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Indiana University-Purdue University Indianapolis (IUPUI) / Paleoproductivity records during the late Pleistocene are sparse. The equatorial Pacific and the Southern Ocean are collectively responsible for the majority of the new production in the oceans. The nutrient and carbon mass balances of these regions must be constrained in order to fully understand net global biological productivity on glacial timescales. The geochemistry of two east-central equatorial Pacific Ocean cores (02° 33.48 N; 117° 55.06 W) and (00° 15.42 S; 113° 00.57 W) are used to examine changes in biological productivity due to nutrient upwelling on glacial timescales during the Pleistocene. The cores were recovered in March 2006 on the AMAT03 cruise, a site survey cruise for IODP Proposal 626. The total concentrations of Ca, Ti, Fe, Al, P, Ba, S, Mg, Sr, Zn and Mn were determined by a total sediment digestion followed by analysis by inductively coupled plasma-atomic emission spectrometry (ICP). Original solid forms of P for 34 evenly spaced samples throughout one core were determined using the P Sequential Extraction technique. This study is attempting to compare upwelling and productivity records by determining temporal records of nutrient proxies, using Latimer and Filippelli (2006) which focused on the Southern Ocean. Equatorial upwelling and Southern Ocean upwelling both appear to exhibit strong glacial timescale variability. The P geochemistry results indicate that the P signal is largely biological. The equatorial Pacific evidence, in accordance with Southern Ocean patterns, supports a nutrient budget-driven productivity signal over time. Gabriel M. Filippelli, Ph. D, Committee Chair

>Magister Scientiae - MSc / The Nuwejaars River flows into the largest natural freshwater lake in South Africa, Soetendalsvlei, which relies on and interacts with the Nuwejaars River. Therefore, the water quality of the Nuwejaars River plays a role in the health of the surrounding ecosystem. Over a period of three years, concentrations of nutrient constituents, physicochemical parameters, chlorophyll and phycocyanin, were measured in an attempt to investigate the water quality of the river. This study aimed to identify the patterns of nutrients, chlorophyll and phycocyanin down the length of the Nuwejaars River by assessing the physico-chemical parameters, nutrients and chlorophyll concentrations in the surface water to determine the temporal and spatial variations of these parameters, and to examine the relationships between the concentrations of selected nutrients, chlorophyll a and phycocyanin in the river water.

Groundwater chemistry is highly variable and dependent on environmental conditions, and it is not entirely understood how all these factors contribute to groundwater chemistry. This study aims to examine some of the factors that contribute to groundwater heterogeneity in the Amazon Rainforest. This was done by collecting groundwater samples from piezometers in three different regions of the Amazon Basin in Brazil, and then analyzing them in the lab for cations and anions, as well as dissolved inorganic and organic carbon. Environmental conditions were measured in the field using portable probes. The results were analyzed and compared with previously established figures for tropical forests. Statistical analyses were performed using SPSS and R in order to establish correlations and linear relationships between the studied variables.Understanding how groundwater supplies are affected is important for being able to predict and manage environmental change that can degrade groundwater sources. This knowledge could also help in developing strategies for groundwater remediation efforts in areas where supplies are contaminated.

Reticulitermids were significantly more likely to discover subterranean baits connected by physical guidelines than freestanding baits under both laboratory and field conditions. In the laboratory, subterranean termites built significantly longer tunnels adjacent to cellulosic guidelines than plastic guidelines. In the field, all guideline materials were equally effective at directing tunneling activity. Reticulitermes spp. workers were tested to determine their preferred substrate temperature. The preferred range for Reticulitermes spp. workers was found to be 18 to 27 degrees C. A laboratory bioassay was performed to determine if Reticulitermes spp. aggregates within thermal shadows. Significantly more Reticulitermes spp. workers aggregated within cool thermal shadows than control areas. In a multiple choice bioassay, mean consumption was higher for paper baits treated with fructose, galactose, glucose, raffinose, sucrose, trehalose and uric acid than for control baits. In a multiple choice bioassay, mean consumption was significantly lower for baits treated with arbutin, and most amino acids than for control baits. In the no-choice bioassay, the amount of paper bait consumed did not differ significantly for any of the treated baits tested and control baits. / Ph. D.

Treatment of Rainbow Trout (Oncorhynchus mykiss) Raceway Effluent Using Baffled Sedimentation and Artificial Substrates. The treatment performance of a 6 m wide by 67 m long by 0.8 m deep, baffled sedimentation basin receiving rainbow trout <i>(Oncorhynchus mykiss)</i> raceway effluent was evaluated with and without the installation of artificial substrates (Aquamats®). Treatment efficiency was also determined using normal rearing condition effluent loading versus cleaning and harvesting events. Total suspended solids (TSS) removal for the total basin averaged 79% and 71% during normal rearing conditions, as compared to 92% and 79% during cleaning and harvesting operations, when the Aquamats® were installed versus removed, respectively. Total phosphorus (TP) removal by the total basin, with and without Aquamats®, was 20% and 23% during normal rearing conditions as compared to 55% and 65% under cleaning and harvesting conditions, respectively. Higher TP removal during cleaning operations was attributed to sedimentation of particulate fractions. Dissolved nutrient removal (ortho-phosphate (OP), total ammonia nitrogen (TAN), nitrate, nitrite, and total organic carbon (TOC)) was not consistent throughout the basin and did not improve when the Aquamats® were installed. A short contact time and periphyton grazing by isopods may have limited the capacity of the Aquamats®. Calculated retention times with and without Aquamats® for the first half and total basin were 37% and 32% and 27% and 17% less than theoretical values, respectively based on a rhodamine WT dye study. Average surface overflow rates were adjusted accordingly and measured 19.1 m³/m²-day when the Aquamats® were installed, versus 14.8 m³/m²-day when the Aquamats® were removed for the overall basin. These rates are lower than previous recommendations for treating aquaculture effluents, but resulted in with high solids removal and consistently low TSS effluent (average < 2 mg/L) which may be necessary for strict discharge permits. Use of the overall basin minimized the occurrence of TSS measurements > 2 mg/L by 50%. For the first half of the sedimentation basin, the overflow rate averaged 44.1 m³/m²-day with Aquamats® versus 35.8 m³/m²-day without Aquamats®. The majority of effluent treatment occurred within the first half of the basin, which was responsible for 84% and 94% of total TSS removal, 42% and 100% and 61% and 80% of total TP removal during normal and cleaning/harvesting conditions, respectively.> Characterization of Nutrient Leaching Rates from Settled Rainbow Trout <i>(Oncorhynchus mykiss)</i> Sledge The leaching of nutrients from settled rainbow trout <i>(Oncorhynchus mykiss)</i> sludge into overlying water was evaluated over a 7 day period. Nutrient leaching was assessed in a stagnant reaction tank and one agitated by aeration to simulate turbulent conditions in stocked production raceways. Leaching of total phosphorus (TP), ortho-phosphate (OP), total Kjeldahl nitrogen (TKN), total ammonia nitrogen (TAN), and total organic carbon (TOC) occurred rapidly during the first 24 h in both stagnant and agitated conditions. The highest 24 h leaching occurred in the agitated tank, and power regression equations accurately described the varying rates of increasing TP, OP, TAN and TKN. In the stagnant tank, linear increases of TP, OP, TKN and TAN concentrations occurred during the first 24 h. These linear increases continued from day 2-7, but at slower rates than occurred during the first 24 h. Average nutrient leaching rates (mg leached/g sludge-h);(dry weight basis) were calculated based on linear concentration increases. In the agitated tank, nutrient concentrations decreased after 60 h, as aerobic bacterial uptake and/or chemical precipitation was suspected. Therefore, average leaching rates could not be determined. These findings reveal that daily cleanout of settling areas could eliminate the release of TP, OP, TAN, TKN, and TOC from settled solids by 66%, 65%, 39%, 76% and 51%, respectively, as compared to weekly cleanout schedules. Sustained leaching rates indicate nutrient release will likely continue beyond 7 days. This information suggests aggressive and continuous sludge management is most beneficial for maintaining high water quality and regulatory discharge compliance in fish production. / Master of Science

Evaluating hydrology and water quality for the Big Black River Watershed in Mississippi was accomplished by using the Better Assessment Science Integrating Point and Nonpoint Source (BASINS 4.5), Loading Simulation Program in C++ (LSPC), and Water Quality Analysis Simulation Program (WASP) models. The watershed model calibration was originally accomplished by using historical data collected from U.S. Geological Survey (USGS). The watershed model was calibrated using data from 2000 through 2018 in order to quantify stream flow and point source discharges under a variety of hydrologic conditions. The model predicted response of hydrology was consistent with the observed data range. The hydrology part of the model was integrated for water quality simulation. Nutrients levels in the river systems were closely examined, without the impacts from point source discharges. The calibrated model could be used as a planning tool to assess the water quality and to calculate total maximum daily load (TMDL) in the nation’s watersheds.

Coastal ecosystems are faced with increasing pressures from human activities. Perhaps one of the most profound impacts is that of excess nitrogen loading which drives a series of negative consequences. Excess nitrogen fuels primary productivity and the subsequent enhanced microbial decomposition of organic matter, consumes oxygen and releases carbon dioxide, which causes large fluctuations in pH. Changes in organic matter availability, oxygen concentrations, and pH can have significant yet unconstrained implications for sediment recycling and removal of biologically important nutrients such as nitrogen and phosphorus. Such changes can also impact the production and consumption of two powerful greenhouse gases – nitrous oxide and methane. Here I use two temperate estuaries, Long Island Sound (New York, USA) and Waquoit Bay (Massachusetts, USA) to assess the role of human impacts on coastal sediment biogeochemical fluxes. In Chapter 1, I investigate the influence of organic matter loading on sediment nutrient cycling, excess nitrogen filtering, and greenhouse gas emissions in Long Island Sound, a heavily nutrient polluted estuary. To provide a comprehensive analysis of these benthic fluxes and their environmental drivers, I incubated sediment cores from five stations along a west to east transect representing a gradient of high to low nutrient inputs and organic matter deposition. I found sediments across the estuary removed only 9% of land-based nitrogen entering the system and had a nitrogen removal efficiency of 30%. Additionally, sediments were often a source of inorganic nitrogen and phosphorus as well as nitrous oxide and methane. This study provides the first directly measured rates of sediment nitrogen removal and production in Long Island Sound. In Chapters 2 and 3, I investigate the effect of coastal acidification on benthic fluxes of greenhouse gases and nutrients across the sediment-water interface in Waquoit Bay. I collected sediment cores from two sites experiencing different rates of nutrient loading and experimentally altered the overlying water pH through a series of incubations representing moderate (pH 7.3) and extreme (pH 6.3) pH conditions. My results show low pH conditions have a strong effect on greenhouse gas and nutrient fluxes and responses vary by site. Specifically, in the high nutrient impacted site, nitrous oxide flux increased and methane flux decreased under acidification. In the low nutrient impacted site acidification drove reduced nitrous oxide flux, while methane flux decreased in the moderate treatment and increased in the extreme treatment. Acidification also affected benthic nutrient fluxes and drove the high nutrient impacted site to become phosphorus limited. Furthermore, the relationships and drivers between nutrient availability and nutrient fluxes shifted under acidification. This dissertation provides additional insight into how coastal ecosystems respond to human impacts. In Chapter 1, I present a critical missing piece of the nitrogen budget of a heavily impacted estuary. In Chapters 2 and 3, I begin to elucidate how low pH conditions can impact sediment biogeochemistry in estuarine ecosystems. Efforts to improve our understanding of human impacts on sediment biogeochemical fluxes will create better informed coastal management practices for these dynamic systems under a changing climate. / 2025-10-23T00:00:00Z

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