A natural laboratory for shallow gas: the R�as Baixas (NW Spain)

García‐Gil, Soledad

doi:10.1007/s00367-003-0159-5

Cited by 52 publications

(26 citation statements)

References 29 publications

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“…The low C:N ratio found in our samples indicate that the organic matter present in biodeposits and sediments was labile, which will favour diagenetic activity. This would have created a demand for oxidants and the formation of anoxic conditions (Otero & Macías, 2002, 2003, which in the Ría de Arousa correspond to sulphate-reducing and methanogenic environments (for more detail see Garcia-Gil, 2003;Otero et al, 2005). Differences in the percentage of TIC were observed depending on the type of material and the zone.…”

Section: Total Organic Carbon (Toc) Total Inorganic Carbon (Tic) Andmentioning

confidence: 92%

Sulphur partitioning in sediments and biodeposits below mussel rafts in the Rı́a de Arousa (Galicia, NW Spain)

Otero

Anta

Macı́as

2006

Marine Environmental Research

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Section: Total Organic Carbon (Toc) Total Inorganic Carbon (Tic) Andmentioning

confidence: 92%

Sulphur partitioning in sediments and biodeposits below mussel rafts in the Rı́a de Arousa (Galicia, NW Spain)

Otero

Anta

Macı́as

2006

Marine Environmental Research

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“…Según Berner (1981) una vez agotados los diferentes aceptores de electrones con energía libre mayor que el sustrato se forma gas metano. La presencia de este gas en la zona interna de la Ría de Pontevedra ha sido recientemente constatada por García-Gil (2002). En esta zona de la ría se registra una menor energía del oleaje que conlleva una mayor acumulación de materiales finos con la consiguiente y bien conocida asociación con la materia orgánica (Rubio et al, 2000a, b).…”

Section: Degree Of Pyritizationunclassified

“…La especiación del Fe también está influenciada por la materia orgánica, lo cual se corrobora por la correlación negativa significativa con el Fe reactivo. Esto indica que durante el proceso de descomposición orgánica se generan las condiciones para que se convierta Fe reactivo en Fe pirítico, proceso que será más intenso en this gas in the internal zone of Ría de Pontevedra has recently been confirmed by García-Gil (2002). Lower wave energy is recorded in this zone, which leads to greater accumulation of fine materials with the consequent and well known association with organic matter (Rubio et al, 2000a, b).…”

Section: Relaciones Entre Las Propiedades Del Sedimento Y Las Formas unclassified

Geochemical phases of Fe and degree of pyritization in sediments from Ría de Pontevedra (NW Spain): Implications of mussel raft culture

León

Méndez²,

Armesto³

2004

Cienc. Mar.

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585Fases geoquímicas del Fe y grado de piritización en sedimentos de la Ría de Pontevedra (NO de España):Implicaciones del cultivo del mejillón en bateas ResumenSe analizaron seis testigos de sedimento de la Ría de Pontevedra para valorar la influencia que ejercen los sistemas de bateas sobre las propiedades texturales y geoquímicas del sedimento (contenido de carbonatos, materia orgánica, fases geoquímicas del Fe y grado de piritización). Cuatro de los testigos se extrajeron en zonas dedicadas al cultivo de mejillón en bateas y los otros dos en áreas adyacentes no sometidas a dicha actividad. El grado de piritización (DOP) osciló entre 11.89% y 67.30%, con un valor medio de 46.36 ± 13.15%. Los valores máximos se obtuvieron en los sedimentos de las zonas con bateas (biodepósitos) que presentaron, a su vez, mayores contenidos de Fe pirítico, fango y materia orgánica que las zonas libres de bateas. Por el contrario, en estas últimas zonas predominó el Fe asociado con los silicatos, junto con las fracciones más gruesas (arena y grava) y elevados porcentajes de carbonatos. Estos resultados muestran un predominio de condiciones más reductoras en los biodepósitos, que favorecen la formación de una mayor cantidad de pirita frente a las áreas donde no hay maricultura. Los valores del DOP indican que el Fe reactivo no se ha convertido en su totalidad en Fe pirítico. La materia orgánica se confirma como el factor limitante en la formación de pirita por la correlación significativa (r = 0.61) encontrada entre ésta y el DOP. Los resultados permiten concluir que el cultivo del mejillón en bateas modifica sustancialmente la textura del sedimento e influye, significativamente, en las formas químicas del Fe, con las consecuentes implicaciones geoquímicas y ambientales.Palabras clave: grado de piritización, Ría de Pontevedra, hierro reactivo, hierro pirítico, bateas. AbstractTo assess the influence of mussel raft systems on several geochemical and sedimentological properties (carbonate and organic matter contents, fractions of Fe and degree of pyritization), six sediment cores were collected from the Ría de Pontevedra area. Four of those cores were collected in mussel raft areas (biodeposits) and the other two in adjacent areas where mussel rafts do not operate. The degree of pyritization (DOP) varied between 11.89% and 67.30%, with a mean value of 46.36 ± 13.15%. The maximum values of DOP were obtained in sediments from the mussel raft areas, which in turn showed higher values of pyrite Fe, organic matter and mud than the areas without mussel rafts. On the contrary, in the latter areas, coarser sediments with high carbonate content and Fe bound to silicates were the predominant phases. The results show a dominance of more reducing conditions in the biodeposit areas than in the adjacent areas. The DOP values indicate that reactive Fe was not totally converted to pyrite Fe. The significant correlation (r = 0.61) between DOP and organic matter confirmed that the latter is the limiting factor in pyrite genesis. These results allow...

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“…This study was conducted on samples from three gravity cores retrieved from three sampling stations in the Ría de Vigo (Fig. ) aboard the research vessel Mytillus of the Spanish National Research Council in November 2012, according to the distribution of gas fields previously mapped in the Ría de Vigo . Two of them (C8‐GI and C11‐GO) were located inside the mapped gas fields.…”

Section: Methodsmentioning

confidence: 99%

Sulfur, Iron, and Manganese Speciation in Anoxic Sediments with Methane (Ría de Vigo, NW Spain)

Ramírez-Pérez

Blas

García‐Gil

2017

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.

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A natural laboratory for shallow gas: the R�as Baixas (NW Spain)

Cited by 52 publications

References 29 publications

Sulphur partitioning in sediments and biodeposits below mussel rafts in the Rı́a de Arousa (Galicia, NW Spain)

Sulphur partitioning in sediments and biodeposits below mussel rafts in the Rı́a de Arousa (Galicia, NW Spain)

Geochemical phases of Fe and degree of pyritization in sediments from Ría de Pontevedra (NW Spain): Implications of mussel raft culture

Sulfur, Iron, and Manganese Speciation in Anoxic Sediments with Methane (Ría de Vigo, NW Spain)

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