9
Influence of Lipids on the
Bioaccumulation and Trophic
Transfer of Organic Contaminants
in Aquatic Organisms
Peter F. Landrum and Susan W. Fisher
9.1. Introduction
9.1.1. Sources of Contaminant Gain and Loss in
Aquatic Systems
In aqueous systems, organisms are exposed to contaminants via multiple routes
(Fig. 9.1). The extent of contaminant accumulation ultimately depends on the
extent and mode of interaction with diverse contaminated media. The influence of
lipids on contaminant uptake likewise varies according to the route by which the
exposure takes place and the lipophilic character of the contaminant. Thus, it is
necessary to clarify the environmental sources of contaminants for accumulation.
The means by which contaminants, once accumulated, can be eliminated from an
organism can also depend on organism lipid content. This elimination can be
modified by the route, contaminant lipophilicity, and extent of contamination of
the environmental compartment into which elimination occurs.
A few definitions will help guide the discussion. When contaminants are freely
dissolved in water, uptake by aquatic organisms occurs when the contaminant is
absorbed across a respiratory surface, the gills (Nichols et ai., 1991, 1990), or less
commonly, across the cuticular epidermis or exoskeleton (Lien et ai., 1994; Lien
and McKim, 1993). If uptake exceeds elimination, then bioconcentration has
occurred. If the ultimate source of the contaminant is not water (i.e., if the
contaminant is bound to some environmental medium such as sediment or is
present in an organism's food), bioaccumulation from solid media can occur.
Because some fraction of the contaminant may detach from solid media and enter
the dissolved phase, some uptake of the contaminant directly from water may
occur (Bruner et aI., 1994a). However, it is difficult to separate the fraction of the
contaminant that originates from solid media and the fraction that is directly
absorbed from water; bioaccumulation, thus, is understood to include both routes
of entry into an organism. Once a contaminant moves from abiotic media such as
water or sediment into living organisms, the contaminants can subsequently move
through the food chain when, for example, contaminated prey are ingested.
Trophic transfer is the term that describes the transfer of contaminants between
203
Influence of Lipids on the
Bioaccumulation and Trophic
Transfer of Organic Contaminants
in Aquatic Organisms
Peter F. Landrum and Susan W. Fisher
9.1. Introduction
9.1.1. Sources of Contaminant Gain and Loss in
Aquatic Systems
In aqueous systems, organisms are exposed to contaminants via multiple routes
(Fig. 9.1). The extent of contaminant accumulation ultimately depends on the
extent and mode of interaction with diverse contaminated media. The influence of
lipids on contaminant uptake likewise varies according to the route by which the
exposure takes place and the lipophilic character of the contaminant. Thus, it is
necessary to clarify the environmental sources of contaminants for accumulation.
The means by which contaminants, once accumulated, can be eliminated from an
organism can also depend on organism lipid content. This elimination can be
modified by the route, contaminant lipophilicity, and extent of contamination of
the environmental compartment into which elimination occurs.
A few definitions will help guide the discussion. When contaminants are freely
dissolved in water, uptake by aquatic organisms occurs when the contaminant is
absorbed across a respiratory surface, the gills (Nichols et ai., 1991, 1990), or less
commonly, across the cuticular epidermis or exoskeleton (Lien et ai., 1994; Lien
and McKim, 1993). If uptake exceeds elimination, then bioconcentration has
occurred. If the ultimate source of the contaminant is not water (i.e., if the
contaminant is bound to some environmental medium such as sediment or is
present in an organism's food), bioaccumulation from solid media can occur.
Because some fraction of the contaminant may detach from solid media and enter
the dissolved phase, some uptake of the contaminant directly from water may
occur (Bruner et aI., 1994a). However, it is difficult to separate the fraction of the
contaminant that originates from solid media and the fraction that is directly
absorbed from water; bioaccumulation, thus, is understood to include both routes
of entry into an organism. Once a contaminant moves from abiotic media such as
water or sediment into living organisms, the contaminants can subsequently move
through the food chain when, for example, contaminated prey are ingested.
Trophic transfer is the term that describes the transfer of contaminants between
203