Flows and budgets of nutrient salts and organic carbon in relation to a red tide in the Ria of Vigo (NW Spain)

14 pages, 11 figures, 8 tables.In late September 1986, a major red tide occurred in the Ria of Vigo. Hydrographic conditions led to water retention, with circulation in a semi-closed circuit. In this study nutrient salts and carbon fluxes were calculated, and their consumption quantified, by use of a box model for the ria. The dinoflagellate Gymnodinium catenatum, scarcely present on 4 September, increased in concentration to 10(up 4) cell dm(-3) by 21 September. This was favoured by chemical causes, such as the high availability of ammonium (6.2 mol s(-1) were delivered to the upper water layer) and organic carbon, and by physical causes, such as the rapid circulation (862 X 10 (up to 3) kg s(-l) ) with reducing mixing, almost half that of the preceding date. The nutrient salts came mostly from the remineralisation of organic matter. The amounts contributed by freshwater, 5 % of the total, did not have an appreciable influence on the formation of the red tide. Vertical migration of the dinoflagellate played an important role. It is estimated that this organism was responsible for 22% of the synthesis of nitrogenous organic matter. The red tide came to an end with the November rains, which created rapid circulation which washed out the ria.The I.E.O. of Vigo for their k1nd inntation to then workshop. Specla1 thanks to Prof. Fernando Fraga, head of the project 'Intercambio de nutrientes entre las rias y la plataforma costera en el NO de la peninsula Ibérica'.Peer reviewe

New Local-scale hydrographic observation on the Flemish Cap in July 1996

8 pages, 7 figures.The research cruise "FC96" was made on the Flemish Cap area on board the RV Cornide de Saavedra from 28 June to 14 July 1996. The survey consisted of a series of 121 random bottom trawls over Flemish Cap inside the boundaries of the 732 m isobath. A CTD station was established either at the beginning or at the end of each trawl for a total of 116 stations. Three different water masses were detected. Two of them are already known: (a) Labrador Current waters, spreading around the Bank; (b) Central Cap seawater, the solar heated Labrador waters retained over the Cap. These waters made an anti-cyclonic gyre of 4–12 cm per sec. Both water masses tended to become stable at 200 m depth, with temperatures about 3.5°C and salinities about 34.85 psu. A third water mass which had not been previously described on Flemish Cap was the Slope Water, found in the southwest area of the Cap between 200–300 m, where it occupied two separate areas with temperatures higher than 4.5°C and salinities higher than 34.90 psu. These intrusions of Slope Water on the Flemish Cap seemed to affect the distribution of some fish species. In particular, they coincided with the breaking of continuity in the geographic distribution of some demersal species, like the redfish Sebastes marinus and S. fasciatusThis paper is a contribution to the UE project "Analysis of exploited fish stocks on Flemish Cap" ref. AIR1-CT92-0558.Peer reviewe

Lead and Zinc contamination of surface sediments in the main harbours of the Galician Rias

The concentration ranges and degree of contamination of lead and zinc in the four principal harbour areas of the northwest Iberian Peninsula have been defined from 130 surface sediment samples (A partir de la fracción fina en 130 muestras de sedimento superficial se han cuantificado los niveles de concentración para plomo y cinc en las rías donde se encuentran los principales puertos de la costa gallega. Los patrones de distribución de Pb y Zn en el sedimento muestran altos contenidos en el litoral próximo a las áreas de actividad portuaria y astilleros: las concentraciones llegan hasta 140, 160, 160 y 320 mg·kg-1 para Pb y hasta 150, 380, 600 y 1960 mg·kg-1 para Zn en Pontevedra, Coruña, Ferrol y Vigo, respectivamente. En base a sus niveles naturales, establecidos mediante cuatro testigos de sedimento, se han definido sus grados de contaminación mediante factores de enriquecimiento. Consecuentemente, se puede definir entre moderada y considerable la contaminación de Pb y Zn en los puertos de La Coruña y Pontevedra, así como severa en Ferrol y Vigo. En otras zonas de las rías la contaminación normalmente decrece, como suele ocurrir en estuarios y costas de nuestro planeta donde existen puertos o astilleros

Fluvial transport patterns of dissolved trace metals to the Ria of Cedeira

5 páginas.-- Interdisciplinary Water Congress CINA 2014, Vigo, 2-6 June 2014Samples of water were withdrawn monthly close to the Das Mestas River mouth, out of the tidal influence, from October 2011 to September 2012 (covering a hydrological year). After filtration through 0.45 policarbonate membrane, nine trace metals were analyzed (Al, Co, Cu, Cr, Fe, Mo, Ni, Pb and V) in the dissolved phase. All procedures were made following trace-metal-clean techniques. Three groups of metals were distinguished: Al, Co, Ni, Cu and Pb correlated with the SPM and the DOC indicating they are related with soil leaching; Iron is related with Chl-a so its behavior depends on the biologic activity; lithological influence on Cr, Mo and V patterns was observed.This study was supported by CTM2011-28792-C02 project, Land-sea exchange of trace metals and its importance for marine phytoplankton in an upwelling coast (MITOFE), financed by Spanish MINECOPeer reviewe

Cephalopod paralarvae and upwelling conditions off Galician waters (NW Spain)

A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 m mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). TheRhynchoteuthion paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW)

Revisión de los eventos de afloramiento en Galicia: eventos fuera de temporada en las rías (1967–2009)

Over the last decades several studies have been conducted on upwelling along the Galician coast that have significantly improved the knowledge of this process. These investigations showed that upwelling along this coast is a frequent phenomenon during the spring and summer months, pumping colder Eastern North Atlantic Central Water into the rias. Nevertheless, several upwelling events in autumn and winter have been characterized in the Galician rias, indicating that the upwelling process along the Galician coast is not a phenomenon restricted to spring and summer. In this study the recurrence of these upwelling events has been reviewed from published articles and analyzed from 1967 to 2009 along the western and northern Galician coasts in terms of an upwelling index. The highest mean number of days under favorable upwelling conditions per month was observed during spring and summer on the western (18–26 days) and northern (12–14 days) coasts. During autumn and winter the number of days was lower (11–18 days, western coast; 8–10 days, northern coast) although not negligible, showing the possibility of observing upwelling events during this period. In fact, during these months a significant probability of observing favorable upwelling conditions along both coasts (26%) was found, though the most probable situation corresponded to unfavorable upwelling conditions (44%). The results thus revealed that these events cannot be considered isolated episodes. Upwelling processes in the rias should be observed under favorable conditions, such as prevalence of northerly wind at the adjacent western Galician shelf, independently of the season.Durante las últimas décadas se han llevado a cabo varios estudios relacionados con el fenómeno de afloramiento a lo largo de la costa de Galicia que han mejorado significativamente el conocimiento de este proceso. De los resultados de estos trabajos se ha encontrado que el afloramiento a lo largo de esta costa es un fenómeno frecuente durante los meses de primavera y verano, introduciendo Agua Central del Atlántico Norte en el interior de las rías. Sin embargo, en las rías gallegas se han caracterizado varios eventos de afloramiento durante otoño e invierno que indican que este proceso no es un fenómeno exclusivo de las estaciones de primavera y verano. En este estudio se hace una revisión de estos eventos teniendo en cuenta artículos ya publicados y también se analiza su recurrencia a lo largo de las costas oeste y norte de Galicia a partir de datos de índice de afloramiento de 1967 a 2009. El número medio de días por mes con condiciones favorables de afloramiento más elevado se observó durante los meses de primavera y verano en la costa oeste (18–26 días) y costa norte (12–14 días). Durante otoño e invierno este número de días fue menor (11–18 días, costa oeste; 8–10 días, costa norte) aunque no despreciable, indicando la posibilidad de observar eventos de afloramiento durante este periodo. De hecho, durante estos meses se observó una cierta probabilidad de obtener condiciones favorables de afloramiento a lo largo de ambas costas (26%), aunque la situación más probable correspondió a condiciones desfavorables (44%). Estos resultados revelaron que estos eventos no se pueden considerar como episodios aislados. De esto se deduce que los procesos de afloramiento en las rías deberían ser observados bajo condiciones favorables, tales como vientos predominantes del norte en la plataforma adyacente, independientemente de la estación.publishe

Hydrography of the Pontevedra Ria: Intra-annual spatial and temporal variability in a Galician coastal system (NW Spain)

In order to ameliorate the dearth of existing scientific knowledge concerning the hydrography of the Pontevedra Ria, a systematic investigation was carried out between October 1997-98. Salinity variations were closely related to river discharge whereas bottom waters presented oceanic characteristics over the whole year. Current was controlled by tide, river discharge, and wind in the internal ria where the highest velocities were directed along the ria channel with a low transverse component. Favorable atmospheric conditions in spring induced coastal upwelling up the continental shelf. In May the upwelling was sufficiently strong to be detected in the inner ria and intensified in July and August, cooling the ria water to 12 degrees -14 degreesC. Upwelling ceased in September, and from November to March seawater transported by the poleward current (35.9; 15 degreesC) was detected on the shelf. From January until March, unanticipated favorable upwelling conditions provoked an influx of poleward inside the ria. Ria intrusion of poleward water and association with occasional winter upwelling conditions has not been observed previously. Isopycnic three-dimensional (3-D) surface and 2-D isopycnal maps show that with high river runoff or intense upwelling, lower-salinity water leaves the ria near the northern margin in the surface layer. Under negative upwelling conditions, the water is partially dammed inside the ria and exits the ria when the wind speed falls. During upwelling events, ENACW penetrated the ria, especially near the southern shore. Arrival of ENACW at the northern entrance impedes the outward water flow through this mouth

Fluvial contributions of nutrient salts, dissolved trace elements and organic carbon to the sea by pristine temperate rivers (SW Europe)

12 páginas, 5 figuras, 3 tablasA summary of the water characteristics of the rivers Sor, Mera and Landro that drain into the Northern Galician Rias (NW Iberian Peninsula) is presented. The analysis was based on fortnightly monitoring during 2008, for major and minor chemical elements in the dissolved phase (Al, As, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, U, V, Zn), nutrients (nitrate, nitrite, ammonium, phosphate, silicate), suspended particulate matter, chlorophyll-a and tracers of water quality chemistry (dissolved inorganic nitrogen and carbon). The data cover rivers not urban, agriculturally or industrially affected. Continental inputs of the material via rivers into the Northern Galician Rias were measured and annual fluxes of the dissolved chemical elements to the rias were calculated. In spite of the high variability in water flow, this study provides a good estimate of the overall amounts of nutrients and dissolved elements discharged to pristine ria systemsThis work is a contribution to the Spanish LOICZ program and was supported by the ‘Spanish Ministry of Science and Technology’ through the CICYT program (INTERESANTE project, ref. CTM2007-62546-C03/MAR). N. Ospina-Alvarez thanks the Spanish National Research Council (CSIC) for their financial support (JAE-Pre contract).Peer reviewe

Basin-scale contributions of Cr, Ni and Co from Ortegal Complex to the surrounding coastal environment (SW Europe)

10 páginas, 6 figuras, 3 tablasThe enrichment of Cr and Ni in the coastal zones is usually associated with anthropogenic sources such as the tanning, galvanization, ceramic, and cement industries. However, geological complexes of specific lithologic composition located near shorelines may act as natural sources of metals to the continental shelf. Cape Ortegal (SW Europe) is an ultramafic complex that has Cr, Ni and Co enriched in rocks due to the minerals chromite, chromospinel, gersdorfite and pentlandite. Thus, the hypothesis that this geological complex contributes to metal enrichment in Ortigueira and Barqueiro Rias and the adjacent continental shelf was tested. Chromium, Ni, and Co were determined in water and in suspended particulate matter of ria tributaries, rainfall, surface sediments, mussels, and algae. High contents of Cr (max. 1670 mg · kg− 1) and Ni (max. 1360 mg · kg− 1) were found in the sediments surrounding Cape Ortegal and the Ortigueira Ria as a result of erosion of exposed cliffs. Dissolved Cr and Ni concentrations in fluvial waters were significantly higher in the rivers that crosses the Ortegal Complex, i.e. Lourido (0.47 μgCr · L− 1; 9.4 μgNi · L− 1) and Landoi (0.37 μgCr · L− 1; 4.3 μgNi · L− 1), in comparison with the nearby basin out of the complex influence (Sor River: < 0.01 μgCr · L− 1; 0.57 μgNi · L− 1). The annual fluvial contributions of Cr and Ni to the Ortigueira Ria were higher than fluxes into the Barqueiro Ria. Moreover, the increase in Cr and Ni in the rainfall in summer demonstrated the importance of the atmosphere pathway for introducing these elements into the aquatic environment. As a consequence, the contents of these metals in soft tissues and shell of mussels and algae from the Ortigueira Ria were higher than the organisms from Barqueiro Ria. Thus, geological complexes, such as the Cape Ortegal, located in an uncontaminated area, can increase the land–sea exchange of trace metals. Gadget timed out while loadingThis article is a contribution to the Spanish LOICZ program and was supported by the research projects INTERESANTE (ref. CTM2007-62546-C03/MAR) and MITOFE (ref. CTM2011-28792-C02) financed by CICYT and MINECO, respectively, in cooperation with the Spanish-Portuguese Action references 2007PT0021 and 9/CSIC/2008. M.Sc. N. Ospina-Alvarez expresses gratitude to CSIC support by means of a JAE-preDoc contract.Peer reviewe

Cadmium, manganese, nickel and lead contents in surface sediments of the lower Ulla River and its estuary (northwest Spain)

The authors determined the total contents of cadmium, manganese, nickel and lead in 16 surface sediment samples along the last 7 km of the Ulla River and in its estuary. Prior to chemical analysis, the grain-size fractions below 500, 63 and 2 μm were separated. The metal concentrations were analysed in the fraction below 63 μm, and in selected samples from the clay fraction ( 2 μm). The soil samples were digested with a HF + HNO₃ + HCl mixture and the total concentrations of Cd, Mn, Ni and Pb were analysed with the AAS method. The highest contents of metals were found in the riverine sediments, near the town of Padrón, and in the estuary. The enrichment of metals in the sediments was mainly related to the proximity of the industrial sources, and to the fine particles transported and deposited in the sediments. The Ni and Mn contents found are considered very high, at some points reaching values of up to 357 mg kg⁻¹ and 2 110 mg kg⁻¹, respectively. Lead and Cd were mainly found within the range considered as natural background levels in the sediments of the Galician rias, with concentrations of 25-68 mg kg⁻¹ for Pb and 0.01-0.92 mg kg⁻¹ for Cd. The lower part of the Ulla River and its estuary present: l) moderate to high contamination levels of Mn and Ni; 2) moderate Pb pollution levels; and 3) no Cd contamination. The highest concentrations of metals were obtained in the river, near the wastewater discharges, and in the estuary, associated with fine particles.El contenido total de cadmio, manganeso, níquel y plomo se determinó en 16 muestras de sedimentos superficiales a lo largo de los últimos 7 km del río Ulla y en su estuario. Previamente a los análisis químicos, se realizó la separación granulométrica de los sedimentos en las fracciones inferiores a 500, 63 y 2 μm. La concentración de metales se determinó en la fracción inferior a 63 μm y, para algunas muestras, en la fracción arcilla ( 2 μm). La digestión del sedimento se realizó en una mezcla ácida de HF + HNO₃ + HCl y se analizó la concentración total de Cd, Mn, Ni y Pb por espectroscopia de absorción atómica. Los contenidos más altos en metales se encontraron en los sedimentos del río, en las inmediaciones de Padrón y en los del estuario. El enriquecimiento de los sedimentos en metales se ha relacionado con la proximidad a las zonas industriales y con el material fino transportado y depositado en los sedimentos. Se han encontrado contenidos muy altos de Ni y Mn con valores de 357 mg kg⁻¹ y 2 110 mg kg⁻¹, respectivamente. Las concentraciones de Cd y Pb son comparables a los valores establecidos como niveles naturales en los sedimentos de las rías gallegas: 25-68 mg kg⁻¹ para el Pb y 0.01-0.92 mg kg⁻¹ para el Cd. El sedimento de la parte baja del río Ulla y su estuario presentan niveles moderados-altos de contaminación para Mn y Ni, moderados para Pb y nulos para Cd. Las mayores concentraciones de estos metales en el sedimento fueron medidas asociadas con las fracciones finas ( 63 μm): cerca de Padrón, zona de influencia fluvial y, también, aunque con valores más bajos, en la desembocadura del Ulla, zona de influencia marina.Instituto Español de Oceanografí