Dissertation
Unit 9 Assignment C Diatoms, Pollen & Soil
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We did this before our assignment A and B. It got a distinction without a need for resubmission. Recommended evaluations and practical work.
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Mollie McMillanEnvironmental Forensics
Unit 9
Assignment C
In this report, I will analyse the soil sampling techniques as well as pollen and diatoms. Also,
I will discuss fibres and how they interact with pollen and things like the strengths and
limitations of sampling and how technology is used to analyse soil, pollen and diatoms.
Furthermore, using practical work to show how pollens and soils interact with fibres and
evidence to provide the location can match specific soil profiles.
Soil Sampling Techniques
There are different techniques to sampling soil, sampling techniques are important to match
soil samples to a crime scene in order to find the offender and conclusively like that they
were there. There are different types of soils. Soils can consist of inorganic matter and
organic matter, organic matter contains ‘humus’ (appears when an animal/plant diesThe
inorganic matter consists of things like mineral grains and can be fully dry (without water),
partly saturated (have air and water), or fully saturated (have no air content). The edaphic
factors are the properties like soil structure and pH that affect the diversity of organisms
living in that soil. There are different types of soils and they
can be sampled using brushing and sieving.
There are different types of soils:
● Podzols - These are acidic, the constituents in the soil
are moved downwards by percolating water (filtered
gradually through a porous substance), and water
dissolves and leeches organic materials of the soil. The
cold climate and acidic conditions of the soil
discourage organisms from being present.
● Brown Earths - It’s got crumbly humus (organic
material) that decomposes organic materials quickly.
There’s a lot of bacteria present in this soil, pH also
increases the further you go into the soil.
● Rendzina - It’s alkaline soil (calcareous) and develops where limestone is present, it
encourages organism activity.
● Gley Soils - This is a grey/blue colour and generally creates anaerobic conditions due
to the fact that water fills up spaces and creates a lack of air.
There are different ways you can analyse soil that being the structure, sediment and colour.
These all create different samples you can analyse. There are multiple different profiles of
soil which can help determine for example, how long a skeleton has been buried based on
how long it has been in the ground for. Colour is a good way of determining the history of
soil, for example, if the soil is white, it could suggest that there’s lime in the soil, or that liquid
, has been passed through it. If it’s grey this could suggest moisture is in the soil, as well as
black soil. This is great for forensic analysis as that means you can conclusively link samples
together, for example if a certain type of soil was found at a crime scene, and were able to
analyse the colour and link it to a suspect with the same type of soil, you’ve conclusively
linked a potential offender to a case. Another way you can distinguish soil is using the
Munsell Colour System, this is where the soil type is determined by the hue and value of the
soil colour, you can use this alongside the sieving method to determine particle size, and link
it to colour. The issue with the colour system is that people may interpret colour hues
differently, so you’d need multiple people to come to a conclusive opinion on which colour
best suits the soil. Using the colour chart is also affordable and is a quick way of evaluating
soil. Soils can also help raise questions like how long a body has been decomposing in the
ground for, which can be affected by pH levels, for example, if the soil is acidic
decomposition happens slower due to the lack of organisms, as in soils like podzol soil,
organisms are unencouraged due to the acidic pH. You can compare this to alkali soil, like
Rendzina, where there is an abundance of organisms, which in turn would make
decomposition happen at a faster rate. Another way soil pH can be shown is through flowers
such as hydrangeas. In alkaline soil, they will turn pink whereas in acidic soil they will turn
blue. This is good as a natural indicator for forensic analysts as it can also help determine
the rate of decomposition.
There are different ways you can collect soil, but you must be sure to not contaminate it, or
any other evidence within it, this can be things such as blood or other bodily fluids. If soil
does contain these pieces of trace evidence, they should be analysed separately so extra
evidence isn’t missed. Moreover, if the soil was from an indoor environment, using a vacuum
would be most effective for collecting the evidence, if a sample is found outdoors, a
teaspoon of soil is placed into a plastic vial, a tool being wrapped in plastic packaging. When
collecting samples off of a body, extra care must be taken to ensure evidence isn’t
contaminated. This is done by different spoons being used each time, if the same one was
used, trace evidence in the soil could be mixed together and lost, meaning the evidence may
be made inadmissible in court.
The sieving method involves using six layers of sieves, placing soil into them and then
shaking them to allow the soil to pass through. After this, use the sieve with the highest
amount of soil present and that will help determine the particle size of the soil. This method
is usually used for sand and gravel. Soil can be classified 3 ways:
● Sand - Sand has a particle size of 0.05mm-2m, it can be viewed better under a
microscope.
● Silt - Silt is very fine and has a particle size of 0.002mm-0.05mm.
● Clay - Clay has has a particle size of <0.002mm.
During sieving, protective equipment can be used for health and safety to avoid any potential
lung damage and breathing in of dust, things like a face mask can be used to help this. Lab
coats can also be worn to protect clothing.
Brushing is a method used when you brush in pockets etc. to find more soil samples in
spaces where you might not be able to collect enough evidence to sieve. Samples can be
used to be wiped on a glass slide and looked at under a microscope.
Once at the laboratory, each sample should be separated into a sample from the victim and
a sample from the potential offender and have separate examiners. Tests can then be done
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