Abiotic Factors

• Abiotic Factors

  Abiotic factors are those that are not related to living things.

  Abiotic Components relate to the Climate and the Habitat

  Climate includes:

  •Heat

  •Cold

  •Wind

  Habitat includes:

  •Soil

  •Water

  •Sand
• Climate: Temperature

  Often referred to as the most important factor in terms of its affect on decomposition

  Increased temperature results in an increased rate of reaction and a subsequent increase in the rate of decomposition

  Decreased temperature results in decreased rate of reaction and subsequent decrease in the rate of decomposition

  
• Climate: Temperature

  Temperature has a significant influence on biotic factors including bacterial action and insect activity.

  Bacteria have an optimal temperature, above or below which, their activity arrests.

  The temperature of human remains can be influenced by other factors including:

  •Larval mass

  •Clothing

  •Wrappings

  •Time since death 

  
• Climate: Humidity

  Humidity can have a significant affect on the decomposition rate through interaction with heat.

  In conditions of high humidity:

  •Low temperature = slowing of decomposition

  •High temperature = rapid increase in the rate of decomposition

  In conditions of low humidity:

  •Low temperature = freeze drying, arrest of decomposition

  •High temperature = Dehydration/Mummification, arrest of decomposition
• Habitat: Rainfall and Water

  -Rainfall acts on the decomposition process through interaction with other factors, e.g. washing away larval masses.

  -Rainfall resulting in standing ground water will change the decomposition pattern, potentially resulting in the formation of adipocere, which will slow decomposition.

  -Water can act as a means of transport or accumulation for remains, moving the remains from their deposition site or disrupting their positioning within the deposition site.
• Habitat: Ground substrate

  -The ground substrate e.g. soil, clay or sand, will influence the decomposition pattern due to the permeability of the substrate.

  Sand – free draining/aerobic

  Sandy soil – relatively free draining/aerobic

  Organic soil – holds some water but relatively free draining/aerobic

  Clay soil – holds some fluid/less aerobic

  Clay – does not drain/anaerobic

  -The pH of the ground substrate may also have an affect, altering the bacteria within the habitat.
• Abiotic winnowing, aggrading or accumulating agents:

  Some agents will also cause winnowing, aggradation or accumulation of remains. These can include:

  •Water

  •Snow

  •Gravity

  Both water and gravity can cause movement of remains, resulting in either separation or accumulation. Understanding these agents is important in being able to interpret a scene, develop a search and recovery strategy etc.

  
• Weather

  Different climates will cause different rates of decomposition and weathering patterns on the bone and soft tissue

  Bone weathering itself can only occur when soft tissue has been lost