Glossary

3.2 Bioconcentration, bioaccumulation, and biomagnification

4 min read•august 7, 2024

Chemicals can build up in living things through bioconcentration, , and . These processes describe how pollutants move from the environment into organisms and up food chains, potentially harming wildlife and humans.

Scientists use factors like BCF, BAF, and BMF to measure chemical buildup in organisms. Understanding these processes helps predict which pollutants might cause the most harm in ecosystems, especially to top predators and humans.

Bioaccumulation Metrics

Measuring Bioconcentration and Bioaccumulation

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  • Bioconcentration factor (BCF) measures the concentration of a chemical in an organism compared to its concentration in the surrounding environment (water)
    • Calculated as the ratio of the chemical concentration in the organism to the concentration in the water
    • Indicates the extent to which a chemical is taken up and accumulated in an organism directly from the surrounding medium
  • Bioaccumulation factor (BAF) measures the concentration of a chemical in an organism compared to its concentration in both the surrounding environment and the organism's diet
    • Calculated as the ratio of the chemical concentration in the organism to the concentration in the water and food sources combined
    • Accounts for chemical uptake from all sources, including water, sediment, and food
    • Provides a more comprehensive measure of a chemical's accumulation potential in an organism

Quantifying Biomagnification

  • Biomagnification factor (BMF) measures the increase in concentration of a chemical as it moves up the food chain
    • Calculated as the ratio of the chemical concentration in a predator to the concentration in its prey
    • Indicates the extent to which a chemical is magnified in concentration at higher trophic levels
    • BMF values greater than 1 indicate that biomagnification is occurring, with higher values signifying greater magnification potential

Trophic Transfer and Food Chain

Trophic Transfer and Biomagnification

  • Trophic transfer refers to the movement of chemicals from one trophic level to another in a food chain
    • Occurs when a predator consumes prey containing accumulated chemicals
    • Enables the transfer and accumulation of chemicals at higher trophic levels
  • Food chain represents the linear sequence of organisms through which energy and chemicals are transferred
    • Consists of primary producers (plants), primary consumers (herbivores), secondary consumers (carnivores), and tertiary consumers (top predators)
    • Chemicals can be transferred and magnified as they move up the food chain from lower to higher trophic levels
  • Biomagnification factor (BMF) quantifies the increase in chemical concentration between trophic levels
    • BMF > 1 indicates that the chemical concentration increases as it moves up the food chain
    • Higher BMF values signify greater biomagnification potential and potential risks to top predators

Factors Influencing Trophic Transfer

  • Trophic level and food chain length
    • Longer food chains provide more opportunities for trophic transfer and biomagnification
    • Top predators at higher trophic levels are more likely to accumulate higher concentrations of chemicals
  • Feeding relationships and diet composition
    • Predators that consume contaminated prey will have higher exposure to chemicals
    • Omnivorous organisms that feed on both contaminated plants and animals may have higher accumulation potential
  • Metabolic rates and body size
    • Organisms with higher metabolic rates may have faster uptake and elimination of chemicals
    • Larger organisms tend to have slower elimination rates and may accumulate higher concentrations over time

Pollutant Properties

Lipophilicity and Bioaccumulation Potential

  • Lipophilicity refers to a chemical's affinity for lipids (fats) and ability to dissolve in lipids
    • Highly lipophilic chemicals tend to partition into the fatty tissues of organisms
    • Lipophilic chemicals are more likely to bioaccumulate and biomagnify in food chains
    • Examples of lipophilic pollutants include PCBs (polychlorinated biphenyls) and DDT (dichlorodiphenyltrichloroethane)
  • Persistent organic pollutants (POPs) are highly lipophilic and resistant to degradation
    • POPs can persist in the environment for long periods and undergo long-range transport
    • Examples of POPs include dioxins, furans, and certain pesticides (e.g., chlordane, heptachlor)
    • POPs have a high potential for bioaccumulation and biomagnification in food chains

Bioaccumulation Metrics and Pollutant Properties

  • Bioconcentration factor (BCF) is influenced by a chemical's lipophilicity
    • Highly lipophilic chemicals tend to have higher BCF values
    • BCF can be used to assess the bioconcentration potential of lipophilic pollutants
  • Bioaccumulation factor (BAF) takes into account both lipophilicity and persistence
    • Chemicals with high lipophilicity and persistence are more likely to have higher BAF values
    • BAF provides a measure of a chemical's overall bioaccumulation potential, considering uptake from water, sediment, and food
  • Understanding the lipophilicity and persistence of pollutants is crucial for predicting their bioaccumulation and biomagnification potential in ecosystems

Key Terms to Review (2)

Bioaccumulation: Bioaccumulation is the process by which organisms accumulate contaminants in their bodies over time, often from their environment or food sources. This phenomenon can lead to higher concentrations of harmful substances in the tissues of an organism compared to the surrounding environment, significantly impacting health and ecological dynamics.
Biomagnification: Biomagnification is the process by which the concentration of toxic substances increases as they move up the food chain, affecting organisms at higher trophic levels more severely. This phenomenon connects various aspects of ecological interactions and highlights the importance of understanding how pollutants behave in ecosystems and impact wildlife health.
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