Sulfuric early atmosphere

Connected with the kinetics of oxygen evolution in the early atmosphere is the question of the origin of sulfate, required by the anaerobic sulfate reducers. Did the latter organisms evolve only after oxygen accumulation led to oxidation of reduced sulfur to sulfate This notion was challenged by Peck (1974), who concluded ... 

Farquhar J, Savarino J, Airieau S, Thiemens M (2001) Observation of wavelength sensitive mass independent sulfur isotope effects during SO2 photolysis Applications to the early atmosphere. J Geophys Res Planets 12 32829-32839... 

The atmospheric conception of H2S has been at odds with these conclusions for several decades. Early atmospheric sulfur balances required input of some... 

Archean rocks occurred between 2.4-2.0 Ga, consistent with a shift from an 02-free early atmosphere in which SO2 photochemistry could dominate among seawater sulfate sources to an 02-rich later atmosphere in which oxidative weathering of sulfide minerals predominated over photochemistry as the major source of seawater sulfate. Sulfur isotope heterogeneities... 

Sulfur on the early Earth has been studied, because it gives insight into the oxidation state of the early atmosphere ocean system (Canfield and Raiswell, 1999). The occurrence of evaporitic sulfate from the 3.5 Ga as in the Warrawoona Group of Western Australia suggests that sulfate must have been present in elevated concentrations at least at some sites. Although now present as barite, the original precipitation occurred... 

Although we have discussed the low oxidation state of the early atmosphere and its implications for the form of sulfur in organisms, today this chemistry is largely restricted to anoxic environments. Here sulfur is available as hydrogen sulhde and can be incorporated into amino acids such as cysteine and methionine and then into proteins. The thiolate group RS of cysteine of the thioether of methionine can act as bases or ligands for transition metals such as iron, zinc, molybdenum, and copper. 

Very likely CO2, CO, and N2 were among the main components by the time of the origin of life within the Earth s early atmosphere. In addition, NO, H2, H2O, and sulfuric gases could also have been present, and probably trace amounts of O2 [23]. Thus, it was not too surprising that several molecular links do exist between the evolution of denitrification enzymes and cytochrome c oxidase, the terminal oxidase of aerobic respiration [24]. Perhaps the most important is the homology between nitric oxide reductase and heme/copper cytochrome oxidases, and the presence of the mixed-valence [Cu " (Scys)2Cu " CuA electron-transfer center in nitrous oxide reductases, the quinol-dependent NO reductase from the gram-positive Bacillus azotoformans, and heme/copper cytochrome oxidases [24-27]. 

The first industrial catalyst was probably the niter pot, which was used in the early sulfuric acid lead chamber process when it became known that oxides of nitrogen catalyzed the oxidation of sulfur dioxide. How was this important process—on which chemical development soon depended—discovered Was it from the observation that cannons corroded or that condensation was acidic following the explosion of gunpowder All the ingredients for chamber acid were there—sulfur, saltpeter, atmospheric air, and heat. Ostwald noted that copious brown fumes were evolved as gunpowder exploded, but did not make any comment on sulfur oxides. Empirical observations, or inspired deductions, ditr-ing the 1800s led to the introduction of several more important catalytic processes. The inevitable development of a chemical industry based on the use of catalysts followed from a mass of experimental observations, such as those shown in Table 1.1, accumulated after Berzelius defined catalysts in 1835 (Figure 1.1). 

A variety of models have been developed to study acid deposition. Sulfuric acid is formed relatively slowly in the atmosphere, so its concentrations are beUeved to be more uniform than o2one, especially in and around cities. Also, the impacts are viewed as more regional in nature. This allows an even coarser hori2ontal resolution, on the order of 80 to 100 km, to be used in acid deposition models. Atmospheric models of acid deposition have been used to determine where reductions in sulfur dioxide emissions would be most effective. Many of the ecosystems that are most sensitive to damage from acid deposition are located in the northeastern United States and southeastern Canada. Early acid deposition models helped to estabUsh that sulfuric acid and its precursors are transported over long distances, eg, from the Ohio River Valley to New England (86—88). Models have also been used to show that sulfuric acid deposition is nearly linear in response to changing levels of emissions of sulfur dioxide (89). 

Scientists believe that the sulfur in Venus atmosphere came from volcanic eruptions. Earth has experienced its fair share of volcanic eruptions, too. However, the sulfur from early eruptions on Earth was incorporated into solid sulfur compounds. Indeed, sulfur is an important element found in many of the compounds that make up Earths crust. 

Biesiadka, J., Loll, B., Kern, J., Irrgang K/D. and Zouni, A. (2004). Crystal structure of cyanobacteria photosystem II at 3.2A resolution. Phys. Chem. Chem. Phys., 6, 4733-4736 Canfield, D.E., Habicht, K.S. and Thamdrup, B. (2000). The Achaean sulfur cycle and the early history of atmospheric oxygen. Science, 288, 658-661... 

Records indicate that Braconnot was interested in the dilute-acid method of hydrolysis as early as 1819. Many other workers have made contributions, but it was not until 1898 that an attempt was made to commercialize the process. At that time Simonsen published a paper on the process. His process consisted in treating sawdust for fifteen minutes with four parts of 0.5% sulfuric acid at about 9 atmospheres pressure. He obtained a 6 % yield of sugar, based on dry wood. 

---