Textural properties of synthetic clay-ferrihydrite associations

13 páginas, 8 figuras, 3 tablas, 35 referencias.Kaolinite-ferrihydrite and montmorillonite-ferrihydrite associations were prepared following a procedure based on the Russell method for the synthesis of ferrihydrite and the texture of the clay-ferrihydrite complexes was studied using different techniques. The textural properties of kaolinite were little affected by the Fe association, showing only a slight .increase in the specific surface area measured by nitrogen adsorption and a decrease in the largest pores (>10 micro m), as measured by mercury porosimetry. In contrast, the nitrogen specific surface area of the montmorillonite complexes was much higher than that of the clay without Fe and the pore structure depended on the amounts of Fe in the complexes. Application of the fractal approach to nitrogen adsorption data indicated that the surface roughness (microporosity) was greater for the complexes prepared from diluted Fe(III) solutions, in agreement with the information obtained from classical interpretation of the adsorption isotherms (shape of the isotherms and t-plots).This study has been supported partially by the CICYT through the project AMB-93-81 , AMB-96-445-C02- 02, the EU project EV 5V-CT94-0470, and by the Research Group RNM 124 of Junta de Andalucía. R. Celis also thanks the Spanish Ministry of Education and Science for his PFPU fellowship.Peer reviewe

Decoloración y detoxificación de aguas de alperujo mediante el empleo de esmectitas e hidrotalcita

2 páginas.-- 1 figura.-- 1 tablas.-- 8 referencias.-- Poster presentado en XXIV Reunión de la Sociedad Española de Arcillas Sevilla. Libro de Resúmenes: Noviembre de 2015 en Sevilla.El alperujo es el residuo sólido del proceso de extracción de aceite de oliva virgen en dos fases, que se produce en grandes cantidades en diversas regiones españolas y cuyo empleo como fertilizante y enmendante de suelos, una vez compostado, facilita una salida sostenible para estos contribuyendo favorablemente al secuestro de carbono (1,2) No obstante también puede dar lugar a algunos efectos adversos: a) Coloración de las aguas, b) Deterioro del suelo por su acidez y sales, c) Solubilización, transporte y lixiviación de algunos metales pesados y plaguicidas (3, 4) y d) Fitotoxicidad sobre plantas y microrganismos acuáticos, si no han sido previamente compostados o tratados (5). Sobre la hipótesis del conocido potencial de los materiales arcillosos de interaccionar con la materia orgánica soluble (MOS) de suelos, sedimentos o residuos (4, 6), el objetivo del presente trabajo ha sido evaluarla capacidad de arcillas catiónicas y aniónicas como adsorbentes de la MOS procedente de alperujo, responsable de los efectos adversos descritos. La finalidad última es el posible desarrollo y utilidad de adsorbentes naturales para reducir la coloración y toxicidad de aguas de lavado de almazaras, o para su posible co-aplicación con alperujo a suelos agrícolas disminuyendo los efectos adversos sobre semillas o plantas o para corregir los efectos de un vertido puntual incontrolado.Este trabajo ha sido financiado a través de los proyectos P07-AGR-03077 y P11-AGR-07400 y AGR-264 de la Junta de Andalucía, cofinanciados por FEDER y FSE; y el Convenio RECUPERA 2020 del MINECO-CSIC.Peer reviewe

Adsorción-desorción de los metales pesados Pb(II) y Hg(II) por modelos de partículas coloidales del suelo

4 páginas, 2 figuras, 1 tabla, 3 referencias.-- Publicado en el Capítulo IV: Contaminación y Medio Ambiente.-- Trabajo presentado a la XVII Reunión Científica de la Sociedad Española de Arcillas, celebrada en Elche (Alicante) y Castellón, del 27-29 de noviembre de 2002.El destino de los metales pesados en el medio ambiente está controlado por las reacciones de adsorción a los coloides del suelo. Por otro lado, las interacciones entre los constituyentes del suelo pueden alterar significativamente la cantidad y naturaleza de la superficie expuesta por los coloides del suelo para la adsorción de contaminantes. Por tanto, las predicciones sobre la extensión de la adsorción basadas en la suma de las capacidades adsorbentes de los constituyentes individuales del suelo pueden desviarse de lo que ocurre en la naturaleza (1). En la bibliografia han sido poco estudiadas las interacciones entre contaminantes y adsorbentes polifásicos, aunque en la última década ha aumentado la atención dada al estudio del comportamiento de modelos de asociaciones coloidales para obtener una interpretación más realista del proceso de adsorción en el suelo (2). En este trabajo se han determinado las capacidades adsorbentes de modelos de partículas coloidales binarias y ternarias que contienen montmorillonita (SW), ferrihidrita (Fh) y ácido húmico (AH) para dos contaminantes inorgánicos, los metales pesados Pb(lI) y Hg(II), Y se compararon con las capacidades de adsorción de los constituyentes individuales. Las partículas modelos se prepararon en el laboratorio y se caracterizaron por análisis elemental, espectroscopía infrarroja, difracción de rayos X y medidas de superficie específica. Se estudió la adsorción-desorción de Pb(lI) y Hg(ll) por parte de los diferentes adsorbentes y se utilizaron las técnicas de espectroscopía infrarroja y difracción de rayos X para analizar los mecanismos de interacción.Este trabajo ha sido financiado por el proyecto del MCYT REN2001-1700-C02- 01/TECNO y por el grupo RNM124 del PAI de la Junta de AndalucíaPeer reviewe

Comportamiento del herbicida fluometurón en un suelo de olivar enmendado con organoarcilla bajo condiciones de campo

7 páginas, 6 figuras, 3 tablas, 19 referencias.-- Publicado en el capítulo Tema 2 – Propriedades e processos do solo.-- Congreso celebrado en septiembre de 2012, en Islas Azores, Portugal.Las arcillas modificadas con cationes orgánicos u organoarcillas suelen presentar buenas propiedades adsorbentes para muchos plaguicidas y se han propuesto en diferentes aplicaciones dirigidas a reducir la movilidad de estos compuestos tras su aplicación a los suelos agrícolas. En trabajos previos realizados en condiciones de laboratorio, observamos que la modificación de una montmorillonita de Wyoming (SWy- 2) con el catión orgánico de origen natural espermina (SPERM) daba lugar a una organoarcilla (SW- SPERM) con una afinidad muy elevada por el herbicida fluometurón y que la adición de SW-SPERM a suelos aumentaba el poder de retención de éstos y reducía la lixiviación del herbicida. El objetivo del presente trabajo ha sido evaluar el efecto de la adición de SW-SPERM a un suelo de olivar mediterráneo en la persistencia, lixiviación y escorrentía del herbicida fluometurón bajo condiciones reales de campo. Se utilizaron dos parcelas de 4 x 1 m, una sin enmendar y otra enmendada con SW-SPERM a 0.2 kg/m2, a las que se aplicó fluometurón a 3 kg/ha. Se tomaron muestras de suelo a diferentes tiempos y profundidades (0-5, 5-10, 10-20 and 20-30 cm) y se determinó la cantidad de herbicida en las mismas así como en las aguas de escorrentía procedentes de cada parcela. En la parcela enmendada con SW-SPERM, el herbicida persistió durante más tiempo en los primeros 0-5 cm de suelo, presentando una menor lixiviación en comparación con la parcela sin enmendar. Las concentraciones de herbicida en las aguas de escorrentía de la parcela enmendada con SW-SPERM fueron superiores que en las aguas procedentes de la parcela sin enmendar, probablemente por la mayor persistencia del herbicida en el horizonte más superficial y el posible arrastre de herbicida asociado a partículas de arcilla. Los resultados apuntan a que SW-SPERM podría ser útil como enmienda de suelos para aumentar el tiempo de residencia de fluometurón en la zona radicular, controlando el posible riesgo por escorrentía del herbicida o aplicando la organoarcilla a una cierta profundidad en el suelo para protegerla de la escorrentía.Este trabajo ha sido financiado por la Junta de Andalucía a través del proyecto P07-AGR-03077, cofinanciado con fondos FEDER-FSE a través del programa Operativo de Andalucía 2007-2013. Beatriz Gámiz agradece a la Junta de Andalucía la concesión de una beca de Formación de Personal Investigador, cofinanciada con fondos FSE.Peer Reviewe

Enantioselective behavior of metalaxyl in soil under repeated applications

10 páginas.-- 5 imágenes.-- 2 tablas.-- 52 referenciasBACKGROUND: Soil incubation and column leaching experiments were conducted to address the question of whether the type of formulation (unsupported versus clay supported) and repeated applications of the chiral fungicide (RS)-metalaxyl affected the enantioselectivity of its dissipation and leaching in a slightly alkaline, loamy sand agricultural soil. RESULTS: Regardless of the type of formulation and the number of fungicide applications, the R-enantiomer of metalaxyl was degraded faster than the S-enantiomer, but the individual degradation rates of R- and S-metalaxyl were highly affected by the different application regimes assayed (t1/2 = 2-104 days). Repeated applications accelerated the degradation of the biologically active R-metalaxyl enantiomer, whereas they led to slower degradation of the non-active S-metalaxyl enantiomer. The type of formulation had less influence on the dissipation rates of the enantiomers. For all formulations tested, soil column leachates became increasingly enriched in S-enantiomer as the number of fungicide applications was increased, and application of metalaxyl to soil columns as clay-based formulations reduced the leaching of both enantiomers. CONCLUSION: Pesticide application conditions can greatly influence the enantioselective dissipation of chiral pesticides in soil, and hence are expected to exert a great impact on both the biological efficacy and the environmental chiral signatures of pesticides applied as mixtures of enantiomers or racemates to agricultural soils. © 2015 Society of Chemical Industry.This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2011-23779) and Junta de Andalucía (Research Group AGR-264), cofinanced by European FEDER-FSE funds (Operative Programme 2007-2013). Beatriz Gámiz thanks the Junta de Andalucía for a post-doctoral contract linked to the project P07-AGR-03077. María Adelino thanks MINECO for a predoctoral FPI fellowship. The authors also thank MJ Calderón (IRNAS, CSIC),MI Cardo (IRNAS, CSIC) and P Franco (Chiral Technologies Europe) for technical assistance, and Dr. S Redondo and Dr. E Mateos (University of Seville) for their help with the statistical treatment of the data.Peer reviewe

Comparison of inorganic and biohybrid layered silicates as adsorbents and carriers of herbicide imazamox for smart control of Striga and Orobanche spp.weeds

Poster presentado en el International Conference on Structural Nano Composites 20-21 May 2014 in Madrid, Spain, pag. 53 (2014) (NANOSTRUC 2014)Parasitic plants as Striga and Orobanche spp. are controlled by the systemic herbicide imazamox, which has to act at early stages of weed seeds germination in the root zone. Imazamox is an ionic herbicide with high water solubility and soil mobility: high risk of water contamination and loss of efficacy.CSIC (JAE-­‐Doc), MINECO (AGL2011-­‐23779), JA (AGR-­‐264 and P11-­‐AGR-­7400) with FEDER-­‐FSE (OP2009-­‐13); BASF for technical imazamox and M.A. Adelino for SW-­CHs samples.Peer Reviewe

Effect of organic amendments on herbicide sorption as related to the nature of the dissolved organic matter

It has been assessed the influence of four organic amendments (OA) consisting of two commercial humic amendments (liquid LF and solid SF) from olive-mill wastes, a solid urban waste (SUW), and a sewage sludge (SS) on the sorption properties and leaching potential of simazine and 2,4-D. A sandy soil (TR) and a sandy-clay soil with a relatively high montmorillonite content (A) were treated with the diverse OA. Dissolved organic matter (DOM) was extracted from the amendments, the soils, and the amended soils and studied by fluorescence spectroscopy. A humification index (HIX) was calculated from the fluorescence data. Sorption was determined with the batch technique. Spectroscopical studies revealed that the DOM of the LF differs from the other OA by having a very low ability to absorb and to fluoresce and by its very low HIX values, which indicates that the LF contains large amounts of nonhumified material and consists of small molecules. On the other hand, the SF amendment contains the highest amounts of highly humified material and a large number of carboxylic groups. Amended soils sorbed simazine and 2,4-D to a greater extent than the untreated soils, except in the case of simazine sorption in the LF amended soil A, which had a lower simazine sorption than the original soil. The small molecules of DOM in the LF compete with simazine for montmorillonite sorption sites in soil A. This is not the case for 2,4-D, since this herbicide does not sorb on montmorillonite. In the case of the soil TR, with a lower montmorillonite content, there is no competition between simazine and the LF molecules for sorption sites. Soils amended with the highly humified SF were the best sorbents for simazine but not for 2,4-D, which can be attributed to repulsion between negatively charged 2,4-D molecules and COOgroups, which are more abundant in SF.This project has been supported by Junta de Andalucía through Research group 4092, CICYT through AMB96-0445- CO2-O2, the Deutsher Akademischer Austauschdienst and Ministerio de Educación y Cultura through Acciones Integradas HA98-0072, and by the European Science Foundation within its Groundwater Pollution Program (G-Poll). Municipal treatment plant EMASESA is also acknowledged for providing the sewage sludge.Peer Reviewe

Efecto de la coaplicación de herbicidas y adición de alperujo como enmienda en el comportamiento de diurón y terbutilazina en un suelo arcillo-limoso

Congreso celebrado del 21-24 de septiembre 2010, en Granada, España.Los herbicidas se aplican a los cultivos como formulaciones que habitualmente incluyen más de un principio activo. Sin embargo, los estudios sobre comportamiento de herbicidas en suelos en el laboratorio suelen hacerse aplicando los herbicidas de forma individual.Peer reviewe

Nanohybrids of Mg/Al layered double hydroxide and long-chain (C18) unsaturated fatty acid anions: Structure and sorptive properties

10 páginas.-- 8 figuras.-- 1 tabla. 59 referencias.-- Appendix A. Supplementary data con 6 páginas (3 tablas y 2 figuras.-- Número espeical: Clay Science & Technology (XV International Clay Conference)Long-chain (C18) unsaturated fatty acid anions, elaidate (ELA), oleate (OLE), linoleate (LINO), and linolenate (LINOLEN), were intercalated into Mg/Al (3:1) layered double hydroxide (LDH) and the resultant organo-LDH nanohybrid materials were characterized and subsequently evaluated as sorbents of six pesticides (clopyralid, imazethapyr, diuron, atrazine, alachlor, and terbuthylazine). The effect of the degree (18:1, 18:2, 18:3) and type (cis/trans) of unsaturation in the fatty acid alkyl chain on both the structure and sorptive properties of the LDH-unsaturated fatty acid nanohybrids was determined. All fatty acid anions were readily intercalated into the LDH, yielding structures with basal spacing values ranging between 32 Å (LDH-LINOLEN) and 40 Å (LDHELA). The bend imposed by the cis geometry of the double bonds present in OLE, LINO and LINOLEN was identified as a major factor determining the arrangement of these anions in the LDH interlayer space. Intercalation of cis-unsaturated fatty acid anions led to less densely packed structures and reduced the interlayer distance of the resultant nanohybrid compared to the structures resulting from intercalation of the linear, trans-unsaturated elaidate anion. All organo-LDHs displayed higher affinity to uncharged pesticides as compared to unmodified LDH, but double bonds in the fatty acid alkyl chain, particularly when present in cis configuration, reduced the affinity of the organo-LDHs to all pesticides, presumably because they led to structures with reduced hydrophobicity as compared to those resulting from the incorporation of linear organic anions.This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2011-23779) and Junta de Andalucía (JA Projects P07-AGR-03077 and P11-AGR-7400 and Research Group AGR-264), cofinanced with European FEDER-FSE funds (Operative Program 2007–2013). B. Gámiz thanks JA for a post-doctoral contract linked to the project P07-AGR-03077. M.A. Adelino thanks MINECO for her pre-doctoral FPI fellowship.Peer reviewe

Influence of Olive Oil Mill Waste Amendment on Fate of Oxyfluorfen in Southern Spain Soils

7 páginas.-- 1 figura.-- 3 tablas.-- 37 referencias.--Oxyfluorfen herbicide residues have been previously reported in surface and ground water in the Guadalquivir river basin in Spain. Soil factors and processes (sorption, dissipation, and leaching) influencing the potential offsite transport of oxyfluorfen to surface and ground water were characterized in laboratory experiments for two soils from Southern Spain. The influence of olive-oil mill waste amendment on the soil processes was also determined. Oxyfluorfen sorption in unamended soils was not significantly affected by soil active components (organic matter and clay fraction). However, a significant increase in soil sorption of the herbicide was observed upon amendment. Laboratory half-life values for oxyfluorfen in unamended sandy clay loam and silty clay soils at 40% moisture content and 25°C were 29 and 19 days, respectively, and it increased by a factor of four upon amendment. Oxyfluorfen's mobility along soil profile increased with the amendment in leaching studies at 25°C, suggesting that dissolved organic matter of amendment can play an important role enhancing soil vertical movement of the pesticide. The increase in soil adsorption and persistence observed with olive-oil mill waste amendment can promote its losses by runoff following winter application, whereas vertical movement of oxyfluorfen can be enhanced following spring application when olive-oil mill waste amendment is also applied.This work has been partially financed by research projects P06-AGR-565, P07-AGR-03077, and AGR-264 from Junta de Andalucia, all of them cofinanced with EU FEDER-FSE funds (Operative Program 2003/06 and 2007/11). This work has been specially supported by I-Link 0025 research project from CSIC. We are grateful to Dow Agrosciences LLC, Indianapolis, IN for supplying 14C-labeled oxyfluorfen. Authors also thank to Dra. L. Cox and Dr. R. Celis for manuscript valuable support, comments and suggestions.Peer reviewe