be in excess of 100,000 metric tons [18]. The largest amount of mercury in the
atmosphere contributing to this washout is of natural origin due to vapor—
ization from the earth’s crust. This source may put from 25,000 metric tons of
vaporized mercury to four times that amount or more into the atmosphere
each year. By comparison, up to 3000 metric tons are discharged annually
from chloralkali plant stacks [19], at least 100 tons from cement works, and as
much as 20,000 metric tons annually from the burning of fossil fuels [20].
Other amounts enter the ocean as the result of liquid waste discharges to riv—
ers. Because of the wide range in the various estimates that have been made, a
precise balance sheet between man—made and natural contributions cannot be
made. Clearly, however, the amount attributable to man is considerable, and
produces serious environmental and human health threats. Before the modern
industrial release of mercury, the contamination of sh by natural methyl
mercury was a localized problem. Industrial pollution, however, has vastly
magnied this contamination” [21]. Other metals with potentially serious im—
plications for marine biology and, in some cases, for human health which now
are released by man in quantities rivaling those in nature include copper,
nickel, chromium, and cadmium [22].
To Ocean from Air and Surface Waters
The United States alone now releases some 100 million metric tons of particu—
late materials to the atmosphere each year from the combustion of fuel used
for transportation and other needs and from various industrial and agricul—
tural activities. This equals the amount disgorged by volcanoes each year.
The amount of particles released to the atmosphere naturally as rock debris
and sea salt may total as much as two billion metric tons each year, far more
than that now produced by man in the United States [23]. However, the par—
ticles released by man, including material such as uorides, beryllium, lead,
and asbestos, can be hazardous to life [24]. Thus man’s pollution can surpass
nature’s in toxicity, if not in quantity. These considerations, plus the need to
account for discharges from expanding technologies in other countries of the
world, led a panel of the National Academy of Sciences (NAS) to conclude
that “a modern industrial society can now compete with natural processes as
a source of materials in the environment. Although the available data are
poor in quality, they suggest that burning of fossil fuels will have a signicant
impact on the marine environment.” [25]
The impact of man-made versus natural pollution at sea can be seen most
sharply in the accumulation of synthetic organic chemicals in the environ—
ment that can be detrimental to life. The list of such chemicals is long, but in
a 1971 NAS report prepared under the auspices of the Ocean Science
mittee, three groups were selected as representative: chlorinated hydro—
carbon insecticides used for agricultural and public health, chlorinated hydrocarbons for industrial use, and volatile organic liquids and gases for various
applications. The table on page 77 presents representative amounts of chlori—‘ '
natéd hydrocarbon insecticides produced and released to the ocean [26]:
To Ocean from Air and Surface Waters
75
atmosphere contributing to this washout is of natural origin due to vapor—
ization from the earth’s crust. This source may put from 25,000 metric tons of
vaporized mercury to four times that amount or more into the atmosphere
each year. By comparison, up to 3000 metric tons are discharged annually
from chloralkali plant stacks [19], at least 100 tons from cement works, and as
much as 20,000 metric tons annually from the burning of fossil fuels [20].
Other amounts enter the ocean as the result of liquid waste discharges to riv—
ers. Because of the wide range in the various estimates that have been made, a
precise balance sheet between man—made and natural contributions cannot be
made. Clearly, however, the amount attributable to man is considerable, and
produces serious environmental and human health threats. Before the modern
industrial release of mercury, the contamination of sh by natural methyl
mercury was a localized problem. Industrial pollution, however, has vastly
magnied this contamination” [21]. Other metals with potentially serious im—
plications for marine biology and, in some cases, for human health which now
are released by man in quantities rivaling those in nature include copper,
nickel, chromium, and cadmium [22].
To Ocean from Air and Surface Waters
The United States alone now releases some 100 million metric tons of particu—
late materials to the atmosphere each year from the combustion of fuel used
for transportation and other needs and from various industrial and agricul—
tural activities. This equals the amount disgorged by volcanoes each year.
The amount of particles released to the atmosphere naturally as rock debris
and sea salt may total as much as two billion metric tons each year, far more
than that now produced by man in the United States [23]. However, the par—
ticles released by man, including material such as uorides, beryllium, lead,
and asbestos, can be hazardous to life [24]. Thus man’s pollution can surpass
nature’s in toxicity, if not in quantity. These considerations, plus the need to
account for discharges from expanding technologies in other countries of the
world, led a panel of the National Academy of Sciences (NAS) to conclude
that “a modern industrial society can now compete with natural processes as
a source of materials in the environment. Although the available data are
poor in quality, they suggest that burning of fossil fuels will have a signicant
impact on the marine environment.” [25]
The impact of man-made versus natural pollution at sea can be seen most
sharply in the accumulation of synthetic organic chemicals in the environ—
ment that can be detrimental to life. The list of such chemicals is long, but in
a 1971 NAS report prepared under the auspices of the Ocean Science
mittee, three groups were selected as representative: chlorinated hydro—
carbon insecticides used for agricultural and public health, chlorinated hydrocarbons for industrial use, and volatile organic liquids and gases for various
applications. The table on page 77 presents representative amounts of chlori—‘ '
natéd hydrocarbon insecticides produced and released to the ocean [26]:
To Ocean from Air and Surface Waters
75