2 The Biogeochemical Theatre - Phosphorus
Cycling and Phosphorus Household in Lakes
For the drama of life is like a puppet show in
which stage, scenery, actors and all are made
of the same stuff. ... and if we would catch
the spirit of the piece, our attention must not
be absorbed in the characters alone, but must
be extended also to the scene, of which they
are born, on which they play their part, and
with which, in a little while, they merge
again.
Alfred James Lotka (1925)
Except for certain arid regions where lakes lose water only by evaporation,
lakes are open flow-through systems whose content of a given element is
determined by the dynamic balance between supply through the inflows,
loss through the outflows, and internal sources and sinks. At sufficiently
long timescales, the lake content of a given element tends to an equilibrium
depending on the properties of both the lake and its catchment area. For
dissolved substances that are unaffected by biological transformations
(conservative elements), inflows and outflows can be different only in transient situations such as after a change in input concentration.
For mineral nutrients like Nand P, net uptake by phytoplankton and
subsequent transfer through the food web will deplete the concentration of
dissolved chemical species in the recipient water, so that dissolved nutrient
concentration in the inflows is always likely to exceed that in the water
body. The biological transformation from a dissolved to a particulate state
also makes the fate of nutrient atoms to be influenced by the force of gravity, thus increasing the probability of an atom being lost from the water
column and permanently buried in the sediments. The retention of mineral
nutrients in lakes has important effects on the dose-response relationship
between nutrient loading and lake nutrient content, and is therefore considered a key element in the kind of nutrient mass-balance models that are
commonly used in water quality management.
Cycling and Phosphorus Household in Lakes
For the drama of life is like a puppet show in
which stage, scenery, actors and all are made
of the same stuff. ... and if we would catch
the spirit of the piece, our attention must not
be absorbed in the characters alone, but must
be extended also to the scene, of which they
are born, on which they play their part, and
with which, in a little while, they merge
again.
Alfred James Lotka (1925)
Except for certain arid regions where lakes lose water only by evaporation,
lakes are open flow-through systems whose content of a given element is
determined by the dynamic balance between supply through the inflows,
loss through the outflows, and internal sources and sinks. At sufficiently
long timescales, the lake content of a given element tends to an equilibrium
depending on the properties of both the lake and its catchment area. For
dissolved substances that are unaffected by biological transformations
(conservative elements), inflows and outflows can be different only in transient situations such as after a change in input concentration.
For mineral nutrients like Nand P, net uptake by phytoplankton and
subsequent transfer through the food web will deplete the concentration of
dissolved chemical species in the recipient water, so that dissolved nutrient
concentration in the inflows is always likely to exceed that in the water
body. The biological transformation from a dissolved to a particulate state
also makes the fate of nutrient atoms to be influenced by the force of gravity, thus increasing the probability of an atom being lost from the water
column and permanently buried in the sediments. The retention of mineral
nutrients in lakes has important effects on the dose-response relationship
between nutrient loading and lake nutrient content, and is therefore considered a key element in the kind of nutrient mass-balance models that are
commonly used in water quality management.