Hydrogen vertical distribution

Fig. 3. Vertical distribution of the concentration of various minor constituents water vapor, H20 methane, CH4 molecular hydrogen, H2 nitrous oxide, N2O and carbon monoxide, CO.

Fig. 2 Vertical distribution of temperature (T), salinity (S), dissolved oxygen (02), hydrogen sulfide (H2S), dissolved manganese (Mn diss), nitrate (NO3), nitrite (NO2), ammonia (NH4), phosphate (P04), silicate (Si), pH (pH), total alkalinity (Aik), methane (CH4), organic phosphorus (Porg), organic nitrogen (Norg), and urea (Urea), at a station near Gelendzhik (St. 2618, September, 2006). Concentrations of chemical parameters are in aM. Distributions are plotted versus depth (m) at the top and versus density (agy kg nr3) at the bottom...

In the anoxic water methane reaches about 16. iM. The vertical distribution of methane differs from that of hydrogen sulfide, ammonia, and phosphate its profile curve bends at 500-600 m and keeps similar concentrations deeper toward the bottom [73]. 

Probably these anomalies of the OM parameters might be connected with the process of chemosynthesis, and the layer of bacterial chemosynthesis should play an important role in the formation of the vertical distribution of nutrient species there. The results of measurements of the dark CO2 fixation [78,79] usually reveal the primary maximum of chemosynthesis (about 0.4-2.0 jiM d x) in a 20-30-m layer below the hydrogen sulfide boundary. The less pronounced secondary maximum is observed about 5-10 m shallower than the hydrogen sulfide boundary and is likely to be connected with nitrification [78]. 

The sulfide vertical distribution correlates with vertical distributions of temperature, salinity, and density in the Black Sea. As a consequence, the H2S vertical distribution vs. salinity (Fig. 3a) and temperature (Fig. 3b) is consistent with the 9 -S curve (Fig. 3b). It is evidence that the thermohaline structure of the water column controls the vertical distribution of hydrogen sulfide in the basin [27]. Physical mixing processes dominate over the in situ sulfide production. Identifiable on the 0 -H2S and S-H2S diagrams, the boundaries of three water masses in the anoxic water column correspond strictly to the boundaries on the 0 -S diagram (Fig. 3b). The temperature-salinity relationship in the Black Sea is a result of large-scale external factors such as water and heat balance of the basin. 

Fig. 8. Vertical distribution of molecular oxygen (Oj) mixing ratio in prebiological paleo-atmosphere. Calculations for molecular hydrogen (Hj) = 17 ppmv, carbon dioxide (CO2) = 280 ppmv, and three different solar ultraviolet fluxes.

Fig. 17. Vertical distribution of formaldehyde (HjCO) concentration (molecules cm ) in prebiological paleoatmosphere. Calculations for molecular hydrogen (H2) = 10 and for four different combinations of carbon dioxide (COj = 1 and 100) and solar ultraviolet radiation (UV = 1 and T-Tauri).

FIGURE 12.7 Vertical distribution of oxygen and hydrogen sulfide (shown as negative oxygen equivalents) in the Gotland Deep between 2003 and 2005 (from Feistel et al., 2006). 

Schmidt, U., 1978 The latitudinal and vertical distribution of molecular hydrogen in the troposphere. J. Geopys. Res. 83,941-946. 

Figure 4.40 shows the contributions of the Lyman a line and the Schumann-Runge bands to the vertical distribution of Jh2o-Photodissociation in the middle atmosphere occurs at wavelengths above about 100 nm, while photoionization occurs for wavelengths less than 98 nm. In the mesosphere and thermosphere, water vapor is photodissociated mainly by the solar Lyman a line, leading to a substantial fraction of the hydrogen atom production at these altitudes. 

The vertical distributions of methane and hydrogen in the stratosphere are shown in Fig. 3-10. The loss of methane is made evident from the decrease of the CH4 mixing ratio with increasing altitude. In the lower stratosphere, reaction with OH is the sole loss process. In the upper stratosphere it is supplemented by reactions of methane with O( D) and Cl atoms. Crutzen and Schmailzl (1983) estimated from two-dimensional model calculations that OH and 0( D) + C1, respectively, contribute about 50% each to the total loss of methane. The global rate of stratospheric CH4 removal according to their estimate is 42 Tg/yr. In Section 4.3 a different method will be employed to derive a value of 55 Tg CH4/yr. 

In contrast to methane, the vertical distribution of hydrogen shows little change with altitude, although reaction rates for H2 and CH4 interacting with OH and O( D) are approximately equivalent. An explanation of the H2 altitude profile thus requires a source of H2. At altitudes below 40 km,... 

Fig. 3-10. Vertical distribution of methane and hydrogen in the stratosphere at midlatitudes (40-60° N). [From observations of Bush et al. (1978), Ehhalt and Heidt (1973), Ehhalt el al. (1974, 1975), Pollock et al. (1980), Heidt and Ehhalt (1980), Fabian et al. (1979, 1981b), and Volz et al. (1981b).]...

Vertical distributions of the molecular density and mixing ratios of H2O and HDO in the Venus mesosphere were measured by Fedorova et al., 2008 [129]. The experiment was carried out on board of Venus express mission (SOIR instrument, 2.32-4.35 pm). The atmosphere was sounded during solar occultation in the range of altitudes from 65 to 130 km. An enrichment of D to hydrogen indicates the escape of water from Venus. Bertaux et al., 2007 [25] report on the detection of a warm layer at 90-120 km. ... 

Fig. 2.—Electron distribution for hydrogen-like states the ordinates are values of D. Z-1. 10 8, in which D = 4mxp, with p the electron density. The vertical lines correspond to r, the average value of r.

A pattern emerges when this molecular beam experiment is repeated for various gases at a common temperature Molecules with small masses move faster than those with large masses. Figure 5 shows this for H2, CH4, and CO2. Of these molecules, H2 has the smallest mass and CO2 the largest. The vertical line drawn for each gas shows the speed at which the distribution reaches its maximum height. More molecules have this speed than any other, so this is the most probable speed for molecules of that gas. The most probable speed for a molecule of hydrogen at 300 K is 1.57 X 10 m/s, which is 3.41 X 10 mi/hr. 

Fig. 47. In silu study of a-methylstyrene hydrogenation in a fixed bed of Pd/ALO catalyst, (a) Schematic representation of the bed and the chosen axial bar. (b) A mixed spatial-spectral 2-D map which corresponds to that axial bar. (c) The distribution of the liquid phase along the axial bar obtained as an integral projection of (b) on its vertical (coordinate) axis, (d f) NMR spectra of the liquid phase at various heights along the bar obtained as horizontal cross-sections of the map in (b). The location of these cross-sections is indicated in (b,c) with horizontal lines. Each spectrum corresponds to a volume of 0.66mmx 1.3mmx 2mm. The two vertical dotted lines are drawn to show the differences in relative positions of the external peaks in the spectra. Reprinted from reference (69) with permission from Elserier, Copyright (2004).

Supermolecular absorption determines significant features of the atmospheres of the planets and their large moons, such as the vertical temperature profile and the high-altitude haze distribution, and offers opportunities for the determination of abundance ratios of helium and hydrogen, ortho- and para-H2, etc. [390, 396]. In certain spectral bands the spectra may sometimes be obtained by Earth-based observations. More commonly, the spectra will be obtained in space missions, such as IRIS of Voyager I and II future missions (Infrared Space Observatory) will doubtlessly enhance the available information significantly. 

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