technical and sustainability aspects was developed. Also, hybrids of different water treatment processes were studied to propose a sustainable water treatment train for OMPs removal. In order to build the QSAR models, the ozone/hydroxyl radical rate constants or percent removals of the OMPs were compiled. Several software packages were used to 5 compute the chemical properties of OMPs and perform statistical analyses. For DSS, MCA was used since it allows the comparison of qualitative (non-monetary, non-metric) and quantitative criteria (e.g., costs). Quadrant plots were developed to study the hybrid of natural and advanced water treatment processes. The QSAR models satisfied both chemical and statistical criteria. The DSS resulted in natural treatment and ozonation as the preferred processes for OMPs removal. The QSAR models can be used as a screening tool for OMPs removal by oxidation. Moreover, the QSAR - defining molecular descriptors help in detailed understanding of oxidation. The DSS can be considered as an aid in assessing a multi-barrier approach to remove OMPs. Hybrids of natural and advanced treatment processes help to develop a more sustainable multi-barrier approach for OMPs removal.

Drainage water management via controlled drainage (CD) and subirrigation (SI) has shown positive effects on water quality. To determine the impact of CD and SI in the Red River Valley (RRV), data from two fields, each with CD and SI, were analyzed. Water samples taken during SI from a North Dakota field during 2012-2018 were significantly different from those taken during CD and free drainage (FD). This was likely due to the SI water source of marginal quality, which also impacted soil quality near the drain tile. Three Minnesota fields were compared during 2013-2019, each with differing drainage practices. Results from a rainfall event showed an intermediate water table depth in the CD and SI field, along with a higher phosphate but lower nitrate concentration in surface runoff samples compared to subsurface drainage samples. Despite differences found between these fields, correlation between drainage practice and crop yield was not present.

Thirteen oxbow lakes, 7 deep (>3.0 m) and 6 shallow (< 1.5m), were studied in the Yazoo River basin (YRB) to identify if divergent water quality characteristics and fish communities were common occurrences. Shallow lakes repeatedly experienced wide diel fluctuations in temperature and oxygen, reduced Secchi depth, and greater levels of suspended solids, turbidity, and chlorophyll-a. Fish communities were mostly comprised of orangespotted sunfish, juvenile crappies, gars, and various backwater fishes. Deep lakes exhibited improved conditions among all water quality variables and harbored fish communities comprised mostly of large-bodied and long-lived individuals, and piscivorous species. Furthermore, effects of smallmouth buffalo on water quality were examined at three different biomass levels in experimental ponds. Ponds with biomasses at 220 and 65 kg ha-1 responded with reduced visibility, elevated turbidity and suspended solids, and lower oxygen levels. These two studies combined provide valuable insight into shallow lake management in the YRB.

Floodplain lakes in the Mississippi Alluvial Valley (MAV) provide valuable freshwater resources for states in which they occur. Thirty lakes in portions of Mississippi and Arkansas were surveyed for chlorophyll-a fluorescence and turbidity using handheld meters to determine relationships between chlorophyll-a concentrations and suspended solids. High applicability of handheld meters in the MAV presents economic benefits for monitoring the numerous lakes in the region. Additionally, twelve lakes within Bear Creek watershed, Mississippi were studied to determine how hydrologic connectivity shapes fish communities. Isolated and permanently connected floodplain lakes exhibited characteristically lacustrine and rheophilic fish communities, respectively, diversifying fishery management opportunities. Lastly, spring diel temperature and oxygen dynamics, as well as juvenile fish communities, were assessed within three habitats in a floodplain lake – pelagic environment, margin and contiguous wetlands. Variability in temperature and oxygen across the three habitats promotes spring habitat heterogeneity while supporting distinct but overlapping juvenile fish assemblages.

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This thesis aimed to study the seventy-two representative wells of Denton County and to determine the possibilities of infection with typhoid organism. The sanitary survey and the test for Colon-Aerogenes bacteria show that 55% of the 72 wells studied are unsanitary, 27% are sanitary, and 18% are doubtful.

A research Report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science, 2018 / Cyanobacteria cells enter water treatment plants from the raw water abstracted from surface water destined to supply the water treatment plants. The presence of cells might interfere with purification processes such as coagulation and flocculation and may subsequently result in the release of taste and odourous compounds. This study is aimed at determining the efficiency of a Recovered Wash Water Plant (RWWP), in removing cyanobacteria cells and associated organic compounds at three stages of treatment, namely raw water, after sedimentation and after filtration. Concentration outcomes were statistically analysed to determine removal ability of the RWWP. The cyanobacteria genera Microcystis, Anabaena and Oscillatoria were detected in the three sampling points (raw water, after sedimentation and after filtration) selected. The organic compounds detected included geosmin, 2-methylisoborneol (2-MIB), and a cyanotoxin, microcystin. It is recommended that the effectiveness of the RWWP should be investigated seasonally during further research / MT 2020

High extraction mining techniques have produced the need to mitigate and understand ground movements associated with this technology.  Tools such as the Surface Deformation Prediction System (SDPS) facilitate sound scientific decision making in the industry and has continually improved since its inception in 1987.  The capabilities of SDPS have expanded on an as-needed basis.  Currently, the regulatory climate has emphasized the need to understand the impact of underground mining on surface waters, physically and chemically. The SDPS program is used to conduct an analysis of ground movements to assess optimal barrier pillar size for stream protection.  Typical analytical and empirical methods used in mine planning were compared against SDPS methods to ensure the validity and advantage to the use of SDPS for this purpose. Finally, underground mining effects on stream chemistry and health were explored by studying the heavily mined and industrialized watershed of Dumps Creek located in Russell County, Virginia.  This watershed has been identified as being impaired since the Virginia 303(d) List of Impaired Waters was created in 1994.  Currently, there are two pumps staged in the headwaters region of Dumps Creek that help to maintain water levels in an inactive underground mine.  The pumping is necessary to control methane levels that rising water could force into an active underground mine that lies stratigraphically above the inactive mine.  Water is pumped on an as-needed basis and discharges directly into Dumps Creek.  Historic measurements of stream conductivity and benthic health scores were compared to assess whether a correlation exists between the two measurements.  These measurements were compared based on regulatory decisions that emphasized that conductivity is a direct indicator of stream health in all watersheds. Scientific contributions associated with this research include: Further developments in the use of SDPS programming in order to account for stream protection on a case by case basis for both mine panel and surface water protection by optimizing barrier pillar size in relation to a nearby stream; the analysis of available and currently obtained water chemistry data in a mining impacted watershed in attempt to further research to appropriately characterize and mitigate specific problems in order to improve stream health; and, assessment of the complexity of water chemistry impacts from underground mining as related to stream health indicators in different chemically dominated watersheds. / Master of Science

The amount of time cattle spend standing in streams is one input parameter needed by computer models when total maximum daily load (TMDL) plans are being developed. This input parameter is estimated using professionals' best judgment because experimental data are not available, and estimations are generally inconsistent. The goal of this study was to gain a better estimate of the amount of time cows spend in streams, since this has a significant impact on direct fecal coliform loadings to streams. Significant factors influencing the amount of time cattle spend in streams were identified, and a relationship was developed for predicting the amounts of time cattle spend in streams. Five farms were studied in southwest Virginia from August 2001 through February 2002. Camera surveillance systems were set up on two beef farms and three dairy heifer operations, and cattle activity in streams was recorded during daylight hours. Climatic data, pasture characteristics, feed characteristics, and farm management practices were collected from each site, and their relationships with the amount of time cattle spend in streams were investigated. No significant difference (p=0.82) was found between the amount of time beef cattle and dairy heifers spent in streams. Overall, cows spent an average of 10.12 min day-1cow-1 standing in streams during the observation period. Throughout the study period from August to February, cows spent the highest amount of time in streams during the month of November (14.3 min day-1cow-1). Feed, climatic, and pasture parameters were found to influence the amount of time cattle spent in streams. These significant parameters were used to develop an empirical equation for predicting cattle presence in streams. This model may not accurately predict the amount of time spent in streams by cows during warmer summer months, since data was collected during fall and winter months. Other limitations may be encountered when using the model to predict the amount of time lactating dairy cows spend in streams when streams are their sole water source, since they have a much higher water requirement than those cows studied. / Master of Science

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