Once in the polar environment SVOCs interact with the local ecosystem. Many
POPs are hydrophobic (dislike water) and are therefore lipophilic (affinity for fats;
see Box 4.14). Consequently, if animals ingest POPs they are partitioned into the
organism’s fat reserves. This partitioning stores the compound in fats, excluding
it from metabolism and excretion. This scenario potentially allows POP concen-
trations to increase up the trophic level within food chains (Fig. 7.27). We should
note here the distinction between bioaccumulation, where higher organisms have
increased body burdens of POPs on account of the organisms being bigger, and
biomagnification, where higher organisms not only have increased body burdens of
POPs but also exhibit a higher concentration of POPs per unit mass of lipid (Fig.
7.27). It was the bioaccumulation and biomagnification of the insecticide DDT
(Fig. 7.25) that was highlighted in Silent Spring, Rachel Carson’s seminal book of
the 1960s. In it, Carson showed how the decline of common North American bird
species was due to consumption of food laden with this poison.
The indigenous humans of the arctic rely on local animals, particularly thoseGlobal Change 277BioaccumulationPOP body burden (g)
10 –1210 –910 –610 –31Polar bear
Seal
Arctic cod
ZooplanktonTropic level2345(a)
Tropic levelBiomagnificationPOP body burden (g)
10 –1210 –910 –610 –31
Polar bear
SealArctic codZooplanktonTropic level2345(b)1101001000 Polar bearSealArctic cod
Zooplankton2345(d)Tropic level1101001000ZooplanktonArctic codSeal Polar bear2345(c)
POP conc. (ng glipid)
–1POP conc. (ng glipid)
–1Fig. 7.27Bioaccumulation (a,c) and biomagnification (b,d) of persistent organic pollutants (POPs) with
increasing trophic level (i.e. position occupied by a species in the food chain). Trophic level 2 animals are
primary consumers (herbivores) while higher-level animals are carnivores.