The variations of the D/H and (18)O/(16)O ratios of nonexchangeable hydrogen and oxygen in plant cellulose reveal systematic differences between terrestrial plant groups. The slope of deltaD versus delta(18)O of cellulose from a variety of aquatic plants is close to 8 (the meteoric water value), while the slope for a number of terrestrial species is greater than or equal to about 24. Two models involving incorporation of CO(2) and H(2)O into cellulose precursors are proposed to account for these differences. Effects of evaporative transpiration on the isotopic composition of water in leaves are measured and discussed in the context of these models.

A peat core from a raised bog covering the period 3100 to 240014C years B.P. has been analysed for D/H and18O/16O ratios. These analyses were applied to cellulose, extracted from 56 successive layers of 1 cm thickness. D/H ratios were determined for the carbon bonded hydrogen; 18O/16O analyses were performed by applying a new method. For the interpretation of the results obtained on peat, the isotopic ratios of 11 living bog plant species were measured, showing a relatively large scatter. Most pronounced is a depletion in D of about 25‰ and in 18O of about 5‰ of the Sphagnummosses relative to the vascular bog plants. This different isotopic composition is reflected by the δD and δ18O records of the peat core, because the abundance of the remains of non-vascular plants is variable. If this effect is taken account of, the remaining δD variations appear to be too large to be attributed to variations in the isotopic compositions of precipitation. As palaeoclimatic indicators the D/H and 18O/16O ratio qualitatively agree with the pollen analytical evidence for the climatic deterioration of the Subboreal-Subatlantic transition.

The discovery of spatial patterns in naturally occurring isotopes (e.g., δ2H, δ13C) at continental scales has been tremendously important in providing a method to infer potential breeding and wintering origins of migratory animals through assignment to tissue-specific isoscapes. Single-isotope (i.e. δ2H) assignments of birds to molting origins in South America have been limited by the lack of strong spatial gradients in precipitation δ2H there. We integrated an mvnpdf (multivariate normal probability density function) approach using δ2H and δ13C values in tail feathers to determine wintering origins of adult Barn Swallows (Hirundo rustica) breeding in eastern Canada (n = 208). Spatial assignments were conducted using precipitation (δ2H) and theoretical plant-based (δ13C) isoscapes for South America calibrated for feathers of Nearctic–Neotropical migrant songbirds. We also measured feather δ34S values of Barn Swallows equipped with geolocators (n = 9) and of a larger group of Barn Swallows (n = 12...

Hydrogen isotope (δ2H) measurements of consumer tissues in aquatic food webs are useful tracers of diet and provenance and may be combined with δ13C and δ15N analyses to evaluate complex trophic relationships in aquatic systems. However, δ2H measurements of organic tissues are complicated by analytical issues (e.g., H exchangeability, lack of matrix-equivalent calibration standards, and lipid effects) and physiological mechanisms, such as H isotopic exchange with ambient water during protein synthesis and the influence of metabolic water. In this study, δ2H (and δ15N) values were obtained from fish muscle samples from Lake Winnipeg, Canada, 2007–2010, and were assessed for the effects of species, feeding habits, and ambient water δ2H values. After lipid removal, we used comparative equilibration to calibrate muscle δ2H values to nonexchangeable δ2H equivalents and controlled for H isotopic exchange between sample and laboratory ambient water vapor. We then examined the data for evidence of trophic δ2H enrichment by comparing δ2H values with δ15N values. Our results showed a significant logarithmic correlation between fork length and δ2H values, and no strong relationships between δ15N and δ2H. This suggests the so-called apparent trophic compounding effect and the influence of metabolic water into tissue H were the potential mechanisms for δ2H enrichment. We evaluated the importance of water in controlling δ2H values of fish tissues and, consequently, the potential of H isotopes as a tracer of provenance by taking account of confounding variables such as body size and trophic effects. The δ2H values of fish appear to be a good tracer for tracking provenance, and we present a protocol for the use of H isotopes in aquatic ecosystems, which should be applicable to a broad range of marine and freshwater fish species. We advise assessing size effects or working with fish of relatively similar mass when inferring fish movements using δ2H measurements.