1. The Use of Isotope Geochemistry in Forensic Geology
Radioactive Isotopes
Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University

2. Nucleus of the Atom Contains protons and neutrons
Contains most of the mass of the atom (determined mostly by protons and neutrons)
Electrons are distributed around the nucleus in shells and orbitals

3. Neutrons
Third major subatomic particle discovered (1932 James Chadwick)
No charge (neutral)
Relative Mass of 1 AMU (1.675 x g)

4. Isotopes
While atoms of the same element have the same atomic number (# of protons) they may have different numbers of neutrons
Creates different isotopes of same elements
Isotopes are atoms of the same element having different masses

5. Nuclide Symbols

6. Nuclide Symbols

7. Natural Isotopes Every element has naturally occurring isotopes
Hydrogen has 3 naturally occurring isotopes
Protium is the most abundant isotope of hydrogen (99.985%) has 1 proton, 0 neutrons, and 1 electron

8. Natural Isotopes
Deuterium (0.015%) has 1 proton, 1 neutron, and 1 electron
Tritium (0.0001% ?) has 1 proton, 2 neutrons, and 1 electron

11. Isotopes Two Categories
Unstable – isotopes that continuously and spontaneously break down/decay in other lower atomic weight isotopes
Stable – isotopes that do not naturally decay but can exist in natural materials in differing proportions

20. Geologic Time
Absolute or Radiometric Date - Finds age of object in years before present based on an absolute scale derived from radioactive isotopes

21. Geologic Time Parent Daughter half-life (y) U-238 Lead-206 4.5 billion
Radioactive Isotopes used in Geologic Dating
Parent Daughter half-life (y)
U-238 Lead billion
U-235 Lead million
Thorium 232 Lead Billion
K-40 Argon billion
Rb-87 Sr billion
C-14 N
Half-life = time it takes for 1/2 of the parent mass to decay into the daughter mass

22. Geologic Time Carbon 14 Dating
A cosmic ray neutron (n) collides with an atom of atmospheric Nitrogen (14N) which decays into 14C and hydrogen (p=proton)
14N + n => 14C + Hydrogen (proton)
14C is rapidly oxidized to 14CO2 which is continuously taken up into living organisms

23. Geologic Time Carbon 14 Dating
When the organism dies it stops taking in 14C which disappears as it decays to 14N
14C => 14N + Beta (beta comes from a neutron going to a proton)

25. Geologic Time 14Carbon Dating
Dating is accomplished by determining the ratio of 14C to non-radioactive 12C which is constant in living organisms but changes after the organism dies

28. Forensic 14Carbon Cases Dead Sea Scrolls – 5-150 AD
Stonehenge – 3100 BC
Hezekiah’s Tunnel BC

29. Forensic 14Carbon Cases ● Cave painting at Lascaux, France
● King Arthur’s Table in Winchester Castle, England 14C dated to 13th century AD
● Cave painting at Lascaux, France
14C dated to 14,000 BC
● Rhind Papyrus on Egyptian math 14C dated to 1850 BC

30. Forensic 14Carbon Cases 14C dated 1260-1390 AD
● The Shroud of Turin was
14C dated AD
which suggests that it is a fake
● However, recent evaluation
shows that the sample measured
was from a medieval patch and/or
that it was seriously contaminated
with molds, waxes, etc
●New estimates date the shroud from
ybp bases on vanillin
retention

31. Forensic 14Carbon Cases
Nuclear testing during put large amounts of 14C into the atmosphere which was incorporated into the enamel of human teeth. Because such testing stopped the 14C input ended and the 14C in the teeth decayed at a fixed rate allowing dating of the teeth

32. Let’s start with exercise 1 C-14 Dating (using M&Ms)
When you finish with your M&M / C-14 analysis, please come to the front of the classroom and enter your data on the spreadsheet provided.
You will also need to access the Calculating C-14 Ages spreadsheet available on the class webpage.

33. The Use of Isotope Geochemistry in Forensic Geology
Stable Isotopes
Modified from a PowerPoint presentation prepared by J. Crelling, Southern Illinois University

34. Stable Isotopes

36. Stable Isotopes Notation R: “ratio” R = heavyElement / lightElement
i.e. for Carbon:
13C / 12C

37. Stable Isotopes

38. Stable Isotopes

42. Stable Isotopes

43. d13C depends on enzyme pathway

45. Forensic Stable Isotope Cases
In 1980 there was a large (80,000gal) gasoline spill from a service station
Unusual large amounts of methane off gasses were found
Borings showed the area was underlain by lake sediments and sawdust
dD (methane) plotted against d13C showed that the methane was coming from the sawdust and not the gasoline.

48. Forensic Stable Isotope Cases
Oil spills were found at an industrial facility where crude oil was stored
Natural seeps of oil and gas were also present as well as numerous pipelines
Large amounts of hydrocarbons, CO2, CH4, H2 were present in the soil
dD (methane) plotted against d13C (methane) showed that the methane was coming from microbial fermentation

49. Forensic Stable Isotope Cases
Isotope Geochemistry of Beer
When plants convert CO2 into sugars by photosynthesis They use two different processes yielding sugars with 3 carbon atoms (C3 plants) and 4 carbon atoms (C4) plants
C3 plants are barley, rice, etc.
C4 plants are corn, cane sugar, etc.
Each plant leaves its isotopic signatures in the resulting beer

52. You Are What You Eat & Drink
The isotopic content of both food and water vary from place to place
People and animals eating and drinking in different places take on the isotopic signatures of their environment
Your travel history is in your hair, teeth, bones, etc.
IF and only if you buy locally grown produce.

53. Isotopic Composition of Water in the USA

54. The Iceman – A Cold Case
Death (murder?) in the Tyrolean Alps
Application of geological and biological forensic science

55. Location of the Body
Location and general view of the discovery site.

57. 23 September 1991. Recovery of the Tyrolean Iceman (Ötzi).

58. Not knowing the importance of the find, parts of the corpse have been damaged before and during recovery.

59. The Iceman was stored in a freezer at the University of Innsbruch, Austria.

60. The Iceman’s survival kit: a flint stone knife and a copper ax.

61. Arrow heads of flint stone, unfinished arrows, and a deerskin quiver.

62. Ötzi (the Iceman)
What can we learn about his life and death from his remains?
An exercise in geological and biological forensic science.

63. How did Ötzi perish?

64. Preparing Ötzi for a CAT scan.

65. Physical evidence
An arrowhead was found embedded in his left shoulder.
There was a cut in the palm of his right hand and into two of his fingers, damaging the tendons. It was inferred that he was holding a blade.

66. DNA Tests Suggest Ötzi Died After Violent Fight But Not Alone
DNA tests conducted by molecular biologist Thomas Loy and his team (from the University of Queensland's Institute of Molecular Bioscience in Brisbane).
During their investigation they saw signs of trauma to Ötzi's body, including bruises (and cuts) on his abdomen (especially on his rib area), which (they concluded) indicates that he may have been beaten.
Samples were taken from the Iceman's antler-skinning tool, his stone-tipped knife, two of his arrows (one broken), his axe handle, and his goatskin coat. Using techniques devised especially for ancient DNA, the team found four different DNA sequences: one on the knife blade, two different sequences on one arrow, and a fourth on Ötzi's goatskin coat. (They also found a small tear in the coat which may have been the entry point of the arrowhead that was found embedded in his shoulder.) 
They interpreted these findings in this way: 
1.The two different blood samples on the arrow may indicate that Ötzi killed two of his assailants and retrieved the arrow to use again.
2. The blood on his coat may indicate that Ötzi carried a wounded friend on his shoulder for some distance.
According to Dr. Loy "On the basis of all my examinations, [Ötzi's] specialty was hunting the high alpine passes for ibex and possibly chamois which would have taken him into boundary conditions where other people would have disputed the territory. His gear was stacked up neatly. He didn't keel over, although he was probably tired, exhausted and hurt like hell." 

67. An Application of C-14 Dating
When did Ötzi die?
An Application of C-14 Dating

68. Where did Ötzi live?

69. Biological evidence
Three grains of Ostrya carpinifolia (Hophornbeam) pollen magnified 1600x.
The majority of the pollen came from the hop hornbeam tree, which grows in a warm environment. The hop hornbeam tree blooms between March and June, and because the sperm inside the pollen grain, which normally decays after a short exposure to air or water, was still intact, it had to have been absorbed relatively soon after its release from the tree. The nearest stands of that tree could have grown to the south of the Hauslabjoch, at least five or six hours away by foot. The high valleys to the north are just too cold to sustain it.
Wheat spiklets derived from Einkorn grain, stuck to the Iceman's clothing. The same material was found in the iceman’s intestine indicating that he had eaten a hard bread shortly before his death. The plant material came from an agricultural area.

70. Vinschgau Valley, Italy

71. Őtzi’s Adult Home
Őtzi’s Body is Discovered
Őtzi’s Childhood Home

72. Could this be what Ötzi looked like?