This report is intended to examine the ecological changes due to mixing in shallow water bodies. Physical, chemical, and biological changes are reported in literature. A literature search revealed the range of mixing nodes or processes. Assessment of ecological changes due to mixing by boating activities had been evaluated in a research project supported by the environmental Protection Agency and conducted at Florida Technological University. The examination of changes due to mechanical mixing on lake ecology simulated in fifty-five gallon drums indicated the sensitivity of such parameters as total Kjeldahl nitrogen, conductivity, pH, temperature, and dissolved oxygen. Problems of reproducibility and simulation are inherent in transporting sediments and water samples from a natural environment to an isolated barrel test. Even though care was taken to insure similar initial conditions for all water quality parameters in all of the drums, differences were recognized. The useful information from a pilot study of this nature comes f r o m the relative comparison of each drum before and after mechanical stirring.

A scarcity of comparable research on the transport of bacteria has forced hydrologic models to assume that bacteria travel as dissolved chemicals. In reality, most bacteria preferentially attach to soil aggregates, and behave very differently from planktonic bacteria. The goal of this research project was to identify and evaluate a laboratory method for partitioning between attached and planktonic bacteria that could be used to improve hydrologic modeling. Attachment was measured indirectly as the difference between total and planktonic bacterial concentration. Planktonic concentration was defined as the concentration of bacteria that could pass through an 8 μm screen. Total concentration was determined by disaggregating attached bacteria through a dispersion treatment. A randomized complete block design was structured to test for the effects of filtering, two dispersion treatment options, and the presence of soil on concentration. Tween-85 surfactant was selected as the best dispersant for use in further studies. About 78% of bovine <I>E. coli</I> in the laboratory samples were adsorbed/associated with sterile soil particles. Twenty samples of different bacteria-soil ratios were analyzed using this method to develop an isotherm equation describing <I>E. coli</I> partitioning. The <I>E. coli</I> used to inoculate these samples was cultured using a chemostat reactor to control cell growth stage and control variability. A linear isotherm (R²=0.88) was selected to describe this experimental data; however, future studies characterizing the partitioning behavior of <I>E. coli</I> under different environmental conditions are recommended in order to better understand attachment prior to modeling attached and planktonic <I>E. coli</I> separately. / Master of Science

Silvicultural activities, particularly forest harvesting operations, have the potential to negatively impact water quality. In order to lessen the probability that water quality degradation will occur, a suite of best management practices has been developed and adopted by southeastern states. The Clean Water Act exempts silvicultural activities from the permitting process of Section 404 as long as federally accepted best management practices are implemented to control nonpoint source pollutants. To demonstrate that these practices are being implemented, states are now inspecting and reporting on best management practice usage on a state wide basis. The Environmental Protection Agency is responsible for executing the Clean Water Act and would like to use the information provided by the individual states to guide water quality protection programs at a regional scale since states have developed their own unique methods or reporting. Currently there it is difficult to compare the information provided by states, and this impedes further development of water quality protection programs. To address this issue, a state of the art review of current inspection and monitoring methods in the southeast was conducted. Forestry professionals were then surveyed to identify opportunities for standardization in the inspection and reporting methodologies employed by states. Using the information resulting from the review and survey, recommendations for standardization were made in the following areas: site selection criteria, field execution method, form design, best management practices evaluated and water quality threat assessment. A standardized form was also developed and tested across three physiographic regions. This information is helpful for future planning and modifications that state agencies can use to standardize their BMP implementation monitoring methods. / Master of Science

Measurements of runoff quantity and quality from three cattle stocking treatments applied to pastureland in southwestern Virginia indicate the need for further research to determine treatment effects. Three cattle stocking treatments (1) Continuous, 2) Rotational, and 3) Mob) were applied to three pastures at the Virginia Tech Prices Fork Research Farm. Rainfall simulations were performed over replicated plots in each treatment to induce runoff for collection of runoff quantity and quality data during the 2012 grazing season. Additionally, rainfall simulations were performed prior to applying the grazing treatments to establish initial conditions. Monitored runoff quantity and quality response variables included runoff depth, mean nutrient concentrations, and nutrient mass loss. Response variables were compared among the three pastures for initial conditions and among treatments for post-treatment conditions. Additionally, the trends in response variables within the 2012 season were compared among treatments. Plot and rainfall conditions that were expected to influence responses were also collected and analyzed in relation to response variables. Analyses of the response variables suggested that the variability within treatments likely muted any treatment effect on the response variables. Therefore, we concluded that further research is needed to determine treatment effects on runoff quantity and quality. / Master of Science

This study was carried out to characterize ponds and aquaculture systems, and also to determine both the potential and actual impacts of pond aquaculture effluents on receiving stream quality in the Ashanti and Brong Ahafo regions of Ghana. Water, fish and macroinvertebrate samples were collected from upstream, downstream and nearby reference streams of, and questionnaires administered to, 32 farms. Total settleable solids were higher in ponds than reference streams (p = 0.0166); suspended solids was higher in ponds than reference streams (p = 0.0159) and upstream (p = 0.0361); and total phosphorus was higher in ponds than reference (p = 0.0274) and upstream (p = 0.0269). Total nitrogen was most clearly higher in ponds than all other locations: p = 0.0016, 0.0086 and 0.0154 for the differences between ponds and reference, upstream, and downstream respectively. BOD5 level was also higher in ponds than all locations (p = 0.0048, 0.0009, and 0.0012 respectively). Also, non-guarding fish species were more abundant in reference streams than downstream (p = 0.0214) and upstream (p = 0.0251), and sand-detritus spawning fish were less predominant in reference streams than upstream (p = 0.0222) and marginally less in downstream locations (p = 0.0539). A possible subsidy-stress response within study streams was also observed. Hence, ponds are potential sources of these water quality variables to receiving streams. Effluent-receiving streams, generally, were not much different from reference streams in terms of most the metrics of community structure and function used in the comparisons. Hence, even though receiving streams in Central Ghana may not be severely impacted by aquaculture effluents at the moment, the management of pond effluents will determine the scale of future impact. Vegetable, cereal, and livestock farming could serve as additional sources of fecal streptococci and coliform bacteria and nutrient-enrichment within the study area, besides aquaculture, and so these industries must also be included in efforts to minimize pollution of these streams. / Master of Science

Nutrient loadings to the Chesapeake Bay are a source of concern for water quality agencies. In particular, excess nitrogen loadings from agricultural production activities threaten water quality in the Bay. Questions have been raised about how effectively traditional BMPs can control nitrogen loss from crop production. This study examines agricultural nitrogen pollution control from an input management perspective. Using an economic and physical model, seven production systems and nitrogen management strategies are compared in terms of input use, profitability, and nitrogen loss potential. Results suggest that several of the production systems will reduce residual nitrogen without reducing profits. However, it is recognized that factors in addition to profitability will influence producers' nitrogen management decisions. Therefore, using the results of a farmer survey, adoption models are estimated to examine the impact of production system characteristics and producer characteristics on the decision to use an alternative production system and nitrogen management strategy. Finally, a sensitivity analysis is conducted to examine the impact of alternative policy tools on adoption incentives. Both financial incentives and education and information programs are found to be important tools for influencing producers' decisions. Producers' interest in the alternative systems and desire for information on the systems suggest that agricultural research will contribute by assuring that producers have access to adequate information on the alternative systems. / Ph. D.

Agricultural nonpoint source nutrient pollution is the leading cause of water quality impairment in the Chesapeake Bay. Agroforestry, the integration of trees with crops or livestock production, or both, achieves production and conservation objectives on a single plot of land. Agroforestry is recognized by the Chesapeake Bay Program's strategy as a means of reducing nonpoint source pollution to improve water quality in the Bay. Despite this, agroforestry adoption remains limited and agroforestry is not recognized in Virginia's water quality trading program. To understand the potential of agroforestry nutrient credit trading, I studied the prospects of agroforestry from both a social and biophysical perspective. First, I surveyed 1,436 randomly selected landowners in four 5th level watersheds of the Chesapeake Bay in Virginia for a mixed-methods analysis of agroforestry adoption interest. Second, I used the Chesapeake Bay Assessment Scenario Tool to analyze the water quality implications of intermediate forest conversion scenarios on four initial agricultural land uses on respondent properties. From these studies, I recommend landowner characteristics, concerns, and objectives concerning agroforestry need to shape research and outreach messaging. Furthermore, agroforestry practices has potential to significantly reduce nonpoint source nutrient pollution in a manner that preserves agricultural production, but the terrestrial nutrient dynamics of agroforestry will need to be better captured in modeling to aid in the design of these systems and to generate adequate and fair crediting standards. / Master of Science / Pollution from farming is one of the largest threats to the health of the Chesapeake Bay. Retiring farmland is one method of reducing pollution. Water quality trading is a new strategy to encourage farmers to retire farmland. As part of this strategy, regulated polluters, such as a property developer, can offset their pollution by paying farmers to retire farmland and plant trees. Agroforestry practices involve the production of trees with crops or livestock on the same piece of land. These integrated systems could reduce pollution to the Bay while allowing farmers to continue farming, but few farmers have been willing to adopt these practices. Additionally, although agroforestry is recognized as part of a larger strategy to clean up the Bay, currently it is not recognized by Virginia's water quality trading program. To understand how agroforestry and water quality trading could help restore the bay, we asked farmers about their interest in agroforestry and used a computer program to estimate how increasing tree coverage on farms could reduce pollution to the Bay. We found that agroforestry could reduce a significant amount of pollution, while allowing farmers to continue farming to some degree. Though, knowledge of how agroforestry reduces pollution and technology that can assist in the design of these systems will need to advance for two reason. First, technology based on a better understanding of how agroforestry reduces pollution will allow us to properly credit farmers for adopting agroforestry. Second, it will assist in designing these systems. Outreach, research, and development of agroforestry should be informed by landowner perceptions, concerns, and objectives.

Salinization of freshwaters by human activities is of growing concern globally. Salt pollution can cause adverse effects to aquatic biodiversity, ecosystem function, ecosystem services, and human health. In many regions of the world, and in coal-mining-influenced streams of the temperate forests of Appalachia USA, specific conductance (SC), a surrogate measure for the dissolved major ions composing salinity, has been linked to decreased diversity of benthic macroinvertebrates. However, assessments used to reach this conclusion have generally not accounted for temporal variability of salinity, as most studies use "snapshot" SC data collected concurrently with biological data at a single point in time. Effective management of salinization requires tools to accurately monitor and predict salinity while accounting for temporal variability. To improve those tools, I conducted analyses of 4.5 years of salinity and benthic macroinvertebrate data from 25 forested headwater streams spanning a gradient of salinity where non-salinity stressors were minimized. My objectives were to: 1) model the annual pattern of salinity, 2) determine if salinity measures derived from continuous data are more precise than snapshot SC as predictors of aquatic biology, and 3) quantify response to salinity of the benthic macroinvertebrate community. A sinusoidal model of the annual cycle of SC using daily measurements for 4.5 years revealed that salinity naturally deviated ± 20% from annual mean levels, with minimum SC occurring in late winter and maximum SC occurring in late summer. The pattern was responsive to seasonal dilution as driven by catchment evapotranspiration dynamics. Alternative discrete sampling intervals can approximate the pattern revealed by continuous SC data if sampling intervals are ≤ 30 days. Continuous SC variables did not significantly improve precision for prediction of benthic macroinvertebrate metrics (p > 0.1) as compared to snapshot SC using generalized additive mixed models. Results suggest that snapshot SC is a capable predictor of benthic macroinvertebrate community structure if sampling is carefully timed. However, continuous SC data can quantify chronic salt exposure, which supports a hypothesis to explain how temporal variability of field-based observations of salt sensitivity of benthic macroinvertebrate taxa may be influenced by life stage. Benthic macroinvertebrate community structure diverged from reference condition as salinity increased, with stronger relationships in Spring than in Fall. Intra-seasonal variation in community structure was also revealed across sampling dates. Non-Baetidae Ephemeroptera were most sensitive to salinity, with richness and abundance lower than reference at SC > 200 =µS/cm in Spring based on snapshot SC. Equivalent effects were predicted by mean monthly SC of 250-300 µS/cm from the prior Fall. Continuous conductivity monitoring may improve assessment of salinity effects because they can describe life-cycle exposure, which may aid investigations of mechanisms driving field-based observations of benthic-macroinvertebrate community alteration. / Ph. D. / Freshwater ecosystems around the world are at risk of contamination from salt pollution resulting from a variety of human activities. All natural freshwaters contain low levels of dissolved minerals, or salts, the combined concentration of which is referred to as salinity. Activities such as crop irrigation, road de-icing, and mining can cause salt pollution in streams and rivers, and excessive salinity can be toxic to many aquatic organisms. In many regions of the world, including in coal-mining-influenced streams of Appalachia USA, elevated salinity has been linked to decreased diversity of benthic macroinvertebrates, which are primarily aquatic insects, a group critical to healthy stream ecosystems. However, assessments used to reach this conclusion have generally not accounted for annual variability of salinity, as most studies use “snapshot” salinity data collected concurrently with biological data at a single point in time. Effective management of salinity impacts requires tools to accurately monitor and predict salinity while accounting for annual variability. Toward improving those tools, I conducted analyses of 4.5 years of salinity and aquatic insect data from 25 small central Appalachian mountain streams spanning a gradient of salinity. My objectives were to: 1) characterize the annual pattern of salinity using high-frequency salinity data, 2) determine if high-frequency salinity data is better than snapshot data for predicting aquatic insect diversity, and 3) measure the response to salinity of the aquatic insect community and identify salinity levels associated with insect biodiversity loss. High-frequency (daily) data revealed that salinity exhibited a predictable cyclic annual pattern with seasonal deviations of ± 20% from annual average salinity levels. Minimum salinity occurred during late winter and maximum salinity occurred in late summer. Lower-frequency salinity data can approximate the annual pattern if sampling interval is ≤ 30 days. Snapshot salinity was equally capable as high-frequency data of predicting aquatic insect diversity provided that snapshot salinity sampling is carefully timed. Diversity of many aquatic insects, especially mayflies, declined with increasing salinity, with stronger relationships in Spring than in Fall. Variation in diversity measures was also somewhat related to sample timing within seasons. Alteration of aquatic insect communities was evident at total salt concentrations levels of approximately 130 – 200 parts per million, depending on time of year. Efforts to manage salinity impacts to aquatic life may be improved by integrating knowledge of annual salinity patterns with how aquatic insects respond to salt pollution.

Sensitivity analysis was performed on the QUAL-II water quality model. The reaeration rate, the ammonia nitrogen oxidation rate, and the carbonaceous deoxygenation coefficient were found to be highly sensitive in the model. Only moderate sensitivity was found with the areal flow contribution, the oxidation rate of nitrite nitrogen, and the organic nitrogen reaction rate. Through the ranges tested, the combined effect of the BOD settling rate and the benthos source rate were found to be insensitive. Based on the projected variations within the most sensitive variables, resultant waste load allocations were found to be too variable for adequate application towards treatment requirements. It is also postulated that due to the complexity of the dissolved oxygen balance within the South River, Virginia, that a revised algal subroutine must be incorporated in the model's application to that system. / M.S.

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