text: In ISCR, many reductive processes can take place. There are hydrogenolysis, β-elimination, hydrogenation, α-elimination, and electron transfer. The specific combination of reductive processes that actually take place in the subsurface depends on the species of contaminant that is present and also the type of reduction being used. The natural and biological processes that take place in the substratum also affect the kinds of reductive processes that are found.