 |  |  |  |  |  |
| Lamont's Environmental Tracer Group
Summer 2001
< back to Columbia Scientists Gauge Hudson Spill -- 08/24/01 The main goal of the project was to study the flow and mixing of water in the tidal part of the Hudson River. This knowledge is crucial for understanding the transport of dissolved substances, including contaminants, in the river, as well as the propagation of perturbations such as freshwater anomalies introduced by high precipitation events in the watersheds feeding the Hudson.
|
|
The method chosen for the study was to inject a small amount of an inert gas into the Hudson close to Newburgh. This gas was then tracked continuously to study the spreading and mixing of the water tagged by the tracer. Injection of such a tracer is the closest analogue to the introduction of a contaminant into the river. Tracking the tracer patch allows us to directly visualize the spreading and mixing of the water.
The Team:
|  Ted and David lowering a pump into the water to obtain samples for measurement of the dissolved tracer. -- Storm King The tracer is a substance that is released at small concentrations (traces) into the river water and that can be followed (traced) over a certain period of time. The tracer used is SF6, an inert gas that can be injected into the river at minute concentrations (traces). | ||
 David adjusting mount for submersible pump. -- Nyack. The pump is used to pump water from the river into the extraction system where the trace gas is separated from the water and injected into a gas chromatograph. The pump is lowered (submersed) to the depth from which the water is being pumped. |  John, Peter and Ted installing mount for submersible pump. -- Garrison The mount holds the pump at a certain water depth below the surface while the boat is moving up and down the river (over the tracer patch) -- in this case, 6 feet below the surface. | ||
 David adjusting gas extraction system. -- a system that allows the scientists to trace extract the gases injected into the river from water samples for measurement in a gas chromatograph. |  Tracer gas extraction system | ||
 Megan marking rope used for profiling water column for tracer. -- North of Newburgh The "water column" is the water from the bottom of the river to the surface. "Profiling" means to take water samples from several depths at a certain location to obtain the distribution of the tracer with depth. The rope is used to lower instruments into the water. The rope is marked to know how deep the instruments have been lowered. |  Megan lowering the CTD. -- Poughkeepsie A CTD is a device that measures Conductivity, Temperature, and Depth. | ||
 Peter and David injecting tracer via diffusion tubing. -- near Newburgh "Injection" means dissolving a certain amount of trace gas in the water (in our experiment at a depth of about 20 feet). |  John logging CTD data. -- Tappan Zee | ||
|
< back to Columbia Scientists Gauge Hudson Spill -- 08/24/01
Related web articles:
|
David Ho, Principal Investigator, Post Doctoral Research Scientist at Lamont-Doherty Earth Observatory.