34
The Radiocarbon Method to Estimate Primary Production
their walls and simultaneously cleans them from any organic contamination
absorbed in their walls during the exposure of samples, because iodine is an
oxidizer. Sterilization of bottles employed for primary production estimations
in the autoclave or dry sterilizator is unacceptable; the walls of the bottles may
absorb the volatile organic matter which is present in such sterilizators, in
which culture media and other organic material are also sterilized. The background CO2 dark assimilation by heterotrophic bacteria can be very high in
bottles sterilized in this way.
To prepare the bottles, previously sterilized with Lugol solution, they are
rinsed twice with water taken from the water body under investigation, to
remove the main portion of iodine remaining. Before the third rinsing, into
each of them one or two drops of 5 % thiosulfate are added, and they are rinsed
another two times with fresh portions of the same water. The water for rinsing
and subsequent filling of bottles should be taken from the water body with a
plastic or enameled bucket. Tap water from the ship water supply system,
either marine or fresh, cannot be used for this purpose as it is usually enriched
with metals and organic contaminants. The bottles are then filled completely
with water, and are ready for use. Before filling with samples, this water is
thrown out, the bottles are rinsed twice with the sampled water and then filled
with the sample. The above procedure for iodine treatment of bottles on continuous use during a cruise must be repeated in tropical waters once every 2-3
days, and in cold and temperate waters once every 4-5 days.
2.3.2.4 Sampling Technique
When measuring the primary production in natural waters, the researcher is
dealing with the functional activity of minute planktonic algae permanently
suspended in the water column. They are not adapted at all to mechanical contacts with solid surfaces, but are very fragile and sensitive to minor changes in
the ambient conditions like the presence of chemical detergents, toxicants,
or heavy metals. This entails special precautions in the quality of materials
selected, the construction of the water bottles, discharging taps, and tubings
used for subs amp ling, as well as in the sampling procedure itself (Price et a1.
1986; Williams and Robertson 1989). The use of metal water bottles for this
kind of sampling can result in a significant inhibition of phytoplankton activity and underestimation of primary production, as also the use of new water
bottles made of Plexiglas vinyl or acrylic plastics, or the use of plastic water
bottles which have metal details or rubber inside them. New water bottles,
especially the Plexiglas ones, should be kept filled with water, periodically
changing it for 1-2 weeks, before use.
The selection of water bottles to be used for sampling depends upon the
kind of water basin. For sampling is shallow freshwater and brackish basins,
the simple Ruttner water bottle with 1-2-1 capacity can be recommended. It
should be manufactured of Plexiglas or polyethylene tubing. Its valves and all
The Radiocarbon Method to Estimate Primary Production
their walls and simultaneously cleans them from any organic contamination
absorbed in their walls during the exposure of samples, because iodine is an
oxidizer. Sterilization of bottles employed for primary production estimations
in the autoclave or dry sterilizator is unacceptable; the walls of the bottles may
absorb the volatile organic matter which is present in such sterilizators, in
which culture media and other organic material are also sterilized. The background CO2 dark assimilation by heterotrophic bacteria can be very high in
bottles sterilized in this way.
To prepare the bottles, previously sterilized with Lugol solution, they are
rinsed twice with water taken from the water body under investigation, to
remove the main portion of iodine remaining. Before the third rinsing, into
each of them one or two drops of 5 % thiosulfate are added, and they are rinsed
another two times with fresh portions of the same water. The water for rinsing
and subsequent filling of bottles should be taken from the water body with a
plastic or enameled bucket. Tap water from the ship water supply system,
either marine or fresh, cannot be used for this purpose as it is usually enriched
with metals and organic contaminants. The bottles are then filled completely
with water, and are ready for use. Before filling with samples, this water is
thrown out, the bottles are rinsed twice with the sampled water and then filled
with the sample. The above procedure for iodine treatment of bottles on continuous use during a cruise must be repeated in tropical waters once every 2-3
days, and in cold and temperate waters once every 4-5 days.
2.3.2.4 Sampling Technique
When measuring the primary production in natural waters, the researcher is
dealing with the functional activity of minute planktonic algae permanently
suspended in the water column. They are not adapted at all to mechanical contacts with solid surfaces, but are very fragile and sensitive to minor changes in
the ambient conditions like the presence of chemical detergents, toxicants,
or heavy metals. This entails special precautions in the quality of materials
selected, the construction of the water bottles, discharging taps, and tubings
used for subs amp ling, as well as in the sampling procedure itself (Price et a1.
1986; Williams and Robertson 1989). The use of metal water bottles for this
kind of sampling can result in a significant inhibition of phytoplankton activity and underestimation of primary production, as also the use of new water
bottles made of Plexiglas vinyl or acrylic plastics, or the use of plastic water
bottles which have metal details or rubber inside them. New water bottles,
especially the Plexiglas ones, should be kept filled with water, periodically
changing it for 1-2 weeks, before use.
The selection of water bottles to be used for sampling depends upon the
kind of water basin. For sampling is shallow freshwater and brackish basins,
the simple Ruttner water bottle with 1-2-1 capacity can be recommended. It
should be manufactured of Plexiglas or polyethylene tubing. Its valves and all