Coastal Marine Environment Sustainability - Sustainable Practices in Geoenvironmental Engineering - page 268

bioconcentration—uptake and storage of contaminants from water. When uptake and stor-
age occur from water and also from food, the more general term bioaccumulation is used.
Available evidence (Chiou, 2002) indicates that there is a correlation between bioaccumula-
tion and the octanol-water coeficient k ow (see Section 2.5.3 in Chapter 2) for many of the
organic chemical contaminants reported in Section 2.3.2 in Chapter 2.

8.2.5 Contamination of Sediments

Historical discharge of contaminants and other toxic substances into the environment and
the receiving waters from industrial development is a matter of record. This discharge
became more signiicant during and after the industrial revolution at around the eigh-
teenth century. Many of the discharges included such substances as heavy metals, PCBs,
dioxins, polycyclic aromatic hydrocarbons, tributyltin, triphenyltin, etc., all of which are
known toxicants. When these substances ind their way into the ocean environment, some
of them will dissolve. However, most of them will ind their way onto the sea bottom
through eventual sedimentation or attachment to suspended solids, a process that is con-
sidered as “dispersion” of noxious substances in the sea. Their effects on the human food
chain can be deduced from Figure 8.1. This igure shows the food chain beginning with
phytoplankton anchoring the lowest trophic level and progressing upward through the
zooplankton, ish, and other marine aquatic species, and inally to humans. Mineral parti-
cles and organic matter settling in seawater can adsorb toxic and hazardous elements and
compounds. The record shows that bioaccumulation of such elements and compounds
as polychlorinated biphenyls (PCB), polychlorinated dibenzo- p - d iox i n s/d iben zo f u ra n s/

Anthropogenic discharge

Disease

Hazardous
substances

Nutrients

Human

Sorption

Suspended solids

Eutrophication

Contamination

Food chain

Phytoplankton Zooplankton

Blue tide

Pollution Fish

Bioconcentration

Red tide

Leaching

Food chain

Water

Benthos

Oxygen
deficiency

Hazardous
substances

Sulfides

Nutrients

Sediments

Anaerobic

FIGURE 8.1
Various processes of dispersion and accumulation of substances in the sea.