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Forensic Biology > Soil Analysis > Flashcards

Soil Analysis Flashcards

1
Q

soil

A

degraded material that lies on Earth’s surface

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2
Q

natural soil examples

A
  • rocks
  • minerals
  • vegetation
  • animal matter
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3
Q

natural soil range

A

can range from 100% inorganic to 100% organic

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4
Q

100% inorganic soil

A

sand

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5
Q

100% organic soil

A

peat

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6
Q

artificial/manufactured soil

A
  • glass
  • paint
  • cinders
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7
Q

soil forensic importance

A
  • easily transferred/transported/unnoticed
  • class evidence
  • exclusion/inclusion of known samples to questioned sample
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8
Q

where soil samples can be found

A
  • boots
  • shovels
  • tires
  • wildlife
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9
Q

crimes where soil evidence could be useful

A
  • murder
  • abduction
  • rape
  • burglary
  • hit & run
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10
Q

variations in soil crime scene

A

if the soil is indistinguishable for miles surrounding the crime scene, it will have limited value in associating soil found on the suspect with that particular site

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11
Q

collection of soil

A

collected at various intervals within a 100-yard radius of the crime scene, as well as the site of the crime, for comparison to the questioned soil

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12
Q

how to collect soil of the body & objects

A
  • must not be removed
  • each object should be individually wrapped in paper & transmitted to the laboratory
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13
Q

soil collection for standard/reference samples

A
  • only a tablespoon or two of the top layer of soil is collected, placed in individual plastic containers, & labeled according to location
  • dry out samples
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14
Q

how is soil analyzed?

A
  • color comparisons
  • soil texture & structure
  • microscopic examination for debris
  • geologically for rocks & minerals
  • density gradient tube technique
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15
Q

munsell soil color chart

A
  • typically soil samples are uniformly dried & compared using standardized colors
  • 1,100 distinguishable colors
  • colors darker when wet
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16
Q

color of soil with low levels of organic matter

A

lighter

17
Q

color of soil with high levels of organic matter

A

darker

18
Q

low power magnification microscopic examination of soil

A

investigates presence of contaminants, plants, & animal debris

19
Q

high power magnification microscopic examination of soil

A
  • can classify rocks & minerals
  • 1000s of minerals
20
Q

high power magnification of 1000s of minerals

A
  • 20 commonly observed in soils (4-5 found together)
  • distinguished by polarized light microscopy
21
Q

which is the largest: sand, silt, clay

A

sand

22
Q

which is the smallest: sand, silt, clay

A

clay

23
Q

sand size

A

2.00-0.05 mm

24
Q

silt size

A

0.05-0.002 mm

25
Q

clay size

A

< 0.002 mm

26
Q

how to separate sand, silt, and clay

A
  • sieves
  • water separation
27
Q

density gradient tubes

A
  • these tubes are typically filled w/ layers of liquids that have different densities
  • when soil is added to the density gradient tube, its particles will sink to the portion of the tube that has a density of equal value
28
Q

ideal soil pH

A

5.5-8 is ideal pH range for plant growth

29
Q

Differential Thermal Analysis

A
  • DTA
  • as soil is heated, reactions happen to physical state or chemical reaction
30
Q

DTA reaction types

A

exothermic or endothermic

31
Q

exothermic

A

reaction with the release of heat

32
Q

endothermic

A

reaction with the absorption of heat

33
Q

Thermogravimetric Analysis

A
  • TGA
  • monitor weight change as soil is heated at a constant rate
34
Q

what is caused by an exothermic reaction?

A

loss of weight

35
Q

Cation Exchange Capacity

A
  • CEC
  • negatively charged conditioner particles hold & store positively charged cations
  • plant roots exchange hydrogen cations for essential nutrients it cannot produce for itself
  • co-insides with soil textures
36
Q

what type of evidence is soil?

A

class evidence

Forensic Biology (17 decks)

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