Global application of stable hydrogen and oxygen isotopes to wildlife forensics

Abstract

Stable isotopes are being increasingly used in wildlife forensics as means of determining the origin and movement of animals. The heavy isotope content of precipitated water and snow (deltaD(p), delta(18)O(p)) varies widely and systematically across the globe, providing a label that is incorporated through diet into animal tissue. As a result, these isotopes are potentially ideal tracers of geographic origin. The hydrogen and oxygen isotope tracer method has excellent potential where (1) spatial variation of precipitation isotopes exist, and (2) strong, mechanistic relationships link precipitation and isotope ratios in biological tissue. Here, we present a method for interpolation of precipitation isotope values and use it to create global basemaps of growing-season (GS) and mean annual (MA) deltaD(p) and delta(18)O(p). The use of these maps for forensic application is demonstrated using previously published isotope data for bird feathers (deltaD(f)) in North America and Europe. The precipitation maps show that the greatest potential for applying hydrogen and oxygen isotope forensics exists in mid- to high-latitude continental regions, where strong spatial isotope gradients exist. We demonstrate that deltaD(f)/deltaD(p) relationships have significant predictive power both in North America and Europe, and show how zones of confidence for the assignment of origin can be described using these predictive relationships. Our analysis focuses on wildlife forensics, but the maps and approaches presented here will be equally applicable to criminal forensic studies involving biological materials. These maps are available in GIS format at http://www.waterisotopes.org.

Tracking human travel using stable oxygen and hydrogen isotope analyses of hair and urine

“…[1][2][3] Many of these studies take advantage of the large-scale continental gradients in the stable hydrogen and oxygen isotope composition of meteoric water. Generally, precipitation in locations at higher latitudes is depleted in both 18 O and 2 H(D) compared with lower latitudes, [4][5][6] although topography and other factors can also influence the d 18 O and dD values of precipitation.…”

“…17,18,22 In animal populations it is generally assumed that animals and the plants or animals that they eat draw on similar sources of water; thus, the d 18 O and dD values of an animal's diet and drinking water should vary in parallel. 1,2,18 However, when an animal's diet includes items expected to have dissimilar d 18 O and dD values from drinking water (e.g. a high latitude terrestrial animal with a marine dietary component), this assumption may not be correct (as others have noted 18 ).…”

“…17 Studies of this type could find a wide variety of forensic applications; for example, establishing the likelihood of reported travel or location of origin. 1,17 Studies using organic d 18 O and dD values to track the movements of modern humans are required to consider the multiple sources of oxygen and hydrogen to nail and hair tissue, and the kinetics by which oxygen and hydrogen isotope signatures change. In many human populations foods are non-locally grown and may derive from a huge range of geographical origins (e.g.…”

Reconstructing seasonality using d18O in incremental layers of human enamel: a test of the analytical protocol developed for SHRIMP IIe/MC ion microprobe

“…How ever, the pat tern of d 18 O de tected in EM 25, 2.1 and 10.1 teeth from Tell Majnuna is roughly con sis tent with de fined seasonal fluc tu a tions ex pected in the area of semi-arid steppe climate in north east ern Syria (Hassaka), where strong an nual fluctu a tions in pre cip i ta tion are typ i cal (Bowen et al, 2005;Bowen, 2015), but ad di tional ir reg u lar i ties of the pat tern have also been rec og nized. It dem on strates a va lid ity of SIMS meth od ol ogy of ox y gen data col lec tion.…”

Multiple isotope forensics of nitrate in a wild horse poisoning incident

“…The ability to measure isotope ratios of more than one element in a single molecule (multiple isotope approach) allows refinement of stable isotope fingerprinting, and the more isotopes that can be measured, the more confidence in the identification of characteristics unique to the compound [1,3]. This technique has been employed to identify unique characteristics of a range of materials used in forensic investigations including explosives [4][5][6], drugs [7][8][9], and geochemical evidence [10][11][12]. This article details a study of the use of stable isotopes of nitrogen and oxygen to test several nitrate source hypotheses in the death of 71 wild horses.…”