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- Creators: Barrett, The Honors College
Description
Objectives: The objective of this research is to develop a better understanding of the ways in which Transition Analysis estimates differ from traditional estimates in terms of age-at-death point estimation and inter-observer error. Materials and methods: In order to achieve the objectives of the research, 71 adult individuals from an archaeological site in northern Sudan were subjected to Transition Analysis age estimation by the author, a beginner-level osteologist. These estimates were compared to previously produced traditional multifactorial age estimates for these individuals, as well as a small sample of Transition Analysis estimates produced by an intermediate-level investigator. Results: Transition Analysis estimates do not have a high correlation with traditional estimates of age at death, especially when those estimates fall within middle or old adult age ranges. The misalignment of beginner- and intermediate-level Transition Analysis age estimations calls into question intra-method as well as inter-method replicability of age estimations. Discussion: Although the poor overall correlation of Transition Analysis estimates and traditional estimates in this study might be blamed on the relatively low experience level of the analyst, the results cast doubt on the replicability of Transition Analysis estimations, echoing the Bethard's (2005) results on a known-age sample. The results also question the validity of refined age estimates produced for individuals previously estimated to be in the 50+ age range by traditional methods and suggest that Transition Analysis tends to produce younger estimates than its traditional counterparts. Key words: age estimation, Transition Analysis, human osteology, observer error
ContributorsPhillips, Megann M. (Author) / Baker, Brenda (Thesis director) / Norris, Annie Laurie (Committee member) / School of International Letters and Cultures (Contributor) / School of Human Evolution and Social Change (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Elevated nitrate (NO3-) concentration in streams and rivers has contributed to environmental problems such as downstream eutrophication and loss of biodiversity. Sycamore Creek in Arizona is nitrogen limited, but previous studies have demonstrated high potential for denitrification, a microbial process in which biologically active NO3- is reduced to relatively inert dinitrogen (N2) gas. Oak Creek is similarly nitrogen limited, but NO3- concentration in reaches surrounded by agriculture can be double that of other reaches. We employed a denitrification enzyme assay (DEA) to compare potential denitrification rate between differing land uses in Oak Creek and measured whole system N2 flux using a membrane inlet mass spectrometer to compare differences in actual denitrification rates at Sycamore and Oak Creek. We anticipated that NO3- would be an important limiting factor for denitrifiers; consequentially, agricultural land use reaches within Oak Creek would have the highest potential denitrification rate. We expected in situ denitrification rate to be higher in Oak Creek than Sycamore Creek due to elevated NO3- concentration, higher discharge, and larger streambed surface area. DEA results are forthcoming, but analysis of potassium chloride (KCl) extraction data showed that there were no significant differences between sites in sediment extractable NO3- on either a dry mass or organic mass basis. Whole-reach denitrification rate was inconclusive in Oak Creek, and though a significant positive flux in N2 from upstream to downstream was measured in Sycamore Creek, the denitrification rate was not significantly different from 0 after accounting for reaeration, suggesting that denitrification does not account for a significant portion of the NO3- uptake in Sycamore Creek. Future work is needed to address the specific factors limiting denitrification in this system.
ContributorsCaulkins, Corey Robert (Author) / Grimm, Nancy (Thesis director) / Childers, Daniel (Committee member) / School of Sustainability (Contributor) / School of Life Sciences (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
This dissertation examines the interrelationships between stress, frailty, growth, mortality, and diet at the Qinifab School site, Sudan, using a combination of osteological, paleopathological, and biogeochemical methods. The skeletal sample, from the fourth cataract region of Nubia, is comprised of 100 individuals from a Late Meroitic to Christian period (~250-1400 CE) cemetery. Standard osteological methods were used to estimate age and sex, and measurements were taken to assess body dimensions. Preadults were aged by dental and skeletal development, producing two independent ages to categorize individuals as developmentally “normal” or “delayed.” Data were collected on nonspecific indicators of stress, including linear enamel hypoplasias (LEHs), porotic hyperostosis (PH), and cribra orbitalia (CO). In preadults, these were compared to World Health Organization (WHO) growth standards to identify individuals who experienced stunting or wasting. For all ages, evidence of stress was compared with age at death and growth/body size. Finally, stable carbon and nitrogen isotope analyses were conducted on bone collagen and carbonate samples from a representative sample of 60 individuals, of which 46 collagen samples and all carbonates had acceptable preservation.“Delayed” preadults generally showed reduced body size relative to “normal” individuals, they were more likely to be stunted, and their growth trajectories were less similar to WHO standards. However, childhood stress had little impact on adult body size. CO occurred at higher frequencies in preadults and individuals with mixed/active lesions died at younger ages. PH rarely developed before age 6 but was present in most individuals over that age. Individuals with earlier formed LEHs tended to experience more stress overall and die younger. Active/mixed CO was associated with stunting in preadults and reduced brachial index in adults.
A greater proportion of individuals in the Christian period were affected by CO compared to the Post-Meroitic. A temporal shift also occurred in diet between the Post-Meroitic and Christian periods based upon the δ13CCOLL and δ15NCOLL values. Lower δ15N and the greater difference in δ13CAP-COLL suggest a shift toward intensified agriculture and decreased use of animal products and a potential dietary etiology for the increase in CO.
ContributorsNorris, Annie Laurie (Author) / Baker, Brenda J (Thesis advisor) / Knudson, Kelly (Committee member) / Dupras, Tosha (Committee member) / Arizona State University (Publisher)
Created2021
Iron Cycling May Lower Methane Fluxes at an Impounded Marsh: Evidence from the Herring River Estuary
Description
Wetlands produce approximately one third of total global methane emissions and sequester significant amounts of CO2. Salt marshes make up 5% of total wetland area, and therefore are key factors affecting global methane and CO2 emissions. Many marshes are anthropogenically managed either by diking, draining, impoundment, or otherwise restricting tidal exchange. This causes marsh freshening, increases methane emissions, and releases sequestered carbon, all of which can lead to a warming effect on the climate by the greenhouse effect. We studied the formerly impounded Old County salt marsh, found in the Herring River Estuary of Wellfleet, Massachusetts, USA. The USGS Woods Hole Coastal and Marine Science Center installed two eddy covariance flux towers in the Herring River Estuary. These showed that Old County had low methane fluxes (17 nmol/m2/s) compared to another site in the same estuary (112 nmol/m2/s). The question became; why did Old County experience lower methane emissions? We then did a focused study on the Old County location to investigate. We sampled various biogeochemical parameters including pH, salinity, ORP, dissolved Fe, sulfate, chloride, CH4, DOC, and DIC from pore water samples taken June 2022. We also measured extractable iron from a 2015 archived sediment core at Old County. Specifically, we explored the role of Fe in reducing methane through Fe coupled anaerobic oxidation of methane (Fe-AOM). The porewater depth profiles ranged from 10cm to 242 cm in depth and showed Old County as acidic (pH of 3-6.5), mostly fresh, anoxic, highly reducing, and high in dissolved organic carbon (DOC; 2,000-10,000 μM). I divided the depth profiles into two distinct zones, one above 50 cm and one below 50 cm. Overall, Fe-AOM was likely to occur below 50 cm because dissolved Fe increased as CH4 decreased, which is the expected pattern for Fe-AOM. Also, because the ratio of the calculated methane flux (-0.552 nmol m-2 s-1) to the dissolved Fe (0.072 nmol m-2 s-1) was 7.6, which closely matched the 1 to 8 stoichiometry of the Fe-AOM reactions.
ContributorsEinecker, Rachel (Author) / Hartnett, Hilairy (Thesis director) / Anbar, Ariel (Committee member) / Eagle, Meagan (Committee member) / Barrett, The Honors College (Contributor) / School of Molecular Sciences (Contributor)
Created2023-12