Acidificación do Mar: Unha consecuencia das emisións de CO2

16 páginas, 10 figuras.-- Discurso de ingreso en la Real Academia Galega de Ciencias, Santiago de Compostela, 18 junio 2015O océano absorbe unha parte significativa de dióxido de carbono (CO2) das actividades humanas, o que equivale a cerca dun terzo das emisións totais durante o período industrial (Khatiwala e col., 2013; Le Quéré e col., 2015). A absorción de CO2 polo océano no só modera o ritmo do cambio climático, senón que provoca cambios sen precedentes na química do océano, diminuíndo o pH pola disolución adicional de CO2 en auga do mar dende a atmosfera. Así, a superficie do océano aumentou nun 30% a concentración de ións de hidroxeno (Raven e col., 2005) desde o principio da Revolución Industrial, o que equivale a un descenso de 0,1 unidades de pH que non é algo irrelevante a respeito dos cambios naturais. O actual episodio de acidificación ocorre unhas 100 veces máis rápidamente do que calquera outro cambio de acidez nos últimos 50 millóns de anos da historia da terra (Pelejero e col., 2010)Peer reviewe

Global ocean storage of anthropogenic carbon

48 páginas, 7 figuras, 7 tablas. -- S. Kathiwala ... et al.-- Proyecto CarbochangeThe global ocean is a significant sink for anthropogenic carbon (Cant), absorbing roughly a third of human CO2 emitted over the industrial period. Robust estimates of the magnitude and variability of the storage and distribution of Cant in the ocean are therefore important for understanding the human impact on climate. In this synthesis we review observational and model-based estimates of the storage and transport of Cant in the ocean. We pay particular attention to the uncertainties and potential biases inherent in different inference schemes. On a global scale, three data based estimates of the distribution and inventory of Cant are now available. While the inventories are found to agree within their uncertainty, there are considerable differences in the spatial distribution. We also present a review of the progress made in the application of inverse and data-assimilation techniques which combine ocean interior estimates of Cant with numerical ocean circulation models. Such methods are especially useful for estimating the air-sea flux and interior transport of Cant, quantities that are otherwise difficult to observe directly. However, the results are found to be highly dependent on modeled circulation, with the spread due to different ocean models at least as large as that from the different observational methods used to estimate Cant. Our review also highlights the importance of repeat measurements of hydrographic and biogeochemical parameters to estimate the storage of Cant on decadal timescales in the presence of the variability in circulation that is neglected by other approaches. Data-based Cant estimates provide important constraints on ocean forward models, which exhibit both broad similarities and regional errors relative to the observational fields. A compilation of inventories of Cant gives us a "best" estimate of the global ocean inventory of anthropogenic carbon in 2010 of 155 Pg C with an uncertainty of ±20%. This estimate includes a broad range of values suggesting that a combination of approaches is necessary in order to achieve a robust quantification of the ocean sink of anthropogenic CO2.Peer reviewe

The oceanic sink for anthropogenic CO2

5 páginas, 5 figuras, 2 tablas.-- Christopher L. Sabine ... et al.Using inorganic carbon measurements from an international survey effort in the 1990s and a tracer-based separation technique, we estimate a global oceanic anthropogenic carbon dioxide (CO2) sink for the period from 1800 to 1994 of 118 ± 19 petagrams of carbon. The oceanic sink accounts for ∼48% of the total fossil-fuel and cement-manufacturing emissions, implying that the terrestrial biosphere was a net source of CO2 to the atmosphere of about 39 ± 28 petagrams of carbon for this period. The current fraction of total anthropogenic CO2 emissions stored in the ocean appears to be about one-third of the long-term potentialPeer reviewe

Seasonal patterns and long-term trends in an estuarine upwelling ecosystem (Ria de Vigo, NW Spain)

16 páginas, 10 figuras, 4 tablasThermohaline properties, nutrient salts, chlorophyll a and meteorological variables have been intensively monitored since February 1987 in the Ría de Vigo (NW Spain), in order to examine the temporal variability and the relationships between these variables over different time scales. In this paper, the seasonal and the long-term components of the 1987–92 time series are analysed. The seasonal changes in thermohaline properties are forced by meteorological factors, but whereas temperature shows a well-defined annual cycle, salinity presents a higher frequency variation pattern due to the influence of upwelling–downwelling events and runoff. Nutrient concentrations change in a regular way through the seasons, so that characteristic and well-defined cycles are observed, but they are different for each nutrient and, for a given nutrient, exhibit a marked contrast between surface and bottom layers. The seasonal changes of nutrients are not explainable by advection and water column processes alone; fractionation of nutrients during recycling and, presumably, sedimentary processes should also play an important role. The annual cycle of chlorophyll a shows a bimodal pattern, which corresponds with the development of the spring and autumn blooms; even though the seasonal cycle accounts for an important amount of the observed temporal variability, variation at lower time scales is also important. Long-term trends, as a change in the mean level of the analysed time series, have been observed for most of the variables. Salinity increased and temperature decreased both for surface and bottom series. The largest trend, in terms of the percentage to the observed variability it represents, was an increase in bottom salinity. In relation to nutrient salts, there was no evidence of increasing eutrophication, although surface dissolved inorganic nitrogen, and surface and bottom phosphate increased slightly. Chlorophyll a concentration showed a decreasing trend, especially at the surface. The observed long-term trends could be attributed to changes of the meteorological factors that operate through an increase in the estuarine residual circulation.Support for this work came from CICYT project AMB 92-0165 and EC MAST project CT90- 0017.Peer reviewe

An update to the surface ocean CO2 atlas (SOCAT version 2)

22 páginas, 9 figuras, 10 tablas.-- D. C. E. Bakker ... et al.-- This work is distributed under the Creative Commons Attribution 3.0 License.-- Proyecto CarbochangeThe Surface Ocean CO2 Atlas (SOCAT), an activity of the international marine carbon research community, provides access to synthesis and gridded fCO2 (fugacity of carbon dioxide) products for the surface oceans. Version 2 of SOCAT is an update of the previous release (version 1) with more data (increased from 6.3 million to 10.1 million surface water fCO2 values) and extended data coverage (from 1968–2007 to 1968–2011). The quality control criteria, while identical in both versions, have been applied more strictly in version 2 than in version 1. The SOCAT website (http://www.socat.info/) has links to quality control comments, metadata, individual data set files, and synthesis and gridded data products. Interactive online tools allow visitors to explore the richness of the data. Applications of SOCAT include process studies, quantification of the ocean carbon sink and its spatial, seasonal, year-to-year and longerterm variation, as well as initialisation or validation of ocean carbon models and coupled climate-carbon modelsSupport for SOCAT has been received from the University of East Anglia (UK), the Bjerknes Centre for Climate Research, the Geophysical Institute at the University of Bergen (Norway), the Climate Observation Division of the Climate Program Office of the US National Oceanic and Atmospheric Administration, the University of Washington, Oak Ridge National Laboratory (USA), PANGAEA ® Data Publisher for Earth and Environmental Data (Germany), the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (Germany), the National Institute for Environmental Studies (Japan), the Korean Institute of Ocean Science and Technology, the European Union projects CarboChange (FP7 264879) and GEO- CARBON (FP7 283080), the UK Ocean Acidification Research Programme (NE/H017046/1; funded by the Natural Environment Research Council, the Department for Energy and Climate Change and the Department for Environment, Food and Rural Affairs), the Research Council of Norway (CARBON-HEAT), the Scientific Committee on Oceanic Research (SCOR, US, OCE-0938349), the US National Science Foundation (OCE-1068958), Swedish Research Council projects (2009–2994; 2008–6228; 2009–2994) and the Swedish National Space Board (RESCUE project; REmote Sensing ocean Carbon UptakE).Peer reviewe

Chemical composition of phytoplankton and Particulate Organic Matter in the Ría de Vigo (NW Spain)

15 pages, 2 figures, 7 tables.Elemental (C, H, O, N, Si, P) and biochemical composition (proteins, carbohydrates, lipids, phosphorus compounds, chlorophyll and opal) in particulate organic matter, diatoms, other autotrophs, heterotrophs and detritus from natural plankton were established simultaneously by measuring relatively few components. Using standard techniques in marine chemistry on board ship, it is possible to infer a great deal about the composition and condition of the plankton. In addition, the organic matter content in terms of cell volume was determined for each group of plankton. Variation of chemical composition with depth was also considered. The ratio carbohydrates/lipids (Cbh/Lip) was used as an indicator of the chemical quality of the plankton.This paper was supported by the Consellería de Educación of the Xunta de Galicia and Comisión Interministerial de Ciencia y Tecnología (CICYT) Grant No. MAR88-245.Peer reviewe

Tracking the variable North Atlantic sink for atmospheric CO2

3 páginas, 1 tabla, 3 figuras.-- Watson, Andrew J. ... et al.The oceans are a major sink for atmospheric carbon dioxide (CO2). Historically, observations have been too sparse to allow accurate tracking of changes in rates of CO2 uptake over ocean basins, so little is known about how these vary. Here, we show observations indicating substantial variability in the CO2 uptake by the North Atlantic on time scales of a few years. Further, we use measurements from a coordinated network of instrumented commercial ships to define the annual flux into the North Atlantic, for the year 2005, to a precision of about 10%. This approach offers the prospect of accurately monitoring the changing ocean CO2 sink for those ocean basins that are well covered by shipping routes.Peer reviewe

CO2 antropogénico en la región de las Azores

The AZORES-I cruise was conducted in August 1998, spanning the length of three latitudinal large-scale sections at 22, 28 and 32ºW. The oceanic carbon system was oversampled by measuring total alkalinity, total inorganic carbon and pH. It is thus possible to estimate anthropogenic CO2 (CANT) and to investigate its relationship with the main water masses that are present. C CANT is calculated using the latest back-calculation techniques: φCTº and TrOCA methods. Although the two approaches produce similar vertical distributions, the results of the TrOCA method show higher CANT variability and produce higher inventories than those of the φCTº method. The large proportion of Mediterranean Water found in the northern part of the study area is the main cause of the observed increase northwards of C CANT inventories. Changes in C CANT inventories between 1981 and 2004 are evaluated using data from the TTO-NAS, OACES-93 and METEOR-60/5 cruises. According to the φCTº and TrOCA approaches, the average long-term rates of C CANT inventory change are 1.32±0.11 mol C m-2 y-1 (P=0.008) and 1.18±0.16 mol C m-2 y-1 (P=0.018), respectively. During the 1993-1998 a significant increase in the C CANT storage rate was detected by the φCTº method. It is thought that this stems directly from the enhanced Labrador Seawater formation after the increased advection observed at the time.La campaña de macro-escala Azores I se desarrolló durante el mes de agosto de 1998 y consta de tres secciones meridionales centradas en 22, 28 y 32ºW. El sobre-muestreo realizado del sistema del carbónico, con medidas de alcalinidad total, carbono inorgánico total y pH, ha permitido el cálculo del CO2 antropogénico (CANT) e investigar su distribución en las masas de agua presentes. El CANT se calculó mediante las últimas técnicas de retro-cálculo disponibles: los métodos φCTº y TrOCA. A pesar de que ambos procedimientos producen distribuciones verticales similares, los resultados del método TrOCA indican mayores inventarios y variabilidad de CANT que los estimados por el método φCTº. La elevada proporción de agua mediterránea presente al norte de la región estudiada es la causa principal del aumento hacia el norte de los inventarios de CANT. Las tasas de cambio en los inventarios de CANT entre 1981 y 2004 se han evaluado utilizando datos de las campañas TTO-NAS, OACES-93 y METEOR-60/5. Según los métodos φCTº y TrOCA, las tasas de cambio promedio a largo plazo del inventario de CANT en esta zona son de 1.32±0.11 mol C m -2 y-1 (p-valor=0.008) y de 1.18±0.16 mol C m-2 y-2 (p-valor=0.018), respectivamente. Durante el periodo 1993-1998 el método φCTº detecta un aumento significativo de la tasa de acumulación de CANT provocado posiblemente por las elevadas tasas de formación de agua de Labrador, derivadas del aumento de la advección observada en dicho periodo

Consistency of cruise data of the CARINA database in the Atlantic sector of the Southern Ocean

13 pages, 9 figures, 1 table.-- M. Hoppema ... et al.Initially a North Atlantic project, the CARINA carbon synthesis was extended to include the Southern Ocean. Carbon and relevant hydrographic and geochemical ancillary data from cruises all across the Arctic Mediterranean Seas, Atlantic and Southern Ocean were released to the public and merged into a new database as part of the CARINA synthesis effort. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean, including 11 from the Atlantic sector. The variables from all Southern Ocean cruises, including dissolved inorganic carbon (TCO2), total alkalinity, oxygen, nitrate, phosphate and silicate, were examined for cruise-to-cruise consistency in one collective effort. Seawater pH and chlorofluorocarbons (CFCs) are also part of the database, but the pH quality control (QC) is described in another Earth System Science Data publication, while the complexity of the Southern Ocean physics and biogeochemistry prevented a proper QC analysis of the CFCs. The area-specific procedures of quality control, including crossover analysis between stations and inversion analysis of all crossover data (i.e. secondary QC), are briefly described here for the Atlantic sector of the Southern Ocean. Data from an existing, quality controlled database (GLODAP) were used as a reference for our computations – however, the reference data were included into the analysis without applying the recommended GLODAP adjustments so the corrections could be independently verified. The outcome of this effort is an internally consistent, high-quality carbon data set for all cruises, including the reference cruises. The suggested corrections by the inversion analysis were allowed to vary within a fixed envelope, thus accounting for natural variability. The percentage of cruises adjusted ranged from 31% (for nitrate) to 54% (for phosphate) depending on the variable.This work has been done and funded as part of the EU project CARBOOCEAN (no. 511176; GOCE). Additional support from the International Ocean Carbon Coordination Project IOCCP (Maria Hood) and the hospitality of the Hanse Institute for Advanced Study (HWK Delmenhorst, Germany) was gratefully accepted. R. M. Key was supported by NOAA grants NA08OAR4320752 and NA08OAR4310820; X. Lin by NOAA grant NA08OAR4310820; A. Velo, F. F. Perez and A. F. R´ıos by grants: PGIDIT05OXIC40203PM Xunta de Galicia and CTM200627116E/MAR MEC; M. A´ lvarez by grant RYC-2006-001836; R. G. J. Bellerby by IPY project Bipolar Atlantic Thermohaline Circulation (BIAC, IPY Cluster #23) and Southern Ocean Biogeochemistry: Education and research (project no. 180328) from the Norwegian Research Council.Peer reviewe

Assessing the internal consistency of the CARINA database in the Indian sector of the Southern Ocean

20 pages, 4 figures, 5 tables.-- C. Lo Monaco ... et al.Carbon and carbon-relevant hydrographic and hydrochemical ancillary data from previously not publicly available cruises were retrieved and recently merged to a new data base, CARINA (CARbon IN the Atlantic). The initial North Atlantic project, an international effort for ocean carbon synthesis, was extended to include the Arctic Mediterranean Seas (Arctic Ocean and Nordic Seas) and all three sectors of the Southern Ocean. Of a total of 188 cruises, 37 cruises are part of the Southern Ocean. The present work focuses on data collected in the Indian sector (20° S–70° S; 30° E–150° E). The Southern Indian Ocean dataset covers the period 1992–2004 and includes seasonal repeated observations. Parameters including salinity, dissolved inorganic carbon (TCO2), total alkalinity (TA), oxygen, nitrate, phosphate and silicate were examined for cruise-to-cruise and overall consistency. In addition, data from an existing, quality controlled data base (GLODAP) were introduced in the CARINA analysis to improve data coverage in the Southern Ocean. A global inversion was performed to synthesize the information deduced from objective comparisons of deep measurements (>1500 m) at nearby stations (generally <220 km). The corrections suggested by the inversion were allowed to vary within a fixed envelope, thus accounting for ocean interior variability. The adjustments applied to CARINA data and those recommended for GLODAP data, in order to obtain a consistent merged dataset, are presented and discussed. The final outcome of this effort is a new quality controlled data base for TCO2 and other properties of the carbon system that can now be used to investigate the natural variability or stability of ocean chemistry and the accumulation of anthropogenic carbon. This data product also offers an important new synthesis of seasonal to decadal observations to validate ocean biogeochemical models in a region where available historical data were very sparse.This work has been funded as part of the EU project CARBOCEAN (no. 511176; GOCE), and additional support from the International Ocean Carbon Coordination Project IOCCP (Maria Hood) and the Hanse Institute for Advanced Study (HWK Delmenhorst, Germany). Support for R. M. Key and X. Lin was primarily from NOAA grant NA08OAR4320752 and NA08OAR4310820. Support for M. A´ lvarez was from grant RYC-2006-001836. B. Tilbrook was supported though the Australian Climate Change Science Program and the Antarctic Climate and Ecosystem CRC. A. F. Rios and A. Velo also acknowledge support from PGIDIT05OXIC40203PM Xunta de Galicia and CTM2006-27116-E/MAR MEC.Peer reviewe