Nutrient cycling in the south east Levantine basin of the eastern Mediterranean: Results from a phosphorus starved system

Krom, Michael D.; Woodward, E. Malcolm S.; Herut, Barak; Kress, Nurit; Carbo, P.; Mantoura, R.F.C.; Spyres, G.; Thingstad, T. Frede; Wassmann, Paul; Wexels-Riser, C.; Kitidis, Vassilis; Law, Cliff S.; Zodiatis, George

doi:10.1016/j.dsr2.2005.08.009

Cited by 155 publications

(109 citation statements)

References 42 publications

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“…The analysis errors calculated for preserved samples are 6.3% for phosphate, 1.6% for nitrate and 2.5% for silicate. These results are consistent with the results from the comparison of preserved and unpreserved nutrient samples from cruises in the NW Mediterranean Sea and with those from studies performed at other locations (Stéfansson and Richards, 1963;Strickland and Parsons, 1972;Riley et al 1975;Chapman and Mostert, 1990;Avanzino and Kennedy, 1993;Valderrama, 1995;Dore et al, 1996;Krom et al, 2005).…”

Section: Nutrient Preservationsupporting

confidence: 81%

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll a from the NW Mediterranean Sea

Noguera¹,

Cruzado²,

Blasco³

2010

Sci. Mar.

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SUMMARY: Oceanographic data from 28 cruises performed in the NW Mediterranean Sea between 1982 and 2003 and data from historical databases, amounting to more than 100000 data points, are used to define the quality control ranges at standard level depths of dissolved inorganic nutrients, dissolved oxygen and chlorophyll a. The quality of each of the key variables and the analytical precision are assessed. The results indicate that freezing is a valid preservation method for phosphate, nitrate, silicate and nitrite in samples from the NW Mediterranean Sea, though their relative error increases (6.3%, -1.6%, -2.5% and -11.4%, respectively). In contrast, freezing nutrient samples on the cruises gathered negatively affected the analytical precision and accuracy of the ammonium analysis. The analysis precision is also estimated using different approximations, the most realistic being the use of replicate samples from the same sampling bottle. Except for phosphate and dissolved oxygen, specific quality control ranges for mixed water columns, usually found in winter, have to be defined, since the surface concentrations are particularly high due to deep water mixing. The quality-controls described in this work are an important and useful tool for validating data and for detecting erroneous or anomalous data obtained in both historical and future works in the NW Mediterranean Sea.Keywords: dissolved inorganic nutrients, dissolved oxygen, chlorophyll a, nutrient preservation, analysis precision, quality control, NW Mediterranean Sea. RESUMEN: Conservación de nutrientes, precisión de los análisis y control de calidad de una base de datos oceanográfica con nutrientes inorgánicos, oxígeno disuelto y clorofila a del Mediterráneo noroccidental. -Se han utilizado datos oceanográficos de 28 campañas realizadas entre 1982 y 2003 en el Mediterráneo noroccidental, así como de bases de datos históricas, para definir rangos de control de calidad en niveles de profundidad estándares para nutrientes inorgánicos, oxígeno disuelto y clorofila a. La calidad de cada una de estas variables clave, así como la precisión analítica, han sido evaluadas. Los resultados indican que la congelación es un método válido para conservar las concentraciones de fosfato, nitrato, silicato y nitrito en muestras procedentes del Mediterráneo noroccidental, aunque el error relativo del análisis incrementa (6.3%, -1.6%, -2.5% y -11.4% respectivamente). En cambio, en las campañas recopiladas la congelación de muestras de nutrientes ha afectado negativamente a la precisión y exactitud del análisis de amonio. La precisión de los análisis también ha sido estimada utilizando diferentes aproximaciones, siendo la más realista el uso de réplicas procedentes de la misma botella de muestreo. Excepto para fosfato y oxígeno disuelto, se han definido rangos de control de calidad específicos en condiciones de columnas de agua mezcladas, típicas de invierno, puesto que las concentraciones superficiales resultan particularmente elevadas debido a la mezcla con aguas profundas. L...

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Section: Nutrient Preservationsupporting

confidence: 81%

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll a from the NW Mediterranean Sea

Noguera¹,

Cruzado²,

Blasco³

2010

Sci. Mar.

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“…Ribera d 'Alcalà et al, 2003;Krom et al, 2005;Pujo-Pay et al, 2011). This fact along with the oligotrophic gradient from west to east could be attributed to the difference in the allochtonous nutrient sources in terms of quantity and quality (Ribera d'Alcalà et al, 2003;Ludwig et al, 2010;Schroeder et al, 2010;Krom et al, 2010) and also to the specific hydrodynamic features of the MedSea (Robinson et al, 2001;Millot and TaupierLetage, 2005;Huertas et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

The CO2 system in the Mediterranean Sea: a basin wide perspective

Álvarez¹,

Sanleón-Bartolomé²,

Tanhua

et al. 2014

Ocean Sci.

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Abstract. The Mediterranean Sea (MedSea) is considered a "laboratory basin" being an ocean in miniature, suffering dramatic changes in its oceanographic and biogeochemical conditions derived from natural and anthropogenic forces. Moreover, the MedSea is prone to absorb and store anthropogenic carbon due to the particular CO 2 chemistry and the active overturning circulation. Despite this, water column CO 2 measurements covering the whole basin are scarce. This work aims to be a base-line for future studies about the CO 2 system space-time variability in the MedSea combining historic and modern CO 2 cruises in the whole area. Here we provide an extensive vertical and longitudinal description of the CO 2 system variables (total alkalinity -TA, dissolved inorganic carbon -DIC and pH) along an East-West transect and across the Sardinia-Sicily passage in the MedSea from two oceanographic cruises conducted in 2011 measuring CO 2 variables in a coordinated fashion, the RV Meteor M84/3 and the RV Urania EuroFleets 11, respectively. In this sense, we provide full-depth and length CO 2 distributions across the MedSea, and property-property plots showing in each sub-basin post-Eastern Mediterranean Transient (EMT) situation with regard to TA, DIC and pH.The over-determined CO 2 system in 2011 allowed performing the first internal consistency analysis for the particularly warm, high salinity and alkalinity MedSea waters. The CO 2 constants by Mehrbach et al. (1973) refitted by Dickson and Millero (1987) are recommended. The sensitivity of the CO 2 system to the atmospheric CO 2 increase, DIC and/or TA changes is evaluated by means of the Revelle and buffer factors.

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“…1, surface sediments in the EMS presently have δ 15 N-values between 5‰ and 3.5‰ with an eastward decreasing gradient. This is explained by either preferential assimilation of 14 NO − 3 (Struck et al, 2001) caused by an excess of nitrate over phosphate in surface waters of the EMS (Krom et al, 2005), or by an eastward increasing supply of fixed N (Pantoja et al, 2002). Although until recently fixed N 2 was the strongest candidate to explain the low modern δ 15 N levels, the observational evidence for significant diazotrophic N 2 fixation is scarce and ambiguous (Mara et al, 2009) and the biogeochemical need is questionable (Krom et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea

2010

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Abstract. The enhanced accumulation of organic matter in Eastern Mediterranean sapropels and their unusually low δ 15 N values have been attributed to either enhanced nutrient availability which led to elevated primary production and carbon sequestration or to enhanced organic matter preservation under anoxic conditions. In order to evaluate these two hypothesis we have determined Ba/Al ratios, amino acid composition, N and organic C concentrations and δ 15 N in sinking particles, surface sediments, eight spatially distributed core records of the youngest sapropel S1 (10-6 ka) and older sapropels (S5, S6) from two locations. These data suggest that (i) temporal and spatial variations in δ 15 N of sedimentary N are driven by different degrees of diagenesis at different sites rather than by changes in N-sources or primary productivity and (ii) present day TOC export production would suffice to create a sapropel like S1 under conditions of deepwater anoxia. This implies that both enhanced TOC accumulation and 15 N depletion in sapropels were due to the absence of oxygen in deep waters. Thus preservation plays a major role for the accumulation of organic-rich sediments casting doubt on the need of enhanced primary production for sapropel formation.

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Nutrient cycling in the south east Levantine basin of the eastern Mediterranean: Results from a phosphorus starved system

Cited by 155 publications

References 42 publications

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll <i>a</i> from the NW Mediterranean Sea

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll <i>a</i> from the NW Mediterranean Sea

The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective

Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea

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Nutrient cycling in the south east Levantine basin of the eastern Mediterranean: Results from a phosphorus starved system

Cited by 155 publications

References 42 publications

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll <i>a</i> from the NW Mediterranean Sea

Nutrient preservation, analysis precision and quality control of an oceanographic database of inorganic nutrients, dissolved oxygen and chlorophyll <i>a</i> from the NW Mediterranean Sea

The CO&lt;sub&gt;2&lt;/sub&gt; system in the Mediterranean Sea: a basin wide perspective

Diagenetic control of nitrogen isotope ratios in Holocene sapropels and recent sediments from the Eastern Mediterranean Sea

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The CO<sub>2</sub> system in the Mediterranean Sea: a basin wide perspective