same techniques as during the open-water sea-
valuable for real-time response to a spill or to
provide planning capabilities for spill response.
son, with the acknowledgment that access may
be difficult and that floating ice may interfere with
operations. Absorbing agents, skimming by
vacuum, skimming by pumping or burning, and
BIOLOGICAL EFFECTS
herding agents have been proposed. Oil spills on
ice are rare. Burning has been proposed, and if
This section reviews the available documen-
the ice is strong enough, scraping by large ma-
tation on the potential ecological effects of ex-
chinery may be possible. Little is known about
tended season navigation on the Great Lakes
system. Most of the work has centered on the St.
the behavior of oil beneath ice; this type of spill
Marys River, where an ice cover is normally present
would probably be the most difficult to deal with.
in winter, effects on the river ice regime due to
It is known that the oil collects in pockets beneath
winter navigation have been most apparent and
the ice; pumping the oil out of these pockets, driv-
the potential for damage would seem the great-
ing out the oil with compressed air, and deploy-
est. Further, significant navigation already occurs
ing booms through the ice (if it is thin) or under
in winter on the St. Clair and Detroit Rivers in-
the ice (if thick) have been suggested.
dependent of any season-extension activities. Vir-
Alaska Clean Seas, a nonprofit organization
tually all of the studies have taken place since
sponsored by 15 oil companies, is devoted to oil
1979, and only one of those years included navi-
spill response in most offshore areas of Alaska.
gation on the St. Marys River significantly beyond
This organization has sponsored research and
the traditional season. Data in other years were
development of better oil spill cleanup equipment
collected to provide baseline information for
and techniques, much of it for use in ice-covered
comparison. Topics considered include water qual-
waters. In addition, it provides manuals, train-
ity, benthic invertebrates, aquatic plants, fish,
ing and equipment for oil spill containment, dis-
waterfowl and raptorial birds.
posal and mitigation. This organization could be
a resource in improving the response capabili-
Water quality
ties and recovery techniques in the Great Lakes
during the extended season navigation periods.
Liston and McNabb (1986) collected baseline
water quality data at seven stations in both ship-
ping and non-shipping channels along the St.
Modeling oil and
Marys River during periods without winter navi-
hazardous substance spills
The ability to model and forecast the trans-
gation. Variables considered include temperature,
port of oil and hazardous substance spills is nec-
pH, dissolved oxygen, turbidity and sedimenta-
essary to speed up response to spills and to ad-
tion rates.
equately and expeditiously deploy existing equip-
Temperature, pH and dissolved oxygen were
ment. The ability to model oil and hazardous
not considered subject to impact by winter navi-
substance spills depends intimately on the un-
gation. Turbidity was a more significant concern
derstanding of the many processes that affect spills.
because of the biological importance of water clar-
These processes include advection by wind and
ity and light penetration for photosynthesis. Fur-
water currents; weathering of the material by
ther, turbidity can directly impact invertebrates
evaporation and dissolution; mechanical spread-
and fish by fouling gill mechanisms, which in turn
ing of the material by viscous, tension and grav-
can affect circulation, respiration, excretion and
ity forces; and interaction of the material with the
salt balance. Turbidity levels sufficient to harm
shoreline. In addition the ability to model move-
invertebrates and fish were not expected to oc-
ment in open-water and ice-covered conditions
cur on the St. Marys River, with or without ex-
can significantly improve response and deploy-
tended season shipping, especially considering
ment in winter. A recent development in model-
the rapid flushing rates in the river. Lake Nicolet,
ing (Shen et al. 1986) has provided a state-of-the-
for example, undergoes about 1.3 volume ex-
art model that incorporates the above consider-
changes daily. From their studies, however, Liston
ations. The model is specifically developed for
and McNabb concluded that slight increases in
the St. Marys River, the St. Clair River, Lake St.
turbidity can limit the outer depth limits of sub-
Clair and the Detroit River. Available on main-
merged macrophyte growth and affect species
frame or desktop computer, the model should be
24
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