Van Veen grab sampler: Difference between revisions
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{{short description|Instrument to sample sediment in water environments}} |
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[[File:BrnBld VanVeenGrabSampler.svg|thumb|Silhouette of a '''Van Veen Grab Sampler''']] |
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| ⚫ | The '''Van Veen |
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[[File:Van Veen.svg|thumb|Closed Van Veen grab sampler]] |
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| ⚫ | The '''Van Veen grab sampler''' is an instrument to sample [[sediment]] in water environments. Usually it is a [[Excavator bucket|clamshell bucket]] made of [[stainless steel]]. Up to 20 [[Centimetre|cm]] deep samples of roughly 0.1 [[m^2|m<sup>2</sup>]] can be extracted with this instrument. It can be light-weight (roughly 5 [[kg]]) and [[low-tech]]. The smallest version even fits into [[hand luggage]]. The sampler<ref>{{cite book |last= Van Veen|first= Johan|date= 1936 |title= Onderzoekingen in de hoofden in verband met de gesteldheid van de Nederlandsche kust |trans-title= Research in the Dover Street in relation to the status of the Dutch coast|url= https://resolver.kb.nl/resolve?urn=MMKB06:000002099:00239 |language= NL|location= Den Haag|publisher= Algemene Landsdrukkerij |page=165}}</ref> was invented by [[Johan van Veen]] (a Dutch engineer) in 1933. |
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A draw-back of the use of this sampler is that it tends to disturb the sediments more than a [[box corer]] does. |
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==Mechanism== |
==Mechanism== |
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While letting the instrument down into the water, the two [[lever |
While letting the instrument down into the water, the two [[lever]]s with [[Excavator bucket|buckets]] at their ends are spread like an open scissor. The levers are locked in this position, and unlocked on hitting the ground. When the rope is pulled upward again, the two buckets close and grab a sample from the [[sea floor]].<ref>{{cite book |last= Eleftheriou |first= Anastasios|date= 2013|title= Methods for the Study of Marine Benthos |url= https://www.wiley.com/en-us/9780470995112 |location= |publisher= John Wiley & Sons, Incorporated |page= 199 |isbn= 9781118542385}} </ref> |
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<gallery> |
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File:VanVeenGrab - Locked.jpg|Van Veen grab when it is locked, ready to be lowered to the floor |
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File:VanVeenGrab - Unlocked.jpg|It is now unlocked after hitting the floor, ready to collect sediment |
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File:Van Veen Grab - Close.jpg|When lifting it after unlocked, the jaws will close to collect sediment inside |
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</gallery> |
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Three small technical changes lead to variations with more mechanical parts or structure: |
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* The '''Ekman grab sampler''' does not close the [[shovels]] instantly on ground contact, but a messenger weight has to be sent down in order to release springs and take the sample. |
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* The '''Ponar type sampler''' is modified also and has additional springs which are released upon bottom contact which might be helpful for harder surfaces. |
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* The '''[[Young grab|Young modified grab sampler]]''' includes a metal frame for additional stability. |
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==See also== |
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* [[Epibenthic sled]] |
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==References== |
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{{Reflist}} |
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==External links== |
==External links== |
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[https://www.whoi.edu/ |
* [https://www.whoi.edu/what-we-do/explore/instruments/instruments-sensors-samplers/grab-sampler-van-veen/ Instrument description at Woods Hole Oceanographic Institute] |
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* [http://www.rickly.com/as/bottomgrab.htm Bottom Sediment Grab Samplers] as offered by the [[Rickly Hydrological Company]] |
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[[Category:Aquatic ecology]] |
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[[Category:Biological oceanography]] |
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[[Category:Oceanography]] |
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[[Category:Oceanographic instrumentation]] |
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Latest revision as of 05:34, 30 November 2021
The Van Veen grab sampler is an instrument to sample sediment in water environments. Usually it is a clamshell bucket made of stainless steel. Up to 20 cm deep samples of roughly 0.1 m2 can be extracted with this instrument. It can be light-weight (roughly 5 kg) and low-tech. The smallest version even fits into hand luggage. The sampler[1] was invented by Johan van Veen (a Dutch engineer) in 1933.
A draw-back of the use of this sampler is that it tends to disturb the sediments more than a box corer does.
Mechanism
[edit]While letting the instrument down into the water, the two levers with buckets at their ends are spread like an open scissor. The levers are locked in this position, and unlocked on hitting the ground. When the rope is pulled upward again, the two buckets close and grab a sample from the sea floor.[2]
-
Van Veen grab when it is locked, ready to be lowered to the floor -
It is now unlocked after hitting the floor, ready to collect sediment -
When lifting it after unlocked, the jaws will close to collect sediment inside
Three small technical changes lead to variations with more mechanical parts or structure:
- The Ekman grab sampler does not close the shovels instantly on ground contact, but a messenger weight has to be sent down in order to release springs and take the sample.
- The Ponar type sampler is modified also and has additional springs which are released upon bottom contact which might be helpful for harder surfaces.
- The Young modified grab sampler includes a metal frame for additional stability.
See also
[edit]References
[edit]- ^ Van Veen, Johan (1936). Onderzoekingen in de hoofden in verband met de gesteldheid van de Nederlandsche kust [Research in the Dover Street in relation to the status of the Dutch coast] (in Dutch). Den Haag: Algemene Landsdrukkerij. p. 165.
- ^ Eleftheriou, Anastasios (2013). Methods for the Study of Marine Benthos. John Wiley & Sons, Incorporated. p. 199. ISBN 9781118542385.