106
3
Quantification of Early Diagenesis: Dissolved Constituents in Marine Pore Water
Lander Systems
In some very shallow waters the in situ measurement at the sediment/bottom water boundary
might be achieved from a ship, or by using light
diving equipment. However, so-called ‘Lander
systems’ have been developed for applications in
greater depths and, above all, in the deep sea.
Lander systems are deployed from the ship and
sink freely, without being attached to the ship,
down to the ocean floor where they softly ‘land’.
Standing on the bottom of the ocean they
conduct measurements (profiles with microelectrodes), experiments (in situ incubations), and/or
remove samples from the sediment or the bottom
water. When the designated tasks are completed,
ballast is released and the whole system emerges
back to the surface to be taken on board.
The lander technique described above is,
especially in the deep sea, more easily outlined in
brief theory than to put into operation, as the involved workers need to invest a considerable
amount of construction effort and operational
experience in the lander systems so far used.
The problems which cannot be discussed here
in detail consist of, for example, deploying the device into the water without imparting any damage
to it, conducting the subsequent performance of
sinking and landing at the proper speed, keeping
the lander in a proper position, recording and
storing the measured values, the timing of ballast
release and thus applying the correct measure of
buoyancy all the way up to the ocean’s surface,
and finally, the lander’s retrieval and ultimate
recovery on board of the ship. The correct performance of the in situ measurements is not even
mentioned in this enumeration. In Figure 3.19
such an appliance is shown according to Jahnke
and Christiansen (1989) which is very similar to
the lander used by Gundersen and Jørgensen
(1990) as well as Glud et al. (1994). A survey and
comparative evaluation of 28 different lander
systems is given by Tengberg et al. (1995) who
also delivers an historical account on the development of landers. One of the first publications
Fig. 3.20 Construction of an oxygen electrode equipped with a Guard-cathode (after Revsbech, 1989).
Oxygen microelectrode
Shaft of
sensing cathode
Epoxy
Silver wire cathode
Ag/AgCl anode
Soda-lime glass
Electrolyte
Schott 8533 glass
Platinum wire
1 cm
Microelectrode tips
Guard Silver
cathode
Platinum
Schott 8533
glass
Sensing gold
cathode
Silicone rubber
membrane
10 µm
3
Quantification of Early Diagenesis: Dissolved Constituents in Marine Pore Water
Lander Systems
In some very shallow waters the in situ measurement at the sediment/bottom water boundary
might be achieved from a ship, or by using light
diving equipment. However, so-called ‘Lander
systems’ have been developed for applications in
greater depths and, above all, in the deep sea.
Lander systems are deployed from the ship and
sink freely, without being attached to the ship,
down to the ocean floor where they softly ‘land’.
Standing on the bottom of the ocean they
conduct measurements (profiles with microelectrodes), experiments (in situ incubations), and/or
remove samples from the sediment or the bottom
water. When the designated tasks are completed,
ballast is released and the whole system emerges
back to the surface to be taken on board.
The lander technique described above is,
especially in the deep sea, more easily outlined in
brief theory than to put into operation, as the involved workers need to invest a considerable
amount of construction effort and operational
experience in the lander systems so far used.
The problems which cannot be discussed here
in detail consist of, for example, deploying the device into the water without imparting any damage
to it, conducting the subsequent performance of
sinking and landing at the proper speed, keeping
the lander in a proper position, recording and
storing the measured values, the timing of ballast
release and thus applying the correct measure of
buoyancy all the way up to the ocean’s surface,
and finally, the lander’s retrieval and ultimate
recovery on board of the ship. The correct performance of the in situ measurements is not even
mentioned in this enumeration. In Figure 3.19
such an appliance is shown according to Jahnke
and Christiansen (1989) which is very similar to
the lander used by Gundersen and Jørgensen
(1990) as well as Glud et al. (1994). A survey and
comparative evaluation of 28 different lander
systems is given by Tengberg et al. (1995) who
also delivers an historical account on the development of landers. One of the first publications
Fig. 3.20 Construction of an oxygen electrode equipped with a Guard-cathode (after Revsbech, 1989).
Oxygen microelectrode
Shaft of
sensing cathode
Epoxy
Silver wire cathode
Ag/AgCl anode
Soda-lime glass
Electrolyte
Schott 8533 glass
Platinum wire
1 cm
Microelectrode tips
Guard Silver
cathode
Platinum
Schott 8533
glass
Sensing gold
cathode
Silicone rubber
membrane
10 µm