The study of past geologic records and present-day oceanographic processes can benefit society by better understanding how climate and biogeochemical processes interact in ocean. I present research that helps better understand these interactions by studying marine sediments, specifically barium in aqueous settings. This dissertation is separated into three projects that utilize geochemical interpretation of sediments and fluxes from the ocean to understand biogeochemical changes in past and present oceans. The first two projects study the export of carbon from ocean surface to deep waters in the tropical Pacific. The Maastrichtian records confirm that organic carbon export proxies related to barite (BaSO4) can be reconstructed at high-resolution using non-destructive X-ray fluorescence (XRF) Ba. This scanning XRF Ba record from 71.5 to 66 million years ago (Ma), after 405 kyr tuning, shows direct precessional cycle influence on organic carbon export during the cool greenhouse conditions of Late Cretaceous in the tropical Pacific. This suggests high frequency climate variability existed in the tropical Pacific and precession had a role in driving these changes, which were enhanced after Deccan volcanism when CO2 concentrations increased. A modern sediment trap record of carbon export determined by analyzing excess-Ba content (proxy for barite) from 2003 to 2013 records changed across a shift in the phase of the Pacific Decadal Oscillation (PDO). This record suggests upwelling is the main driving force for carbon export in the Eastern Tropical Pacific (ETP) by the carbon export showing variations following the PDO phases as similar to the upwelling magnitude changes, rather than the surface dust input. The dust deposition at the surface decoupled from dust export at depth leads to the conclusion that dust has limited role as a micronutrient source. Together these records suggest that hydrological changes in the tropical Pacific are important drivers of change for organic carbon export in both the Late Cretaceous and modern oceans. The last project presents selenium (Se) and arsenic (As) speciation within natural barite samples which reflect the aqueous environment oxidation state (i.e., oxic, suboxic, and anoxic). Natural barite sample (n=12) Se(VI)/Se(IV) and As(V)/As(III) results were obtained through X-ray absorption near edge structure (XANES) spectroscopy from marine pelagic, marine diagenetic, continental, hydrothermal, and cold seep barite. The results suggest that Se and As speciation reflect the redox condition of the environment in which barite precipitates, and further potentially provide information about biological sulfate reduction.

(Cont.) phosphoproteomics technology, IMAC/LC/MS/MS, [approximately] 200 phosphosites were identified from HT-29 cells, some of which were detected only from insulin-treated cells. Our phosphoproteomics approach also enabled us to detect alteration of both known and unknown phosphorylation states of apoptosis-related proteins at two time points during early apoptosis induced by tumor necrosis factor-[alpha].

For many years, the field of anthropology has encouraged anthropologists to assume that population variation exists in skeletal aging although interpretations of population specificity in skeletal aging have been inconsistent. This project investigates age progressive changes in modern East and Southeast Asian populations, and attempts to quantify the magnitude of differences or similarities in skeletal aging between different Asian groups as a first step to develop a more inclusive age estimation method for Asian populations. Specifically, this study explores the utility of currently available age estimation methods for Asian populations, asks whether a population-specific aging method should be region-specific (Thai vs. Japan) or continental-specific (Asian), and investigates whether population specificity in age estimation is needed at all. To achieve these goals, data from four skeletal collections representing 20th century Japanese and modern Thais were collected. The four age estimation methods were applied: Transition Analysis (TA) (Boldsen et al. 2002b), plus three ‘conventional’ methods of Suchey and Katz (1998), Lovejoy et al. (1985a), and Meindl and Lovejoy (1985). To develop age estimation models for the Asian samples, while minimizing methodological error a multivariate ordered probit regression model was fitted to the Asian skeletal data under a Bayesian framework. The results of this study show that Japanese-specific age estimation models do not necessarily increase error in age estimates of Thai populations, and vice versa. Thus, multivariate ordered probit models fitted on a pooled sample of Japanese and Thais yielded significantly improved age estimates. Although TA and conventional methods yielded reasonable age estimates for Japanese and Thai populations, the probit models of pooled Asian groups outperformed those methods. The results are even more promising when the scores of TA and conventional methods were combined to fit a multivariate ordered probit model. Broader implications of this research is that, at least for Japanese and Thais, a single age estimation method can be developed. In addition, any error and bias in ages at death estimation may not be due to differences in population-specificity in skeletal aging and age estimation error induced by biased reference samples may be greater than expected.