Carbon Isotope Ratio Analysis Research Articles

Adaptive significance of arboreality: field evidence from a tree-climbing land snail

Arboreality has evolved in a wide range of taxa, but its adaptive significance has rarely been examined in natural ecosystems. Euhadra brandtii sapporo is an arboreal land snail distributed in a restricted area of Hokkaido, Japan. We hypothesized that arboreality provides the species with significant survival advantages, which we tested via field observations and experiments. A monitoring census showed that E. b. sapporo hibernates in winter in the ground litter, climbs into the canopy in early spring and returns to the ground in late autumn. This seasonal movement appears to be effective for escaping from predation by ground-dwelling carabine beetles, whose activity was high during the summer based on a pitfall-trap census. Manipulative field experiments were conducted to compare survival rates in arboreal and ground-dwelling environments. We collected 120 E. b. sapporo individuals in summer and tethered 40 in tree canopies and 80 on the ground; half those on the ground were covered by baskets to prevent predation by large animals. The survival rate after 11 days was highest in the canopy, followed by that on the ground with a basket and was lowest on the ground without a basket. Predation was the main cause of death, but some died from other causes. Similar results were obtained in autumn, except for higher survival rates of the ground treatments. Analyses of carbon and nitrogen isotope ratios suggest that the land snail uses epiphytic lichens and mosses as food resources. In conclusion, arboreality has a marked advantage in reducing mortality in E. b. sapporo and is probably supported by food availability as well.

Reconstructing diet in Napoleon's Grand Army using stable carbon and nitrogen isotope analysis.

Historical evidence has provided information regarding disease and mortality in Napoleon Bonaparte's Grand Army, but dietary information beyond individual soldier accounts remains scarce. The purpose of this research is to reconstruct the diets of Napoleon's multiethnic army who were associated with the Russian Campaign of 1812. We conducted stable carbon and nitrogen isotope ratio analysis on femoral bone collagen of 78 individuals recovered from a salvage excavation at the mass gravesite of Šiaurės miestelis in Vilnius, Lithuania. These individuals were later discovered to be Napoleonic soldiers and camp followers who participated in the 1812 Russian Campaign. Stable carbon isotope ratios range from -19.2‰ to -11.8‰, with a mean of -17.8‰ ± 1.5‰ (1 σ). Stable nitrogen isotope ratios range from 7.1‰ to 13.6‰, with a mean of 10.5‰ ± 1.4‰ (1 σ). Both δ13 C and δ15 N values show a wide range of variation. Stable isotope data indicate considerable dietary variation in this population associated with a multiethnic and socially stratified military population. Diets ranged from predominantly C3 -based to predominantly C4 -based, with varying inputs of terrestrial, freshwater, and marine animal protein. Comparison with other European populations further denotes the exceptional range of dietary variation of soldiers and camp followers in Napoleon's army.

Compatibility of preparatory procedures for the analysis of cortisol concentrations and stable isotope (δ13C, δ15N) ratios: a test on brown bear hair.

The measurement of naturally occurring glucocorticoids and stable isotopes of several elements has gained importance in wildlife studies in recent decades and opened a myriad of ecological applications. Cortisol and stable isotopes equilibrate in animal tissues over periods of integration related to the growth rate of the tissue, providing information reflecting systemic cortisol secretion and dietary intake. Sample preparation shares the common step of first cleaning the sample of external contamination. However, it is not well understood how different solvents used in sample preparation affect isotopic and cortisol values, and whether it is safe to follow the same procedures for both measures to optimize analyses of the same sample. We conducted an experiment to compare different preparation protocols for the analysis of cortisol concentrations and stable carbon (δ13C) and nitrogen (δ15N) isotope ratios in hair. Hair samples from 12 brown bears (Ursus arctos) were each divided into five aliquots; two aliquots were rinsed with a 2:1 chloroform:methanol (v/v) mixture with one aliquot ground prior to cortisol analysis and the other left intact for stable isotope analyses; two aliquots were washed with methanol with one aliquot ground prior to cortisol analysis and the other left intact for stable isotope analyses; and one aliquot washed with methanol and ground prior to stable isotope analyses. The cortisol, δ13C and δ15N values remained consistent following all treatments. Our results indicate that hair samples rinsed with a 2:1 chloroform:methanol mixture or washed with methanol can be used for both types of analyses. Further, hair that has been ground in a standard hair cortisol procedure can also be used for stable isotope analysis. This information is important for improving laboratory efficiency and compatibility of procedures used for wildlife physiological ecology studies where concurrent measurements of cortisol and stable isotopes in hair are required.

The subsistence patterns of the Shengedaliang site (~4,000 yr BP) revealed by stable carbon and nitrogen isotopes in northern Shaanxi, China

In order to explore subsistence patterns in northern Shaanxi Province around 4,000 yr BP, 28 human and 24 animal bones from the Shengedaliang site were sampled for stable carbon and nitrogen isotope ratio analysis. The results show that most people primarily subsisted on C4 resources, e.g. millet and millet-related animal products, despite the fact that there was some intake of C3 plants by some individuals. Stable nitrogen isotope values indicate that there were differences in meat consumption between individuals at the site. Pigs were mainly foddered with millet and millet byproducts, as well as some cattle, according to their high δ 13C values. However, most cattle and the sheep/goats consumed wild C3 plants at Shengedaliang. Our above findings indicates that subsistence patterns in northern Shaanxi around 4,000 yr BP were characterized by millet farming, while the grassland animal husbandry, e.g. cattle and sheep/goats raising, displayed very little contribution to local economy. The intensive millet farming in northern Shaanxi provided enough food for population growth, ensured the accumulation of wealth, and consequently accelerated social differentiation and complexity.

Carbon and nitrogen stable isotope ratio analysis of Bronze Age humans from the Xiabandi cemetery, Xinjiang, China: Implications for cultural interactions between the East and West

The Andronovo culture of Central Asia is characterized by wheat agriculture and sheep/goat and cattle animal husbandry. Sometime during the beginning to the middle of the 2nd millennium BC, the Andronovo migrated from the Kazakh Steppe into the modern-day Xinjiang Uyghur Autonomous Region of China and became one of the most important archaeological complexes in this area. At about the same time or earlier, populations from the East characterized by: millet agriculture, Mongolian race, and painted pottery spread westward from northern China along the mountain ranges of the Gansu Corridor and met the Andronovo culture in the central part of Xinjiang. It is not known how and when these cultures originating from the East and West first started to interact with each other in Xinjiang, and this is especially true in the southwest region of Xinjiang, which is a crucial transport corridor between the Eurasian Steppe and the populations of Central Asia. The analysis of stable isotope ratios of carbon ( δ 13C) and nitrogen ( δ 15N) permits an investigation of human diets and lifeways and has the potential to shed light on cultural interactions between the East and the West. Here δ 13C and δ 15N results of human bone collagen ( n =27) are presented to reconstruct dietary patterns and cultural communications at the Xiabandi cemetery site in the Xinjiang Uyghur Autonomous Region of China.

Positive carbon isotope excursions: global correlation and genesis in the Middle–Upper Ordovician in the northern Tarim Basin, Northwest China

Stable carbon isotope ratio (δ13Ccarb) analysis has been widely applied to the study of the inter-continental or global marine carbonate correlation. Large-scale Cambrian–Ordovician carbonate platforms were developed in the Tarim Basin. But research on fluctuation characteristics and global correlation of δ13Ccarb is still weak. Based on conodont biostratigraphy and whole-rock δ13Ccarb data in the Tahe oil–gas field of the northern Tarim Basin, the global correlation and genesis of positive carbon isotope excursions in the Darriwilian—Early Katian was examined. Three positive excursions were identified in the Tahe oil–gas field including the middle Darriwilian carbon isotope excursion (MDICE), the Guttenberg carbon isotope excursion (GICE), and a positive excursion within the Pygodus anserinus conodont zone which is named the Early Sandbian carbon isotope excursion (ESICE) in this paper. Furthermore, these positive excursions had no direct relation with sea level fluctuations. MDICE and GICE could be globally correlated. The Middle–Upper Ordovician Saergan Formation source rocks of the Kalpin outcrops were in accordance with the geological time of MDICE and ESICE. GICE had close relationship with the source rock of the Lianglitag Formation in the basin. Massive organic carbon burial was an important factor controlling the genesis of these positive excursions.

Contrasting annual cycles of an intratropical migrant and a tropical resident bird

Throughout their annual cycle, migrants often adopt different foraging and microhabitat usage strategies. Previous studies treat migrants as niche-trackers/niche-followers, i.e., they track similar niches along their annual cycle, almost exclusively based on food resource availability, which is inferred based on the climate at either the wintering or breeding grounds. An alternative approach is the use of such techniques as stable isotope analyses that allow researchers to more directly infer a migrant’s niche across seasons. While the use of carbon isotopes enables an assessment of microhabitat traits, that of nitrogen isotopes provides information on a bird’s trophic level. In the study reported here, we performed comparative analyses of stable carbon and nitrogen isotope ratios in tissues of the resident Plain-crested Elaenia and the intratropical migrant Lesser Elaenia to evaluate their year-round ecological niches. Our data suggest that both residents and migrants were consistent in their use of similar microhabitats throughout the year, which indicates a niche-tracking behavior on the part of migratory individuals. Migrants often fed at higher trophic levels than residents, but both species exhibited similar trophic level shifts through the year, feeding on higher trophic levels during breeding and on the lowest ones while wintering. The observed patterns could be due to several factors, including differential energetic demand needed for the migratory journey, species-specific nutritional needs during each stage of the year, and/or the use of multiple wintering grounds by migrants.

Measurement of position-specific 13C isotopic composition of propane at the nanomole level

We have developed a novel method for analyzing intramolecular carbon isotopic distribution of propane as a potential new tracer of its origin. The method is based on on-line pyrolysis of propane followed by analysis of carbon isotope ratios of the pyrolytic products methane, ethylene and ethane. Using propane samples spiked with 13C at the terminal methyl carbon, we characterize the origin of the pyrolytic fragments. We show that the exchange between C-atoms during the pyrolytic process is negligible, and thus that relative intramolecular isotope composition can be calculated. Preliminary data from 3 samples show that site-preference (SP) values, defined as the difference of δ13C values between terminal and sub-terminal C-atom positions of propane, range from −1.8‰ to −12.9‰. In addition, SP value obtained using our method for a thermogenic natural gas sample is consistent with that expected from theoretical models of thermal cracking, suggesting that the isotope fractionation associated with propane pyrolysis is negligible. The method will provide novel insights into the characterization of the origin of propane and will help better understand the biogeochemistry of natural gas deposits.

Origin Identification of Carbonaceous Aerosol Particles by Carbon Isotope Ratio Analysis

We applied stable carbon isotope ratio (^(13)C/^(12)C) and radiocarbon (^(14)C) analysis for the quantification of three main aerosol sources (coal, biomass and liquid fossil fuel derived aerosol emissions). Submicron aerosol samples (PM1) were collected from 27^(th) October, 2014 to 19^(th) January, 2015 at a suburban site of Vilnius city (Lithuania). To determine fossil and non-fossil contributions to submicron carbonaceous aerosol particles, ^(14)C measurements of total carbon (TC) were performed using single stage accelerator mass spectrometer (SSAMS, NEC, USA). The concentrations of TC and δ^(13)C in PM_1 fraction were measured using elemental analyzer interfaced to isotope ratio mass spectrometer (EA-IRMS). The TC concentration during measurement period ranged from 1.3 to 9.6 μg m^(-3). The variation of TC concentrations can be explained by the influence of long-range transport and dispersion properties of the boundary layer (mixed layer depth). We found that biomass-derived aerosol sources are prevailing in Vilnius during wintertime and ranged from 57% to 84% of total carbonaceous aerosol fraction. Applying isotope mass balance calculations the traffic emissions were estimated to be 15 ± 7% and coal combustion made up 14 ± 9% in PM_1. To provide better information about the pollution sources, the carbon isotope analysis along air mass transport pattern was performed. Our results demonstrated that the high contribution to PM_1 from coal burning (up to 40%) was observed for air masses transported from highly industrialized Western Europe regions. Combination of stable carbon isotope ratio with the radiocarbon data allow to distinguish coal from liquid fossil fuel in the aerosol particle emissions.

An effective method of UV-oxidation of dissolved organic carbon in natural waters for radiocarbon analysis by accelerator mass spectrometry

Radiocarbon (14C) measurement of dissolved organic carbon (DOC) is a very powerful tool to study the sources, transformation and cycling of carbon in the ocean. The technique, however, remains great challenges for complete and successful oxidation of sufficient DOC with low blanks for high precision carbon isotopic ratio analysis, largely due to the overwhelming proportion of salts and low DOC concentrations in the ocean. In this paper, we report an effective UV-Oxidation method for oxidizing DOC in natural waters for radiocarbon analysis by accelerator mass spectrometry (AMS). The UV-oxidation system and method show 95%±4% oxidation efficiency and high reproducibility for DOC in both river and seawater samples. The blanks associated with the method was also low (about 3 µg C) that is critical for 14C analysis. As a great advantage of the method, multiple water samples can be oxidized at the same time so it reduces the sample processing time substantially compared with other UV-oxidation method currently being used in other laboratories. We have used the system and method for 14C studies of DOC in rivers, estuaries, and oceanic environments and have received promise results.

Identification of Recycled Cooking Oil and Edible Oils by Iodine Determination and Carbon Isotopic Analysis

AbstractElemental iodine determination by ICP‐MS and carbon isotope analysis by EA‐IRMS were jointly employed to identify recycled cooking oil from edible oils. Iodine in 204 oils demonstrated that recycled cooking oils can be distinguished from soybean oil, maize oil, colza oil, peanut oil, sunflower oil and olive oil with the exception of tea oil and mixed oil. These two types of oils can be definitively distinguished from recycled cooking oil in the carbon isotope ratio analysis. It was proposed to use total iodine analysis as the primary screening method and the carbon isotope ratio measurement as a secondary method for confirmation and verification. For routine screening, threshold values of Iodine determination and δ13C measurement were determined to be 20 ng g−1 iodine and a range of −27.3 to −28.5 of δ13C, respectively.

Design and modeling of a photoacoustic gas analyzer with a thermal source for carbon isotope ratio analysis

A diagram is suggested and numerical simulation is carried out of a photoacoustic gas analyzer with a thermal source and first order interference filter for carbon isotope ratio analysis. An optimal spectral range for gas analyzer operation is selected. In the wavelength range selected, the spectral parameters of the atmosphere are analyzed, as well as of some gases, which, being present in samples under study, could affect the measurement results. The gas analyzer suggested allows us to measure the carbon isotope ratio 13C/12C in CO2 samples with a minimal error of about 0.5‰, and could be useful for detection of such gases as SO2, CO, and NH3, absorption lines of which fall in the selected spectral range.

Cattle Management for Dairying in Scandinavia's Earliest Neolithic.

New evidence for cattle husbandry practices during the earliest period of the southern Scandinavian Neolithic indicates multiple birth seasons and dairying from its start. Sequential sampling of tooth enamel carbonate carbon and oxygen isotope ratio analyses and strontium isotopic provenancing indicate more than one season of birth in locally reared cattle at the earliest Neolithic Funnel Beaker (EN I TRB, 3950-3500 cal. B.C.) site of Almhov in Scania, Sweden. The main purpose for which cattle are manipulated to give birth in more than one season is to prolong lactation for the production of milk and dairy-based products. As this is a difficult, intensive, and time-consuming strategy, these data demonstrate complex farming practices by early Neolithic farmers. This result offers strong support for immigration-based explanations of agricultural origins in southern Scandinavia on the grounds that such a specialised skill set cannot represent the piecemeal incorporation of agricultural techniques into an existing hunter-gatherer-fisher economy.

A method for stable carbon isotope ratio and concentration measurements of ambient aromatic hydrocarbons

Abstract. A technique for compound-specific analysis of stable carbon isotope ratios and concentration of ambient volatile organic compounds (VOCs) is presented. It is based on selective VOC sampling onto adsorbent-filled cartridges by passing large volumes of air (up to 80 L) through the cartridge. The hydrocarbons are recovered by thermal desorption followed by two-step cryogenic trapping and then are separated by gas chromatography in the laboratory. Once separated, individual VOCs are subjected to online oxidation in a combustion interface and isotope ratio analysis by isotope ratio mass spectrometry. The method allows measurements of stable carbon isotope ratios of ambient aromatic VOCs present in low pptV to ppbV levels with an accuracy of typically better than 0.5 ‰. The precision of concentration measurements is better than 10%. Examples of measurements conducted as part of a joint Environment Canada–York University (EC-YU) measurement campaign at a semi-rural location demonstrate that the ability to make accurate measurements in air with low VOC mixing ratios is important to avoid bias from an overrepresentation of samples that are strongly impacted by recent emissions.

Natural gas potential of Neoproterozoic and lower Palaeozoic marine shales in the Upper Yangtze Platform, South China: geological and organic geochemical characterization

In this article, we describe the geological features of the Ediacaran (upper Sinian), lower Cambrian and lower Silurian shale intervals in the Upper Yangtze Platform, South China, and report on the gas potential of 53 samples from these major marine shale formations. Reflected light microscopy, total organic carbon (TOC) measurement, Rock-Eval, carbon isotope ratio analysis, thermovaporization gas chromatography (Tvap-GC), and open pyrolysis gas chromatography (open py-GC) were used to characterize the organic matter. Measured TOC in this research is normally >2% and averages 5%. TOC contents are roughly positively correlated with increasing geological age, i.e. lower Silurian shales exhibit generally lower TOC contents than lower Cambrian shales, which in turn commonly have lower TOC contents than Ediacaran shales. Kerogen has evolved to the metagenesis stage, which was demonstrated by the abundant pyrobitumen on microphotographs, the high calculated vitrinite reflectance (Ro = 3%) via bitumen reflectance (Rb), as well as δ13 C of gas (methane) inclusions. Pyrolysates from Tvap-GC and open py-GC are quantitatively low and only light hydrocarbons were detected. The lower Silurian shale generally exhibits higher generation of hydrocarbon than the lower Cambrian and Ediacaran shale. Cooles’ method and Claypool’s equations were used to reconstruct the original TOC and Rock-Eval parameters of these overmature samples. Excellent original hydrocarbon generation was revealed in that the original TOC (TOCo) is between 5% and 23%, and original S1+S2 (S1o+S2o) is ranging from 29 to 215 mg HC/g rock.

Use of stable carbon isotope ratio for foraging behavior analysis of capybara (Hydrochoerus hydrochaeris) from Esteros del Iberá, Argentina

We analyzed different aspects of the foraging behavior and habitat use for feeding of the capybara (Hydrochoerus hydrochaeris) using carbon stable isotopes (13C/12C) measured in bone collagen and by direct observation. Stable carbon isotope ratio analysis is used to determine the proportion of plant functional types consumed (C3 and C4 photosynthetic patterns). These data were further compared with the distribution of the plant functional types available in the different environments of the study area. There was a high variability in bone isotope values, and although some specimens showed a C4-based diet, data suggested a tendency toward a predominant consumption of C3 plants. The proportion of functional types in the diet of capybaras differed from their availability in the study area indicating a differential use of environments. We obtained similar conclusions by direct observation of capybaras. The high variability in isotope values and foraging behavior of the species may explain its high ecological plasticity in terms of both diet composition and selection of foraging sites.

Isotope ratio analysis of carbon and nitrogen by elemental analyser continuous flow isotope ratio mass spectrometry (EA-CF-IRMS) without the use of a reference gas

A new approach to normalize carbon and nitrogen isotope ratios measured by EA-CF-IRMS without using a reference gas for correction of instrumental drifts and instrumental isotope fractionation.

New Frontiers for Sulfur Isotopic Analyses

Measurements of sulfur stable isotope ratios (34S/32S) have suffered in the past from technical difficulties in analyzing low-S materials reducing their use despite their undeniable scientific interest. The measurement of 34S/32S ratios is a powerful tool for deciphering problems such as determining the sources of environmental pollutants, to detect adulteration, tracking the evolution of the redox state of the oceans, and quantifying the role of the bacterial activity in sulfide minerals genesis. We have used an innovative high–precision, easy and rapid method of simultaneous analysis of carbon (13C/12C), nitrogen (15N/14N) and sulfur (34S/32S) isotope ratios as well as elemental concentrations using a new combination of elemental analyzer and isotopic ratio mass spectrometer. This new technique provides multiple isotopic signatures on smaller sample aliquots with high precisions especially for sulfur determinations. The technique described here is Isotopic Ratio Mass Spectrometry (IRMS) on line in continuous flow mode with an Elemental Analyzer (EA) based on “purge and trap” technology rather than conventional packed-GC gas separation. Emphasis is put on the efficiency of the system to reliably combust sulfur–bearing compounds of both organic and inorganic origin with high conversion yields. This new technique demonstrates the high quality of 34S/32S measurements for samples with S concentrations lower than 1 wt%. International calibrated references of diverse sulfur-bearing materials were used to calibrate two low (<1%) S -bearing phosphorites used as compositional reference material for future use as isotopic references: BCR32 and NBS120c. High quality of 34S/32S determinations is illustrated using various international reference materials. Working calibrated material has been selected and characterized for all three isotopic signatures as well in order to fully use the capacities of the system in future work. The possibilities of such a system to reliably measure S isotopes as well as N and C within the same aliquot of sample opens up new fields of investigation in many domains where multi-isotopic approaches are required.

Identification of dried shark fins by analysis of seven sugars using pre-column derivatization high-performance liquid chromatography and stable carbon isotope ratio analysis

A simple and sensitive method using pre-column high-performance liquid chromatography (HPLC) was developed for the simultaneous detection of seven sugars, which was also applied for the preliminary identification of dried shark fins.

Optimization of sample clean-up for the GC–C-IRMS and GC–IT-MS analyses of PAHs from air particulate matter

The optimization of sample clean-up for the analysis of air particulate matter PAHs' stable carbon isotope ratio using Solid Phase Extraction (SPE) cartridges is described in this paper. Various adsorbents, such as silica gel, alumina, and florisil, commercially available for sample purification were compared. Best performance for the clean-up of 24-h air particulate matter samples was obtained with activated silica-gel columns in terms of selectivity and reproducibility. One step clean-up was optimized for concentration determination and in case of co-elutions, a second step was additionally used for carbon isotope ratio analysis. The method was subsequently validated with standard reference material and was checked for carbon isotope fractionation artifacts. No significant differences in δ13C values were found for unprocessed solution of PAHs and solution subjected to the extraction and purification procedure. The procedure was tested on air particulate matter samples collected in three different locations in Belgium. Statistically significant differences in carbon isotope ratio of PAHs between Borgerhout location and Zelzate or Gent were noticed, confirming the differences in distribution and diagnostic ratios found during the concentration analyses and different PAH sources in these locations. The results, therefore, seem very promising for the use of δ13C of PAHs as an additional information helpful in source identification of these pollutants.