Experimental systems in agrochemicals-contaminated soils phytoremediation research

MERINI, LJ; CUADRADO, V; GIULIETTI, AM

Handbook of Phytoremediation

Nova Science Publishers

Lugar: Hauppauge ; Año: 2011; p. 667 - 690

Contamination of soil and water has overcome as an environmental problem along with the increase of human activities. Among the main pollutants involved, agrochemicals are of major concern, since millions of tons are applied every year for crops and forestry, expecting than nature takes care of them. Despite there are many effective physical-chemical methods for soil and water decontamination, the application cost of such techniques and the wide extension of moderately polluted areas make them inappropriate. In this context, phytoremediation has arisen as an environmental friendly, low cost and effective alternative for this kind of pollution. Nevertheless, the effectiveness of the process depends on the particular characteristics of the soil, the contaminant and the environmental conditions and their interactions, which makes phytoremediation a site-specific technology. The field-scale applicability of the results obtained at lab research mainly depends on the accuracy of the selected experimental system. In this way, there are two divergent positions: on one hand, a simplified system (cell cultures, organ cultures, hydroponics) where the variables are reduced at minimum and fully controlled, gives precise information about the mechanisms involved in the remediation process. On the other hand, a complex experimental system (microcosms) gives information closely related to real scale, but having less control over the experimental variables involved. We have designed and optimized experimental systems of different complexity for studying phytoremediation of soils contaminated with agrochemicals. Azinphos–methyl, 2,4-dichlorophenoxyacetic acid, 2,4-dichlorophenoxybutyric acid and atrazine were selected since they are among the most controversial agrochemicals, because of their toxicity and potential as environmental pollutant. In the designed experimental systems, the biodegradation potential of model and novel tolerant plant species and their influence on soil microflora was observed. At the same time, the systems were used to investigate the mechanisms involved in plant tolerance to herbicides. The soil, contaminant, microflora and plant interactions observed in lab scale experiments and the degradation profiles of the different agrochemicals will be discussed. Conclusions about the influence of experimental system complexity on mechanisms elucidation and reliability of the scaling-up will be presented.