BIOACCUMULATION AND BIOMAGNIFICATION - Marine Pollution: What Everyone Needs to Know - page 142

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BIOACCUMULATION AND
BIOMAGNIFICATION
What is bioaccumulation and what is biomagnification?
Organisms take pollutants up from the environment through
their skin, gills, or digestive system. The term bioaccumulation
is generally used to describe uptake, but there are specific terms
that refer to specific ways they do so. Bioaccumulation refers to
uptake from all sources in the environment. The bioaccumula-
tion factor (BAF) refers to the concentration of the chemical in
the organism compared to that of the sediment, when that is
the major source of uptake. Bioconcentration is a more specific
term that refers to uptake from water. The bioconcentration fac-
tor (BCF) is the concentration of a chemical in the organism rel-
ative to that in the water. Biomagnification refers to increasing
levels of a contaminant from one trophic level to the next in a
food chain (Figure 1.3), due to accumulation from food (trophic
transfer). The biomagnification factor (BMF) is the concentra-
tion in a species at one trophic level divided by that at the tro-
phic level below (the food of the species in question). Warmer
temperatures cause greater bioaccumulation, probably because
animals need to eat more due to their elevated metabolism.
What happens once a metal is taken up into an organism?
Once a chemical is taken up, the organism may store it, metab-
olize it, or eliminate some of it through gills or urine. Metals