Natural abundance of stable carbon and nitrogen isotopes in Cannabis sativa reflects growth conditions

Stable carbon and nitrogen isotope signatures (delta C-13 and delta N-15) of Cannabis sativa were assessed for their usefulness to trace seized Cannabis leaves to the country of origin and to source crops by determining how isotope signatures relate to plant growth conditions. The isotopic composition of Cannabis examined here covered nearly the entire range of values reported for terrestrial C-3 plants. The delta C-13 values of Cannabis from Australia, Papua New Guinea and Thailand ranged from -36 to -25 parts per thousand, and delta N-15 values ranged from -1.0 to 15.8 parts per thousand. The stable isotope content did not allow differentiation between Cannabis originating from the three countries, but delta C-13 values of plantation-grown Cannabis differed between well-watered plants (average delta C-13 of -30.0 parts per thousand) and plants that had received little irrigation (average delta C-13 of -26.4 parts per thousand). Cannabis grown under controlled conditions had delta C-13 values of -32.6 and -30.6 parts per thousand with high and low water supply, respectively. These results indicate that water availability determines leaf C-13 in plants grown under similar conditions of light, temperature and air humidity. The delta C-13 values also distinguished between indoor- and outdoor-grown Cannabis; indoor- grown plants had overall more negative delta C-13 values (average -31.8 parts per thousand) than outdoor-grown plants (average -27.9 parts per thousand). Contributing to the strong C-13-depletion of indoor- grown plants may be high relative humidity, poor ventilation and recycling of C-13-depleted respired CO2. Mineral fertilizers had mostly lower delta N-15 values (-0.2 to 2.2 parts per thousand) than manure-based fertilizers (7.6 to 22.7 parts per thousand). It was possible to link delta N-15 values of fertilizers associated with a crop site to soil and plant delta N-15 values. The strong relationship between soil, fertilizer, and plant delta N-15 suggests that Cannabis delta N-15 is determined by the isotopic composition of the nitrogen source. The distinct delta N-15 values measured in Cannabis crops make delta N-15 an excellent tool for matching seized Cannabis with a source crop. A case study is presented that demonstrates how delta C-13 and delta N-15 values can be used as a forensic tool.

Reliability of stable carbon and oxygen isotope compositions of pedogenic needle fibre calcite as environmental indicators: examples from Western Europe.

Stable carbon and oxygen isotope analyses were conducted on pedogenic needle fibre calcite (NFC) from seven sites in areas with roughly similar temperate climates in Western Europe, including the Swiss Jura Mountains, eastern and southern France, northern Wales, and north-eastern Spain. The δ(13)C values (-12.5 to-6.8 0/00 Vienna Pee Dee Belemnite (VPDB)) record the predominant C(3) vegetation cover at the sites. A good correlation was found between mean monthly climatic parameters (air temperature, number of frost days, humidity, and precipitation) and δ(18)O values (-7.8 to-3.40/00 VPDB) of all the NFC. Similar seasonal variations of δ(18)O values for monthly NFC samples from the Swiss sites and those of mean monthly δ(18)O values of local precipitation and meteorological data point out precipitation and preferential growth/or recrystallisation of the pedogenic needle calcite during dry seasons. These covariations indicate the potential of stable isotope compositions of preserved NFC in fossil soil horizons as a promising tool for palaeoenvironmental reconstructions.

Stable carbon isotope composition of perirenal adipose tissue fatty acids from Engadine sheep grazing either mountain or lowland pasture

To provide further insights into ruminant lipid digestion and metabolism, and into cis9, trans-11 18:2 synthesis, 12 growing Engadine lambs grazing either mountain pasture (2,250 m above sea level; n = 6) or lowland pasture (400 m above sea level; n = 6) were studied. Both pastures consisted exclusively of C-3 plants. Before the experiment, all animals grazed a common pasture for 6 wk. Grasses and perirenal adipose tissues of the sheep were analyzed for fatty acids by gas chromatography. Stable C-isotope ratios (delta C-13 values in % vs. the Vienna Pee Dee Belemnite standard) were determined in the composite samples by elemental analysis-isotope ratio mass spectrometry. The delta C-13 of the individual fatty acids were measured by gas chromatography-combustion-isotope ratio mass spectrometry. The delta C-13 value of the entire mountain pasture grass was -27.5% (SD 0.31), whereas that of the lowland pasture grass was -30.0% (SD 0.07). This difference was reflected in the perirenal adipose tissues of the corresponding sheep (P < 0.05), even though the delta C-13 values were less in the animals than in the grass. The delta C-13 values for cis-9 16:1 and cis-9 18:1 in perirenal fat differed between mountain and lowland lambs (P < 0.05). The 16:0 in the adipose tissue was enriched in C-13 by 5% compared with the dietary 16:0, likely as a result of partly endogenous synthesis. The d13C values of cis-9, trans-11 18:2 (cis-9, trans-11 CLA) in the adipose tissue were smaller than those of its dietary precursors, cis-9, cis-12 18:2 and cis-9, cis-12, cis-15 18:3; conversely, the delta C-13 values of trans-11 18:1 were not, suggesting that large proportions of perirenal cis-9, trans-11 18:2 were of endogenous origin and discrimination against C-13 occurred during Delta(9)-desaturation. The same discrimination was indicated by the isotopic shift between 16:0 and cis-9 16:1 in the mountain grazing group. Furthermore, the delta C-13 values of cis-9, trans-11 18:2 were smaller relative to the precursor fatty acids in the mountain lambs compared with the lowland group. This result suggests a reduced extent of biohydrogenation in lambs grazing on mountain grass in comparison with those grazing on lowland grass. This was supported by the smaller cis-9, trans-11 18:2 concentrations in total fatty acids found in the adipose tissues of the lowland lambs (P < 0.001). The results of this study demonstrate that natural differences between delta C-13 values of swards from different pastures and the adipose tissue fatty acids could be used as tracers in studies of lipid metabolism in ruminants.

Stable carbon isotope Composition of c9,t11-conjugated linoleic acid in cow's milk as related to dietary fatty acids

This study explores the potential use of stable carbon isotope ratios (delta C-13) of single fatty acids (FA) as tracers for the transformation of FA from diet to milk, with focus on the metabolic origin of c9,t11-18:2. For this purpose, dairy cows were fed diets based exclusively on C-3 and C-4 plants. The FA in milk and feed were fractionated by silver-ion thin-layer chromatography and analyzed for their delta C-13 values. Mean delta C-13 values of FA from C-3 milk were lower compared to those from C-4 milk (-30.1aEuro degrees vs. -24.9aEuro degrees, respectively). In both groups the most negative delta C-13 values of all FA analyzed were measured for c9,t11-18:2 (C-3 milk = -37.0 +/- A 2.7aEuro degrees; C-4 milk -31.4 +/- A 1.4aEuro degrees). Compared to the dietary precursors 18:2n-6 and 18:3n-3, no significant C-13-depletion was measured in t11-18:1. This suggests that the delta C-13-change in c9,t11-18:2 did not originate from the microbial biohydrogenation in the rumen, but most probably from endogenous desaturation of t11-18:1. It appears that the natural delta C-13 differences in some dietary FA are at least partly preserved in milk FA. Therefore, carbon isotope analyses of individual FA could be useful for studying metabolic transformation processes in ruminants.

Stable carbon isotopes in archaeobotanical remains and palaeoclimate

Es descriu una metodologia recent per a inferir la precipitació en el passat basada en l’anàlisi de la composició isotòpica del carboni (δ13C) en restes arqueobotàniques. Un cop descrita la base fisiològica de la tècnica, s’il·lustra l’aplicabilitat de δ13C mitjançant un exemple referent al NE peninsular. Hom pretén proporcionar una estimació quantitativa de l’evolució de la precipitació estacional (primavera) i anual al llarg dels darrers quatre mil anys basada en δ13C. Les mostres analitzades comprenen carbons (pi blanc) i llavors carbonitzades (blat i ordi), i s’obtenen estimes pluviomètriques superiors en el passat que actualment, amb una tendència gradual cap a condicions progressivament més àrides. No obstant això, aquesta tendència no esdevé uniforme, i es detecten dues fases de major precipitació (1800-900 aC; 300 aC - 300 dC) alternadament amb períodes relativament secs (900-300 aC; 900 dC - present). Dels resultats presentats també es desprèn que la importància relativa de la pluja primaveral en el passat fou variable. Des d’aproximadament el 300 aC en endavant, el període primaveral subministrà una major proporció de pluja anual que actualment. Contràriament, durant el període 1800-800 dC la seva contribució va esdevenir inferior, i va aparèixer una fase transitòria (800-300 aC) que mostra una recuperació sobtada en aportació primaveral. Posteriorment a aquesta fase la sincronia de canvis en δ13C en granes i carbons suggereix l’arribada del clima mediterrani a la regió.

The traceability of animal meals in layer diets as detected by stable carbon and nitrogen isotope analyses of eggs

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Stable carbon (delta(13)C) and nitrogen (delta(15)N) isotopes as natural indicators of live and dry food in Piaractus mesopotamicus (Holmberg, 1887) larval tissue

This study proposed the use of the stable isotope technique to track the type of food utilized by pacu Piaractus mesopotamicus larvae during their development, and to identify the moment when the larvae start using nutrients from the dry diet by retaining its carbon and nitrogen atoms in their body tissues. Five-day-old pacu larvae at the onset of exogenous feeding were fed Artemia nauplii or formulated diet exclusively; nauplii+formulated diet during the entire period; or were weaned from nauplii to a dry diet after 3, 6 or 12 days after the first feeding. delta(13)C and delta(15)N values for Artemia nauplii were -15.1 parts per thousand and 4.7 parts per thousand, respectively, and -25.0 parts per thousand and 7.4 parts per thousand for the dry diet. The initial isotopic composition of the larval tissue was -20.2 parts per thousand and 9.5 parts per thousand for delta(13)C and delta(15)N respectively. Later, at the end of a 42-day feeding period, larvae fed Artemia nauplii alone reached values of -12.7 parts per thousand and 7.0 parts per thousand for delta(13)C and delta(15)N respectively. Larvae that received the formulated diet alone showed values of -22.7 parts per thousand for delta(13)C and 9.6 parts per thousand for delta(15)N. The stable isotope technique was precise, and the time at which the larvae utilized Artemia nauplii, and later dry diet as a food source could be clearly defined.

Poultry offal meal traceability in meat quail tissues using the technique of stable carbon (13C/12C) and nitrogen (15N/14N) isotopes

Studies on the detection of animal by-products in poultry meat are rare, and non-existent on quail meat. This study aimed at detectiong increasing levels of poultry offal meal (POM) in quail meat, using carbon (13C/12C) and nitrogen (15N/14N) stable isotopes technique. Sixty four on-day-old male quails derived from a commercial farm were randomly distributed into seven different groups, which were fed experimental diets containing 0, 1.5, 3.0, 4.5, 6.0, 7.5, and 15% of POM. Diets were formulated to contain equal energy, protein, and amino acid levels. Four individuals per treatment were sacrificed at 42 days of age for breast muscle (Pectoralis major), keel, and tibia collection, which were subsequently submitted to analyses. Isotopic δ13C and δ15N enrichment was observed in all analyzed tissues, with the lowest detection level of 3% dietary inclusion of poultry offal meal.

Modelling and determination of metabolic pools by stable carbon isotopes in the avian duodenal mucosa and albumen

Stable isotope analyses have helped in assessing dietary switches if the diet undergoes metabolic alteration (isotopic exchange). However, when considering the effects over time of switching from one diet to another, one can assess how quickly the new diet is incorporated into tissues via the isotopic renewal or incorporation rate, or turnover. Turnover is obtained using exponential curves that fit the original data, allowing the determination of practical order parameters such as the half-life (T) and the turnover constant (k). Researchers have found that metabolic incorporation can be fractionated. The resulting fractions, called metabolic pools, are identified using the linearization of the isotopic exchange model and its linear fit. This fractionation methodology is still not well defined. The objective of this study was to assess the behaviour of the metabolic renewal rate (turnover) in fractionated form, explain the theory, and apply it to data from the avian duodenal mucosa and albumen. We concluded that the duodenal mucosa has one metabolic pool, with a half-life of 1.23 days, and that the albumen has two metabolic pools, with half-lives of 1.89 and 6.32 days.

A reconstruction of atmospheric carbon dioxide and its stable carbon isotopic composition from the penultimate glacial maximum to the last glacial inception

The reconstruction of the stable carbon isotope evolution in atmospheric CO2 (δ13Catm), as archived in Antarctic ice cores, bears the potential to disentangle the contributions of the different carbon cycle fluxes causing past CO2 variations. Here we present a new record of δ13Catm before, during and after the Marine Isotope Stage 5.5 (155 000 to 105 000 yr BP). The dataset is archived on the data repository PANGEA® (www.pangea.de) under 10.1594/PANGAEA.817041. The record was derived with a well established sublimation method using ice from the EPICA Dome C (EDC) and the Talos Dome ice cores in East Antarctica. We find a 0.4‰ shift to heavier values between the mean δ13Catm level in the Penultimate (~ 140 000 yr BP) and Last Glacial Maximum (~ 22 000 yr BP), which can be explained by either (i) changes in the isotopic composition or (ii) intensity of the carbon input fluxes to the combined ocean/atmosphere carbon reservoir or (iii) by long-term peat buildup. Our isotopic data suggest that the carbon cycle evolution along Termination II and the subsequent interglacial was controlled by essentially the same processes as during the last 24 000 yr, but with different phasing and magnitudes. Furthermore, a 5000 yr lag in the CO2 decline relative to EDC temperatures is confirmed during the glacial inception at the end of MIS5.5 (120 000 yr BP). Based on our isotopic data this lag can be explained by terrestrial carbon release and carbonate compensation.

Social stratigraphy in Late Iron Age Switzerland: Stable carbon, nitrogen and sulphur isotope analysis of human remains from Münsingen

The Iron Age cemetery of Münsingen in Switzerland with 220 abundantly equipped burials marked a milestone for Iron Age research. The horizontal spread throughout the time of its occupancy laid the foundation for the chronology system of the Late Iron Age. Today, skulls of 77 individuals and some postcranial bones are still preserved. The aim of the study was to obtain information about diet, mobility and social stratification of the individuals. Stable isotope ratios of carbon, nitrogen and sulphur were analysed for 63 individuals. For all of them C3 plants were found to be the staple food. There are significant differences between males and females in δ13C and δ15N values. This points to a gender restriction in the access to animal protein with males probably having more access to meat and dairy products. Differences in δ15N values were also observed for different age classes. δ34S values indicate a terrestrial-based diet with no significant intake of marine or freshwater fish. Seven adults with enriched δ34S values might have immigrated to Münsingen, four of which were found in the oldest part of the cemetery. Furthermore, possible changes of the vegetation are indicated by the more positive stable carbon ratios in the later phases. The results lead to the suggestion that especially males buried with weapons might have played a special role in the Iron Age society.