| method | Pore water is sampled directly from sediment using rhizon soil moisture samplers (artificial root). The sampler is connected to a standard syringe using luer-lock fittings and PVC tubing. Evacuating the syringe by drawing the piston is sufficient to withdraw filtered porewater from marine sediments. |
| setup | 
|
| sampling rate | approx. 2 mL / 20 min for a 50 mm length sampler in marine sediment with the setup as above. Sample flow rate may be enhanced by using greater filter length and better vacuum. |
| pore size | 0.15 µm mean (0.2 µm max.) |
| filter dimensions | diameter 2.5 mm x 50 mm length, other sizes and materials available |
| filter material | microporous tube (0.15 µm pore width) supported by a glassfiberepoxy (SS316), nylon or stainless steel wire. (titanium wire on special request) |
| dead volume | less
than 0.3 mL (70 to 100 µL membrane) |
| advantages | direct
pore water sampling. no extra filtering needed since the sampler has a 0.15 µm pore width. no wet sediment has to be sampled and squeezed or centrifuged. only a small hole in the sediment is left after sampling. pore water sampling is even possible through liner caps or through liner wall of closed cores by drilling a 2.5mm hole and pushing the Rhizon sampler in. |
| 50
mm Rhizon sampler connected to standard 2 mL syringe this is an old picture with male connector rhizon and a female female adapter to connect syringe. We now use 19.21.23 F Rhizon CSS 5 cm rhizons with female adapter (blue) that connect directly to the syringe. |
 |
| pore water yield (approx. 0.5 mL) after 5 minutes. Vacuum is kept by distance piece attached to syringe piston |  |
|
pore water sampling from closed plastic liner with water saturated marine sediment by drilling 3.8mm holes and gently inserting rhizon pore water samplers. Sampling with disposable 20 mL syringes. Syringe holds vacuum by keeping plunger in place with wooden spacer. Rhizons are 5cm flat tip 19.21.23 F Rhizon CSS rhizons with female adapter (blue). When
you stick rhizons into sediment, be sure to hold the
tube together with the supporting fiberglass stick
firmly between your fingers and thumb ! Do not push the
rhizon from the connecting tube between porous part
(white) and tubing (transparent) before the rhizon is
fully in the sediment. If
sediment is stiff or sandy, use a 2.5mm stainless steel
or plastic stick (knitting needle works) to prepare a
hole. the OD
of connecting tube is 0.15" or 3.8 mm so it seals
perfectly in a 3.8mm hole |
|
| pore
water sampling from the open core (gravity corer) 5 cm Rhizon CSS with female luer adapter connected to a 10 mL disposable syringe. The vacuum is kept by a wooden spacer that holds the plunger Rhizons come with a light blue cap on the luer connector to keep the connector clean. You have to take this cap off !! Otherwise there is no flow!! The caps are perfect to close the syringes after sampling. |
 |
| tipps |
For
the application above we use a special flat tip version
of the Rhizones( Rhizon
CSS - Core Solution Sampler), where tip diameter =
porous tubing diamter, so the contact between sediment
and sampler is very smooth in soft sediments. If
sediment is stiff a hole has to be prepared before
insertion in order to protect the microporous tube from
breaking (i.e. knitting needle of appropiate diameter).
For
all Rhizons add "F" to the order number if you want a
female luer connector (for directly connecting syringe)
instead of the standard male connector
(for connecting needle and vacutube) |
| manufacturer |
Rhizosphere
Research Products |
| also available from | Eijkelkamp Agriresearch (www.eijkelkamp.com) |
| references |
F.W.Meijboom
and M.van Nordwijk (1992): Rhizon Soil
Solution Samplers as artificial roots. In: L. Kutschera
et. al (Eds.): Root Ecology and its practical
Application.- Proc 3rd ISSR Symp., 2.-6. Sep 1991, Wien
Austria; pp 793-795. |
