Using a Continuous Flow Centrifuge to Collect Suspended Sediment

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Detailed Description

Kathy Conn, a U.S. Geological Survey Water Quality Specialist, demonstrates a new USGS field method using a continuous flow centrifuge to collect suspended sediment from large volumes of water in the Duwamish River near Seattle Washington.
 

Details

Image Dimensions: 1280 x 720

Date Taken:

Length: 00:03:37

Location Taken: Duwamish River, WA, US

Video Credits

Music "Arcade Paradise" by Scott Holmes License (CC BY-NC 4.0) freemusicarchive.org

Transcript

[Sound]

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Narrator:  We are using a new USGS field method that uses a continuous flow centrifuge to separate out and collect suspended sediment from large volumes of water so we’re here on the Duwamish River collecting the suspended sediment out of river.

The really nice thing about this centrifuge I that it’s light, small, it’s portable and so we can bring it right here to the river and collect our sample right here and this is overcoming some of the challenges of using a large industrial centrifuge.  Those are big and they’re heavy and usually we have to send large volumes of water to the lab which is very costly. With this method we end up with just a small jar of sediment that we can ship t the lab for chemical analysis.

[Centrifuge starting and spinning]

Narrator: The centrifuge runs a 10,000 rpm or revolutions per minute and so the water’s continuously flowing into a bowl inside the centrifuge and the sediment gets captured in that bowl that’s spinning and then the, the sediment free water is continuously discharged out the other end of the bowl and so over time we can process thousands of liters of water and collect all the sediment in that water.

One of the advantages of this method is that we are able to analyze chemicals that re bound to the sediment that would otherwise go undetected in a water sample, because these chemicals prefer to be stuck to the sediment rather than dissolved in the water.  Without measuring what’s on the suspended sediment we might be underestimating how many chemicals are there and therefor underestimating the exposure of salmon, of shellfish, of other organisms to these chemicals.

What we hope to provide our cooperators is an improved estimate of how much sediment is being transported by the river to the lower Duwamish Waterway Superfund Site and what chemicals are being loaded with that sediment and hopefully because it’s small and light weight and portable it can be incorporated into water quality monitoring programs and provide new information about sediment bound chemicals.

[Music]

[Metal Door Closing]

[Combination lock clicking  ]