Degrees of Change

The transition between the Paleoindian (13,000-8,000) and Archaic (8,000-1,000) Periods continues to elude North American archaeologists. It is inferred from archaeological evidence that human populations were nomadic hunter-gatherers during both periods. The creation of storage pits, however, provides evidence for some seasonal sedentism during the Archaic Period. This development may have been influenced by climate change at the end of the Ice Age. Stable Isotopic Analysis of faunal remains allows archaeologists to capture a snapshot of past climate in a given area. Water Canyon in Magdalena, New Mexico, has yielded two overlapping bison kill sites. The older kill site dates to the late Paleoindian while the younger site dates to the Early Archaic. Stable Isotopic Analysis can be performed on the bison remains to determine the paleoecology of the area for two different periods. Data derived from Stable Isotopic Analysis may then provide archaeologically based evidence for the effects of climate change as a factor contributing to cultural continuity and change in the American Southwest. The transition from nomadic lifestyles to seasonal sedentism in the region, for example, may have been influenced by environmental agents visible within isotopic signatures

Stable isotopic analysis of atmospheric methane by infrared spectroscopy by use of diode laser difference-frequency generation

An infrared absorption spectrometer has been constructed to measure the stable isotopic composition of atmospheric methane samples. The spectrometer employs periodically poled lithium niobate to generate 15 μW of tunable difference-frequency radiation from two near-infrared diode lasers that probe the ν3 rotational-vibrational band of methane at 3.4 μm. To enhance the signal, methane is extracted from 25 l of air by use of a cryogenic chromatographic column and is expanded into the multipass cell for analysis. A measurement precision of 12‰ is demonstrated for both δ13C and δD

An Isotopic analysis of the hydrology and riparian vegetation water sources on Bishop Creek

Five power generation plants along an eleven kilometer stretch divert Bishop Creek water for hydro-electric power. Stream diversion may be adversely affecting the riparian vegetation. Stable isotopic analysis is employed to determine surface water/ground-water interactions along the creek. surface water originates primarily from three headwater lakes. Discharge into Bishop Creek below the headwaters is primarily derived from ground water. The average δD and δ18O values are significantly different for surface water and ground water that an isotopic analysis can delineate between these two components of flow. Therefore isotopic shifts along the creek can determine gaining reaches. In addition, by knowing the isotopic signatures of various waters in the watershed, it may be possible to examine tree waters to determine their water source(s)

Stable isotopic analysis of prehistoric human diet in the Mariana Islands, western Pacific

Stable isotopic analyses of human and faunal bones provide a valuable means to differentiate marine and terrestrial food use in prehistoric tropical island environments (Keegan and DeNiro 1988; McGovern-Wilson and Quinn 1996; Ambrose et al. 1997). Because stable carbon and nitrogen isotope values in bone collagen are quantitatively related to the isotopic composition of ingested foods (Schoeninger and Moore 1992; Pate 1994), isotopic analyses of archaeological human bone may provide quantitative information about past diet that enhances qualitative data derived from artefacts and floral and faunal remains

An Evaluation of Laser Extraction for Stable Isotopic Analysis of Carbonate and Hydrous Minerals

High-energy laser ionization of geologic materials is a potential replacement for conventional stable isotope extraction techniques because the former requires less sample material, requires less sample preparation and, most importantly, may allow direct in situ analysis. The laser extraction process explored in this study uses a pulse, focused Nd:YAG laser to excite the surface of carbonate and hydrous minerals producing a plasma. The plasma subsequently cools and condenses to form stable gaseous species such as CO and CO2 from carbonates or H2 and H20 from hydrous minerals. These species may be cryogenically separated and analyzed to obtain their isotopic compositions. .

Stable Isotopic Analysis of Equid (Horse) Teeth from Mongolia

This study examines the carbon and oxygen isotopic composition of bioapatite in equid tooth enamel as a potential record of environmental change in a north-central Mongolian sampling area between 51.4°N, 99.0°E and 44.6°N, 106.9°E (northwest to southeast). Mammal tooth enamel is useful as a palaeoclimate proxy because it is a durable material that directly reflects the isotopic composition of the body, and therefore organism diet and water intake. In addition, tooth enamel accumulates sequentially from crown to root over the period of months to years and often records seasonal variation. Thus, the inter- and intra-tooth variations in the stable carbon (ä13C) and oxygen (ä18O) isotopic composition of horse tooth enamel may provide a high-resolution record about climatic factors such as temperature and moisture availability as well as the composition and availability of forage during the tooth growth period. Sequential incremental samples from modern horses were analyzed to provide a record of the carbon and oxygen isotopic values preserved during tooth enamel formation and mineralization. To constrain the final composition of the bioapatite, modern enamel stable isotopic compositions were compared with the compositions of meteoric waters and plants from comparable localities. Modern teeth displayed a marked regional seasonal oscillation in ä18O and record a latitudinal shift observed in the ä18O of meteoric waters. In addition, bulk and sequentially sampled profiles from the modern teeth were used as a comparative set with samples from archaeological teeth (Bronze Age, ca. 1000 B.C.) and suggest that climatic patterns were roughly equivalent during both periods, with a similar plant communities, and similar summer precipitation/temperature patterns. However, seasonality may have been more intense in Bronze Age ca. 1000 B.C., with similar summer highs but more severe winters. The difference could be due to This work contributes to ongoing research into the climatic history of Central Asia and to the application of equid tooth enamel as an environmental proxy in this region

Suitability of Paleosols from the early Miocene Kiahera Formation, Rusinga Island, Kenya for Stable Isotopic Analysis

Climate change and concurrent environmental changes play an important role in understanding biological evolution through time, because climate change may be a stressor that promotes flora and fauna adaptations. Nearly a century of geological and paleontological study on Rusinga Island, Lake Victoria, Kenya, has made it a touchstone for understanding early Neogene floral and faunal evolution. This is because sediments that were deposited between ca. 20-17 Ma, during the early Miocene, are famous for the presence of the early ape, Ekembo, as well as more than 100 species of mammals. The basal Kiahera Formation has largely been understudied, but recent preliminary work suggests it contains an abundance of fossil soils (paleosols), as well as uniquely preserved fossils. Here we report on the clay mineralogy of four different paleosols within the Kiahera Formation using x-ray diffraction (XRD) analysis. Preliminary XRD analysis reveals samples dominated by illite, kaolinite, and mixed layer clay minerals. In particular, sample LM17KF contained an abundance of clay minerals, no evidence of diagenetic alteration, and the desired two clay mineral suite of illite and kaolinite. This sample was determined to be the most robust candidate for future stable isotopic analysis. These results advance our ability to quantitively assess climate on the island, particularly in a formation that is important for its small mammal communities. Furthermore, this work, suggests there are phyllosilicates that are appropriate for 18O analysis which may result in our better understanding the role the East African monsoon played in the environment during this time

Source identification of N2O produced during simulated wastewater treatment under different oxygen conditions using stable isotopic analysis

Nitrous oxide (N2O), a potent greenhouse gas which is important in climate change, is predicted to be the most dominant ozone depleting substance. It is mainly produced by oxidation of hydroxylamine (NH2OH) or reduction of nitrite (NO2-) during microbiological processes such as nitrification and denitrification. Wastewater treatment plant (WWTP) is one of the anthropogenic N2O sources because inorganic and organic nitrogen compounds are converted to nitrate (NO3-, in the case of standard system) or N2 (in the case of advanced system) by bacterial nitrification and denitrification in WWTP. We investigated the N2O production mechanisms during batch experiments that simulate wastewater treatment with activated sludge under various dissolved oxygen (DO) concentrations by stable isotope analysis. About 125mL of water was sampled from 30L incubation chamber for several times during the incubation, and concentration and isotopomer ratios of N2O and N-containing species were measured using gas chromatography/isotope ratio mass spectrometry (GC/IRMS). Ammonium (NH4+) consumption was accompanied by increment of nitrite (NO2-), and at the same time dissolved N2O concentration gradually increased to 4850 and 5650 nmol kg-1, respectively, during the four-hour incubation when DO concentrations were 0.2 and 0.5 mg L-1. Observed low SP values (0.2-8.9‰ at DO-0.2 mg L-1, -5.3-6.3‰ at DO-0.5 mg L-1, -1.0-8.3‰ at DO-0.8 mg L-1) in N2O and relationship of nitrogen isotope ratios between N2O and its potential substrates (NH4+, NO3-) suggested that N2O produced under the aerobic condition derived mainly from NO2- reduction by ammonia-oxidizing bacteria (nitrifier–denitrification).DOI: http://doi.dx.org/10.5564/mjc.v15i0.313Mongolian Journal of Chemistry  15 (41), 2014, p4-10

Paleoamerican diet, migration and morphology in Brazil

During the early Holocene two main paleoamerican cultures thrived in Brazil: the Tradição Nordeste in the semi-desertic Sertão and the Tradição Itaparica in the high plains of the Planalto Central. Here we report on paleodietary singals of a Paleoamerican found in a third Brazilian ecological setting--a riverine shellmound, or sambaqui, located in the Atlantic forest. Most sambaquis are found along the coast. The peoples associated with them subsisted on marine resources. We are reporting a different situation from the oldest recorded riverine sambaqui, called Capelinha. Capelinha is a relatively small sambaqui established along a river 60 km from the Atlantic Ocean coast. It contained the well-preserved remains of a Paleoamerican known as Luzio dated to 9,945±235 years ago; the oldest sambaqui dweller so far. Luzio's bones were remarkably well preserved and allowed for stable isotopic analysis of diet. Although artifacts found at this riverine site show connections with the Atlantic coast, we show that he represents a population that was dependent on inland resources as opposed to marine coastal resources. After comparing Luzio's paleodietary data with that of other extant and prehistoric groups, we discuss where his group could have come from, if terrestrial diet persisted in riverine sambaquis and how Luzio fits within the discussion of the replacement of paleamerican by amerindian morphology. This study adds to the evidence that shows a greater complexity in the prehistory of the colonization of and the adaptations to the New World