Stable isotopes in hair reveal dietary protein sources with links to socioeconomic status and health

Carbon and nitrogen isotope ratios in hair sampled from 65 communities across the central and intermountain regions of the United States and more intensively throughout 29 ZIP codes in the Salt Lake Valley, Utah, revealed a dietary divergence related to socioeconomic status as measured by cost of living, household income, and adjusted gross income. Corn-fed, animal-derived proteins were more common in the diets of lower socioeconomic status populations than were plant-derived proteins, with individual estimates of animal-derived protein diets as high as 75%; United States towns and cities averaged 57%. Similar patterns were seen across the socioeconomic status spectrum in the Salt Lake Valley. It is likely that corn-fed animal proteins were associated with concentrated animal-feeding operations, a common practice for industrial animal production in the United States today. Given recent studies highlighting the negative impacts of animal-derived proteins in our diets, hair carbon isotope ratios could provide an approach for scaling assessments of animal-sourced foods and health risks in communities across the United States.Fil: Ehleringer, James R.. University Of Utah. Department Of Biology; Estados UnidosFil: Covarrubias Avalos, Stephannie. University Of Utah. Department Of Biology; Estados UnidosFil: Tipple, Brett J.. University Of Utah. Department Of Biology; Estados UnidosFil: Valenzuela, Luciano Oscar. Universidad Nacional del Centro de la Provincia de Buenos Aires. Facultad de Ciencias Sociales. Departamento de Arqueología. Laboratorio de Ecología Evolutiva Humana (Sede Quequén); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tandil; ArgentinaFil: Cerling, Thure E.. University Of Utah. Department Of Biology; Estados Unido

Strontium isotope ratios of human hair record intra-city variations in tap water source

Abstract The oxygen (18O/16O) isotope analysis of hair is commonly applied to reconstruct an individual’s residence history. However, region-of-origin as determined from oxygen isotope values (δ 18O) alone is often spatially indistinct. Adding additional geochemical recorders can refine region-of-origin estimates. In this capacity, strontium (87Sr/86Sr) isotope analysis has attracted increased interest. While 87Sr/86Sr reflects the influences of local geology, 87Sr/86Sr of hair includes both external environmental signals as well as the internal dietary indicators. To better understand the impact of these contributions to the spatial signal encoded within 87Sr/86Sr of hair, human hair was collected from three locations within Salt Lake City, Utah along with the donor’s sex. The 87Sr/86Sr and δ 18O of hair and local tap water were measured. There were no significant relationships between sex and either δ 18O or 87Sr/86Sr of hair, nor between collection location and the δ 18O of hair. However, we found significant associations between collection location and 87Sr/86Sr of hair. These findings suggest that interactions with local water may be an important source of Sr to human hair and that the 87Sr/86Sr of hair may have the capacity to record differences in 87Sr/86Sr of tap waters on small spatial scales

Projected reversal of oceanic stable carbon isotope ratio depth gradient with continued anthropogenic carbon emissions

Uptake of 13C-depleted anthropogenic carbon dioxide in the surface ocean may eliminate or reverse the natural vertical gradient in the isotopic composition of dissolved inorganic carbon in the ocean, analogous to events at the Paleocene-Eocene Thermal Maximum, suggest ocean model simulations. Paleoceanographic records suggest that the present-day vertical gradient in the stable carbon isotopic composition (delta C-13) of dissolved inorganic carbon in the ocean was reversed during the Paleocene-Eocene Thermal Maximum, an early period of relatively rapid release of carbon into the climate system. Here we present simulations from an observationally constrained ocean model under various greenhouse gas emissions scenarios. We project a decrease in the globally averaged delta C-13 of dissolved inorganic carbon in the surface ocean of between -1.8 to -6.3 parts per thousand by 2100. This reduction is driven by oceanic absorption of anthropogenic carbon dioxide, which is depleted in carbon-13. Our findings suggest an elimination or reversal of the natural vertical gradient in the delta C-13 of dissolved inorganic carbon by 2100 unless anthropogenic carbon emissions are reduced soon. We conclude that the Paleocene-Eocene Thermal Maximum is a geologic analogue of future global carbon cycle perturbations under continued rapid anthropogenic carbon emissions

Fast exchange of strontium between hair and ambient water: Implication for isotopic analysis in provenance and forensic studies.

Trace elements in hair originate from intake (e.g., diet, inhalation, skin absorption), are transported in the bloodstream, and then incorporated during hair formation. However, the trace element abundance and isotopic compositions may be altered by post-eruption environmental processes. Such alterations must be addressed to obtain a meaningful interpretation of hair analysis for biomonitoring. In this study, we used strontium (Sr) isotopic analysis together with sorption kinetics of ionic Sr to quantify the rate and extent of replacement of endogenous Sr in hair by exogenous Sr from ambient water. We found that with only 10 minutes of exposure at room temperature (22°C), more than 30% of original endogenous Sr in hair was replaced with exogenous Sr from the solution. After 16 days of exposure to the solution, more than 90% of endogenous Sr was replaced, with a warmer temperature (60°C) accelerating the exchange substantially. We also found that acid leaching of exposed hair did not remove or isolate the exogenous Sr; therefore, neither the original endogenous nor the exogenous 87Sr/86Sr signal could be separated. Nonetheless, these findings illustrated that the quantitative correlation between the fraction of exogenous Sr and the soaking time, if established, could be used to estimate the length of water contact time for hair in forensic studies. Even if such time since initial contact cannot be established, the combination of acid leaching and 87Sr/86Sr analysis of hair samples may still be valuable in provenance studies to identify recent changes in the exogenous Sr pool, including movements or changes in water source

Life form-specific gradients in compound-specific hydrogen isotope ratios of modern leaf waxes along a North American Monsoonal transect

The use of hydrogen isotope ratios (?2H) of sedimentary n-alkanes from leaf waxes has become an important tool for reconstructing paleoenvironmental and ancient hydrologic conditions. Studies of modern plant waxes can elucidate driving ecological mechanisms behind geologic deposits. Here, we used a transect across the North American Monsoon region of the western USA from Tucson, Arizona to Salt Lake City, Utah to study variations in leaf wax ?2H among co-occurring plants. Three co-occurring life forms were selected: perennial shrub (rabbit brush, Chrysothamnus nauseosus; sagebrush, Artemisia tridentata); tree (Gambel’s oak tree, Quercus gambelii); and annual (sunflower, Helianthus annuus). Our results showed that the distributions and abundances of n-alkanes in perennial plants were similar across all sites and generally did not vary with environmental conditions (e.g., precipitation and temperature). In contrast, variations in n-alkane ?2H were significantly correlated with the fraction of the annual precipitation coming during the summer monsoon period. We use a modified Craig–Gordon model to speculate on the possible drivers of the ?2H values of leaf wax n-alkanes of plants across the region. The model results suggest that the most likely explanation for variation in wax ?2H values was a combination of seasonal source water usage and subsequent environmental conditions

The influences of cultivation setting on inflorescence lipid distributions, concentrations, and carbon isotope ratios of Cannabis sp

While much is known about how the growth environment influences many aspects of floral morphology and physiology, little is known about how the growth settings influences floral lipid composition. We explored variations in paraffin wax composition in Cannabis sp., a cash crop grown both indoors and outdoors across the United States today. Given an increased focus on regulation of this crop, there are additional incentives to certify the setting of Cannabis cultivation. To understand the impacts of the growth environment, we studied distributions, concentrations, and carbon isotope ratios of n-alkanes isolated from Cannabis sp. inflorescences to assess if variations within these lipid parameters were related to known growth settings of specimens seized by federal agents. We found that Cannabis plants cultivated under open field settings had increased inflorescence paraffin wax abundances and greater production of lower molecular weight n-alkane relative to plants grown in enclosed environments. Further, the carbon isotope ratios of n-C29 from Cannabis plants grown in enclosed environments had relatively lower carbon isotope (δ13C) values compared to plants from open-field environments. While this set of observations on seized plant specimens cannot address the particular driver behind these observations, we posit that (a) variations in irradiance and/or photoperiod may influence the distribution and concentration of inflorescence lipids, and (b) the δ13C value of source CO2 and lipid concentration regulates the δ13C values of inflorescence n-C29 and bulk Cannabis plant materials. Nonetheless, by using a cultivation model based on δ13C values of n-C29, the model correctly identified the growth environment 90% of time. We suggest that these lipid markers may be used to trace cultivation methods of Cannabis sp. now and become a more powerful marker in the future, once the mechanism(s) behind these patterns is uncovered

Stable Isotopes Trace the Truth: From Adulterated Foods to Crime Scenes

Stable isotopes are valuable biogeochemical markers for solving problems faced by society today, such as distinguishing authentic from adulterated foods and beverages or tracing the origins of illicit drugs. Hydrogen and oxygen isotopes in water exhibit distinct continental patterns (isoscapes), which provide useful region-of-origin information. We ourselves reflect the stable isotope ratios of the water we drink and the food we eat: our hair records any isotopic changes to our diets, which can often be related to location. This latter aspect can be of interest to law enforcement in determining the origins and travel histories of unidentified murder victims.Fil: Ehleringer, James R.. University of Utah; Estados UnidosFil: Chesson, Lesley A. IsoForensics; Estados UnidosFil: Valenzuela, Luciano Oscar. Universidad Nacional del Centro de la Provincia de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tipple, Brett J.. IsoForensics; Estados UnidosFil: Martinelli, Luiz A.. Universidade de Sao Paulo; Brasi

Isotope and elemental geochemistry of human hair from the United States

Hair samples were collected throughout the United States, with particular focus on major metropolitan areas of the western United States. Hair samples were collected in 2004 as well as between 2013-2015. Here hydrogen (d2H) and oxygen (d18O) isotope values along with strontium isotope ratios (87Sr/86Sr) and element abundances were measured. d2H and d18O values, 87Sr/86Sr, and elemental compositions of 560, 385 and 306 hair samples were analyzed following Tipple et al., 2018 (Scientific Reports, 8, 2224), respectively. The purpose of these data was to assess geospatial variations in isotope and elemental geochemistry of human hair. We found that the isotope and elemental geochemistry of human hair largely corresponded to the geochemistry of drinking and bathing water, which in turn varied by water source and management practice. These data provide a foundation to reconstruct human movements using the geochemistry of modern or ancient human hair