biodegradation. Furthermore, the study of Sayara et al. (2010b) revealed a positive
impact of the presence of humic-like substances from organic matter on the degradation of organic contaminants in soil. The humic acids (HAs) surfactant effect
depends on the applied concentration as well as on the present soil conditions.
Depending on the dose and pH value of treated soil mixture, humic acids may
inhibit, enhance, or show no effect on contaminant biodegradation (Liang et al.
2007). The amount of humic acids optimal for enhancement of the degradation
•Increased soil porosity
enhanced air supply
•Increased WHC
maintenance of
humidity
•pH stabilization and
neutralization
•Nutrient supply
•Microbial diversity
enhancement
•Microbial activity
enhancement
•„Catabolic memory”
supply
Soil
microflora
Physicochemical
properties
Mass
transfer
phenomena
Mineralization
Intermediate
metabolite
production
Sorption
Desorption
Decrease
Increase
Volatilisation
Organic matter
Addition to soil
TPH in soil
Biodegradation
Soil toxicity
Fig. 5.4 Processes which occur after addition of pretreated organic matter to soil. Organic matter
improved soil properties and provide wide number of microorganisms including degrading agents.
Humic-like substances present in organic matter helps to desorb weathered contaminants as well
normalize excess concentrations. Abbreviations: TPH total petroleum hydrocarbons, WHC water
holding capacity
260
A. Gielnik et al.