Temperature dissolved inorganic Carbon

The water samples were analysed for pH, electrical conductivity (EC), temperature (T), dissolved oxygen (DO), redox potential (Eh), reduced iron (Fe2+) and alkalinity (dissolved inorganic carbon, DIC, as HC03") in the field. A few special water samples were collected to determine background levels of CD4, SF6 and Kr in the headspace gas. SWL and T were recorded hourly in 3 shallow (Sites H, I, R) and 3 deep (Sites J, V, W) open bores using automatic data loggers, which were downloaded biannually. 

Sampling sites are also referred to as station locations. For water column work, depth profiles are constructed from seawater samples collected at representative depths. Temperature and salinity are measured in situ with sensors. Remote-closing sampling bottles deployed from a hydrowire are used to collect water for later chemical analysis, either on the ship or in a land-based laboratory. The standard chemical measurements made on the water samples include nutrients (nitrate, phosphate, and silicate), dissolved O2, and total dissolved inorganic carbon (TDIC) concentrations. 

Effect of temperature, pressure, and salinity on speciation of the dissolved inorganic carbon for 2co2 = 2mmol/kg. Source After Zeebe, R.E. and D. Wolf-Gladrow (2001) Elsevier Oceanography... 

Fig. 2.15 Oxygen isotope fractionations between dissolved inorganic carbon (DIC) and water as a function of pH and temperatures (after Beck et al. 2005)...

Dissolved inorganic carbon DIC C02. Quantity depending on pH, temperature, and partial pressure of C02 TIC = DIC + PIC... 

Fig. 7. Dissolved inorganic carbon, salinity, phosphate, nitrate and temperature along an approximate north-south line at 90° west longitude, in 1974. Note that high CO2 and nutrients extend southward at least 15° from the equator in this section, which is closer to the South American coast than that shown in Fig 6. (From GEOSECS Atlas, vol. 4).

Fig. 9. Dissolved inorganic carbon, salinity, phosphate, nitrate, and temperature in surface ocean waters, during the 1982-83 El Nino, at the same longitude as in Fig. 7. Note that the high values for CO2 and nutrients south from the equator have disappeared while the water temperature has become warmer as warm waters from the Western Pacific flooded over the region. Measurements by C. D. Keeling, R. F. Weiss and others.

We determined the shell C and O isotopic composition of the cultured foraminifera, and compared these isotopic values with the water chemistry of the culture chambers, and also with the shell chemistry of field specimens collected from sites on the North Carolina and South Carolina (USA) continental margin. The culmred foraminifera showed substantial offsets from the 8 C of system water dissolved inorganic carbon (—0.5 to —2.5%c, depending on species) and smaller offsets (0 to — 0.5%o) from the predicted 8 0 of calcite in equilibrium with the culture system water at the growth temperature. These offsets reflect at least three factors species-dependent vital effects ontogenetic variations in shell chemistry and the aqueous carbonate chemistry ([COJ] or pH) of the experimental system. 

In addition to the above factors, there is a general correlation between increasing temperature and methylation, while demethylation rates reduce with increased temperature.Dissolved organic carbon may also inhibit methylation in a similar manner to sulfide again by reducing the amount of available for methylation. For inland waters, there is an inverse correlation between pH and methylation. Finally there is a positive link between sediment " inorganic mercury concentration and methylation. 

To sum up, the Pco2 distribution pattern in estuaries results from a combination of various processes the production/degradation/export of organic carbon, the production/dissolution/export of carbonates, the input of dissolved inorganic carbon by vertical mixing processes and/or freshwater runoff, and the thermodynamic effects related to both water temperature variations and water mass mixing. 

Temperature affects the equilibrium constants of dissolved inorganic carbon and, in particular, the solubility coefficient of CO2, so that Pco2 rises by 4% with an increase of 1 °C in temperature. In the sampling region, the surface water temperature decreased from the west to the east, similar to that of Pcos (Fig- 4.5). Thus this was another possible factor causing the Pco2 distribution to show such a pattern in this study. 

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