Arctic Station Dirigibile Italia

Arctic Dissolved CO2 (AR-DIS-CO2)

Call year: 2018 Status: active IADC_id: 120

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The study of gases concentrations and fluxes in the climate system ocean-atmosphere-land represents a suitable and valid tool to monitor the climate conditions and its evolution and effects at global scale. Polar regions, far from urban and industrial sites, represent a suitable natural laboratory to monitor the global changes in the equilibrium of greenhouse gases within ocean-atmosphere-land ecosystem. rnSince industrial age, incessant production and emission into the atmosphere of greenhouse gases, in particular CO2, caused continuous increasing of its concentration in air. This global process is still active, despite in last decades climate agreements between nations have defined common strategies to reduce the emission of greenhouse gases and, therefore, to limit/mitigate the global warming. Pre-industrial CO2 air concentration was 280 ppm and nowadays it exceeds 400 ppm (https://www.esrl.noaa.gov/gmd/ccgg/trends/). Gas concentrations changes into the atmosphere cause several physical-chemical modifications in ocean and land, influencing biological and biochemical activity of living organism. One of the main studied process active at global scale is the “ocean acidification” (Orr, 2005; Raven, 2005; Barker and Ridgwell, 2012). It consists of lowering in seawater pH due to rising of CO2 concentration in atmosphere and, consequently, the increase of dissolved CO2 concentration into the ocean. Therefore, oceans represent a natural CO2 sink “medium”, having the property to dissolve atmospheric CO2: since the industrial revolution, around a third of the CO2 emitted by fossil fuel burning, deforestation and cement production was absorbed by the ocean (Sabine et al., 2004). The ability of sea water to buffer variations of CO2 concentration in atmosphere (and then pH of seawater) depends from the temperature, availability of CO3= ions (e.g. from dissolution of CaCO3 sediments and/or solid particles present in the water) and biological-biochemical activity. Reciprocal interactions between these variables can magnify or depress the effect on the dissolved CO2 concentration (and also on seawater pH). Many studies and monitoring activities are carried out around the world collecting data on the seawater carbonate system (see the ICOS STATIONS NETWORK - https://www.icos-ri.eu/ and the GLOBAL OCEAN ACIDIFICATION OBSERVING NETWORK - http://portal.goa-on.org/Explorer). The geographical distribution of pH values in the mixed surface layer (?50m) of the oceans suggests that Equatorial Pacific zone and Arabian and Bering Seas show lower values, due to the up-welling of deep ocean water, whereas sub-polar and polar Regions have waters with higher values, since intense photosynthetic activity is present (Raven et al., 2005; Takahashi et al., 2014). Also, it depends from the presence of large rivers in coastal areas at low latitudes, since they are characterized by high solid load and presence of pollutants (Hinga, 2000).rnTherefore, Polar Regions represent main areas in which atmospheric CO2 is transformed in organic carbon (via photosynthetic activity), which is transferred to deep levels (?100m), generating deep streams which rise at up-welling zones. The equilibrium “atmospheric CO2 ? dissolved CO2”, and more in general, the carbon cycle, can be affected by global warming in different ways. Moreover, rising temperature produces ice caps melt, reduces albedo and enhances the heating of surface water levels. The solubility of CO2 is inversely correlated to water temperature and, as the ocean surface warms, more of the produced anthropogenic CO2 remains in the atmosphere. Conversely, cold and fresh waters originated from ice melting, reach the ocean and can be able to influence the temperature of the surface waters: this condition promotes the dissolution of atmospheric CO2 since its solubility increase.rnTogether with CO3= and HCO3- ions and carbonic acid, the dissolved CO2 contributes to the Total Dissolved Inorganic Carbon (TDIC). Therefore, TDIC represents one of the most important parameters to study and monitor the ocean acidification process and the temporal evolution of the ocean carbonate chemistry in relation to the variation of atmospheric CO2 concentration. As detailed by Takahashi and coworkers (2014), “the most desirable way for computing pH and carbonate chemistry parameters is to use pCO2 and TCO2 (i.e. TDIC)” because their measurements are based on well-established air-CO2 gas mixture standards and the solubility of CO2 and dissociation constants for carbonic acid in seawater are the only information needed. However, since the number of TDIC measurements/observations are very few compared to those for pCO2, the identification of climatological global distributions of pH and other carbonate chemistry parameters may be defined using pCO2 and total alkalinity (TA) data, even if additional parameters are necessary (concentration of boric, phosphoric silicic acids, nitrate, ecc.). The scarcity of TDIC data justifies the effort to improve the method for determination of PCO2 and TDIC, in particular taking into account the development of portable instrument which can be easily used directly on the field (e.g. from the boat).rnPCO2 and TDIC measurements in surface ocean water, also in continuous mode, are present on icebreakers, which cover a large part of the Atlantic Ocean with different marine routes. These routes also reach the Svalbard islands, but just in the Isfjorden-Longyearbien (see ICOS STATIONS NETWORK - https://www.icos-ri.eu/ and also the GLOBAL OCEAN ACIDIFICATION OBSERVING NETWORK - http://portal.goa-on.org/Explorer), and no measurements on dissolved gases seem to be performed in the Kongsfjorden.rnThe Kongsfjorden is characterized by lack of civil and industrial settlements and only the glacial drains represent fjord’s freshwater supplies. This natural condition gives the chance to study directly the effects of global warming on the equilibrium “atmospheric CO2 - dissolved CO2“, without interferences or effects induced by other processes.rnrnIn this framework, and taking into account the research activities that have been carrying out in Svalbard Islands, we propose the development of portable instruments for determining directly on the field (in this case the fiord’s water from the boat) the concentration of dissolved gases (in particular CO2, but also O2, N2, Ar, CH4, H2) and TDIC in ocean water into the Kongsfjorden. This kind of measurements, performed in selected sites of the fjord and at different depth (i.e. vertical profile), will allow to define better the dynamics of ocean streams inside the fjord and to study the evolution of dissolved carbon-rich gases (CO2 and CH4) from ocean surface towards deep levels (>100m), through the mixed surface layer (?50m).rnThese scientific activities can well relate to the actions that are being carried out at the Svalbard Islands (e.g. “Marine activities within Kongsfjorden”) and with the activities of other research groups (e.g. “FIKO” and “pHinS” projects- ISMAR groups - and ISMOGLAC project-IGG group”).rn

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Arctic Dissolved CO2 (AR-DIS-CO2)