Geoscience Reference
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medicines, additives, food preserving agents, fertilizers) are produced and
used daily. Among these compounds more than 7000 are produced and
commercialized in large quantities. 64-66
In addition, and possibly more important, the diversity of synthesized
chemical compounds increases annually by 500 to 1000 new products. Most
of these new chemical compounds are now being traded internationally on
a large scale. Also important is that for approximately 80% of the total
number of chemical products produced there are no data regarding their
potential toxic effects, for 18% there are incomplete and uncertain data, and
for only 2% do we have a complete database of toxic effects.
This picture is even more complicated if we correlate correct toxicity data.
Much of the waste from the technological processes has a significantly high
risk for human health and that of ecological systems. In industrialized coun-
tries 70% of waste comes from the chemical and petro-chemical industries.
And the risk is even higher in the case of radioactive waste.
Finally, there has been a great amount of data collected (in fact exceeding
a critical mass necessary for an empirical understanding). Although chemical
compounds may not have immediate identifiable effects, there are resounding
long-term effects as a result of accumulation over time. These effects may
endanger the ecological systems as well as the human population.
• It has been recognized that all chemical compounds produced, or resulting as
by-products in technological processes, when released into the “environment”
follow similar pathways for mass movement and cycling similar to natural
chemical elements and compounds. Thus, management of harmful chemical
compounds needs to be promoted with new conceptual and methodological
developments as shown in Figures 2.9, 2.10 , and 2.11 .
2.5
CHALLENGES FOR ECOSYSTEM MODELING
The following has logically emerged from the foregoing design and analysis: This
has a broad formulation instead of being focused only on lagoon systems, to underlie
their applicability to all types of ecological systems (including socio-economic
systems) to again stress existing opportunities and gaps in the operational infrastruc-
ture for sustainability. Some of these are further discussed and applied to lagoon
systems (see following chapters).
According to Jorgensen 67 more than 4000 ecological models have been developed
and used in the last three decades as tools in the research of complex and dynamic
ecological systems or in environmental management. A few years ago, Jorgensen 68
published an excellent book that integrated the best available experience in the field
of ecological modeling, following review of more than 400 models. However, the
power of existing models to describe the complexity and dynamic behavior of different
categories of ecological systems or to explain and give reliable prognoses for specific
environmental problems is still very limited due to the following constraints:
Poor or very poor identification of the particular ecological systems at a
spatial and temporal scale before developing the models. This results in
limited real world assessment.
 
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