Hyporheic Zone in Rivers, working with another group of scientists Options

[Tom_Crumrine]

29 June 2005

On Monday I had the chance to work with Mike Gooseff and his crew of researchers on a stream south of Toolik Lake. A great part about Toolik is that there are so many different researchers that you can see a little about each type of research. Basically there is someone here working on each part of the environment. Land, streams, stream beds, lakes, benthic zones in lakes, fish, etc. So before I left I thought I should check out what some of the other scientists here are doing.



The stream that we were sampling was about 1 mile south of camp so we walked down and set up our gear for the day. Earlier in the summer they had set up 9 stations of pizeometers at various points along the stream. Pizeometers are small tubes that are places at various depths below the stream bed, allowing water to be pulled from the water in the sediments below the stream. The pizeometers at this site were set at 10 and 30 centimeters below the bed of the stream. The picture above shows Morgan Johnston using a syringe to draw water from the pizeometer. Before any experimenting began we took samples from each of the spots where pizeometers were along the stream.



When all the preliminary testing was done Jay Zarnetski went upstream and began to add a rotamine drip which can be seen in this picture (the red/orange color seeping into the top.) The rotamine is a non-hazardous indicator that can be used to track the flow of the stream. At the outlet end of the stream Mike had set up a fluorometer attached to a computer. This would allow them to see when the dye had completed moving through the stream. Every 20 minutes we sampled from the pizeometers and from the stream near them.

The idea with doing all of this is to learn more about hyporheic flow--that is the flowing of water in the stream bed. Parts of it seem obvious. If there is a stream bed that is filled with large stones with lots of openings between them then nutrients can more easily move lower into the hyporheic zone. If the bed is made of small sediments that pack together then the nutrients might travel more slowly to the areas below the bed.



This picture shows the length of the stream and many of the sampling sites. Ken Turner is shown helping Morgan to reach the pizeometers that are hard to get to. What we did was continue sampling until Mike got a reading on the fluormeter that indicated that the rotamine had passed through the section of the stream that they were analyzing. We sampled for many hours and wound up with over 500--20 milliliter sample bottles. These would be taken to the lab and analyzed to determine how the nutrients are transported in this stream. It is quite a bit of work but in concept it makes sense. Once you have data for one stream you can then compare it to all kinds of other streams.