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E. de Blas
CITACA (Agri-Food Research and Transfer Cluster, Campus Auga), University of Vigo, 36310 Vigo, Spain

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Journal article
Published: 19 September 2020 in Minerals
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A gravity core (220 cm depth) was collected to investigate the geochemistry, enrichment, and pollution of trace metals in anoxic sediments from San Simon Bay, an ecosystem of high biological productivity in the northwest of Spain. A five-step sequential extraction procedure was used. The Cu, Pb, and Zn contents decreased with depth, with maximum values in the top layers. Ni and Zn were bound to pyrite fractions, while Cd and Pb were associated with the most mobile fractions. The analyzed metals were associated with the fractions bound to organic matter, mainly with the strongly bound to organic matter fraction. High Cd and Cu values were observed. The fractionation showed a high mobility for Cd (28.3–100%) and Pb (54.0–70.2%). Moreover, the pollution factor and the geoaccumulation index reflected a high contamination for Pb and a moderate contamination for Cu and Zn in the superficial layers, pointing to a possible ecotoxicological risk to organisms in San Simon Bay.

ACS Style

A.M. Ramírez-Pérez; M.A. Álvarez-Vázquez; E. De Uña-Álvarez; E. De Blas. Environmental Assessment of Trace Metals in San Simon Bay Sediments (NW Iberian Peninsula). Minerals 2020, 10, 826 .

AMA Style

A.M. Ramírez-Pérez, M.A. Álvarez-Vázquez, E. De Uña-Álvarez, E. De Blas. Environmental Assessment of Trace Metals in San Simon Bay Sediments (NW Iberian Peninsula). Minerals. 2020; 10 (9):826.

Chicago/Turabian Style

A.M. Ramírez-Pérez; M.A. Álvarez-Vázquez; E. De Uña-Álvarez; E. De Blas. 2020. "Environmental Assessment of Trace Metals in San Simon Bay Sediments (NW Iberian Peninsula)." Minerals 10, no. 9: 826.

Journal article
Published: 08 January 2020 in Estuarine, Coastal and Shelf Science
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Ría de Vigo show over-pyritization of Fe. Pyrite formation is limited by the exhaustion of reactive Fe in deep sediments. The presence of methane gas in the sediment increase the Fe pyritization. Download : Download high-res image (277KB)Download : Download full-size image

ACS Style

A.M. Ramírez-Pérez; Esther de Blas; X.L. Otero. Iron pyritization in shallow methane fields in sediments of the Ría de Vigo (NW Iberian Peninsula). Estuarine, Coastal and Shelf Science 2020, 235, 106568 .

AMA Style

A.M. Ramírez-Pérez, Esther de Blas, X.L. Otero. Iron pyritization in shallow methane fields in sediments of the Ría de Vigo (NW Iberian Peninsula). Estuarine, Coastal and Shelf Science. 2020; 235 ():106568.

Chicago/Turabian Style

A.M. Ramírez-Pérez; Esther de Blas; X.L. Otero. 2020. "Iron pyritization in shallow methane fields in sediments of the Ría de Vigo (NW Iberian Peninsula)." Estuarine, Coastal and Shelf Science 235, no. : 106568.

Article
Published: 13 September 2017 in CLEAN – Soil, Air, Water
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High sedimentation rates and high organic matter contents promote the development of anoxic conditions in the Ría de Vigo (NW Spain). In these anoxic environments, elements such as S, Fe, and Mn are involved in redox processes affecting the CH4 dynamic. In this work, speciation of S, Fe, and Mn was evaluated through a five-step sequential extraction procedure (exchangeable form and bound to carbonate, present in the reductive phase bound to Fe/Mn oxides, weakly bound to organic matter, strongly bound to organic matter, and residual fractions) in order to identify the origin of S, Fe, and Mn, distinguishing between fractions bound to organic compounds from those in the sulfide phase in these anoxic sediments. The study was conducted on samples from three gravity cores retrieved in the inner and outer zones of the ría in November 2012. S was mainly found in the fraction strongly bound to organic matter, showing that S is incorporated in the organic matter. However, the S in this fraction was associated with total organic carbon only in the inner zone (r = 0.833). More than 65% of total Fe and Mn was found in the residual fraction at all zones, being the highest in the outer zone, and showing an intense diagenesis in the ría, where precipitation of these elements as sulfides is favored by anoxic conditions. SO42− reduction, Fe and Mn reduction processes coexist in the same area within the cores.

ACS Style

Alexandra María Ramírez-Pérez; Esther de Blas; Soledad García-Gil. Sulfur, Iron, and Manganese Speciation in Anoxic Sediments with Methane (Ría de Vigo, NW Spain). CLEAN – Soil, Air, Water 2017, 45, 1 .

AMA Style

Alexandra María Ramírez-Pérez, Esther de Blas, Soledad García-Gil. Sulfur, Iron, and Manganese Speciation in Anoxic Sediments with Methane (Ría de Vigo, NW Spain). CLEAN – Soil, Air, Water. 2017; 45 (9):1.

Chicago/Turabian Style

Alexandra María Ramírez-Pérez; Esther de Blas; Soledad García-Gil. 2017. "Sulfur, Iron, and Manganese Speciation in Anoxic Sediments with Methane (Ría de Vigo, NW Spain)." CLEAN – Soil, Air, Water 45, no. 9: 1.

Journal article
Published: 01 May 2017 in Chemosphere
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The high sedimentation rates and high organic matter contents in the sediments of the Ría de Vigo (NW Spain) promote the development of anoxic conditions, determining the dynamics of elements like Fe and conditioning his speciation and reactivity. Four gravity cores were retrieved in anoxic sediments of the Ría de Vigo in November 2012. In order to understand the behavior of Fe in these complex environments different fractions of reactive iron were analyzed. The decrease in highly reactive iron and sulfide contents with depth showed the relationship between the iron and sulfur cycle in the middle and outer zones of the ría. In the inner zone, the apparition of shallow methane gas may cause the slower decrease of the highly reactive iron contents. In zones without methane, sediment layers enriched in iron -with a reactivity higher than in other sediment samples- were observed. An increase was observed in the dithionite and total reactive iron contents from the inner to the outer zone of the ría, according to the gas depth. Furthermore, a decrease in Fe (III)-bearing minerals contents with depth was observed in the outer and middle zones, but not in the innermost area where the gas is shallow. The high organic matter and sulfide contents, mainly in the inner zone of the ría, indicate that the most of the Fe (II) is FeS. Moreover, the high contents of total reactive iron and pH values (6.86-7.98) could contribute the formation of stable minerals like pyrite along the Ría de Vigo.

ACS Style

A.M. Ramírez-Pérez; E. De Blas. Iron reactivity in anoxic sediments in the Ría de Vigo (NW Spain). Chemosphere 2017, 174, 8 -19.

AMA Style

A.M. Ramírez-Pérez, E. De Blas. Iron reactivity in anoxic sediments in the Ría de Vigo (NW Spain). Chemosphere. 2017; 174 ():8-19.

Chicago/Turabian Style

A.M. Ramírez-Pérez; E. De Blas. 2017. "Iron reactivity in anoxic sediments in the Ría de Vigo (NW Spain)." Chemosphere 174, no. : 8-19.

Journal article
Published: 01 May 2017 in Continental Shelf Research
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ACS Style

Natalia Martínez-Carreño; Soledad García-Gil; V. Cartelle; Esther de Blas; A.M. Ramírez-Pérez; Tania L. Insua. Geochemical and geological factors controlling the spatial distribution of sulfate-methane transition zone in the Ría de Vigo (NW Spain). Continental Shelf Research 2017, 140, 47 -59.

AMA Style

Natalia Martínez-Carreño, Soledad García-Gil, V. Cartelle, Esther de Blas, A.M. Ramírez-Pérez, Tania L. Insua. Geochemical and geological factors controlling the spatial distribution of sulfate-methane transition zone in the Ría de Vigo (NW Spain). Continental Shelf Research. 2017; 140 ():47-59.

Chicago/Turabian Style

Natalia Martínez-Carreño; Soledad García-Gil; V. Cartelle; Esther de Blas; A.M. Ramírez-Pérez; Tania L. Insua. 2017. "Geochemical and geological factors controlling the spatial distribution of sulfate-methane transition zone in the Ría de Vigo (NW Spain)." Continental Shelf Research 140, no. : 47-59.

Journal article
Published: 01 December 2015 in Science of The Total Environment
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The Ría de Vigo (NW Spain) has a high organic matter content and high rates of sedimentation. The microbial degradation of this organic matter has led to shallow gas accumulations of methane, currently distributed all along the ría. These peculiar characteristics favor the development of anoxic conditions that can determine the dynamics of iron and manganese. In order to study the role played by iron and manganese in the processes that take place in anoxic sediments with shallow gas, four gravity cores were retrieved in anoxic sediments of the Ría de Vigo in November 2012. Methane was present in two of them, below 90cm in the inner zone and below 200cm, in the outer zone. Pore water was collected and analyzed for vertical profiles of pH, sulfide, sulfate, iron and manganese concentrations. Sulfate concentrations decreased with depth but never reached the minimum detection limit. High sulfide concentrations were measured in all cores. The highest sulfide concentrations were found in the inner zone with methane and the lowest were in the outer zone without methane. Concentrations of iron and manganese reached maximum values in the upper layers of the sediment, decreasing with depth, except in the outer zone without gas, where iron and manganese concentration increased strongly toward the bottom of the sediment. In areas with shallow gas iron reduction, sulfate reduction and methane production processes coexist, showing that the traditional redox cascade is highly simplified and suggesting that iron may be involved in a cryptic sulfur cycle and in the oxidation of methane.

ACS Style

A.M. Ramírez-Pérez; E. de Blas; S. García-Gil. Redox processes in pore water of anoxic sediments with shallow gas. Science of The Total Environment 2015, 538, 317 -326.

AMA Style

A.M. Ramírez-Pérez, E. de Blas, S. García-Gil. Redox processes in pore water of anoxic sediments with shallow gas. Science of The Total Environment. 2015; 538 ():317-326.

Chicago/Turabian Style

A.M. Ramírez-Pérez; E. de Blas; S. García-Gil. 2015. "Redox processes in pore water of anoxic sediments with shallow gas." Science of The Total Environment 538, no. : 317-326.

Journal article
Published: 01 June 2014 in Quaternary Science Reviews
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Castor Muñoz Sobrino; Iria Garcia-Moreiras; Yoel Castro; Natalia Martínez-Carreño; Esther de Blas; Carlos Fernandez Rodríguez; Alan Judd; Soledad García-Gil. Climate and anthropogenic factors influencing an estuarine ecosystem from NW Iberia: new high resolution multiproxy analyses from San Simón Bay (Ría de Vigo). Quaternary Science Reviews 2014, 93, 11 -33.

AMA Style

Castor Muñoz Sobrino, Iria Garcia-Moreiras, Yoel Castro, Natalia Martínez-Carreño, Esther de Blas, Carlos Fernandez Rodríguez, Alan Judd, Soledad García-Gil. Climate and anthropogenic factors influencing an estuarine ecosystem from NW Iberia: new high resolution multiproxy analyses from San Simón Bay (Ría de Vigo). Quaternary Science Reviews. 2014; 93 ():11-33.

Chicago/Turabian Style

Castor Muñoz Sobrino; Iria Garcia-Moreiras; Yoel Castro; Natalia Martínez-Carreño; Esther de Blas; Carlos Fernandez Rodríguez; Alan Judd; Soledad García-Gil. 2014. "Climate and anthropogenic factors influencing an estuarine ecosystem from NW Iberia: new high resolution multiproxy analyses from San Simón Bay (Ría de Vigo)." Quaternary Science Reviews 93, no. : 11-33.

Journal article
Published: 01 September 2013 in Geoderma
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ACS Style

E. De Blas; Gonzalo Almendros; J. Sanz. Molecular characterization of lipid fractions from extremely water-repellent pine and eucalyptus forest soils. Geoderma 2013, 206, 75 -84.

AMA Style

E. De Blas, Gonzalo Almendros, J. Sanz. Molecular characterization of lipid fractions from extremely water-repellent pine and eucalyptus forest soils. Geoderma. 2013; 206 ():75-84.

Chicago/Turabian Style

E. De Blas; Gonzalo Almendros; J. Sanz. 2013. "Molecular characterization of lipid fractions from extremely water-repellent pine and eucalyptus forest soils." Geoderma 206, no. : 75-84.

Articles
Published: 04 November 2011 in CyTA - Journal of Food
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We discuss the problems arising from the intensification of the land use conflict on the basis of three main threats that may compromise the food safety and its quality. We focused on: (A) the importance of soil conservation to protect the water resources and the consequences of inadequate soil use planning on the water quality and food, (B)the problem of soil as destination of organic wastes and its use in agriculture, (C) finally we discuss the problem of the competence for energy production, highlighting the conflict between biofuels and food production. Se discuten los problemas derivados de la intensificación del conflicto de los usos del suelo en base a las tres amenazas que pueden comprometer la calidad y seguridad alimentaria. Este trabajo se centra en analizar: A) la importancia de la conservación del suelo como protector de los recursos hídricos y las consecuencias de la mala ordenación de usos del suelo sobre la calidad del agua y los alimentos, B) el problema del empleo del suelo como receptor final de residuos orgánicos y la compatibilidad con su uso agrícola, C) finalmente se abordará el problema de la competencia del uso del suelo para la producción de energía, destacando el conflicto entre la producción de biocombustibles y alimentos.

ACS Style

P. Pérez-Rodríguez; Esther de Blas; B. Soto; Xabier Pontevedra-Pombal; J.E. López-Periago. El conflicto de uso del suelo y la calidad de los alimentos The soil use conflict and food quality. CyTA - Journal of Food 2011, 9, 342 -350.

AMA Style

P. Pérez-Rodríguez, Esther de Blas, B. Soto, Xabier Pontevedra-Pombal, J.E. López-Periago. El conflicto de uso del suelo y la calidad de los alimentos The soil use conflict and food quality. CyTA - Journal of Food. 2011; 9 (4):342-350.

Chicago/Turabian Style

P. Pérez-Rodríguez; Esther de Blas; B. Soto; Xabier Pontevedra-Pombal; J.E. López-Periago. 2011. "El conflicto de uso del suelo y la calidad de los alimentos The soil use conflict and food quality." CyTA - Journal of Food 9, no. 4: 342-350.

Journal article
Published: 20 January 2011 in Estuarine, Coastal and Shelf Science
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Ría de Vigo is a river valley flooded by the sea, with a bay (San Simón Bay) at its innermost part. The accumulation of Holocene sediment in San Simón Bay has been studied by the integration of 1) large scale high resolution seismic data, and 2) detailed geochemical analysis of a gravity core. In San Simón Bay the majority of the seismic records are obscured by acoustic turbidity which represents gassy sediments, but on records from Rande Strait it is possible to distinguish two Quaternary seismic sequences; an Upper Pleistocene sequence (SQ1) and a Holocene sequence (SQ2). Only SQ2 is recognized in San Simón Bay where it is comprised of two seismic units; the upper unit represents the HST sediment, i.e. the period of highest sea level. A gravity core taken within the gassy zone at 10 m water depth provided 3.55 m of fine-grained sediments (muds) from the youngest seismic unit (4 m thick). Geochemical analysis show high values (4 to 10%) of TOC. Sediment and porewater analyses indicate a distinct sulphate–methane transition zone (SMTZ) between 60 and 80 cm where sulphate is depleted (to 0.4 mM). The top of the acoustic turbidity (the gas front) at 80 cm corresponds to the lower limit of the SMTZ. The methane cannot have been derived from the underlying metamorphic and granitic rocks, but was probably derived by microbial degradation of the organic matter in the Holocene sediments. We estimate that the sediments of the Bay contain approximately 1.8 × 106 m3 of organic carbon and 275 ton of methane.

ACS Style

S. García-Gil; Esther de Blas; Natalia Martínez-Carreño; J. Iglesias; Raquel Rial; Jesus Simal-Gandara; A.G. Judd. Characterisation and preliminary quantification of the methane reservoir in a coastal sedimentary source: San Simón Bay, Ría de Vigo, NW Spain. Estuarine, Coastal and Shelf Science 2011, 91, 232 -242.

AMA Style

S. García-Gil, Esther de Blas, Natalia Martínez-Carreño, J. Iglesias, Raquel Rial, Jesus Simal-Gandara, A.G. Judd. Characterisation and preliminary quantification of the methane reservoir in a coastal sedimentary source: San Simón Bay, Ría de Vigo, NW Spain. Estuarine, Coastal and Shelf Science. 2011; 91 (2):232-242.

Chicago/Turabian Style

S. García-Gil; Esther de Blas; Natalia Martínez-Carreño; J. Iglesias; Raquel Rial; Jesus Simal-Gandara; A.G. Judd. 2011. "Characterisation and preliminary quantification of the methane reservoir in a coastal sedimentary source: San Simón Bay, Ría de Vigo, NW Spain." Estuarine, Coastal and Shelf Science 91, no. 2: 232-242.

Journal article
Published: 15 March 2010 in Geoderma
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Soil organic matter characteristics in extremely water-repellent soils developed under forests of Pinus pinaster and Eucalyptus globulus in Galicia (Northwestern Spain) were analyzed with special emphasis paid in lipid and humic acid fractions. A total of sixteen soils were studied including Leptic Regosols and Leptic Umbrisols developed on granites and schists, and showing extreme water repellency: up to 6 h using water drop penetration time (WDPT) test, i.e., ranging from strongly to extremely hydrophobic (ethanol percentage test, MED). The experimental design involved the measurement of the water repellency as WDPT after the successive removal of lipid and humic fractions by: (i) direct extraction of the soil free lipid with petroleum ether (40–60 °C), (ii) extraction of the ‘fixed’ lipid from the soil residue after 2m H3PO4 treatment and further recovery from the aqueous phase with petroleum ether and (iii) final extraction of humic substances with alkaline solutions. The results showed significant decrease in the WDPT (from class 6 to classes 4 or 5) after removing free lipid. Nevertheless, removal of ‘fixed’ lipid resulted into the most substantial decrease of the WDPT, which occurred on almost all soils (to classes 0–3). This fact is to large extent associated to the simultaneous removal of hydrophobic particulate fractions (free organic matter) which — even after extraction of free lipid — resulted extremely water-repellent in laboratory conditions (>1 h WDPT). Finally, the extraction of humic and fulvic acids was required for the total disappearance of the water repellency (class 0). Regarding vegetation types, lipid removal (free + ‘fixed’ fractions) was significantly more effective in increasing wettability in the case of forest soil samples under pine than under eucalypt. Concerning geological substrate, water repellency in soils under granites remained comparatively more persistent than in soils under schists. After treatment with 2m H3PO4, all samples from soils on granite–eucalyptus remained slightly water-repellent, whereas all samples from soils developed on schist–pine samples became wettable. Multivariate data treatments (multiple regression models, variable ordination by multidimensional scaling, and discriminant analysis) were useful to identify the soil characteristics most significantly associated to its water repellency. These treatments suggest that water repellency in the soils under study is a complex emergent property, reflected in specific patterns depending on vegetation type and geological substrate and arising from the interaction between different soil organizational levels (mainly free lipid, ‘fixed’ lipid, macroscopic particulate organic matter and the concentration and maturity of humic substances).

ACS Style

Esther de Blas; María Rodríguez-Alleres; Gonzalo Almendros. Speciation of lipid and humic fractions in soils under pine and eucalyptus forest in northwest Spain and its effect on water repellency. Geoderma 2010, 155, 242 -248.

AMA Style

Esther de Blas, María Rodríguez-Alleres, Gonzalo Almendros. Speciation of lipid and humic fractions in soils under pine and eucalyptus forest in northwest Spain and its effect on water repellency. Geoderma. 2010; 155 (3-4):242-248.

Chicago/Turabian Style

Esther de Blas; María Rodríguez-Alleres; Gonzalo Almendros. 2010. "Speciation of lipid and humic fractions in soils under pine and eucalyptus forest in northwest Spain and its effect on water repellency." Geoderma 155, no. 3-4: 242-248.

Journal article
Published: 15 August 2007 in Hydrological Processes
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The aim of this work was to examine the distribution and persistence of water repellency in soils of different texture in the Spanish humid region as a function of land use and management. At 34 locations, samples of soil under different land uses (maize crop, grassland, Pinus pinaster forest and Eucalyptus globulus forest) and various geological materials were collected from the surface layer (0–5 cm). In addition, P. pinaster and E. globulus forest soil samples were collected at four different depths (0–5, 5–10, 10–20 and 20–40 cm) at 10 of the previous locations. Water repellency was determined by using the water drop penetration time (WDPT) test on field‐moist samples (actual WDPT) collected during summer and was compared with the values for samples dried at 25 and 105 °C (potential WDPT). Based on the results, the prevailing vegetation and land use dictate the development and persistence of surface water repellency in the studied soils. The E. globulus forest soil samples were found to be the most water repellent, followed by the P. pinaster forest samples (73 and 64%, respectively, with actual WDPT > 6 h); on the other hand, 79% of the field‐moist samples from soils under maize and 71% of those under grass were non‐repellent. The influence of vegetation on water repellency was found to be related to the type and content of soil organic matter. Each type of vegetation resulted in significant differences in surface water repellency between soils with sandy‐loam texture and also between soils with loam or silt‐loam texture; repellency was higher in the samples with coarser textures. The persistence of water repellency decreased with increasing soil depth, the decrease being more marked in the finer‐textured soils than in the coarser ones and also in the pine forest soils than in the eucalypt forest soils. The water repellency of most of the samples dried at 25 and 105 °C was similar to that of the field‐moist samples collected during the dry period (r = 0·90, p < 0·01). Copyright © 2007 John Wiley & Sons, Ltd.

ACS Style

M. Rodríguez-Alleres; Elena Benito; Esther De Blas. Extent and persistence of water repellency in north-western Spanish soils. Hydrological Processes 2007, 21, 2291 -2299.

AMA Style

M. Rodríguez-Alleres, Elena Benito, Esther De Blas. Extent and persistence of water repellency in north-western Spanish soils. Hydrological Processes. 2007; 21 (17):2291-2299.

Chicago/Turabian Style

M. Rodríguez-Alleres; Elena Benito; Esther De Blas. 2007. "Extent and persistence of water repellency in north-western Spanish soils." Hydrological Processes 21, no. 17: 2291-2299.

Journal article
Published: 25 May 2007 in Science of The Total Environment
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The water repellency of soils with different texture under different types of plant cover was determined by applying the WDPT and MED methods to both whole samples and the following size fractions: 2–1, 1–0.5, 0.5–0.25, 0.25–0.05 and < 0.05 mm. Based on the results, the soils under maize crop and grassland, which were mostly wettable in the whole samples, exhibited water repellency in the finest fraction (< 0.05 mm) as a result of its higher organic carbon content. On the other hand, all fractions in the forest soils, which were extremely water repellent, contributed to the overall repellency; in any case, the MED test revealed that the finest fraction was strongly repellent in the forest soils as well.

ACS Style

María Rodríguez-Alleres; Esther de Blas; Elena Benito. Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods. Science of The Total Environment 2007, 378, 147 -150.

AMA Style

María Rodríguez-Alleres, Esther de Blas, Elena Benito. Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods. Science of The Total Environment. 2007; 378 (1-2):147-150.

Chicago/Turabian Style

María Rodríguez-Alleres; Esther de Blas; Elena Benito. 2007. "Estimation of soil water repellency of different particle size fractions in relation with carbon content by different methods." Science of The Total Environment 378, no. 1-2: 147-150.

Journal article
Published: 30 November 2005 in Hydrological Processes
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Soil water repellency (hydrophobicity) is a naturally occurring phenomenon that can be intensified by soil heating during fires. Fire‐induced water repellency, together with the loss of plant cover, is reportedly the principal source of increased surface runoff and accelerated erosion in burned soils. In this study, the surface water repellency of several soils affected by summer forest fires in northwest Spain was studied and compared with that of adjacent unburned soils. Soil water repellency was determined using the ethanol percentage test (MED). Most of the unburned soil samples exhibited water repellency that ranged from strong to very strong; only four of the unburned soil samples were non‐repellent. Water repellency in the unburned soils was significantly correlated with the organic carbon content (r = 0·64, p < 0·05). Overall, fires increased the surface water repellency in soils with previously low degrees of water repellency and caused little change in that of originally strongly hydrophobic soils. In order to examine in detail the changes in water repellency with temperature, three unburned soil samples were subjected to a controlled heating program. Water repellency increased between 25 and 220 °C, water repellency peaked between 220 and 240 °C and disappeared above 260–280 °C. Extrapolation of the results of the heating tests to field conditions suggested that the intensity of fire (temperature and time of residence) reached by most soils during fires is not too high. Based on the results, the determination of water repellency could be used as a simple test for the indirect estimation of the intensity levels reached on the soil surface during a fire. Copyright © 2005 John Wiley & Sons, Ltd.

ACS Style

M. E. Varela; Elena Benito; Esther de Blas. Impact of wildfires on surface water repellency in soils of northwest Spain. Hydrological Processes 2005, 19, 3649 -3657.

AMA Style

M. E. Varela, Elena Benito, Esther de Blas. Impact of wildfires on surface water repellency in soils of northwest Spain. Hydrological Processes. 2005; 19 (18):3649-3657.

Chicago/Turabian Style

M. E. Varela; Elena Benito; Esther de Blas. 2005. "Impact of wildfires on surface water repellency in soils of northwest Spain." Hydrological Processes 19, no. 18: 3649-3657.

Journal article
Published: 30 April 2004 in Harmful Algae
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The relationship between growth rate versus phosphorus concentration and cellular toxin content was determined for Alexandrium minutum AL1V, Alexandrium tamarense MDQ1096, A. tamarense EF04 and Alexandrium andersoni EF12 under different nitrogen and phosphorus supplies. The aim was to determine whether those species with a lower phosphorus uptake affinity, and hence potentially of lower competitive ability at low phosphorus concentrations, were more toxic. The range and mean of toxic content per cell (as fmol per cell) of the species were 13.5–256.5 and 140.2±50.8 for A. tamarense MDQ1096, 0.5–16.5 and 2.9±2.6 for A. minutum, 0–2.0 and 0.2±0.3 for A. tamarense EF04 and, 0–3.3 and 0.06±0.4 for A. andersoni. Ks for culture cell growth (per day),representing the phosphate concentration at which the specific culture cell growth rate is one half the maximum rate, and Kmin (per day), the phosphate concentration at which the specific culture cell growth rate is zero, were used as indicators of species’ potential competitive ability at low phosphorus concentrations. Low values for both Ks and Kmin indicate a high relative ability of the species to use low levels of phosphate and, hence, expected to outcompete higher Ks and Kmin species under phosphorus limitation. Ks and Kmin were 1.68 and 0.48 for A. tamarense MDQ1096, 1.16 and 0.39 for A. minutum, 1.0 and 0.38 for A. tamarense EF04 and, 0.74 and 0.34 for A. andersoni, respectively. There was a significant positive relationship between toxin content per cell with both Ks and Kmin, indicating that those species with lower ability to compete under phosphorus limitation were more toxic. The findings support the hypothesis that toxin production by dinoflagellates species could be an adaptation evolved to offset the ecological disadvantage of having low nutrient affinity.

ACS Style

M Frangópulos; C Guisande; Esther de Blas; I Maneiro. Toxin production and competitive abilities under phosphorus limitation of Alexandrium species. Harmful Algae 2004, 3, 131 -139.

AMA Style

M Frangópulos, C Guisande, Esther de Blas, I Maneiro. Toxin production and competitive abilities under phosphorus limitation of Alexandrium species. Harmful Algae. 2004; 3 (2):131-139.

Chicago/Turabian Style

M Frangópulos; C Guisande; Esther de Blas; I Maneiro. 2004. "Toxin production and competitive abilities under phosphorus limitation of Alexandrium species." Harmful Algae 3, no. 2: 131-139.

Research article
Published: 01 January 2004 in International Journal of Wildland Fire
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Two forest soils rich in organic matter but differing in texture (sandy loam and silty loam) were heated under controlled laboratory conditions in order to examine the consequences of the heating effect that accompanies the passage of a fire on the physical properties of soil. Three samples of both soils were heated for 30 min in a muffle furnace at temperatures of 25, 170, 220, 380 and 460°C. At each temperature, the following parameters were determined: dry aggregate size distribution, water aggregate stability, total porosity, pore size distribution, water repellency and hydraulic conductivity. Heating the soils at 170 and 220°C caused no significant changes in aggregate size distribution or total porosity but increased water aggregate stability and the volume of pores 0.2–30 μm. Also, increased water repellency and strongly decreased the hydraulic conductivity. All parameters underwent much more dramatic changes at 380 and 460°C that can be ascribed to the combustion of organic matter. At such temperatures, water repellency was destroyed and the low hydraulic conductivity can be attributed to the aggregate breakdown observed under dry and wet conditions.

ACS Style

R. García-Corona; E. Benito; E. De Blas; M. E. Varela. Effects of heating on some soil physical properties related to its hydrological behaviour in two north-western Spanish soils. International Journal of Wildland Fire 2004, 13, 195 .

AMA Style

R. García-Corona, E. Benito, E. De Blas, M. E. Varela. Effects of heating on some soil physical properties related to its hydrological behaviour in two north-western Spanish soils. International Journal of Wildland Fire. 2004; 13 (2):195.

Chicago/Turabian Style

R. García-Corona; E. Benito; E. De Blas; M. E. Varela. 2004. "Effects of heating on some soil physical properties related to its hydrological behaviour in two north-western Spanish soils." International Journal of Wildland Fire 13, no. 2: 195.

Article
Published: 01 February 2003 in Earth Surface Processes and Landforms
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At three adjacent sites in steeply sloping woodland in Galicia (NW Spain), surface runoff and associated erosion under simulated rainfall (64 mm h−1) were measured on five occasions between June 1998 and July 1999. Two of the three sites had recently been deforested and topsoil added, and one of these two had been sown with grass, which was germinating at the onset of the study. Deforestation greatly increased runoff and erosion rates, and the recovery of plant cover reduced erosion. All three soils were very hydrophobic due to high levels of poorly humified organic matter, which led to higher runoff rates than expected, especially during dry periods. However, great structural stability prevented there being a significant correlation between runoff rate and soil erosion. Copyright © 2003 John Wiley & Sons, Ltd.

ACS Style

Elena Benito; Jose-Luis Santiago; Esther De Blas; M.E. Varela. Deforestation of water-repellent soils in Galicia (NW Spain): effects on surface runoff and erosion under simulated rainfall. Earth Surface Processes and Landforms 2003, 28, 145 -155.

AMA Style

Elena Benito, Jose-Luis Santiago, Esther De Blas, M.E. Varela. Deforestation of water-repellent soils in Galicia (NW Spain): effects on surface runoff and erosion under simulated rainfall. Earth Surface Processes and Landforms. 2003; 28 (2):145-155.

Chicago/Turabian Style

Elena Benito; Jose-Luis Santiago; Esther De Blas; M.E. Varela. 2003. "Deforestation of water-repellent soils in Galicia (NW Spain): effects on surface runoff and erosion under simulated rainfall." Earth Surface Processes and Landforms 28, no. 2: 145-155.

Journal article
Published: 01 September 2001 in Land Degradation & Development
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Between February 1998 and March 1999 physical soil degradation was studied in temperate‐humid NW Spain after deforestation and slope modification. Changes in bulk density, total porosity, pore size distribution, aggregate stability and soil mechanical strength indicated the degradation process. Slope levelling produced the greatest impact. A rapid recovery of physical properties was observed, with the exception of those related to the soil mechanical strength. The increased soil erosion needs agronomic studies to understand the long‐term benefits and adverse aspects of the land‐use changes. Copyright © 2001 John Wiley & Sons, Ltd.

ACS Style

M.E. Varela; Esther De Blas; Elena Benito. Physical soil degradation induced by deforestation and slope modification in a temperate-humid environment. Land Degradation & Development 2001, 12, 477 -484.

AMA Style

M.E. Varela, Esther De Blas, Elena Benito. Physical soil degradation induced by deforestation and slope modification in a temperate-humid environment. Land Degradation & Development. 2001; 12 (5):477-484.

Chicago/Turabian Style

M.E. Varela; Esther De Blas; Elena Benito. 2001. "Physical soil degradation induced by deforestation and slope modification in a temperate-humid environment." Land Degradation & Development 12, no. 5: 477-484.

Journal article
Published: 01 October 1993 in Land Degradation & Development
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ACS Style

M. C. Trasar-Cepeda; Esther De Blas; I. Garcia-Rodeja; M. C. Leirós; F. Gil-Sotres; Carmen Trasar-Cepeda. Modifications of the phosphorus cycle with development of lignite mine soils. Land Degradation & Development 1993, 4, 131 -142.

AMA Style

M. C. Trasar-Cepeda, Esther De Blas, I. Garcia-Rodeja, M. C. Leirós, F. Gil-Sotres, Carmen Trasar-Cepeda. Modifications of the phosphorus cycle with development of lignite mine soils. Land Degradation & Development. 1993; 4 (3):131-142.

Chicago/Turabian Style

M. C. Trasar-Cepeda; Esther De Blas; I. Garcia-Rodeja; M. C. Leirós; F. Gil-Sotres; Carmen Trasar-Cepeda. 1993. "Modifications of the phosphorus cycle with development of lignite mine soils." Land Degradation & Development 4, no. 3: 131-142.

Journal article
Published: 31 December 1991 in Soil Biology and Biochemistry
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Ca(OH)2 was added under laboratory conditions to an acid soil rich in organic matter and with variable charge surfaces, and the effects on phosphatase activity and extractable P fractions were studied. During 39 days of initial incubation at room temperature (until the various limed soil samples reached the desired pH values of pH 5.5, 6.0 or 6.5), there were decreases in phosphatase activity and bicarbonate-extractable Po that were greater the greater the dose of lime; during 9 weeks of subsequent incubation at 28°C, net P mineralization that was uncorrelated with phosphatase activity occurred in all samples. In the samples limed to pH 6.5, mineralization of organic P, especially HCO−3 Po and NaOH Po, was significantly greater than in less heavily limed and unlimed samples.

ACS Style

Ma.C. Trasar-Cepeda; T. Carballas; F. Gil-Sotres; E. de Blas. Liming and the phosphatase activity and mineralization of phosphorus in an andic soil. Soil Biology and Biochemistry 1991, 23, 209 -215.

AMA Style

Ma.C. Trasar-Cepeda, T. Carballas, F. Gil-Sotres, E. de Blas. Liming and the phosphatase activity and mineralization of phosphorus in an andic soil. Soil Biology and Biochemistry. 1991; 23 (3):209-215.

Chicago/Turabian Style

Ma.C. Trasar-Cepeda; T. Carballas; F. Gil-Sotres; E. de Blas. 1991. "Liming and the phosphatase activity and mineralization of phosphorus in an andic soil." Soil Biology and Biochemistry 23, no. 3: 209-215.