Systems, compositions, and methods for synergistic additives for use in the scavenging of sulfur-containing compounds encountered in oilfield operations are provided. In one embodiment, the methods comprise injecting a sulfide scavenging additive that does not comprise a significant amount of an aldehyde into at least a portion of a subterranean formation where one or more sulfur-containing species are present; and injecting a synergistic additive comprising at least one base into at least the portion of the subterranean formation.