Lecture № 2,3 The stability of ecosystems and their resistance to contamination

The concept of ecosystem resilience The stability of natural biological systems (population, or biocoenosis) should understood as the ability for many generations continuously preserve the natural structure and function in a dynamic equilibrium with the environmental changes and the ability to repair itself after structural disturbance due to external influences

Ecosystem - an open, self-regulating and self-developing system Provided by: resistant relationships between their components (community of organisms and abiotic components); trophic relationships and energy; variety of organisms that perform the same function, but occupy different ecological niches; permanent self-reproduction of populations, the capacity for evolution of species and microevolution of populations Rapid adaptation to environmental changes

The biosphere natural unit principles Stability of populations Сirculation of substances Сirculation of substances The pyramid of energy The pyramid of energy Adaptability of species

Features of natural and man-made ecosystems Homeostasis - population or ecosystem ability to maintain stability in a changing environment Under natural conditions: variability of ecosystem continuing violation of equilibria fluctuations in population size due to internal and external influences, interactions of different species The stability of ecosystems: individual physical, chemical and biological balance stability of mass and energy exchange process, stability of matter and energy cycles

The stability of ecosystems ability to return to its original state after the system was derived from an equilibrium state Stable mobile equilibrium: old relationships are renewed more rapidly, the duration of the resumption depends on the violations scale and on the specific system properties Unstable equilibrium: series of changes begin to develop rapidly and irreversibly even for small violations of existing relationships in natural systems. Self Regulating Systems

resistant stability - the ability to remain in the steady state under the load elastic resistance - the ability to recover quickly Three degrees of ecosystems’ deviation from equilibrium under the external factors: stress - the composition of biological communities is practically unchanged, the structure is changed significantly, there is a redistribution of species as a function of the dominant degree; resistant state - is sharply reduced species diversity and the changing composition of the community; resistant to the external factor population develop; this condition is characterized by the biomass stability of the total organisms community; repression - the complete suppression of the organisms’ development

Resistant and resilient ecosystem sustainability Ecosystem functioning ecosystem disturbance range of normal operation overall ecosystem sustainability measure resistance measure of elasticity

Biogeochemical Cycles Circulation of gases in which the atmosphere is the main reservoir of elements and compounds: C, N and H2O. Sedimentary cycle of elements (sedimentary cycle) that is the part of the sedimentary rocks: P, S (elements circulate through erosion, sedimentation, mountain building and volcanic activity, biological transfer) cycling of matter that make up the pollution: Hg, Pb, (90)Sr - analogue Ca, (137)Cs - similar to K, pesticides

The mechanism of carbon transformation under aerobic conditions: all substances of biological origin is completely or partly oxidized (to CO2 and H2O) under anaerobic conditions: natural biopolymers (proteins, nucleic acids, carbohydrates, lipids, waxes, compounds with aromatic structures, vitamins, toxins can be partially transformed into reduced carbon compounds (oil, coal) or degraded to carbon dioxide and methane

Biogeochemical cycle of toxicants destructive processes decomposition and mineralization of biochemical synthesis products, transformation; mineralization of chemical synthesis products

Mechanisms of biological oxidation microorganisms Microorganisms (biomass) non-oxidizing organic solutes Heterotrophic oxidation Autotrophic oxidation (nitrification) biologically indestructible part of the cell substance

Participating groups of bacteria : a - enzymatic acidogenes, b- acetogenes forming H2, c- acetogenes using H2 d- methanogenes, reducing CO2, f - methanogenes using acetate

Nitrogen cycle the nitrogen cycle takes place in the atmosphere, lithosphere and hydrosphere. Majority (in the form of N2) is concentrated in the atmosphere (75.6%) Part is dissolved in the sea water; In the form of dissolved ammonium, nitrite and nitrate ions - nitrogen presents in the organic matter and in the soil

Involvement of nitrogen in the natural cycle Abiotic processes for capturing - lightning, damaging of UV rays, burning, (no more than 10-20% of fixed nitrogen); Biological transformation involving inorganic nitrogen metabolism - nitrogen fixation, assimilation, ammonification, nitrification, denitrification - a vicious cycle that has no any effect on the atmosphere

Biological nitrogen cycle

Sulfur cycle composed of various inorganic and organic compounds; in the form of deposits of sulfide minerals - breakdown products of parent rocks; on the surface as brimstone; in the air as SO2, H2S, sulphate aerosols

Deposition of sulfur sulfur cycle, as well as all the biogeochemical cycles is not closed completely, including reducing and oxidizing processes accumulation of excess weight of sulfur in the hydrosphere, and atmosphere pedosfere doesn’t happen excess of sulfur is removed in the form of iron sulfides (hydrotroilite, pyrite, marcasite), at the bottom of the oceans and seas, as well as soluble calcium sulfate, and magnesium)

Sulfur in transit environments at the top, aerobic water column: biogenic hydrogen sulfide forming due the reduction processes, is oxidized by chemical or biological ways; in the atmosphere: hydrogen sulfide quickly (within 2 days) is oxidized to SO2, further to SO3 (under the influence of oxygen on the dust particles of metal oxides (catalysts) or particles of moisture under the influence of sunlight, with the further formation of sulfuric acid); transit: highly soluble sulfates and acid washed out of the atmosphere and migrate into the aquatic environment; in water under the action of sulfate reducing bacteria pass into the soluble sulfides, which are accumulated in the sediments

Sulfur conversion in soils sulfur undergoes chemical and biochemical changes going from inorganic to the organic form and back; Part of the sulfur is assimilated by plants and microorganisms in the form of sulfates; hydrogen sulfide is formed under sulfate reduction processes and the as the result of decaying and decomposing processes

Aerobic Zone (aerobic chemolithotrophic sulfur bacteria, thione, thermoacidophilic bacteria) Aerobic Zone (aerobic chemolithotrophic sulfur bacteria, thione, thermoacidophilic bacteria) Anaerobic Zone (photosynthetic bacteria) Thione bacteria and sulfur bacteria are permanent residents of waste water containing can reduce content of sulfur compounds (mercaptans, dimethyl sulfide, etc.) elementary sulfur, sulfates Microbial sulfur oxidation in nature