Carbon monoxide from ocean

The main source of carbon monoxide, aside from the fossil fuel burning flux, is ffom oxidation of CH4 (Table 9.3). The remainder comes ffom decomposition of organic matter in soils, and bacteria and algae in the ocean that actively generate CO from respiration processes according to ... 

Carbon monoxide (CO) is also formed in aquatic environments from the photochemical degradation of DOM [3,4,8,22,94-105]. Strong gradients of CO have been observed in the lowest 10 metres of the atmosphere over the Atlantic Ocean [97]. The samples nearest the ocean surface were some 50 ppb higher than at the 10-metre altitude-sampling inlet. This implies that the ocean is a source of CO to the atmosphere and that this source can increase the atmospheric concentration. CO is reactive in the troposphere and thus its emissions from the ocean may influence the hydroxyl radical (OH) and ozone concentrations in the marine atmospheric boundary layer that is remote from strong continental influences. 

According to the results of measurements carried out in the ocean (Seiler, 1974) the carbon monoxide concentration in near surface marine layers is 5 x 10 s mil 1 on an average. This water concentration would be in equilibrium with a surface air CO level of 2.5 ppm. However, the carbon monoxide concentration in air over the ocean surface is between 0.04 ppm and 0.20 ppm, which means that the ocean water is supersaturated with CO. It follows from these data that the ocean is a CO source, the global strength of which is about six times less than the total anthropogenic emission (Table 7). 

Fig. 4-7. Latitudinal distribution of carbon monoxide over the Atlantic Ocean. Open circles in the upper troposphere, from aircraft measurements. Filled circles at sea level, from measurements onboard of ships. Solid curve air mass-weighted average CO mixing ratio. [Adapted from Seiler and Schmidt (1974a).]...

Schmidt (1974) in the northern and southern Atlantic varied from 0.8 to 5.4 with an average of 2.5. From these data, extrapolated to other oceans, Schmidt (1974) and Seiler and Schmidt (1974b) estimated a global emission rate of 4Tg/yr. In contrast to CO, the aqueous concentrations of H2 do not undergo diurnal variations. This does not preclude a photochemical production of H2, as was shown for carbon monoxide, but other production mechanisms for hydrogen, such as by bacteria or in the digestive tracts of zooplankton, may be more effective. 

More recently, iron sulflde has been shown to play a catalytic role in the synthesis of pymvate from alkyl thiols and carbon monoxide at 250 °C and pressmes between 500 and 2000 bar (conditions that conld be found at the bottom of the ocean or in a shallow oceanic crust) [20]. The overall reaction may be written as ... 

Large amounts of smoke from oil slick burning can result in oil rain. The formation and possible sinking of extremely viscous and dense residues can damage the sea bed and its inhabitants. The viscous residue may also be transported to shorelines and beaches by ocean tides or currents. Airborne irritants and possibility of secondary fire are sources of concern when combustion has to be carried out close to residential areas. Carbon monoxide, sulfur dioxide, and polycyclic aromatic hydrocarbons (PAH) are common toxic compounds emitted while burning oil on water. 

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