Pollution from industrial sources, such as leather tanneries, jewelry factories, car batteries, and construction refuse, has been linked to increased concentrations of toxic heavy metals in rivers in Costa Rica. This study focused on the concentrations of arsenic, cadmium, chromium, copper, nickel, and lead in sediment and water in Rio Baru, Costa Rica, which has not been previously studied. The concentrations in Rio Baru were compared to two controls and the Environmental Protection Agency toxicity limits to determine pollution levels. Inductively coupled plasma mass spectrometry was utilized to determine the concentrations of heavy metals in water and sediment samples from Rio Baru, Terciopelo, and Rio Tarcoles. Watershed analysis for Rio Baru was expected to reveal mostly agricultural sources of contaminants. Rio Baru was predicted to have levels of inorganic heavy metals between Rio Tarcoles and Terciopelo, with Tarcoles containing the highest levels. As, Cr, and Ni in Rio Baru were between unpolluted levels in Terciopelo and polluted levels in Rio Tarcoles, but Rio Baru had lower concentrations of Cu and Pb than both Rio Tarcoles and Terciopelo. Analysis of watersheds determined that Rio Baru’s watershed contained intermediate ratios of human development and agricultural sources of pollution. Further comparisons of watershed size with total dissolved sediment levels found a positive linear relationship, indicating a portion of differences in heavy metal concentrations were due to watershed sizes. Concentrations of heavy metals in Rio Baru’s water were below toxic limits for drinking water and placed Rio Baru within “good” sediment levels for As, Cd, Cr, Ni, and Pb. As geochemistry and proximity to industrial sources was not accounted for in methodology, further research would be necessary for determination of natural concentrations of heavy metals in Rio Baru.

The purpose of this thesis is to examine the projected future changes in the global and Sub-Saharan Africa climate. These changes are expected to have varying effects depending on the region of the globe being examined. Sub-Saharan Africa is expected to be one of the most vulnerable regions in the future because of the already-variable and unpredictable climate. Population growth and lack of financial and informational resources further exacerbates the climate problems, making it even more difficult for African farmers to respond to their changing environment. In order to respond to these climate changes within an already dry and nutrient-lacking environment, farmers must be given the necessary adaptation information and aid from outside investors. However, without the proper information available to investors, regarding future expectations about precipitation, temperature, extreme weather events, soil nutrients, and available adaptation strategies, investors cannot efficiently allocate capital or other forms of aid. Therefore, I stress the importance of developing accurate climate models on a regional scale that investors can use to better allocate aid. Each region is affected in very different ways by the climate as a result of local topographical factors and global factors, such as the Intertropical Convergence Zone. Therefore, tools, such as models and simulations must be able to take these factors into account in order to accurately project future changes. This thesis examines a wide range of existing literature in the area of climate change and food security on both a global and regional scale. I investigate the current and future climate of Sub-Saharan Africa, as well as the farming culture, in order to provide an in-depth understanding of the various factors that are interacting. Although many steps have been made to develop models and provide aid to Sub-Saharan Africa farmers, the lack of food security is only expected to become worse as the environment becomes harsher on food crops. Therefore, in order to respond to the expanding population and harsher farming environment, farming adaptations must continue to be intensified.

Two significant pieces of legislation in California have mandated that cities and counties must reduce their waste streams. Assembly Bill 341 establishes that California must divert 75% of its waste from landfills by the year 2020. The first bill that included composting, Assembly Bill 1826, was passed in 2014 and requires that commercial users enact composting beginning in 2016. These initiatives have led cities and counties to seek ways of implementing composting programs. Using the City of Napa as a case study, this thesis argues that a composting program can be integrated into any existing waste hauling service. Although there are some challenges, including effectively reaching all residents eligible for the program and finding ways to encourage people to change waste disposal habits, other communities should be able to adopt Napa’s model. Napa’s program should act as an outline for other communities to develop similar outreach strategies, public education initiatives, and pilot programs. Once implemented, cities can continue creating a sustainable community through the use of new technologies. Not only will creating a composting program allow cities and counties to be in compliance with Assembly Bill 1826, it will also offer benefits that extend beyond the local scope, such as reducing greenhouse gas emissions.

Water resources are becoming increasingly important to protect, but doing so has proven challenging due to the complex nature of resource management. Many researchers have been trying to develop “usable science” to aid in this endeavor, and one method of this is the development of decision support systems. This has led to the employment of this method as a potential tool for decision makers, scientists, and the interested public to use; yet little literature is available on the success of their implementation. This study attempted to fill the gaps by gathering data through surveys and interviews from stakeholders who are part of institutions that fund the University of South Florida’s Water Atlas. The study found that the tool was used for both educational outreach and scientific research support. Decision making was mostly supported through the program’s use as a research tool. Stakeholders also expressed that conditions found in the literature to contribute to successful implementation were largely met through the Water Atlas development process and continued use.

Water quality has evolved legislatively from protection of navigation routes and quantity of sources to more emphasis on impairments on water quality for surface and groundwater sources. Nonpoint or diffuse sources of impairments represents a major challenge for management due to the complexity of its sources and difficulty in tracking. The most cited sections on public policy analysis focuses on the overall process agencies employ to understand the results the program yields. Often overlooked are finer details and mechanisms, such as decision-making and priority setting, which have a great impact on the overall process. To investigate these factors, we need to analyze the decision-making process used by managers. This study focuses on using information from those with direct involvement in the establishment and implementation of the Total Maximum Daily Load program for the state of Florida. This study used decision-making analysis models from Rational-Decision-Making and Multi-Criteria Decision Analysis concepts to construct questionnaires that looks to develop priorities as seen by managers’ preferences for several presented options. This methodology allowed us to structure the viewpoints and processes water quality managers use to breakdown decisions. The analyzed results show water quality managers prefer strong management options, involvement from stakeholders with scientific knowledge, and data collected from the source or point of impact. Interestingly, opinions in the group show that urban best management practices are considered more effective than their agriculture counterparts with a disfavor for volunteer derived data. Ultimately, the survey highlights the need for more robust enforcement and reliable measurement of non-point source of impairments. Continued public outreach and education, especially through workshops, are denoted as important tasks to completing successful TMDLs and should be expanded and strengthened by both the Florida Department of Environmental Protection and its boundary programs.

Future impacts from climate change can be better understood by placing modern climate trends into perspective through extension of the short instrumental records of climate variability. This is especially true for extreme climatic events, such as extreme precipitation and wildfires, as the period of instrumental records provides only a few examples and these have likely have been influenced by anthropogenic warming. Multi-parameter records showing the past range of climate variability can be obtained from lakes. Lakes are particularly good recorders of climate variability because sediment from the surrounding environment accumulates in lakes, making them sensitive recorders of climate variability and providing high-resolution histories of local environmental conditions in the past. In some cases, such as at Basin Pond, sediment is persevered efficiently enough to produce distinguishable annual laminations (varves) in the sedimentary record. The varved record at Basin Pond was used to construct an accurate, highly-resolved age-to-depth model over the past 300 years. Using a multi-proxy analysis, including organic biomarker analysis of molecular compounds and sedimentological features preserved in the sediment record, a history of environmental and climatic change at Basin Pond was constructed. These analyses were compared with the record of known extreme events (from instrumental measurements and historical documents), including 129 years of high-resolution precipitation and temperature meteorological data, 19 tropical systems over the past 145 years, and two known wildfire events over the past 200 years. Long-term trends in precipitation, including the increase in precipitation seen throughout the last half of the 20th century and the drought of the 1940’s, were captured in the analysis of long-chain n-alkane distributions and through varve thickness measurements obtained through X-Ray Fluorescence analysis. Furthermore, Polycyclic Aromatic Hydrocarbons (PAHs), a class of organic compounds that can be used to trace combustion activity, were found in abundance in the Basin Pond sedimentary record. Peaks in the abundances of two PAHs (retene and chrysene) and the ratio retene/(retene + chrysene) were found to be highly correlated with the known wildfire events occurring in the historical period, giving promise as using these compounds and ratio as a robust proxy for regional wildfire events in the northeastern U.S.

Organic aerosols have significant effects on human health, air quality and climate. Secondary organic aerosols (SOA) are produced by the oxidation of primary-volatile organic compounds (VOC). For example, α-pinene reacts with oxidants such as hydroxyl radical (OH), ozone (O3), and nitrate radical (NO3), accounting for a significant portion of total organic aerosol in the atmosphere. Experimental studies have shown that the oxidation process between α-pinene and ozone has the most significant impact in the formation of SOA (Hoffmann et al., 1997). Most of the models used to predict SOA formation, however, are limited in that they neglect the role of water due to uncertainty about the structure and nature of organic compounds, in addition to uncertainty about the effect of varying relative humidity (RH) on atmospheric organic particulate matter (OPM) (Kanakidou et al., 2005). For this study, structures of organic compounds involved in the formation of SOA are estimated, and the role of water uptake is incorporated in the process. The Combinatorial Aerosol Formation Model (CAFM) is a deterministic model used to determine the amount of organic mass (Mo µg m-3) formation based on the predicted structures. Results show that the amount of SOA that is formed is almost negligible when the amount of parent hydrocarbon involved in the reaction is low (i.e. around 5 µg m-3), especially at lower RH. Observing compounds with a greater number of polar groups (alcohol and carboxylic acid) indicates that structure has a significant effect on organic mass formation. This observation is in agreement with the fact that the more hydrophilic the compound is, the higher RH, leading to more condensation into the PM phase.

The effects of varying concentrations of two chelators: EDTA, citric acid (CA), and phosphorus on the accumulation of arsenic in soil by two perennial grasses, Leersia oryzoides and (rice cut-grass) Festuca arundinacea (tall fescue). Each experiment was run for eight weeks, after which plants were harvested, oven-dried, digested in acid and analyzed using an ICP-OES. Phosphorus soil amendments were applied as 0, 15, 30, 60, 120 mg P/kg soil. For the first chelator experiment, CA and EDTA concentrations of 0, 2.5, and 5.0 mmol/kg soil were added in pulse form to the soil. In the second chelator experiment, concentrations of CA were added in 0, 2.0, 4.0 mmol/kg soil and EDTA was added as 0, 0.25, 0.50 mmol/kg soil. Both plant species accumulated enough arsenic in the root and shoot tissues to be considered at hyperaccumulator species. Citric acid produced comparable results with EDTA, and is considerable much safer for the environment than any synthetic chelator. Certain soil amendments (citric acid and phosphorus) and hyperaccumulator species used in this study warrant further research in the field.

Water filters and sediment trap samples were collected weekly from late May to early September 2009 from four lakes of the Lofoten archipelago, northwestern Norway, and were used to explore the applicability of the alkenone unsaturation index (UK37) for temperature reconstruction in limnic systems in the area. For the first time, we observed the occurrence of long-chain alkenones (LCAs) within the water columns of lakes in this region. Water filters from two of the four studied lakes contained measurable concentrations of alkenones that were restricted to spring turnover and disappeared with the onset of summer stratification. These results indicate that alkenones in the lake sediment of these lakes reflect biological production and temperature during lake mixing, taking place in late spring to early summer. Measurements from sediment trap material collected over the sampling season combined with water temperature measurements from automated data loggers provide an in situ calibration of the alkenone paleothermometer (Temperature = 33.0 x UK37 + 22.8; N=10; R2=0.95). Notably, this calibration reveals a UK37 sensitivity to temperature (i.e., the slope of the relationship) that is very similar to previous calibrations reported from both marine and lacustrine environments. LCAs can therefore serve as the first quantitative proxy for reconstructing past temperature variability from the Lofoten Islands. Based on this temperature calibration, a high-resolution temperature record was reconstructed over the past millennium, which shows unprecedented lake surface temperature warming during the past decades.

Carbon sequestration is paramount to reducing climate change. Grasslands, representing 40% of all terrestrial area, can serve as a primary sequestration location if optimal management strategies can be realized. This study used system dynamics modeling to examine the temporal dynamics of carbon stocks and flows in response to grass species composition, grazing intensity, and temperature and precipitation changes at the landscape level. While there are other biogeochemical models in existence, they are either meant to model large areas, including globally, or are meant to be at a farm level and have limited plot sizes, limiting the options for rangeland managers to test management strategies in larger areas. The aims included conducting a field study of the rangeland, create an initial model; evaluate how the model responded to grazing, temperature, and precipitation changes; and compare the model outcomes to prior work to test the behavior of the model as the start of validation. This thesis used four plant functional groups (C3 and C4 grasses, forbs, and legumes) as the base groups for the model. C4 grasses were not found in in the field study but served to test whether the model detected changes in sequestration when grassland composition is changed. The results demonstrated an approach of using functional groups in system dynamics modeling to optimize carbon sequestration while accounting for diverse management strategies, as has been seen in other biogeochemical models. The model was aligned with prior field research in terms of carbon sequestration levels. The model was able to note differences in grazing regimes, temperature, and precipitation changes in terms of carbon sequestration. Grazing scenarios showed that while increased grazing impacted aboveground litter, it had little impact on sequestration; there was only a 4% increase in carbon with no grazing, Changes in temperature, up to 3°C, were predicted to increase carbon sequestration by 16% from 0.442 to 0.514 kg*m-2*day-1 while decreases in precipitation, both alone and in combination with increasing temperatures, was predicted to decrease sequestration up to 44%. This has to do with the grassland composition, ii especially as this was a C3 dominated grassland which grows in the winter and early spring and required more water but lower temperatures for growth. Future research should continue model validation, test additional functional groups like shrubs, implement more soil carbon pools and flows and add a nitrogen component to the model.