Environmental problems – An overview - Environmental Deterioration and Contamination: Problems and their Management - page 6

Figure 1.3 Nutrient and energy fluxes in the ecosystem.
in biofilms (e.g., in corroding surfaces of iron or in a flock of wastewater sludge). The
ecosystems of waters, soils, and sediments may vary in size and complexity to a large
extent. Billions of microorganisms may live together with complex trophic structures,
forming local, regional, and finally, the global ecosystem, the whole of the biosphere of
the globe, interacting with the abiotic compartments of the atmosphere, hydrosphere,
and lithosphere.
The global ecosystem is an open system. Its main intake is the solar energy, to
a smaller extent geothermic energy and the element sources in the lithosphere (C, S,
metals, semimetals) and the atmosphere (N). The fluxes between atmosphere, litho-
sphere, and biota are shown in Figure 1.3. Energy and material intakes are utilized by
the subecosystems. The final outputs are heat and metabolic end products. Outputs
control inputs by negative feedback, stopping decline from the ideal balance. Positive
feedback is also present in the ecosystems, stressing the decline from an ideal state by
continuously increasing the production, the efficiency of energy utilization, and the
velocity of element cycling. The result is not a constant state but a constant trend in a
direction which may ensure higher efficiency, flexibility and adaptability. The ecosys-
tem should find its stability in this continuously changing system, ensuring a so-called
homeostatic plateau which means a well-balanced situation between the population