Ensayo de arcillas modificadas con materia orgánica soluble para la eliminación de Cu y Zn

La contaminación por metales pesados es un tema de gran preocupación. Entre las diversas actividades que contribuyen a aumentar la presencia de metales pesados en el medio ambiente, se encuentra la agricultura. Por ejemplo, el uso de fertilizantes de tipo fosforados y algunos fungicidas incrementan la aparición Cu y Zn en aguas de zonas agrícolas e incluso residuales de la industria agroalimentaria. La eliminación de metales pesados mediante el uso de minerales de la arcilla tipo montmorillonita ha sido objeto de numerosos trabajos (Barbier et al., 2000) dada su alta capacidad de adsorción principalmente asociada a su capacidad de intercambio catiónico (CIC), fácil accesibilidad de su interlámina y a la presencia de grupos hidroxilos de los bordes de ruptura de la capa octaédrica.Este trabajo ha sido financiado con los proyectos de la Junta de Andalucía (P11-AGR-7400) y RECUPERA 2020 (MCINN_CSIC). E. Durán agradece la concesión de la Beca Predoctoral FPI asociada (P11-AGR-7400). A Fertiormont y a Spuny Morón por el material suministrado.Peer Reviewe

Tricyclazole-clay complexes as potential smart delivery systems: release in water and environmental fate in alluvial and sandy soils

Natural mineral clays (SWy-2, CTI and SH) were modified with natural inorganic cation (Fe3+) and the biopolymer (chitosan (ch)) to increase the adsorption capacity for tricyclazole. Three ways to prepare tricyclazole-clay complexes (ground mixing, GM, weak complex, WC and strong complex, SC) were assayed with the aim to develop possible components for controlled release formulations (CRFs) of this fungicide. The greatest adsorption (> 93%) was measured in the natural clays modified with Fe3+. The release of tricyclazole in water was higher for GMs of SWch6 (77%), SWch4 (84%) and CTIFe (85%). No significant differences were observed in the dissipation in soil of tricyclazole applied as commercial product or as formulation. However, the leaching of the fungicide depended on the type of soil: tricyclazole was not detected in any leachate from the soil with higher clay content (alluvial) whereas the SWch6 weak complex (WC) reduced the leaching of tricyclazole (65%) as compared to the commercial formulation (75%) in a sandy soil after 60 days. This last tricyclazol-clay complex could be considered as appropriate component for CRF, to be used in sandy soils. The other modified clays assayed, showing very high, strong and irreversible adsorption could find application as filters to eliminate tricyclazole from contaminated waters. Clay-fungicide interaction mechanisms are discussed and related to their soil and water behavior.CSIC (JAE-Doc program), MINECO (AGL2011-23779 project) and Junta de Andalucía (P11-AGR-7400), co-funded by EU FEDER-FSE (OP 2009-2013) funding.Peer Reviewe

Influence of biochar on the enantioselective behavior of the chiral fungicide metalaxyl in soil

Comunicación oral presentada en la EGU General Assembly 2015, held 12-17 April, 2015 in Vienna, Austria. Id.15367Chiral pesticides comprise an emerging and important class of organic pollutants currently, accounting for more than a quarter of used pesticides. Consequently, the contamination problems caused by chiral pesticides are concern matter and factors affecting enantioselective processes of chiral pesticides in soil need to be understood. For example, certain soil management practices, such as the use of organic amendments, can affect the enantioselective behavior of chiral pesticides in soils. Recently, biochar (BC), i.e. organic matter subjected to pyrolysis, has been proposed as organic amendment due to beneficial properties such as its high stability against decay in soil environments and its apparent ability to influence the availability of nutrients. BC is considered to be more biologically inert as compared to otherforms of organic carbon. However, its side-effects on the enantioselectivity of processes affecting the fate of chiral pesticides is unknown. The aim of this study was to assess the effect of biochar (BC) on the enantioselectivity of sorption, degradation, and leaching of the chiral fungicide metalaxyl in an agricultural soil. Amending the soil with BC (2% w/w) resulted in 3 times higher sorption of metalaxyl enantiomers compared to unamended soil, but no enantioselectivity in the process was observed. Moreover, both enantiomers showed some resistance to be desorbed in BC-amended soil compared to unamended soil. Dissipation studies revealed that the degradation of metalaxylwas more enantioselective in the unamended soil than in BC-amended soil. In unamended soil, R-metalaxyl(biologically active) and S- metalaxyl had half-lives (t1/2) of 3 and 34 days, respectively. BC enhanced the persistence of both enantiomers in the soil, with R-metalaxyl being degraded faster (t1/2=43 days) than S-metalaxyl (t1/2= 100 days). The leaching of both S-and R-metalaxyl was almost suppressed after amending the soil with BC; less than 10% of the fungicide applied to soil columns was recovered in leachates, in contrast to significantly higher percentages leachedin unamended soil, being the process more enantioselective in the latter case. Finally, total recoveries of both enantiomers were greater for BC-amended soil columns than for unamended soil columns, indicating reduced degradation in BC- amended soil. Our findings illustrated the ability of biochar to modify the enantioselectivity behavior of metalaxyl in soil by its high sorption capacity. BC could contribute to reduce the current agronomic doses used for chiral pesticides to deplete the contamination problems associated with their use, and also to act as an immobilizing amendment in soil remediation strategies.MINECO (AGL2011-23779), FACCE-JPI (Designchar4food), JA (AGR-264) and FEDERF-SE (OP 2007-2013).Peer Reviewe

Assessing the Effect of Organoclays and Biochar on the Fate of Abscisic Acid in Soil

10 páginas.-- 6 figuras.-- 2 tablas.-- 56 referencias.-- The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.jafc.6b03668The potential use of allelopathic and signaling compounds as environmentally friendly agrochemicals is a subject of increasing interest, but the fate of these compounds once they reach the soil environment is poorly understood. This work studied how the sorption, persistence, and leaching of the two enantiomers of the phytohormone abscisic acid (ABA) in agricultural soil was affected by the amendments of two organoclays (SA-HDTMA and Cloi10) and a biochar derived from apple wood (BC). In conventional 24-h batch sorption experiments, higher affinity toward ABA enantiomers was displayed by SA-HDTMA followed by Cloi10 and then BC. Desorption could be ascertained only in BC, where ABA enantiomers presented difficulties to be desorbed. Dissipation of ABA in the soil was enantioselective with S-ABA being degraded more quickly than R-ABA, and followed the order unamended > Cloi10-amended > BC-amended > SA-HDTMA-amended soil for both enantiomers. Sorption determined during the incubation experiment indicated some loss of sorption capacity with time in organoclay-amended soil and increasing sorption in BC-amended soil, suggesting surface sorption mechanisms for organoclays and slow (potentially pore filling) kinetics in BC-amended soil. The leaching of ABA enantiomers was delayed after amendment of soil to an extent that depended on the amendment sorption capacity, and it was almost completely suppressed by addition of BC due to its irreversible sorption. Organoclays and BC affected differently the final behavior and enantioselectivity of ABA in soil as a consequence of dissimilar sorption capacities and alterations in sorption with time, which will affect the plant and microbial availability of endogenous and exogenous ABA in the rhizosphere.This work has been financed by the Spanish Ministry of Economy and Competitiveness (MINECO Project AGL2014- 51897-R), EU FACCE-JPI (Designchar4food Project), and Junta de Andalucıa (P011-AGR-7400 and Research Group ́ AGR-264), cofinanced with European FEDER funds. The use of trade, firm, or corporation names in this paper is for the information and convenience of the reader. Such use does not constitute an official endorsement or approval by the U.S. Department of Agriculture, the Agricultural Research Service, or the Instituto de Recursos Naturales y Agrobiologıa de Sevilla ́ (IRNAS-CSIC) of any product or service to the exclusion of others that may be suitablePeer 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

Hidden non-Fermi liquid behavior due to crystal field quartet

We study a realistic Kondo model for crystal field quartet ground states having magnetic and non-magnetic (quadrupolar) exchange couplings with conduction electrons, using the numerical renormalization group method. We focus on a local effect dependent on singlet excited states coupled to the quartet, which reduces the non-magnetic coupling significantly and drives non-Fermi liquid behavior observed in the calculated quadrupolar susceptibility. A crossover from the non-Fermi liquid state to the Fermi liquid state is characterized by a small energy scale very sensitive to the non-magnetic coupling. On the other hand, the Kondo temperature observed in the magnetic susceptibility is less sensitive. The different crystal-field dependence of the two exchange couplings may be related to the different $x$ dependence of quadrupolar and magnetic ordering temperatures in Ce$_x$La$_{1-x}$B$_6$.Comment: 7 pages, 5 EPS figures, REVTe

Results of temperature gradient and heat flow in Santiam Pass Area, Oregon, Volume 1

The conclusions of this report are: (1) There is a weakly defined thermal anomaly within the area examined by temperature-gradient holes in the Santiam Pass area. This is a relict anomaly showing differences in permeability between the High Cascades and Western Cascades areas, more than a fundamental difference in shallow crustal temperatures. (2) The anomaly as defined by the 60 F isotherms at 400 feet follows a north-south trend immediately westward of the Cascade axis in the boundary region. It is clear that all holes spudded into High Cascades rocks result in isothermal and reversal gradients. Holes spudded in Western Cascades rocks result in positive gradients. (3) Cold groundwater flow influences and masks temperature gradients in the High Cascades to a depth of at least 700 feet, especially eastward from the major north-south trending faults. Pleistocene and Holocene rocks are very permeable aquifers. (4) Shallow gradient drilling in the lowlands westward of the faults provides more interpretable information than shallow drilling in the cold-water recharge zones. Topographic and climatological effects can be filtered out of the temperature gradient results. (5) The thermal anomaly seems to have 2 centers: one in the Belknap-Foley area, and one northward in the Sand Mountain area. The anomalies may or may not be connected along a north-south trend. (6) A geothermal effect is seen in holes downslope of the Western-High Cascade boundary. Mixing with cold waters is a powerful influence on temperature gradient data. (7) The temperature-gradient program has not yet examined and defined the geothermal resources potential of the area eastward of the Western Cascades-High Cascades boundary. Holes to 1500-2000 feet in depth are required to penetrate the high permeability-cold groundwater regime. (8) Drilling conditions are unfavorable. There are very few accessible level drill sites. Seasonal access problems and environmental restrictions together with frequent lost circulation results in very high costs per foot drilled

Efecto de la adición de organo-hidrotalcita a un suelo agrícola en el comportamiento de los fungicidas tebuconazol y metalaxil bajo condiciones reales de campo

2 páginas.-- 2 tablas.-- 2 referencias.-- Poster presentado en XXIV Reunión de la Sociedad Española de Arcillas Sevilla. Libro de Resúmenes: Noviembre de 2015 en Sevilla.Existen numerosos trabajos que abordan las aplicaciones de arcillas naturales, inalteradas o modificadas, como adsorbentes de pesticidas para la depuración de aguas e incluso para actuar como soportes en formulaciones de liberación lenta del pesticida o como barreras inmovilizantes en suelos (Cornejo et al., 2008). La mayoría de estos estudios se han realizado bajo condiciones controladas en el laboratorio y usando minerales de la arcilla naturales del grupo de las esmectitas. En los últimos años, ha aumentado el interés por explotar las propiedades adsorbentes de los hidróxidos dobles laminares (HDLs), también conocidos como hidrotalcitas (HTs) o arcillas aniónicas, cuyas características estructurales guardan cierta relación con las de las esmectitas (Cornejo et al., 2008). Los LDHs consisten en láminas del tipo brucita de un metal divalente con sustituciones isomórficas que proporcionan a las láminas una carga permanente positiva y que es compensada con aniones intercambiables que se sitúan en el espacio interlaminar. Aunque los resultados obtenidos hasta ahora ponen de manifiesto la elevada capacidad de adsorción de los LDHs para muchos pesticidas y la versatilidad que les confiere la posibilidad de modificarlos mediante la intercalación de aniones orgánicos en el espacio interlaminar (Celis et al., 2014), su utilidad como enmendantes para aumentar la capacidad de adsorción de los suelos bajo condiciones ambientales reales aún no ha sido evaluada.Este trabajo ha sido financiado por el Ministerio de Economía y Competitividad (MINECO) a través de los proyectos AGL2011-23779 y AGL2014-51897-R y por la Junta de Andalucía a través del Grupo de Investigación AGR-264, con parte de fondos FEDER-FSE. R. López-Cabeza agradece al MINECO la concesión de una beca pre-doctoral de FPI asociada al proyecto AGL2011-23779.Peer reviewe

Effect of synthetic clay and biochar addition on dissipation and enantioselectivity of tebuconazole and metalaxyl in an agricultural soil: Laboratory and field experiments

10 páginas.-- 4 figuras.-- 3 tablas.-- referencias.-- Supplementary data associated with this article can be found, in the online version, at http://dx.doi.org/10.1016/j.agee.2016.05.017Laboratory and field experiments were conducted to assess how the addition of oleate-modified hydrotalcite (clay) and biochar (BC) to an agricultural soil affected the sorption, leaching, persistence, and enantiomeric composition of soil residues of two chiral fungicides, tebuconazole and metalaxyl. Laboratory experiments showed that the sorption of both fungicides ranked as follows: unamended soil < BC-amended soil < clay-amended soil. The addition of clay at a rate of 1% increased metalaxyl soil sorption coefficient (Kd) from 0.34 to 3.14 L kg−1 and that of tebuconazole from 2.4 to 47.4 L kg−1. In our experimental set-up, field plots were either unamended or amended with clay (2 t ha−1) or BC (4 t ha−1), and subsequently treated with a mixture of tebuconazole and metalaxyl at 3 and 6 kg ha−1, respectively. The leaching, persistence, and enantiomer composition of fungicides residues were monitored by sampling at different soil depths (0–5, 5–10, 10–20 cm) for 98 days. No significant changes in the scarce mobility and long persistence of tebuconazole upon amending the soil with clay or BC were observed. In contrast, sorption to clay and BC particles reduced the leaching and degradation of metalaxyl and the clay increased its persistence in the topsoil compared to the unamended soil. The enantioselective analysis of tebuconazole and metalaxyl soil residues indicated that tebuconazole remained mostly racemic along the experiment, whereas for metalaxyl the concentration of S-enantiomer was greater than the concentration of R-enantiomer, more so at longer experimental times and deeper horizons. Nevertheless, for the top 0–5 cm soil layer metalaxyl remained more racemic in clay- and BC-amended soil than in unamended soil. Our results show that addition of amendments with high sorptive capacities can be beneficial in reducing leaching and degradation losses of chiral pesticide enantiomers from the topsoil, and that sorption by the amendments can influence the final enantiomeric composition of pesticide residues.This work was financed by the Spanish Ministry of Economy and Competitiveness (MINECO Projects AGL2011-23779, AGL2013-48446-C3-1-R and AGL2014-51897-R) and Junta de Andalucía (JA Research Group AGR-264), with FEDER-FSE funds. R. López-Cabeza thanks MINECO for a pre-doctoral fellowship linked to the Project AGL2011-23779 (Grant BES-2012-059945). The authors also thank P. Franco (Chiral Technologies Europe) and I. Girón (IRNAS) for their technical assistancePeer reviewe