50 years,
but then rose another 2 ppm
in only one—quarter of that time during
the 12—year period from 1955—1967. This sudden, accelerated rise was similar
to the trend in Lake Eric as eutrophication intensified in that body of water.
Even though estimates were that Michigan salt and brine industries in—
jected at least half of the average daily chloride input into Lake Michigan in
1971, the broader importance of the rising level of various dissolved materials
was that it was indicative of ever—increasing amounts of many different types
of pollutants from activities such as steelmaking, food processing, chemical
manufacturing, paper making, and petroleum processing. The industrial
problems at Lake Michigan can be found throughout America and other industrialized lands.
Pollutants reach Lake Michigan in air pollution as well as in liquid wastes.
Prevailing westerly winds carry pollutants, discharged from industrial smoke—
stacks at the south end of the lake, over the water where they can be depos—
ited as dry fallout or in rainfall. The degree to which this may happen was es—
timated recently for metals by john W. Winchester and Gordon D. Nifong,
both at the University of Michigan, Ann Arbor [19]. On the basis of produc—
tion gures, published emissions measurements, and other information, the
authors calculated that signicantly large amounts of iron (95,000 tons), man—
ganese (5100 tons), copper (3500 tons), and zinc (4300 tons) are discharged
into the atmosphere each year by Chicago, Milwaukee, and northwest ln—
diana businesses, primarily the iron and steel industries. Large amounts of ti—
tanium (2600 tons) and nickel (1100 tons) are released into the air annually by
coal, coke, and fuel oil burned for heating, manufacturing, and generation of
electricity. Lead (2400 pounds per year) is in the exhaust from gasoline—burn—
ing engines and, to a lesser degree, in smoke from other fuel.
On the basis of the strength and direction of prevailing winds and previous studies of the rate at which airborne particles are deposited in water,
the investigators concluded that some ten percent of the overall metal pollu—
tion would end up
in Lake Michigan, and part of what was left in the air un—
doubtedly would travel to other bodies of water. The scientists assumed that
an increase in the concentration of any
element in the water by as much as
0.1 mg/l (about the same as 0.1 ppb) was potentially signicant to the ecol—
ogy of the lake. Allowing for natural input of metals into the lake and for nat—
ural flushing of them from the lake, a number of metals from the air pollution
were building up
in the water in important amounts—among them copper,
nickel, and lead, each of which could have detrimental effects on the lake’s
ecosystem. In addition to the metals studied by Winchester and his colleagues, other air pollutants ranging from chemicals such as pesticides to asbestos fibers from construction projects find their way into the water. Even
sulfur dioxide, a gas product of combustion, is changed to an acid pollutant in
the atmosphere and washed down in rain [20].
Still other sources of pollution plagne Lake Michigan. Harbors ll with
sediment from rivers to the point that dredging is necessary
to maintain ade—
quate depths for navigation. In 1970, 30 harbors were scheduled for dredging
Problems Accumulote
23
but then rose another 2 ppm
in only one—quarter of that time during
the 12—year period from 1955—1967. This sudden, accelerated rise was similar
to the trend in Lake Eric as eutrophication intensified in that body of water.
Even though estimates were that Michigan salt and brine industries in—
jected at least half of the average daily chloride input into Lake Michigan in
1971, the broader importance of the rising level of various dissolved materials
was that it was indicative of ever—increasing amounts of many different types
of pollutants from activities such as steelmaking, food processing, chemical
manufacturing, paper making, and petroleum processing. The industrial
problems at Lake Michigan can be found throughout America and other industrialized lands.
Pollutants reach Lake Michigan in air pollution as well as in liquid wastes.
Prevailing westerly winds carry pollutants, discharged from industrial smoke—
stacks at the south end of the lake, over the water where they can be depos—
ited as dry fallout or in rainfall. The degree to which this may happen was es—
timated recently for metals by john W. Winchester and Gordon D. Nifong,
both at the University of Michigan, Ann Arbor [19]. On the basis of produc—
tion gures, published emissions measurements, and other information, the
authors calculated that signicantly large amounts of iron (95,000 tons), man—
ganese (5100 tons), copper (3500 tons), and zinc (4300 tons) are discharged
into the atmosphere each year by Chicago, Milwaukee, and northwest ln—
diana businesses, primarily the iron and steel industries. Large amounts of ti—
tanium (2600 tons) and nickel (1100 tons) are released into the air annually by
coal, coke, and fuel oil burned for heating, manufacturing, and generation of
electricity. Lead (2400 pounds per year) is in the exhaust from gasoline—burn—
ing engines and, to a lesser degree, in smoke from other fuel.
On the basis of the strength and direction of prevailing winds and previous studies of the rate at which airborne particles are deposited in water,
the investigators concluded that some ten percent of the overall metal pollu—
tion would end up
in Lake Michigan, and part of what was left in the air un—
doubtedly would travel to other bodies of water. The scientists assumed that
an increase in the concentration of any
element in the water by as much as
0.1 mg/l (about the same as 0.1 ppb) was potentially signicant to the ecol—
ogy of the lake. Allowing for natural input of metals into the lake and for nat—
ural flushing of them from the lake, a number of metals from the air pollution
were building up
in the water in important amounts—among them copper,
nickel, and lead, each of which could have detrimental effects on the lake’s
ecosystem. In addition to the metals studied by Winchester and his colleagues, other air pollutants ranging from chemicals such as pesticides to asbestos fibers from construction projects find their way into the water. Even
sulfur dioxide, a gas product of combustion, is changed to an acid pollutant in
the atmosphere and washed down in rain [20].
Still other sources of pollution plagne Lake Michigan. Harbors ll with
sediment from rivers to the point that dredging is necessary
to maintain ade—
quate depths for navigation. In 1970, 30 harbors were scheduled for dredging
Problems Accumulote
23