<Table> <Tr> <Td> </Td> <Td> This section may be confusing or unclear to readers . Please help us clarify the section . There might be a discussion about this on the talk page . (March 2017) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This section may be confusing or unclear to readers . Please help us clarify the section . There might be a discussion about this on the talk page . (March 2017) (Learn how and when to remove this template message) </Td> </Tr> <P> Sulfur is found in oxidation states ranging from + 6 in SO to - 2 in sulfides . Thus elemental sulfur can either give or receive electrons depending on its environment . Minerals such as pyrite (FeS) comprise the original pool of sulfur on earth . Owing to the sulfur cycle, the amount of mobile sulfur has been continuously increasing through volcanic activity as well as weathering of the crust in an oxygenated atmosphere . Earth's main sulfur sink is the oceans SO, where it is the major oxidizing agent . </P> <P> When SO is assimilated by organisms, it is reduced and converted to organic sulfur, which is an essential component of proteins . However, the biosphere does not act as a major sink for sulfur, instead the majority of sulfur is found in seawater or sedimentary rocks especially pyrite rich shales and evaporite rocks (anhydrite and baryte). The amount of sulfate in the oceans is controlled by three major processes: </P>

What is the main reservoir of sulfur on earth
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