Stable Carbon Isotope Ratio Analysis Research Articles

CO2 conversion to CO by fluidized bed biomass gasification: Measuring CO2 utilization via stable carbon isotope ratios

Thermochemical conversion of CO2 in biomass gasification is a promising technology for utilizing CO2 as a feedstock to produce a CO-rich gas. Simultaneous decomposition reactions of biomass and various gas-solid and gas-gas reactions form the product gas in this process. The overlap in sub-processes makes it challenging to assess the conversion of feedstock CO2 with common methods like mass balancing. This work introduces stable carbon isotope ratio analysis (δ13C) to identify the sourcing of carbonaceous product gas components and determine the conversion of CO2. This methodology is applied to evaluate experiments conducted for one hour of continuous operation in a lab-scale fluidized bed gasifier. Softwood pellets and wood char are used as fuel, with Olivine as a bed material, a target heating temperature of 1000 °C and atmospheric pressure. Product gas with more than 80 vol% CO was generated when wood char was used as fuel. Stable carbon isotope measurements show that CO2 is converted at 48–93% in this process, underpinning the position of biomass CO2 gasification as carbon capture and utilization technology. These results were up to 25% higher than suggested by mass balancing, with higher discrepancies at lower CO2 conversions when using softwood as fuel. Therefore, stable carbon isotope ratio measurement can be a valuable tool for improving the process understanding of biomass CO2 gasification. The results can be used for carbon accounting and the technical development of gasifiers with high CO2 utilization efficiency.

Using stable carbon isotope ratio analysis to detect adulteration in red yeast rice dietary supplements

Red yeast rice (RYR) is marketed as a dietary supplement because it contains natural 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors (statins), including monacolin K. However, there is concern that some RYR supplements may be adulterated with the pharmaceutical drug lovastatin to enhance health claims. We have developed an optimized method to isolate monacolin K/lovastatin from complex RYR dietary supplement matrices to then test for adulteration in RYR supplements using stable carbon isotope (δ13C) analysis. Samples were initially screened for monacolin K/lovastatin using liquid chromatography with mass spectrometric detection (LC-MS). To ensure the extraction process did not affect the measured isotopic values (i.e., isotopic fractionation effects), neat lovastatin standards were spiked into two types of blank RYR matrices (powder and gel). The monacolin K/lovastatin peaks were detected using high performance liquid chromatography with ultraviolet detection (HPLC-UV) and isolated using fraction collection. Residual matrix components were removed from targeted fractions by solid phase extraction (SPE) using graphitized carbon black cartridges. The resulting isolates were then analyzed using elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) to measure δ13C values. The δ13C values of the extracted lovastatin standards were compared to their respective neat lovastatin δ13C values and demonstrated negligible isotopic fractionation effects. Using this optimized clean up method and carbon isotope analysis, thirty-one samples were screened. Eight RYR dietary supplement samples had >0.8 mg/g of monacolin K/lovastatin, our minimum threshold for analyzing samples using this method. Four of these eight samples had δ13C values greater than −28.3‰, a previously proposed cutoff value for natural monacolin K, indicating likely adulteration. Additionally, five RYR powder samples were analyzed as part of a collaborative study using in-house methods from two laboratories and the data shows acceptable agreement in the δ13C values of monacolin K/lovastatin (differences ranging from ±0.02‰ to ±0.76‰). This optimized method represents a robust, reproducible procedure for detecting lovastatin adulteration in dietary supplements with minimal isotopic fractionation.

Polluting characteristics, sources, cancer risk, and cellular toxicity of PAHs bound in atmospheric particulates sampled from an economic transformation demonstration area of Dongguan in the Pearl River Delta, China

The Songshan Lake Science and Technology Industrial Park is a national economic transition demonstration area, which centers at a traditional industrial region, in Dongguan, China. We were interested in the involved atmospheric particulates-bound PAHs regarding their sources, cancer risk, and related cellular toxicity for those in other areas under comparable conditions. In this study, the daily concentrations of TSP, PM10, and PM2.5 were averaged 127.95, 95.91, and 67.62 μg/m3, and the bound PAHs were averaged 1.31, 1.22, and 0.77 ng/m3 in summer and 12.72, 20.51 and 40.27 ng/m3 in winter, respectively. The dominant PAHs were those with 5–6 rings, and 4–6 rings in summer and winter, respectively. The incremental lifetime cancer risk (ILCR) (90th percentile probability) of total PAHs was above 1.00E-06 in each age group, particularly high in adolescents. Sensitivity analysis indicated that slope factor and body weight had greater impact than exposure duration and inhalation rate on the ILCR. Moreover, treatment of human bronchial epithelial BEAS-2B cells with mixed five indicative PAHs increased the formation of ROS, DNA damage (elevation in γ-H2AX), and protein levels of CAR, PXR, CYP1A1, 1A2, 1B1, while reduced the AhR protein, with the winter mixture more potent than summer. For the sources of PAHs, the stable carbon isotope ratio analysis and diagnostic ratios consistently pointed to petroleum and fossil fuel combustion as major sources. In conclusion, our findings suggest that particulates-bound PAHs deserve serious concerns for a cancer risk in such environment, and the development of new power sources for reducing fossil fuel combustion is highly encouraged.

Application of 13C Quantitative NMR Spectroscopy to Isotopic Analyses for Vanillin Authentication Source

The carbon stable isotope ratio (δ13C) is a valuable chemical parameter in the investigation of the geographic origin, quality, and authenticity of foods. The aim of this study is the evaluation of the feasibility of 13C-NMR (Nuclear Magnetic Resonance) spectroscopy to determine the carbon stable isotope ratio, at natural abundance, of small organic molecules, such as vanillin, without the use of IRMS (Isotope Ratio Mass Spectrometry). The determination of vanillin origin is an active task of research, and differentiating between its natural and artificial forms is important to guarantee the quality of food products. To reach our goal, nine vanillin samples were analyzed using both 13C quantitative NMR spectroscopy (under optimized experimental conditions) and IRMS, and the obtained δ13C values were compared using statistical analysis (linear regression, Bland–Altman plot, and ANOVA (analysis of variance)). The results of our study show that 13C-NMR spectroscopy can be used as a valuable alternative methodology to determine the bulk carbon isotope ratio and to identify the origin of vanillin. This makes it attractive for the analysis in the same experiment of site-specific and total isotope effects for testing authenticity, quality, and typicality of food samples. Moreover, the improvement of NMR spectroscopy makes it possible to avoid the influence of additives on carbon stable isotope ratio analysis and to clearly identify fraud and falsification in commercial samples.

Stable carbon isotope ratio analysis of Philippine honeys for the determination of adulteration with C4 sugars

The Internal Standard Stable Carbon Isotope Ratio Analysis (ISCIRA) or AOAC 998.12 is a method for detecting honey adulteration using C4 sugars, such as cane and corn syrup. This method was developed and used mainly on European honeybees (Apis mellifera) and may not necessarily be applicable to honey produced by other bee species. In this study, the applicability of the ISCIRA method was validated for honeys produced by bees common to the Philippines, namely the native giant honeybees Apis breviligula, the stingless bee Tetragonula biroi, as well as Apis mellifera. Results show that authentic honeys from all three bee species collected across the Philippines (n = 14 for A. breviligula, 13 for T. biroi, and 11 for A. mellifera) displayed ISCIRA indices greater than − 1.0, validating the applicability of the ISCIRA method. Furthermore, removing suspended insoluble pollen from honey via centrifugation and filtration is not recommended as this additional step tends to shift the honey protein δ13C to a more positive value, potentially adding more leeway for C4 sugar adulteration. When the ISCIRA method was used for assessing adulteration in honey products available in the Philippine market, it was found that 12 of 16 (75%) local store-bought, 0 of 41 (0%) imported store-bought, and 64 of 74 (86.5%) local online-bought honey brands were adulterated with C4 sugars. Among the 76 adulterated honeys, 71 (93.4%) contain more than 78% apparent C4 sugar. These results demonstrate the need for stricter honey quality regulations and policies to protect the Philippines’ bee industry and its consumers.

Archives of human-dog relationships: Genetic and stable isotope analysis of Arctic fur clothing

Among Indigenous populations of the Arctic, domestic dogs (Canislupus familiaris) were social actors aiding in traction and subsistence activities. Less commonly, dogs fulfilled a fur-bearing role in both the North American and Siberian Arctic. Examples of garments featuring dog skins were collected during the 19th-20th centuries and are now curated by the National Museum of Denmark. We sequenced the mitochondrial genomes of macroscopically identified dog skin garments. We conducted stable carbon and nitrogen isotope ratio analysis of the dog furs and of fur samples from contemporaneous pelts of Arctic (C. lupus arctos) and grey (C. lupus) wolves. Despite the presence of biocides used to protect the fur clothing during storage, we extracted well-preserved DNA using a minimally-invasive sampling protocol. Unexpectedly, the mtDNA genomes of one-third of the samples were consistent with wild taxa, rather than domestic dogs. The strong marine component in the diets of North American dogs distinguished them from Greenland and Canadian wolves, but Siberian dogs consumed diets that were isotopically similar to wild species. We found that dog provisioning practices were variable across the Siberian and North American Arctic, but in all cases, involved considerable human labor.

Using 13C/12C isotopic ratio analysis to differentiate between rice spirits made from rice and cane molasses

In this paper, we used automated 15N 13C analysis MS (ANCA-MS) and stable carbon isotope ratio analysis to analyze samples of rice- and cane molasses-based spirits and their constituent principal ingredients. This methodology was developed to distinguish, in a scientifically accurate manner, rice spirits made of rice from that made of cane molasses. Spirits with different mixed ratios of rice and cane molasses were also prepared for a detection capability test. Series dilution for spirit samples was performed to assess operational consistency. Test results demonstrated that 13C/12C values, as measured by ANCA-MS, can be used as reliable benchmark to distinguish between the two types of rice spirits. It is recommended that test samples should be distillated or diluted to an equivalent level of ethanol prior to measuring 13C/12C values. Data established in this paper can provide criteria necessary to monitor rice spirits sold in the marketplace.

Diversity in Labrador Inuit sled dog diets: Insights from δ13C and δ15N analysis of dog bone and dentine collagen

Sled dogs were an integral part of Labrador Inuit life from the initial expansion and settlement of northeastern Canada to the present day. Tasked with pulling sleds and assisting people with other subsistence activities in the winter, dogs required regular provisioning with protein and fat. In this paper, we conduct stable carbon and nitrogen isotope ratio analysis of the skeletal remains of dogs (n = 35) and wild fauna (n = 68) from sites located on the north and south coasts of Labrador to characterize dog provisioning between the 15th to early 19th centuries. In addition, we analyse bone (n = 20) and dentine (n = 4) collagen from dogs from Double Mer Point, a communal house site in Hamilton Inlet to investigate how dog diets intersected with Inuit subsistence and trade activities at a local level. We find that dog diets were largely composed of marine mammal protein, but that dogs on the north coast consumed more caribou and fish relative to dogs from the central and south coast sites. The diets of dogs from Double Mer Point were the most heterogenous of any site, suggesting long-distance movement of people and/or animals along the coast.

Identification of wintertime carbonaceous fine particulate matter (PM2.5) sources in Kaunas, Lithuania using polycyclic aromatic hydrocarbons and stable carbon isotope analysis

Abstract The study aimed at demonstrating the application of PAHs and δ13C indoor and outdoor measurements towards resolving airborne carbonaceous particle sources in wintertime. Concurrent outdoor and indoor measurements of PM2.5 and size-resolved (PM0.056-2.5) particulate matter were conducted at 6 one-family houses in Kaunas, Lithuania during January–March 2013. PM2.5 and size-resolved filter samples were analyzed for total carbon (TC) and stable carbon isotopic composition by elemental analyzer connected to isotope ratio mass spectrometer. Moreover, the indoor-outdoor concentrations of 10 selected polycyclic aromatic hydrocarbons (PAHs) in PM2.5 were quantified. The simultaneous stable carbon isotope ratio and PAHs diagnostic ratio analysis enabled to identify main anthropogenic sources (traffic, biomass burning, and coal combustion) of PM2.5. Our study indicated that during winter period outdoor PM2.5 in Kaunas were mainly derived from biomass burning (solid fuel stoves) and vehicular emissions. Whereas indoor particulate matter had different stable carbon isotope composition of TC indicating the existence of pollution sources which was likely cooking emissions. The differences of indoor/outdoor stable carbon isotope composition in PM2.5 and size-resolved aerosol particles supported the existence of distinct TC sources and suggested that cooking emissions inside the house could strongly affect δ13C values.

Effect of tannic acid combined with fluoride and lignosulfonic acid on anaerobic digestion in the agricultural waste management chain

Livestock waste is stored and used as soil fertilizer or directly as substrate for biogas production. Methane emissions from manure storages and ammonia inhibition of anaerobic digesters fed with manure, are well-known problems related to manure management. This study examines the effect of adding tannic acid with fluoride (TA-NaF) and lignosulfonic acid (LS) on methanogenic activity in batch reactors with ammonia inhibited maize silage digestate and in batch reactors with manure. Lignosulfonic acid counteracted urea induced ammonia inhibition of methanogenesis, whereas TA-NaF inhibited methanogenesis itself. Stable carbon isotope ratio analysis and methanogen community analysis suggested that TA-NaF affected acetoclastic methanogens the most. The combined findings suggest that TA-NaF could be used to reduce methane emissions from stored manure. Conversely, LS could be used as supplement in anaerobic digesters prone to urea induced ammonia inhibition.

Tracing Carbon Isotope Variations in Lake Sediments Caused by Environmental Factors During the Past Century: A Case Study of Lake Tapeliai, Lithuania

ABSTRACTIn this study, we examined how land use and urbanization changes in adjacent areas affected biological productivity and carbon cycling in a lake ecosystem over 100 years and how these changes are reflected in carbon isotope variations. We performed radiocarbon (14C) activity and stable carbon isotope ratio analysis in two organic fractions: humin and humic acids of lake sediment. Additionally, we performed pigment and diatom analysis and determined the carbonate and organic matter (OM) content in sediments. Over the last century, the estimated 14C reservoir age in both sediment organic fractions varied from 1136 ± 112 yr to 5733 ± 122 yr. The increase in the reservoir age by 1175 ± 111 yr was related with higher inputs of pre-aged organic carbon and 14C depleted hard water due to the opening of the channel connecting two lakes. Nuclear weapons tests caused an increase in the reservoir age of up to 5421 ± 135 yr and 5733 ± 122 yr in humin and humic acids, respectively. 13C values in the humic acid fraction showed a tendency to decrease, depending on the content of autochthonous versus allochthonous OM in sediments, while changes in the sources of OM had a minor impact on the stable carbon isotope composition in the humin fraction.

Supercritical Water Oxidation as a Pretreatment Method for Stable Carbon Isotope Ratio Analysis of Rice

Supercritical Water Oxidation as a Pretreatment Method for Stable Carbon Isotope Ratio Analysis of Rice

Dorset Pre-Inuit and Beothuk foodways in Newfoundland, ca. AD 500-1829.

Archaeological research on the Canadian island of Newfoundland increasingly demonstrates that the island’s subarctic climate and paucity of terrestrial food resources did not restrict past Pre-Inuit (Dorset) and Native American (Beothuk) hunter-gatherer populations to a single subsistence pattern. This study first sought to characterize hunter-gatherer diets over the past 1500 years; and second, to assess the impact of European colonization on Beothuk lifeways by comparing the bone chemistry of Beothuk skeletal remains before and after the intensification of European settlement in the early 18th century. We employed radiocarbon dating and stable carbon and nitrogen isotope ratio analysis of bulk bone collagen from both Dorset (n = 9) and Beothuk (n = 13) cultures, including a naturally mummified 17th century Beothuk individual. Carbon and nitrogen isotope analysis of 108 faunal samples from Dorset and Beothuk archaeological sites around the island were used as a dietary baseline for the humans. We combined our results with previously published isotope data and radiocarbon dates from Dorset (n = 12) and Beothuk (n = 18) individuals and conducted a palaeodietary analysis using Bayesian modelling, cluster analysis and comparative statistical tests. Dorset diets featured more marine protein than those of the Beothuk, and the diets of Beothuk after the 18th century featured less high trophic level marine protein than those of individuals predating the 18th century. Despite inhabiting the same island, Dorset and Beothuk cultures employed markedly different dietary strategies, consistent with interpretations of other archaeological data. Significantly, European colonization had a profound effect on Beothuk lifeways, as in response to the increasing European presence on the coast, the Beothuk relied more extensively on the limited resources of the island’s boreal forests and rivers.

Online wet oxidation/isotope ratio mass spectrometry method for determination of stable carbon isotope ratios of water-soluble organic carbon in particulate matter.

Water-soluble organic carbon (WSOC) is formed by oxidation of organic compounds in particulate matter (PM) and accounts for 25-80% of the organic carbon in PM. Stable carbon isotope ratio (δ13 C) analysis is widely used to identify the sources of PM, but determining the δ13 C values of WSOC is complicated and requires a time-consuming pretreatment process. We have developed an online wet oxidation/isotope ratio mass spectrometry method with a reduced pretreatment time. We have measured the δ13 C values of WSOC by using this method. The method showed high accuracy (0.1‰) and precision (0.1‰) for levoglucosan, and the limit of detection was sufficiently low for WSOC analysis. Using this method, we determined δ13 C values of WSOC in PM2.5 samples collected in Japan during the period from July to November 2017 and found that the values ranged from -26.5‰ to -25.0‰ (average, -25.8‰). Our simple, low-blank method could be used for rapid quantitative analysis of the δ13 C values of WSOC in PM2.5 . We propose that this online method be used as a standard method for δ13 C analysis of WSOC.

Variability along the frontier: stable carbon and nitrogen isotope ratio analysis of human remains from the Late Roman–Early Byzantine cemetery site of Joan Planells, Ibiza, Spain

Carbon (δ13C) and nitrogen (δ15N) stable isotope analysis of human bone collagen from 38 individuals was undertaken to assess diet at the Late Roman–Early Byzantine (AD 300–700) cemetery site, Joan Planells, in Ibiza, Spain. The results (δ13C = − 18.7 ± 0.5‰ and δ15N = 10.1 ± 1.3‰) show that the diet of this population was derived predominantly from C3 terrestrial resources; plant foods were likely dietary staples along with meat and/or dairy produce comprising an important component of diet. Variation in stable isotope ratio values suggests individual differences in diet. Two individuals, both males, are statistical outliers with distinctive δ15N values (14.4 and 14.8‰) that point to significant consumption of marine resources. Females, on average, have higher δ13C values than males. The parsimonious explanation for this observation is the greater inclusion of C4 resources such as millet in the diets of females. Comparison of the diet of the Joan Planells population with other Late Roman period sites on the Hispanic mainland and other parts of the Mediterranean region suggests that populations may have been responding to a combination of socio-political and environmental factors that could have included Roman influence of food consumptive practices in some of these distant locales.

Pilot study for elucidating paleo diet by stable carbon and nitrogen isotope ratio analysis of charred residue of foods

Pilot study for elucidating paleo diet by stable carbon and nitrogen isotope ratio analysis of charred residue of foods

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.

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.

Differentiation of Pigment in Eggs Using Carbon ((13)C/(12)C) and Nitrogen ((15)N/(14)N) Stable Isotopes.

Consumers prefer natural and healthy food, but artificial pigments are often abused in egg products. The study aimed at differentiating the origin of pigments in eggs by applying the technique of carbon ((13)C/(12)C) and nitrogen ((15)N/(14)N) stable isotope analysis. Five hundred sixty laying hens were randomly distributed into 14 treatments, which were divided into four groups: maize, carophyll red pigment, carophyll yellow pigment, and a mixture of carophyll red and yellow pigments. Eggs were collected and pretreated to determe the values of the Roche Yolk Color Fan (RCF), δ(13)C, and δ(15)N. With increasing maize content, the RCF and δ(13)C values of yolks increased. Moreover, the RCF values in the three pigment groups were significantly influenced by the artificial colors, but δ(13)C values were not significantly different, regardless of the existence of pigment. The δ(15)N values in all treatments did not vary as regularly as the carbon stable isotope. A strong positive correlation was found between RCF and δ(13)C in the maize group, but no such correlation was be observed in the pigment groups. It is concluded that carbon stable isotope ratio analysis (δ(13)C) of the yolk can be used to differentiate the origin of the pigment added to eggs.

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.