Showing papers by "María Cristina Diez published in 2010"

Biological aspects involved in the degradation of organic pollutants

Abstract: Worldwide use of pesticide has increased dramatically during the last two decades. As a consequence, pesticide residues and their transformation products are frequently found in groundwater and surface waters. This review summarizes information about polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), some chlorophenols; it mainly empathizes on pesticides, their incorporation into the environment, microorganisms involved in their degradation and, some physicochemical aspects of pesticides behavior in soils. Details about residues of pesticides in groundwater and superficial water found in some foreign countries and in Chile are reported, as well. The fungal degradation of organic pollutants (xenobiotics) is considered as an effective method to remove these pollutants from the environment by a process which is currently known as bioremediation. Therefore, the degradation of pesticides by soil microorganisms with particular attention to white-rot fungi is also addressed. Finally, a simple and effective system (biobed) to minimize environmental contamination from pesticide manipulation, especially when filling the spraying equipment, a typical point source of contamination, is presented here.

Biostimulation of agricultural biobeds with NPK fertilizer on chlorpyrifos degradation to avoid soil and water contamination.

Abstract: Degradation of the insecticide chlorpyrifos (160 a.i mg kg -1 ) using a biomix of a biobed system biostimulated with inorganic fertilizer (NPK) was investigated. Three concentrations of the fertilizer (0.1%, 0.5% and 1.0% ww -1 ) were evaluated on chlorpyrifos degradation, TCP (3, 5, 6-trichloro-2-pyrinidol) accumulation and biological activity of the biomix. The chlorpyrifos was dissipated efficiently (>75%) after 40 days of incubation and no additional dissipation was obtained with increasing concentration of NPK after 20 days of incubation. TCP accumulation occurred in all evaluated NPK concentrations and its concentration increased with the increment of NPK addition raising the probability of leaching of this compound. Biological activity (FDA and ligninolytic enzyme activity) in the biomix increased by the NPK presence in all evaluated concentrations. The DGGE analyses showed that combined treatments with lower amounts of NPK (0% and 0.1%) and chlorpyrifos showed no significant modifications in the microbial community in the biomix. However, combined overdoses of NPK (0.5 and 1.0%) and chlorpyrifos caused significant modifications in the bacterial communities that could be associated with TCP degradation reduction in the biomix. In conclusion, the obtained results demonstrated that the biomix prepared with Andisol and biostimulated with NPK nutrient can be recommended in biobeds as a viable alternative of chlorpyrifos dissipation avoiding soil and water contamination probability.

Use of sludge from kraft mill wastewater treatment as improver of volcanic soils: effect on soil biological parameters

Abstract: Sludge from kraft mill wastewater treatment was applied on two soils derived from volcanic ashes and, the effect on biological parameters of the soils was evaluated. The soils used in this study were an Andisol belonging of Gorbea Series and an Ultisol belonging of Collipulli Series. The sludge was added at rates of 0, 10, 20, 30 and 50 t ha -1 . Previously, germination of red clover (Trifolium pratense), white clover (Trifolium repens), alfalfa (Medicago sativa) and ryegrass (Lolium perenne) was tested to assess phytotoxicity of the sludge. The different soil-sludge mixtures were incubated at controlled temperature for 60 days and microbial respiration, microbial biomass carbon, fluorescein diacetate hydrolysis and acid phosphatase activity were evaluated throughout the incubation time. All biological parameters evaluated were sensitive enough to shown the effect of sewage sludge application on soil microorganisms. The sludge application at different rates increased significantly (P<0.05) the microbial activity and enzymatic activity of the sludge amended soils. The maximum levels of activity were observed between 15 and 30 days after sludge application in both Gorbea soil and Collipulli soil, obtaining the highest values when were applied between 30 and 50 t ha -1 . The results of this study suggest that sludge from kraft mill wastewater treatment may have potential as a beneficial soil amendment for improving biological properties of the soils.