Environmental problems – An overview - Environmental Deterioration and Contamination: Problems and their Management - page 11

and adaptation of the microbiota. The current soil microflora is able to degrade
thousands of xenobiotics, persistent and toxic chemical substances by producing
energy from them or through co-metabolic pathways. The decline in diversity,
which is the main warning sign of our current environmental problems, is a rela-
tive term. So many species never have lived together on earth, as today, but this
does not preclude the fact that many of the sensitive or noncompetitive species are
extinct, which may or may not influence the metagenome and the functions of the
ecosystem.

- The rate of the accumulation of organic matter in the environment, primarily

in the soil, decreases the balance between mineralization and humus formation
or fossilization is shifted toward mineralization. The humus content is gradually
decreasing in the soils, which can be inferred by the fact that the soil type of
moder humus was widespread in the Jurassic period, but later on the less humus
containing mull type soils dominated, and today the tropical soils have practically
no humus content.

- The absolute mass of the elements participating in the biogeochemical cycles is

continuously increasing, and a growing part of the biogenic elements is built into
the living organisms, meaning that the earth's surface may become depleted in the
same elements. The supply of the surplus is carbonate rocks (C), sulfide minerals
(S), the atmosphere (N), etc.

- An increasing part of the elements is under biological control and as the biomass

production and degradation are efficient and well synchronized, the cycle time of
element cycling becomes shorter and shorter.

- The biomass production needs solar energy incorporation (chemically a reduction

type reaction) and biomass degradation (mineralization). Energy transport is faster
when compared with element cycling.

- The efficiency of the capture and conversion of solar energy is gradually increasing.

Here, the biosphere works as an energy pump. A more complex canalization of
energy enables a more efficient and community-level energy utilization. Amongst
microorganisms, the aerobic ones which have the best energy utilizing ability are
dominant.

- Productivity of the biosphere is continuously growing. This is not only because of

shorter cycle time, but also because of the genetic perfection of the biota. Species
benefiting from a more efficient utilization of the solar energy have an advan-
tageous position in the communities and may be active at formerly noninhabited
locations, such as the poles and low-quality habitats. Productivity is not only man-
ifested in growing quantity and efficiency, but also in increasing the diversity of
the biosynthesized molecules.

- Species diversity has been continuously growing during the geological ages. The

current species count on earth is about 2 millions. Such a great number of species
ensures functional stability and safety in the global ecosystem. This stability
is endangered by environmental stress which causes a decline in diversity and
unfavorable changes in the ecosystem structure.

- Genetic and biochemical evolution and diversity of the microorganisms have

been accelerated by chemical stress, the increased number and concentration of
contaminants in the environment, resulting in the emergence of new genes and
flexible mechanisms to disseminate these beneficial new genes (jumping genes,