Mediation of waste and toxins

Mediation of waste and toxins is an ecosystem service whose function is based on the ability of micro-organisms to neutralize potentially harmful substances in soil and ground water.

There are several naturally occurring compounds, which may be harmful for organisms if their concentrations reach a certain level. Some compounds are products of metabolism in organisms, and others are produced by abiotic processes, e.g. ruptures of volcanos.

By the effect of natural selection organisms have adapted to certain levels of natural toxicants and developed metabolic mechanisms to reduce harmful effects of harmful compounds. E.g. bacteria and fungi have complex enzyme mechanisms for decomposing organic compounds and they are crucial for regulating levels of potentially harmful compounds in terrestrial and aquatic environments. Meso- and macrofauna are part of the regulation services, because they improve the habitats of terrestrial bacteria and fungi and act as balancers in soil ecosystems.

Besides the biotic processes, compounds are composed and decomposed by abiotic physical- chemical processes. The most important regulators of these environmental processes are moisture, acidity and temperature. Because natural processes regulate the levels of potentially harmful compounds, their concentrations do not reach effective levels usually, unless there are some kind of disturbances.

Contamination of soils and water systems may be caused by discharges and emissions produced by industry and households or leaking chemical storages. Other common contaminant sources are worn petrol tanks in old gas stations and illegal dumps.       

Terrestrial microbes and fungi are able to decompose hydrocarbons constituting only hydrogen and coal with moderate effort, but hydrocarbons containing e.g. chlorine degrade slower, because the process demands anaerobic conditions and all bacteria strains haven’t developed enzymes to break chlorine bonds. Generally speaking, the closer the structure of synthetic hydrocarbon compound is to naturally occurring compounds, the more likely the bacteria have enzymes to degrade it. However, there are exceptions to this rule.

 

References:

Paul A.E. (2015): Soil Microbiology, Ecology and Biochemistry. 4th edition.

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