Abstract: This disclosure provides a method for scavenging hydrogen sulfide (H2S) from a fluid containing H2S and metal ions by introducing into the fluid at least one metal chelant in an amount effective to chelate metal ions in the fluid to form at least one metal-chelate complex; and removing at least a portion of the H2S from the fluid with an effective amount of the at least one metal-chelate complex. The method may further comprise the step of introducing at least one enzyme having an ability to scavenge H2S into the fluid in an amount effective to scavenge H2S from the fluid, where the amount of the at least one metal-chelate complex is effective to influence the ability of the at least one enzyme to scavenge H2S.