Diatoms, Forams, Phytoliths and Pollen Flashcards
1
Q
What are diatoms?
A
- Type of eukaryotic algae
- Found in bodies of water or near it
- Make up most of the sequestration of carbon
2
Q
How are diatoms used as trace evidence?
A
- Enter the body during drowning
- but have to be careful because diatoms can be consumed in foodstuff, inhaled in low quality cigars, and contamination of equipment
3
Q
Why are diatoms a good form of trace evidence?
A
- diverse group of species with small size range which makes their entry inside organs feasible
- Hard silica wall - resistant to chemical changes
- can be recovered when little other evidence is available
- growth corresponds to certain specific parameters of the environment (cause and site of death can be determined)
- loads of different species
4
Q
Analytical workflow for diatoms
A
- identify them
- hydrogen peroxide fixing
- transition light microscope
- SEM microscope
5
Q
Transfer and persistence of diatoms
A
- not all diatoms will transfer onto a material
- smoother surface diatom is less likely to transfer compared to a diatom with spines
- species morphology affects the level of transfer and persistence from a water source to clothing or footwear
6
Q
What are the disadvantages of diatoms?
A
- cross-contamination
- secondary transfer
6
Q
What are the future research for diatoms?
A
- molecular barcoding combined with big-data approaches - rapid tracing and identification
- automated AI - speed up identification workflows enabling the usage of diatoms
6
Q
What are foraminifera/forams?
A
- single celled organism
- live on the sea floor
- can be found in sand and linked to certain beaches
7
Q
What are phytoliths?
A
- plant microfossils made of silica
- found in some plant tissue
- persist after the death and decay of plants
- released into soil after plant death
8
Q
How is pollen dispersed?
A
- wind
- water
- animals
9
Q
Why is pollen a good form of trace evidence?
A
- hard coat to protect them - relatively resistant to destruction
- surface texture is diverse and identifiable to particular plants
- a single anther will produces thousands of pollen grains
- easily dispersed
- small size
10
Q
What are the challenges of pollen as trace evidence?
A
- lack of skilled people in handling and identification - high chances of contamination
- limited national or international databases of pollen
11
Q
What is the pollen analytical workflow?
A
- pollen chemically processed and prepared for identification and methodology
- SEM considered the standard but is time consuming
- semi-automated TLM & fluorescence - rapid and accurate alternative
- molecular barcoding with high throughput sequencing - future
12
Q
Where should you look for pollen evidence?
A
- clothes
- hair
- drugs
- soils
- vehicles
- stomach contents
