D is for Delta #AtoZChallenge

Delta values are how we report the relative amounts of the different isotopes of a single element. For example δ13C (said delta-thirteen-see) provides a measure of the relative amounts of carbon-13 and carbon-12 in a material.

The “delta notation” or delta value used in stable isotope geochemistry is often confusing, especially to people outside of the science trying to understand our work. It’s confusing because these delta values are reported in “permil” (‰) which is often interpreted as a concentration like percent (%). But the permil in the delta notation is not a concentration at all, which becomes a little more clear when we realize that delta values can be negative, but concentrations cannot. (You can’t buy lemonade that -15% lemon juice!) Continue reading “D is for Delta #AtoZChallenge”

C is for Carbon #AtoZChallenge

Isotopes of carbon can be used to interpret available vegetation and diet of ancient ecosystems and individual animals.

Carbon has two stable isotopes, carbon-12 and carbon-13. Carbon also has a rare radioactive isotope, carbon-14, which is used for assigning ages to objects less than 40,000 years old. At SIREAL, we don’t have the capability to measure carbon-14, which is fine because “stable isotopes” is part of our name. Continue reading “C is for Carbon #AtoZChallenge”

B is for Bioapatite #AtoZChallenge

Bioapatite is the mineral component of bones and teeth.

Apatite is a general term for a group of minerals made of calcium phosphate. Different apatite minerals have differing amounts of other elements and atomic groups like fluorine (-F), hydroxyl (-OH), and carbonate (-CO3). Bones and teeth are composed of tiny crystallites of minerals in the apatite mineral group. For simplicity, we just refer to any apatite mineral in bones and teeth as bioapatite, so we don’t have to argue about what the precise composition of the apatite mineral is. Continue reading “B is for Bioapatite #AtoZChallenge”

A is for Amount Effect #AtoZChallenge

The “Amount Effect” is a phenomenon observed in the stable isotope composition of rain water related to how much rain has fallen.

Water is composed of the elements of hydrogen and oxygen. Hydrogen has two stable isotopes, 1H (hydrogen, most abundant) and 2H (deuterium). Oxygen has several stable isotopes, the most abundant being 16O (common) and 18O (rarer). As a body of water (like an ocean or a lake) evaporates, water composed of the lighter isotopes of hydrogen and/or oxygen evaporates first. The result is that clouds (water vapor in the air) is isotopically ‘lighter’ than the original body of water, and the lake or ocean becomes isotopically ‘heavy’. How much heavier the lake becomes depends upon the air temperature. And it’s the lake water that is consumed by animals and goes into forming minerals that we can analyze. Continue reading “A is for Amount Effect #AtoZChallenge”

SIREAL is blogging from A to Z

The Blogging from A to Z challenge is an event each April in which bloggers worldwide prepare 26 posts – one for each letter of the English alphabet – and present them over the course of the month.

SIREAL (Stable Isotopes Ratios in the Environment, Analytical Laboratory) is joining the fun through their manager, Penny, who has participated in the Blogging from A to Z challenge many years in the past. Our posts will be mirrored on her blog over at Scroll to the end to see her A to Z themes.

The A to Z posts by SIREAL will all relate to terms, methods, and scientific results from the analysis of light stable isotopes from natural materials.

Since “Isotope” isn’t a term that will turn up right away, we will quickly define it here: Continue reading “SIREAL is blogging from A to Z”

Mass Spectrographs and the Birth of Stable Isotope Geochemistry

Originally published January 7, 2016 on by Penny Higgins:

I’ve been working on a little project that has required me to dig a little into the history of stable isotope geochemistry. Today I learned about the first mass spectrometers. I’ve found the results interesting and thought I might share them here. This is research in progress…

The First Mass Spectrographs Continue reading “Mass Spectrographs and the Birth of Stable Isotope Geochemistry”

From the Archives – Lake Effect Snow – An Isotopic Study: Some Results

Originally published February 13, 2013 on by Penny Higgins:

A while ago, I proposed an experiment in which I collected snow at regular intervals during a Lake Effect Snow event. I made some predictions and collected the snow, and have now finally succeeded in analyzing the waters. The results weren’t quite what I expected.

I had predicted that isotopic values in the snow would not change over the course of the event. This was because all the snow would be forming directly off the lake, which is only a few miles away from the collection point. (This is in contrast to other synoptic storms, where we have precipitation coming from a single vapor mass, which will evolve isotopically over time. Read more about that here.) The temperature of the lake water, and its isotopic value would not change consequentially over the course of such a short event.

What I saw instead was an increase isotopic values overnight, and then a decrease the next day.

Results from January 22-23 Lake Effect Snow Event
Results from January 22-23 Lake Effect Snow Event. Click to enlarge.

Continue reading “From the Archives – Lake Effect Snow – An Isotopic Study: Some Results”

From the Archives – An Isotopic Study of Lake Effect Snow

First published January 19, 2013 at by Penny Higgins:

I’ve written a few blog posts about what can be done with isotopes from precipitation, and how that might assist us in understanding how to interpret isotopic data collected from ancient rocks and fossils. (Look here and here.) As I live here in western New York state, close to Lake Ontario, I frequently have opportunities to further study how the isotopes from precipitation (in this case Lake Effect snow) are related to the isotopes of the water that originally evaporated to make the clouds that do all the snowing.

Right now, we’re looking at a Lake Effect snow event that’s due to start sometime tomorrow, so I’m throwing together is quick and fun isotopic study that I’ll share with you when the data come in. I’ll describe it here.

As review, let’s think about isotopes in water. First, what do I mean by isotopes? The term worries people, because they immediately think of radioactive isotopes and OMG, we’re gonna die! No, it’s not like that. The word isotope just refers to the fact that some atoms of the same element are heavier or lighter than the others. Continue reading “From the Archives – An Isotopic Study of Lake Effect Snow”

Introducing SIREAL online

SIREAL has been a functioning laboratory since the spring of 2005. We wish to expand our services beyond the walls of the University of Rochester, particularly to reach scientists and other interested scholars to help improve the overall understanding of stable isotopes and their importance in understanding the world around us.

Good company in a journey makes the way seem shorter. — Izaak Walton