Algal blooms in Lake Erie have worsened in severity, extent, and duration due to agricultural phosphorus (P) loading. Science, policy, and community action are needed to identify and implement feasible solutions for freshwater protections. To improve conservation action for P-reduction in the Lake Erie watershed, we must understand landscape drivers that enhance P runoff across agricultural regions with seasonal and spatial variation. The goals of this thesis were to assess landscape determinants of seasonal P variations in the understudied Canadian Lake Erie watershed, and to develop tools to amplify community stream monitoring and environmental engagement. A seven-year dataset revealed that P loading has significantly increased on an annual basis (2012 – 2019) in the late-winter-early-spring (February, March, April) in three separate Lake Erie tributaries (the East Sydenham River, the Thames River, and the Grand River). I demonstrated that year-over-year increases in tile drainage area on farms explained 23 – 49% of the year-over-year increases in P loading; however, I found the effects of tile drainage were moderated by differences in soil texture, land use/land cover, regional climate, and urban point sources. Using a nested-watershed approach for one year in 13 monitoring stations of the mixed-use Grand River watershed, I determined that row crop area was a strong predictor of P concentration in the Grand River when fields are bare, soils exposed, and nutrient assimilation by biota nonexistent. I recommend the use of year-round field cover by cover crops as a conservation measure to attenuate P-enrichment in the Grand River since sub-watersheds with increased cover crop proportion had reduced P concentrations and turbidity throughout the year. In another one-year study of 13 sub-watersheds across a gradient row crop and tile-drained sub-watersheds of the East Sydenham River and Grand River, I provided quantitative evidence of the negative effects of intensively row crop and tile-drained sub-watersheds on soluble reactive P export during late-winter-early-spring, and particulate loss during the growing season. To engage agricultural communities in monitoring P export from farms, I developed a bioassay that uses stream algae to determine P concentration in low-order streams. This method involving substrate rods (i.e., Peristix) is cost-effective, requires very little training, and yielded data that were significantly related to P concentrations in agricultural streams in the growing season. I recommend that environmental agencies and landowners use this bioassay to identify areas to implement conservation measures to reduce P export from the Lake Erie watershed. For greater application of community-science tools, I created the CommunityFIRST framework, which emphasizes feasible community collaborations, inclusive volunteerism involving a range of abilities and knowledge systems, using tools developed in this thesis that are relevant to the community’s environmental issues and carried out in a supportive and trusting environment between researchers and community members. My research integrates science and community methods to advance our understanding of agricultural land management and seasonal P loading from the Canadian Lake Erie watershed. / Thesis / Doctor of Philosophy (PhD) / After decades of improvement, Lake Erie eutrophication continues to be a water-quality issue in the Great Lakes Basin. Year after year, algae blooms cover the lake and call scientists, politicians, and communities to action. Phosphorus runoff from agricultural activities is at the core of this issue, and a better understanding of phosphorus runoff is needed across all Lake Erie watersheds and during all seasons of the year. The goals of this thesis were to assess landscape determinants of seasonal variations in phosphorus in the understudied Canadian Lake Erie watershed, and to develop tools to amplify community stream monitoring and environmental engagement. Spanning three major Canadian Lake Erie tributaries, I analyzed the effects of agricultural intensity, agricultural management practices, and changing seasonality on phosphorus export. I determined critical periods and specific landscape characteristics and compositions that can enhance phosphorus runoff from agricultural fields, and I offered recommendations to guide management decisions in the Canadian Lake Erie watershed. At the local scale, I developed a feasible stream monitoring tool for community-science initiatives. My research integrates science and community methods to advance the overall understanding of agricultural land management and seasonal phosphorus export from the Canadian Lake Erie watershed.

Intensive tillage practices in the Mississippi Delta degrade soil health, impacting downstream water quality. To address this, two experiments were conducted from 2019 to 2021 and 2020 to 2022 to evaluate the impact of sugarcane biochar and flue gas desulfurization (FGD) gypsum on nutrient leaching losses and soil properties in cotton and soybean cropping systems. Study I applied four biochar rates (0, 10, 20, and 40 Mg ha-1) to cotton and found improvements in soil properties and subsurface quality, with reduced nutrient leaching losses, except for sulfate and sodium ions. Study II evaluated biochar (10 and 25 Mg ha-1) and FGD gypsum (2.24 and 6.72 Mg ha-1) application rates in soybean, resulting in reduced nitrate leaching losses and soil property improvements, mostly observed in the second year. These findings suggest that reevaluating management practices with biochar and gypsum can improve soil health and water quality, but may require a lag time to realize benefits.

The environmental impacts of agricultural non-point source pollution, due in part to the intensification of agriculture to meet the nutritional needs of a growing population, indicate a need for the further implementation of Best Management Practices (BMPs) that can mitigate soil erosion and reduce the export of sediment and nutrients to receiving waters. Water and Sediment Control Basins (WASCoBs) and cover crops are both considered effective in-field BMPs that have been utilized by landowners to reduce soil and nutrient losses from fields. While each of these BMPs has been individually researched for their impacts on soil and water quality, there is little existing research that examines the impact of WASCoBs paired with cover crops on water quality. This study compared four sub-watersheds on the same field near Atterberry, Illinois: 1) a basin drained by a WASCoB, 2) a basin drained by a WASCoB and planted with a cover crop, 3) a basin drained by an ephemeral gully and planted with a cover crop, and 4) a control basin drained by an ephemeral gully. Runoff samples were collected from these watersheds and analyzed for total phosphorus, dissolved reactive phosphorus (DRP), ammonium-nitrogen, nitrate-nitrogen, and total suspended solids (TSS). Nutrient and sediment concentrations were used along with the discharge and duration of runoff events in order to determine event loads for each watershed. The WASCoBs utilized in this study were able to trap 97.3-99.2% of total phosphorus, 84.3-94.4% of DRP, 51.4-78.6% of ammonium-nitrogen, 11.8-56.3% of nitrate-nitrogen, and 98.68-99.21% of TSS. The cover crop treatments in this study did not show a significant impact on water quality, which was likely attributed to poor establishment of the cover crop. These results suggest that early planting is critical for maximizing cover crops establishment and benefit. Reductions in nutrient and sediment loads in this study suggest that WASCoBs have the potential to reduce the discharge of nutrients and sediment to waterways, indicating that their continued implementation may help to accomplish water and soil conservation goals.

For an agricultural watershed, best management practice (BMP) is a conservational way to prevent non-point source pollution, soil and water loss and mitigate groundwater declination. In this dissertation, several BMPs of tail water recovery system, conservation tillage system and crop rotation were selected and evaluated in order to demonstrate the impacts of those activities on stream water quality and quantity. Besides, a land use change scenario was also evaluated. In order to evaluate the scenarios comprehensively, Soil and Water Assessment Tool (SWAT) and Annualized Agricultural Non-point Source Pollution (AnnAGNPS) were applied to simulate surface hydrology scenarios, and Modular flow (MODFLOW) models was used to simulate groundwater level change. This dissertation contains several novel methods regarding to model simulation including (i) using satellite imagery data to detect possible tail water recovery ponds, (ii) simulating surface and groundwater connected, (iii) selecting land use change area based on local trend and spatial relationship, (iv) comparing scenarios between two models. The outcomes from this dissertation included scenarios comparison on surface water quantity and quality, groundwater level change for long term simulation, and comparison between surface water models.

In its 2012 National Lakes Assessment, the EPA determined that nutrients are the most widespread stressor of US Lakes, with one-third of US lakes containing excess nitrogen and/or phosphorus. In response, states are developing numeric nutrient criteria to regulate the allowable amount of nutrients in surface waterbodies. In this study, we estimate the recreational value of improved water quality as a result of reduced nutrients in Mississippi lakes using a travel cost model. A major challenge, however, is the lack of water quality data for many Mississippi lakes. We introduce a water quality prediction model to impute water quality measures for lakes that lack water quality data. We compare welfare estimates from travel cost models based on the limited available water quality data to models using predicted water quality measures to evaluate the extent to which inadequate data affects welfare estimates for improved water quality.

The mass loadings of pollutants common in surface waters result from the discharges of many different sources. In the last few years it has been noted that nonpoint sources contribute more pollutants than point sources. This is because in many cases the point source discharges have been, by law, reduced drastically. In the State of Florida many water quality parameters were examined to estimate the mass loadings in streams related to, drainage area, average flow, land use, soil type and management practices. A total of sixteen streams were examined. The information was first calculated for mass loadings as a function of stream flow. Next the slopes and intercepts were related to drainage area. Both steps were accomplished using bi-variate regression analysis. The final results show a relationship of Total Organic Carbon, Orthophosphate, Total Phosphate and Nitrate to drainage area and stream flow. However, the final results of this study when related to another study in Florida showed different mass loading rates for TOC and TP. The differences were attributed to background levels of pollutants, local geology, hydrologic variability and management practices.

A trace metal speciation scheme proposed by Batley and Florence (1976) was applied to determine the physiochemical forms of zinc, cadmium, lead, and copper in two Central Florida highway drainage systems. The linearity and limitations of the ASV technique were also examined. The measurements showed that (a) more than 70% of the soluble Zn and Cd in all of the waters analyzed existed as liable ionic metal (b) lead was divided between labile and non-labile inorganic forms, but one particular form, PbCO3, predominated (c) a substantial fraction of copper is associated with organic colloids if humic substances are present. In addition a computerized chemical model for trace and major element speciation was applied to the waters in both drainage systems using measured average water quality for input parameters. A comparison between metal species measured by ASV and those predicted by the computer model are presented. There appears to be good agreement between the metal fractions measured in the water samples by ASV and those predicted by the chemical model.

This research investigates organic polymers, inorganic coagulants and separate unit operations for their effect on the total tri-halogenated (TTHM) residuals in a finished water. The water samples utilized for this project were taken from a highly colored Central Florida potable water supply which is used by municipality which has a TTHM concentration in the finished water in excess of the proposed Federal limit. Results indicate that (1) organic polymers are not a significant source of THM precursors, (2) organic polymers, when used as a settling aid after coagulation in Jar tests, are an effective means of filtration for removing THM precursors, (3) THM residuals produced after coagulation increased directly with chlorination pH, (4) there was no significant difference in the THM precursor removal after coagulation for any coagulant tested and (5) coagulation removed a significant amount of THM precursor from the raw water.

In large enough quantities, heavy metals may be detrimental to human health. Metals in raw water may pass through a water treatment plant without being completely removed. Once in a the distribution system, the water may experience metal pick-up due to corrosion. During the course of this study, an attempt was made to determine the heavy metal concentrations in the University of Central Florida's potable water systems. Samples were fun on the plasma spectrophotometer, Spectraspan III, and analyzed for heavy metal content. The results indicate pick-up of Fe, Al, Cu, and Zn in the distribution system. The arsenic and lead concentrations in the drinking water samples should be verified. The UCF sewage treatment plant offers adequate heavy metal removal with the metal ions being removed concentrating in the activated sludge.

For temperate lakes which receive a variable nutrient loading with seasonal variance in their hydrology, it is necessary to consider the dynamic response of the lake to these variable nutrient loadings. An approach to evaluate Lake Eola water quality responses to dynamic discharge of nutrients is presented. The major source of nutrients for this lake is stormwater runoff containing nitrogen and phosphorus. A mass balance of nutrient sources and sinks for the period of one year (April 1980 - March 1981) was performed. To accomplish this, a field determination for various parameters of the hydrologic budget was performed on a monthly basis. A monthly water quality analysis of the lake was measured. It was determined that Lake Eola was phosphorus limited and that 87% of the Total Phosphorus entering the lake via stormwater runoff was retained in the bottom sediments. Retention of various nutrients ranged from 77% to 93%. In order to evaluate the dynamic response of this lake, it was necessary to consider the retention of the nutrients as a function of time. The inductive methodology for this analysis and an example for Total Phosphorus is presented.