Hydrogen in ocean

Craig, H., Lupton, I. (1976) Primordial neon, helium and hydrogen in oceanic basalts. Earth Planet. Sci. Lett., 31, 369-85. 

Oxygen occurs free in air in which it forms 21% by volume. It is also found combined with hydrogen in water and constitutes 86% of the oceans, and with other elements such as minerals constituting ca 50% of the earth s crust. In the laboratory it is usually prepared by the thermal decomposition of potassium chlorate in the presence of manganese dioxide catalyst ... 

Methanogens, may be the Earth s oldest organisms, produce methane from carbon dioxide and hydrogen. They can survive only in an anaerobic (i.e., oxygen-free) environment and have been found in ocean trenches, in mud, in sewage, and in cow s stomachs. 

Poreda R, Schilling J-G, Craig H (1986) Helium and hydrogen isotopes in ocean-ridge basalts north and south of Iceland. Earth Planet Sci Lett 78 1-17... 

An analogous expression can be derived for 8 Mo x in terms of /ox (or/m). Such a model illustrates that changes in ocean redox, which affect the relative proportions ofand/ x, should result in changes in the isotopic composition of hydrogenous Mo in both euxinic and Mn-oxide sediments. Hence, measurements of 8 MOepx or 8 Mo x could yield information about changes in ocean redox through time. 

A difficnlty in measnring D/H isotope ratios is that, along with the H2+ and HD+ formation in the ion source, H3+ is produced as a by-prodnct of ion-molecule collisions. Therefore, a H3+ correction has to be made. The amonnt of H3+ formed is directly proportional to the number of H2 molecules and H+ ions. Generally the H3+ current measured for hydrogen from ocean water is on the order of 16% of the total mass 3. The relevant procedures for correction have been evaluated by Brand (2002). 

Hydrate dissociation is of key importance in gas production from natural hydrate reservoirs and in pipeline plug remediation. Hydrate dissociation is an endothermic process in which heat must be supplied externally to break the hydrogen bonds between water molecules and the van der Waals interaction forces between the guest and water molecules of the hydrate lattice to decompose the hydrate to water and gas (e.g., the methane hydrate heat of dissociation is 500 J/gm-water). The different methods that can be used to dissociate a hydrate plug (in the pipeline) or hydrate core (in oceanic or permafrost deposits) are depressurization, thermal stimulation, thermodynamic inhibitor injection, or a combination of these methods. Thermal stimulation and depressurization have been well quantified using laboratory measurements and state-of-the-art models. Chapter 7 describes the application of hydrate dissociation to gas evolution from a hydrate reservoir, while Chapter 8 describes the industrial application of hydrate dissociation. Therefore in this section, discussion is limited to a brief review of the conceptual picture, correlations, and laboratory-scale phenomena of hydrate dissociation. 

Schmidt also measured the H2 content of surface waters in the North and South Atlantic Oceans. The data varied from 0.8 to 5.0 x 10 mL/L(H20), corresponding to saturation factors of E = 0.8 5.4, where F = represents equilibrium conditions between surface water and air, while F < 1 or E > 1 indicate undersaturation or supersaturation, respectively. The H2 supersaturation in ocean water may be due to the production of hydrogen by microbiological activity. 

Oxygen reacts with hydrogen in a ratio of one to two, as does sulfur, selenium, and tellurium. It is this chemical reactivity, the ability of elements to join chemically into compounds, that is responsible for transformation of the elements of the cosmos into the materials of Earth and ultimately the materials of life. Although we have to put off our detailed discussion of the complex molecules of life until we have a firmer foundation, we already have enough information to discuss two of the most important chemicals of life and decidedly life s necessary precursors salt and water. The first life formed in the salty oceans, as evidenced by the salty solutions of our cells, and is always present in the salty character of our bodies. 

The reverse situation may be true with respect to the distribution of dissolved molecular hydrogen in the ocean. Schink s observations (4) of diel variation of hydrogen concentrations in the controlled ecosystem population experiment containers and in the Marine Ecosystem Research Laboratory tanks have been confirmed in the open ocean by Herr et al. (5). Hydrogen is probably produced either in the guts of zooplankton or fish, or by cyanobacteria. Dissolved hydrogen typically decreases with depth below the photic zone apparently, the gas is consumed by microflora in the deep ocean. Such consumption occurs in freshwater (6) and anaerobic (7) systems. 

Extraction. Simard et al. (1) previously demonstrated that carbon tetrachloride quantitatively extracts hydrocarbons from refinery waste water. This solvent is advantageous to use because it is transparent to IR in the carbon-hydrogen absorption region of hydrocarbons thus the extract can be measured directly. To demonstrate the suitability of carbon tetrachloride in this method, numerous blends of hydrocarbons in ocean water at concentrations in the range of 5-20 ppb for 3-1. samples were extracted. 

Although little water manages to pass through the cold trap, there are other sources of hydrogen in the upper air. As mentioned above, methane emissions from the surface mix upwards from the surface, as methane has no cold trap, and in the upper air photolysis leads eventually to release of H. In addition, there is a small emission of H2 from the surface, some of which will reach the upper part of the atmosphere however. Earth also sweeps up H and H2 from space. Over time, net hydrogen loss must have been limited we have kept the oceans. 

---