256
Use of Radioisotopes to Study Biogeochemical Cycling of Elements
A
B
Fig. S.l2A,B. Rate of sulfate reduction
H,m 0
3
6
9 12
0
2
4
6
8
(As. flg S I-I day-I) in water column of
0
0
meromictic basins. A Mountain Lake
10
Ger Gel (Caucasus). B Black Sea; Hm
depth, m; hatched stupe in water column
400
- position of zedox zone
20
800
1200
60
1600
zZ
' " ,
>lVh >lWhVh
Vh z
bottom
bottom
objective. The same 35SO/- reduction experiments are performed in this case
with and without the organic substrate (+sulfate, if necessary) added to the
parallel samples. In this case, the increased sulfate reduction rates in samples
with the added organic substrate, being estimated during short-term incubations of some 1O-20h, will be determined by the abundance of active sulfatereducing bacteria in corresponding samples. As substrate Ca-lactate or ethanol
are used, added as portions of about 0.5-1 g dm- 3 of silt or 0.1-0.3 g 1-1 of water.
A comparison of the radioactivity of sulfides (R;) measured after such an
experiments, made in the series of samples taken on vertical profiles of water
or sediment column, indicates the layers harboring the active communities of
sulfate-reducing bacteria.
5.7 Study of the Dynamics of Phosphorus
5.7.1 General Remarks
Besides nitrogen, phosphorus is a key nutrient which controls the level of
primary production and, consequently, the functional activity, structure, and
productivity of aquatic ecosystems (Pomeroy 1970; Dugdale 1976). From this
aspect, phosphorus is even more important than nitrogen as a nutrient,
because its depletion cannot be replenished by biological fixation from the
atmosphere, while inorganic phosphate can be replenished only during regeneration by animals or by physical transport from the aphotic up to the photic
zone or from its external sources. The key role of phosphorus in controlling
the processes of biological productivity and the secondary eutrophication of
water basins has received due attention from scientists and managers. The
monitoring of inorganic phosphorus (P04-P) standing stock was respected as
Use of Radioisotopes to Study Biogeochemical Cycling of Elements
A
B
Fig. S.l2A,B. Rate of sulfate reduction
H,m 0
3
6
9 12
0
2
4
6
8
(As. flg S I-I day-I) in water column of
0
0
meromictic basins. A Mountain Lake
10
Ger Gel (Caucasus). B Black Sea; Hm
depth, m; hatched stupe in water column
400
- position of zedox zone
20
800
1200
60
1600
zZ
' " ,
>lVh >lWhVh
Vh z
bottom
bottom
objective. The same 35SO/- reduction experiments are performed in this case
with and without the organic substrate (+sulfate, if necessary) added to the
parallel samples. In this case, the increased sulfate reduction rates in samples
with the added organic substrate, being estimated during short-term incubations of some 1O-20h, will be determined by the abundance of active sulfatereducing bacteria in corresponding samples. As substrate Ca-lactate or ethanol
are used, added as portions of about 0.5-1 g dm- 3 of silt or 0.1-0.3 g 1-1 of water.
A comparison of the radioactivity of sulfides (R;) measured after such an
experiments, made in the series of samples taken on vertical profiles of water
or sediment column, indicates the layers harboring the active communities of
sulfate-reducing bacteria.
5.7 Study of the Dynamics of Phosphorus
5.7.1 General Remarks
Besides nitrogen, phosphorus is a key nutrient which controls the level of
primary production and, consequently, the functional activity, structure, and
productivity of aquatic ecosystems (Pomeroy 1970; Dugdale 1976). From this
aspect, phosphorus is even more important than nitrogen as a nutrient,
because its depletion cannot be replenished by biological fixation from the
atmosphere, while inorganic phosphate can be replenished only during regeneration by animals or by physical transport from the aphotic up to the photic
zone or from its external sources. The key role of phosphorus in controlling
the processes of biological productivity and the secondary eutrophication of
water basins has received due attention from scientists and managers. The
monitoring of inorganic phosphorus (P04-P) standing stock was respected as