A bottom-resting tripod equipped with a suite of sensors sits on the deck of the research vessel Laurentian, awaiting deployment near the Isolated Sinkhole. Click image for larger view and image credit.
Sinkhole Interactions with Lake Huron
September 10, 2008
Dr. Nathan Hawley
Oceanographer
NOAA Great Lakes Environmental Research Laboratory
Watch a bottom-resting tripod being deployed near the Middle Island Sinkhole. (Quicktime, 2.6 Mb.)
My interest is in how the water discharged from the underwater vents interacts with the ambient water masses in Lake Huron throughout the year. Although the plumes from several of the vents have been mapped, these are just snapshots: there is no information on how, or if, the discharge of the vent water changes throughout the year.
Since the chemistry of the vent water is quite different from most of the water in the lake, we can use sensors that measure the properties of the water (in particular, the water temperature, salinity, and concentration of dissolved oxygen) to describe how the vent water interacts with the rest of the lake.
Nathan Hawley and Steve Constant prepare to deploy a tripod near the Middle Island Sinkhole. Click image for larger view and image credit.
Out near the Isolated Sinkhole, Nathan Hawley recovers a transmissometer (an instrument that measures turbidity) from a previously deployed tripod. Click image for larger view and image credit.
I am making time-series measurements at both the Isolated Sinkhole and the Middle Island vents, using bottom-resting tripods. Each of these tripods has several sensors attached to it at various heights above the bottom. The sensors will make hourly measurements of water temperature, salinity, and dissolved oxygen concentration. The data will be recorded internally and will be recovered next summer, when the tripods are retrieved.
I have also deployed current meters near both the Middle Island and Isolated Sinkhole vents in order to measure the amount of water discharged from the vents into the lake.
I hope to use the data collected to help quantify the amount of water discharged from the vents into Lake Huron, and to better understand how the vent water mixes into the lake.
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