The Modified Hesslein In-situ Pore Water Sampler,
also called a "peeper" or dialyzer is based on the
principle that given enough time, a contained
quantity of water in the sampler will diffuse and
equilibrate through dialysis membrane, or other
materials such as porous TEF, with the
surrounding water and its dissolved solutes. The
in-situ equilibrator can either be removed to the
surface or the pore water can be collected through
attached tubing while the device remains in the
sediments.
This sampler is made of two sheets of acrylic
plastic (a 0.3 cm thick cover sandwiched with a 1.3
cm thick body) that are held together by screws.
Horizontal, elongated sampling compartments are
machined 1 cm apart, through the 0.3 cm cover and
into the acrylic body. Different types of dialysis
membranes are used with these samplers. The membrane
is usually pierced with a syringe needle when
sampling pore water. Options are 0.2 µm pore size
polycarbonate membranes, biologically inert PVC
membranes with 0.45 µm pore size and 3 µm TEF.
A nonporous 75 µm (3 mil TEF) membrane would
allow for diffusion of gases but not ionic chemical
species into the sampling compartments.
603-132 Sampler, Pore,
In-Situ, TEF 3
lbs.
603-135 Sampler, Pore,
In-Situ, Acrylic 3
lbs.
