Author: paleololigo

X is for Xenarthra

The Xenarthra is a group of mammals known for a “strange joint” (what ‘xenarthra’ roughly translates to) in their vertebral column. Xenarthrans include sloths and armadillos, and the extinct giant ground sloths and massive armored glyptodonts.

That some sloths were massive leads scientists to question what made up the diet of these giant mammals. There is evidence that most giant sloths were herbivores, but there are some characteristics that suggest that at least some giant sloths could have been carrion feeders or even active hunters. Bochrens et al. (2017) use stable isotopes to address this question. Continue reading “X is for Xenarthra #AtoZChallenge” →

W is for Wax

Leaves tend to cover themselves with wax to prevent water loss. This is convenient for us, because leaf waxes are often preserved in rocks. Analyses of these waxes can provide isotopic values for carbon, which can tell us about the plants present and general information about paleoenvironments. With specialized extractions, hydrogen isotopes from leaf waxes can provide important information about water availability in past environments. Continue reading “W is for Wax #AtoZChallenge” →

V is for Vienna

Vienna, Austria is the home of the International Atomic Energy Agency (IAEA). The IAEA is the organization which determines the values of and distributes international isotopic reference materials such as SMOW and NBS-19. Continue reading “V is for Vienna #AtoZChallenge” →

U is for Uranium

Uranium is known best for its radioactive isotopes. As scientists working with stable isotopes – and light ones at that – we regularly grapple with the misconception that anything called an “isotope” is radioactive and is a potential component of dirty bombs. Continue reading “U is for Uranium #AtoZChallenge” →

T is for Temperature

In stable isotopes, there are lots of implications for the word ‘temperature.’ For one, we can use isotopes of oxygen, and oxygen plus carbon, to estimate the temperature at which an analyzed compound formed. Temperature could also refer to the temperature at which we react a sample during its analysis, whether it be room temperature or 1450 °C.

One of the original uses for the study of isotopes was to determine the past temperature of the ocean. A relationship between δ¹⁸O and water temperature was developed, and the shells of tiny, single-celled organisms were perfect for these analyses. Today, we have refined these methods, and have a much better understanding of the complexity of the relationship between δ¹⁸O and temperature.

S is for Sulfur

Sulfur is an element that can be particularly challenging to measure. Most labs have a dedicated instrument for its analysis because sulfur is known to be ‘sticky.’ That is, it tends to stay in the mass spectrometer and affect analysis of other elements later, so it’s not something that you just randomly measure and then go back to day-to-day work.

Sulfur isotopes are useful for understanding the origins of sulfide ore deposits, whether bacterial activity resulted in the growth of sulfide minerals, or if it came from some igneous activity deep within the Earth. Sulfur is also useful for tracking pollution in ecosystems, as the sulfur in acid rain may have a distinctive isotopic signature.

R is for Reference Materials

Reference Materials, usually referred to as standards, are materials (powders, liquids, or gasses) of known isotopic value. All stable isotope labs globally use the same reference materials, so that we can all compare our data. Continue reading “R is for Reference Materials #AtoZChallenge” →