The Enrichment of Stable Cesium and Rubidium in Savannah River Site Soils

The following dissertation investigates the sequestration of Cs and Rb in the wedge zone regions of hydroxy-interlayered vermiculite (HIV), a clay mineral commonly found in the southeastern United States. Savannah River Site soils are studied from the highly contaminated Department of Energy Site. The soils are found to preferentially adsorb Cs and Rb (to a lesser extent) with respect to K and be highly enriched with respect to upper continental crust. Enrichment is found to be a function of weathering progression. Molecular modeling results support the hypothesis that Cs is the sterically favorable ion in the interlayer wedge zone of HIV

Coral records of radiocarbon variability in the central tropical pacific during the last millennium

Ocean circulation changes in the tropical Pacific strongly influence global climate, as demonstrated during El Niño-Southern Oscillation (ENSO) extremes. Understanding the causes of past variability in tropical Pacific circulation and their relationship to climate change will help to predict how future climate may evolve under anthropogenic radiative forcing. I measure fossil coral radiocarbon (Δ¹⁴C) from Palmyra (6°N, 162°W) and Christmas (2°N, 157°W) Islands in the central tropical Pacific to reconstruct high-resolution records of tropical Pacific ocean circulation variability over the last millennium. Variations in coral Δ¹⁴C from Palmyra and Christmas reflect a combination of the atmospheric concentration of ¹⁴C at the time of growth, Δ¹⁴C-depleted waters associated with equatorial upwelling, and Δ¹⁴C -enriched waters advected from the western tropical Pacific. Existing oxygen isotopic (δ ¹⁸O) records of the Palmyra and Christmas fossil corals reveal a rich history of interannual to centennial variability in sea-surface temperature (SST) and salinity over the last millennium [Cobb et al., 2003b]. My approach targets specific time intervals associated with strong interannual to centennial-scale coral δ ¹⁸O anomalies for high-resolution Δ¹⁴C analysis. Seasonally-resolved Δ¹⁴C measurements are used to compare interannual Δ¹⁴C variability across the 10th, 13th, 15th, 17th, and 20th centuries. Annually-resolved Δ¹⁴C measurements are used to compare decadal to centennial-scale Δ¹⁴C variations from the 10th, 12th - 15th and 17th centuries. SEM photos are used to assess the fidelity of the coral Δ¹⁴C records with respect to post-depositional alteration of the coral skeleton. I find evidence for minor dissolution and addition of secondary aragonite, but my results indicate that coral Δ¹⁴C is only compromised after moderate to severe diagenesis. Despite strong ENSO signals in modern and fossil coral δ ¹⁸O, our data show no statistically significant interannual variability in coral ¹⁴C. There is a centennial-scale increase in coral radiocarbon from the Medieval Climate Anomaly (MCA, ~900-1200AD) to the Little Ice Age (LIA, ~1500-1800). I use a box model of central tropical Pacific Δ¹⁴C contributions to show that this centennial-scale trend over the last millennium is largely explained by centennial-scale changes in atmospheric ¹⁴C. However, large 12th century depletions in Palmyra coral ∆¹⁴C data cannot be explained by atmospheric ¹⁴C variability and likely reflect a roughly two-fold increase in upwelling and/or a significant change in the ¹⁴C of higher-latitude source waters reaching the equatorial Pacific during this time. Conversely, significantly enriched Christmas coral ∆¹⁴C values during the 16th century are consistent with a two-fold reduction in upwelling strength and/or the advection of high-¹⁴C waters to the equatorial thermocline from higher latitudes.M.S.Committee Chair: Kim Cobb; Committee Member: Annalisa Bracco; Committee Member: Ellery Ingall; Committee Member: Jean Lynch-Stieglitz; Committee Member: Yuhang Wan

Spatiotemporal Dynamics of Benthic Microalgae in South Carolina Shelf Sediments

Benthic microalgae (BMA) play essential roles in food webs and regulating nutrient exchange at the sediment-water interface in continental shelf ecosystems. However, shelf BMA are not widely studied due to the difficulties sampling the upper few millimeters of shelf sediments. A few published studies have highlighted the high spatiotemporal distribution of BMA, but detailed explanations for this known variability are limited. The objectives of this study were to quantify BMA biomass variability on scales of cm to km and relate these measurements to in situ nutrient concentrations, sediment grain size, in situ irradiance, depth, and other environmental factors. Water and sediment samples for BMA and porewater nutrient analyses were collected by SCUBA divers on 11 nearshore cruises in 2018-2020 off Charleston, SC. BMA accounted for over half of total microalgal chlorophyll a, with BMA biomass reaching as high as 10 times that of phytoplankton in the overlying waters. High variability in BMA biomass was observed between and within sites, indicating BMA are likely influenced by small-scale (\u3c1 \u3em) environmental differences. BMA biomass was positively correlated with percentage of fine grain sediments, but not with dissolved inorganic nitrogen (DIN) concentrations in either the water column, porewater, or submarine groundwater. However, porewater DIN was much higher than in the water column, suggesting that higher BMA biomass may be more dependent on N from the sediments rather than the overlying waters. Understanding how BMA vary spatially can be useful for making larger generalizations about BMA distribution over continental shelves and for modeling BMA biomass, production, and contribution to both benthic and pelagic food webs

Declining Wages Increase Selfish Redistribution in an Environment with Fixed Income Inequality

We use a highly-controlled laboratory experiment to study the causal impact of income decreases on redistribution decisions, in an environment where the income inequality that may be created with wage changes is kept fixed. First, we investigate the role of a decreasing wage compared to one’s past wage (intra-personal decrease). Second, we investigate the role of a wage that decreases relative to the wage of another person (inter-personal decrease). If intra-personal or inter-personal decreases create dissatisfaction for an individual, that person may support redistribution policies that compensate him or her for the situation or rectify it. Overall, we find evidence that individuals indeed behave more selfishly when they experience decreasing wages. While many studies examine the effect of income inequality on redistribution decisions, this is the first to isolate the effect of income changes

Connecting Sarcomere Protein Mutations to Pathogenesis in Cardiomyopathies: The Development of “Disease in a Dish” Models

Recent technological and protocol developments have greatly increased the ability to utilize stem cells transformed into cardiomyocytes as models to study human heart muscle development and how this is affected by disease associated mutations in a variety of sarcomere proteins. In this perspective we provide an overview of these emerging technologies and how they are being used to create better models of ‘disease in a dish’ for both research and screening assays. We also consider the value of these assays as models to explore the seminal processes in initiation of the disease development and the possibility of early interventions

The effects of eco-labels and eco-claims on consumers’ purchase intention : the moderating role of regulatory focus

As consumers increasingly realize the impacts of their consumption patterns on the environment, many try to pursue a more sustainable purchase behavior by dedicating particular attention to environmentally friendly product attributes. In response to the growing interest in sustainable products, brands adjust their marketing strategies accordingly. To persuade consumers to purchase a certain product, companies voluntarily display eco-labels and eco-claims designating environmental friendliness on their packaging. However, due to different foci in how people regulate their behavior, these types of nudges may not be equally effective for all types of customers. Since little research sheds light on that combination of topics, this study aims to fill the gap by investigating the effects of eco-labels and eco-claims as well as the potential moderating impacts of regulatory focus on purchase intentions. It further examines how the suspicion of greenwashing influences the effectiveness of eco-labels and eco-claims. By collecting quantitative data, the researchers took an explanatory approach to scrutinize the effects of eco-labels and eco-claims on consumers’ purchase intentions. Data was obtained from 306 participants in a 2 (no eco-label, eco-label) × 2 (no eco-claim, eco-claim) between-subjects factorial design. Afterwards, the participants were classified and analyzed according to their regulatory focus. The research scope is narrowed down to the MSC eco-label for seafood and German residents. The key findings reveal that eco-labels and eco-claims have the potential to differently affect consumers’ purchase intention. On the one hand, the expected moderating effect between regulatory focus and eco-labels could not be identified in this study. On the other hand, the results show a significant mediation effect of the suspicion of greenwashing on the effectiveness of eco-labels for prevention-focused consumers. The suspicion of greenwashing tends to increase for prevention-focused consumers if exposed to eco-labels alone. Yet, supporting the eco-label with an eco-claim seems to reduce prevention-focused consumers’ suspicion of greenwashing.nhhma

Has Toxicity Testing Moved into the 21st Century? A Survey and Analysis of Perceptions in the Field of Toxicology.

BackgroundTen years ago, leaders in the field of toxicology called for a transformation of the discipline and a shift from primarily relying on traditional animal testing to incorporating advances in biotechnology and predictive methodologies into alternative testing strategies (ATS). Governmental agencies and academic and industry partners initiated programs to support such a transformation, but a decade later, the outcomes of these efforts are not well understood.ObjectivesWe aimed to assess the use of ATS and the perceived barriers and drivers to their adoption by toxicologists and by others working in, or closely linked with, the field of toxicology.MethodsWe surveyed 1,381 toxicologists and experts in associated fields regarding the viability and use of ATS and the perceived barriers and drivers of ATS for a range of applications. We performed ranking, hierarchical clustering, and correlation analyses of the survey data.ResultsMany respondents indicated that they were already using ATS, or believed that ATS were already viable approaches, for toxicological assessment of one or more end points in their primary area of interest or concern (26-86%, depending on the specific ATS/application pair). However, the proportions of respondents reporting use of ATS in the previous 12 mo were smaller (4.5-41%). Concern about regulatory acceptance was the most commonly cited factor inhibiting the adoption of ATS, and a variety of technical concerns were also cited as significant barriers to ATS viability. The factors most often cited as playing a significant role (currently or in the future) in driving the adoption of ATS were the need for expedited toxicology information, the need for reduced toxicity testing costs, demand by regulatory agencies, and ethical or moral concerns.ConclusionsOur findings indicate that the transformation of the field of toxicology is partly implemented, but significant barriers to acceptance and adoption remain. https://doi.org/10.1289/EHP1435

Human resource accounting: An historical perspective

Recent years have witnessed the emergence of numerous treatises on the relative merits of human resource accounting. While the unprecedented pervasiveness of human resource literature suggests that the topic is new to our era, the debate itself is by no means novel. Indeed, the concept of human resource accounting is deeply rooted in the history of economic thought