Suchergebnisse

Soils impregnated with creosote contain high concentrations of polycyclic aromatic hydrocarbons (PAH). To bioremediate these soils and avoid PAH spread, different bioremediation strategies were tested, based on natural attenuation, biochar application, wheat straw biostimulation, Pleurotus ostreatus mycoremediation, and the novel sequential application of biochar for 21 days and P. ostreatus 21 days more. Soil was sampled after 21 and 42 days after the remediation application. The efficiency and effectiveness of each remediation treatment were assessed according to PAH degradation and immobilization, fungal and bacterial development, soil eco-toxicity and legal considerations. Natural attenuation and biochar treatments did not achieve adequate PAH removal and soil eco-toxicity reduction. Biostimulation showed the highest bacterial development but low PAH degradation rate. Mycoremediation achieved the best PAH degradation rate and the lowest bioavailable fraction and soil eco-toxicity. This bioremediation strategy achieved PAH concentrations below Spanish legislation for contaminated soils (RD 9/2005). Sequential application of biochar and P. ostreatus was the second treatment most effective for PAH biodegradation and immobilization. However, the activity of P. ostreatus was increased by previous biochar application and PAH degradation efficiency was increased. Therefore, the combined strategy for PAH degradation have high potential to increase remediation efficiency ; This work was financially supported by the Ministry of Science and Innovation of Spain (Project CTM2009-13140-C02-02)

46 páginas, 5 figuras, 3 tablas, 4 tablas suplementarias. -- The final version is available at http://www.elsevier.com ; The spread of organic pollutants from soil to other environments is one important source of environmental pollution. The addition of organic amendments to soil is an interesting strategy to control pollutants leaching. However, the contribution of different carbon types of organic amendments to organic pollutants adsorption is not clear. Hence, the objective of this work was to determine the role of carbon types of organic amendments into the adsorption of four herbicides. To this extent, organic amendments were characterized by elemental analysis and 13C-NMR and adsorption–desorption isotherms of herbicides by the organic amendments and two soils amended with them were obtained. Adsorption coefficients were correlated with the organic carbon content of the organic amendments and the adsorption process was enhanced by the hydrophobicity of herbicides and the aliphatic and aromatic carbon of amendments. Organic amendments increased the adsorption of herbicides by soils but it is not possible to extrapolate results from one soil to another because organo-mineral interactions between soils and organic amendments can modify this process. Desorption isotherms of herbicides from organic amendments and/or amended soils presented hysteresis indicating the irreversible adsorption of herbicides. Desorption results indicated, the abundance of O-alkyl and N-alkyl groups in organic amendments enhanced the hysteresis in amended soils ; This work was funded by the Spanish Ministry of Economy and Competitiveness (MINECO/FEDER) and the Regional government, Junta de Castilla y Leon as part of the projects AGL2015-69485-R and CSI240U14. ; Peer reviewed

49 páginas, 5 figuras, 3 tablas suplementarias. -- The final version is available at http://www.elsevier.com ; This paper reports the mobility and total balance of chlorotoluron (CTL), flufenacet (FNC) and bromide ion (Br−) throughout a sandy soil profile after the application of spent mushroom substrate (SMS) and green compost (GC). Obtaining mobility dataset is crucial to simulate the herbicides' fate under amended soil scenarios by application pesticide leaching models with regulatory application (FOCUS models). The application of organic residues is nowadays increased to improve the crop yields and there is a gap in the simulations of this kind of amended scenarios. A two-year field experiment involving unamended soil (S) and SMS- or GC-amended soil plots was conducted. CTL, FNC, and Br− were annually applied and their residual concentrations were determined in soil profiles (0–100 cm) regularly sampled. In all the treatments the order of mobility is followed as FNC < CTL < Br−. SMS and GC increased herbicide retention in the top 10 cm by the higher organic carbon (OC) content than the unamended soil, and their ability to increase the soil's water-holding capacity and to decrease water percolation. Simultaneously dissolved organic carbon (DOC) content facilitated herbicide transport being it favoured by the initial soil moisture content and the rainfall shortly after the chemicals' initial application. Over the first year, residual amounts (<2.6%) of Br−, CTL and FNC were leached down to 90–100 cm depth in the three treatments. However, over the second year low CTL and FNC amounts (<1.0%) reached the bottom layer only in S + SMS although high Br− concentrations did so in the three treatments (<20%). According to the total balance of Br−, CTL, and FNC in the soil profiles other processes (degradation, mineralisation, bound residues formation, and/or crop uptake) different from leaching below 1 m depth might play a key role in their dissipation especially in the amended soil profiles. SMS and GC are likely to be used as organic amendments to preserve the soil and water quality but in the case of SMS, its higher DOC content could imply a higher potential risk for groundwater contamination than GC. ; This work has been funded by MINECO/FEDER UE (Project AGL2015-69485-R) and MCIU/AEI/FEDER,UE (Project RTI2018-101587-J-I00). M. J. Carpio thanks for her 28 predoctoral contract co-funded by European Social Fund (ESF) and the Consejería de Educación (Junta de Castilla y León Government). C. García-Delgado and J.M. Marín Benito thank MINECO for their respective Juan de la Cierva-Formación (JCFI-2015-23543) and Juan de la Cierva-Incorporación (IJCI-2014-19538) contracts. ; Peer reviewed