MAP Technical Reports Series No. 106 UNEP

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Cycle B: refers to aspects that relate to human ie the socio-economic environment,
within which eutrophication is perceived as a problem that affects, either directly or indirectly,
the socio-economic activities and interests of the resident population, and within which decisions
are made.
While these two outlooks are often treated as distinct (the scientific aspects addressed
separately from the socio-economic involving two communities, scientists versus
administrators/politicians), they must be linked as soon as large scale remedial interventions are
at stake. Whether these are technological, or administrative, the matter at this point becomes
inevitably political and requires a model different from that discussed in Chapter 3, ie a
consolidated integrative model. This is the meaning of the two cycles (A and B).
The scientific/technological aspects that relate to cycle (A) have been discussed in
details in previous chapters of this report. Little instead has been said about the second aspect.
With regard to the first it is important to recognize a) that there are conditions and processes
external to the system, which cannot be altered at all (e.g., meteo-climatic conditions; natural
background supply of nutrients from the drainage basin); b) that the critical points of possible
attack by which the system processes can be manipulated are essentially only three:
- control at source,
- interventions along the transitional paths,
- interventions into the receiving water body.
Each of these major points of attack involve different approaches that are defined by
the properties of the physical system, and by the available technologies and resources.
With regard to the second aspect, it is further important to recognize that the decision
to do something about eutrophication, and if so, that the actual choice between options, will not
be determined by science alone, but will rather depend on the degree of societal perception of
the problem, i.e., the kind of damages and its seriousness in terms of socio-economic activities,
as well as on the perceived intent of intervention, i.e., the purpose, and scope to be achieved
dealing with the problem. In practice, as with any societal problem that requires solution, the
choice between technologically and administratively feasible options is primarily driven by the
cost/benefit ratio connected with each particular type of intervention versus the expected gains.
If carried out correctly, the evaluation process that considers all the available
alternatives, and in which, both scientists and administrators/politicians are involved, will have
to run repeatedly through cycle (B), whereby for each alternative the potential effect on cycle (A)
is to be evaluated. The final selection will then be determined by the c/b ratio that is considered
optimal in terms of societal expectations. Clearly, the selected alternative will not always be that
of the highest c/b ratio; in the contrary most often it is not. Also, the optimal ratio is rarely defined
by one unique technological option, but rather by a judicious mix of different
technological/administrative options, each one with its own c/b ratio. It must be noted that the
c/b ratio includes also time, i.e., the time to realize the intervention, and most importantly, the
time that lapses between implementation and the time when benefits will materialize.
Taking as example the reduction of the phosphorus load: this may involve reduction at
source (e.g., reduction of polyphosphates in detergents; relatively rapidly to achieve by
industries, and indeed already implemented in many countries), precipitation of phosphorus