Page 245 - NS-2 Textbook

240 NAUTICAL SCIENCES

nahrral accmnulation in the sea. As a result, increased trations were found in parts of Maryland and Virginia that
traces of mercwy have been fmmd in shellfish and other border on the Chesapeake Bay. Prolonged exposure to
fish species throughout the world, including the Arctic such contamination can cause cancer in hunlans.
Ocean and the Great Lakes. Sea life, especially shellfish, ab- Litter. Marine litter is solid waste of society and
sorb the mercury. Fish, oysters, and clams retain it, and it ships at sea. It is trucked, barged, and dll1l1ped into
continues to build up, never being cast off. In certain rivers and into the oceans at a rate of more than 6 mil-
coastal areas neal' where the pollution enters the watel, lion tons each year. The ocean floor and coastal areas are
dangerous concentrations occur in the fish. This has oc- littered with this debris; much of it consists of packing
curred in Minimata Bay at Kyushu Island, Japan. Many materials-plastic, aluminum, wood, and glass-all of
people have become severely crippled and mentally ill which may take centuries, at best, to be broken down by
from eating mercllly-poisoned seafood caught in the bay. the salts of the sea. In recent years various types of med-
Radioactive Materials. Since World War II, many cmm- ical refuse have become of particular concern. Much of
h'ies have begun to develop nuclear power stations and this litter is not biodegradable. In other words, it will
fuel-processing plants to help solve their energy short- never decay and break down. Beaches all over the world
ages. In theory such plants can be made safe from leaks are cluttered with this trash, some of which floats to the
so they will not contaminate nearby land and water en- farthest corners of Earth. It is unsightly, it is a hazard to
vironments. The fact is that the cost for so doing is very s\vin1IDers and small craft navigation} it clogs harbors}
high, and accidents have occurred. Increasing amounts and it may destroy the natural habitat of shorebirds and
of radioactive pollutants have found their way into the animals.
'vater. On the sea bottom} however} smne of this trash ac-
In recent years Inuch concern has arisen over ra- tually helps create habitats for plant and animal life.
dioactive waste products and reactor parts dtunped into Derelict ships, cal' bodies and tires, and cement blocks,
the seas over the years. In some cases old sunken sealed among other things, have been used to make artificial
drums of radioactive wastes have corroded and leaked, reefs that are eventually covered by marine growth.
causing contamination of local fish populations. Most The vegetation brings fish, and a flourishing cycle of
countries with nuclear capabilities have agreed to dis- sea life is created where previously there may have
pose of future wastes in land dumps as the result of in- been none. This beneficial result of litter} however} is
ternational accords dealing with this issue. unique and differs greatly from its usual effect on the
Chemical and Synthetic Compounds. Chlorine, fluorine, envirOlunent.
bromine, and iodine are proving very dangerous to ma- Sewage. The organic pollutants from sewage are es-
rine life. These compmmds fall into two main groups: (1) pecially troublesome in enclosed water areas. They con-
pesticides, such as DDT and other chemical weed and in- tain high levels of nutrients that promote rapid plankton
sect killers; and (2) the biphenols, such as aerosol propel- growth, in both fresh and salt water. This great increase
lants, solvents, refrigerants, and cleaning agents. in plankton population uses up the available oxygen,
DDT is known to cause reproductive problems in upsetting the natural ecosystem. Some 8,000 tons of
some marine birds. The brown pelican, for instance, is an sewage sludge is dll1l1ped daily from barges into the At-
endangered species in some areas now. When the peli- lantic Ocean off New York City. Many coastal areas, es-
cans eat fish that have absorbed DDT from field and river pecially along the shores of the Mediterranean, have
runoff into coastal bays, their eggs have flimsy shells that been contaminated by unprocessed sewage flow.
break in the nest. Coastal ·wetlands have become U dead JJ areas} choked
Most of the adult fish in the Great Lakes have ab- with algae and filled with disease-bearing bacteria. When
sorbed pesticide and herbicide runoff froll farmlands such areas are destroyed, either by raw sewage or by
along the rivers that drain into the lakes. Pesticides often draining, filling, or reclamation projects, a devastating
kill the eggs and small fry, so they have greatly reduced blow is struck to the natural reproductive capacity of
the nahtral reproduction of game fish in streams, rivers, marine wildlife.
and ponds, especially in the upper Midwest and in the To help prevent pollution of iniand waterways and
Great Lakes states. As a result, these states nO\l\' have to harbors, Navy ships are equipped with two types of
restock their waters annually from fish hatcheries in sewage systems: (1) marine sanitation devices (MSDs),
order to sustain fish populations. which enable sewage to be treated before it is discharged
Pesticides nmnmg off from farmlands can eventually from the ship; and/or (2) collection, holding, and trans-
find their way into drinking water. In some recent shtdies fer systems (CHTs), which collect and hold sewage
more than sixty agricultural pesticides were found in the until it can be transferred ashore in port 01' pll1l1ped
drinking water of people in fourteen states in the mid-At- overboard in unrestricted waters beyond the territorial
lantic and southeastern regions. Especially high concen- limits (at least 12 miles from shore). Many commercial