THE BIOGEOCHEMISTRY OF HYDROGEN-SULFIDE - PHYTOPLANKTON PRODUCTION INTHE SURFACE OCEAN

Hydrogen sulfide can exist in oxic waters in the form of a dissolved g as, dissociated ions, dissolved metal sulfide complexes, and particula te metal sulfides. The sum of the dissolved species is termed total di ssolved sulfide (TDS). In addition to the hydrolysis of carbonyl sulfi de, it has been speculated that phytoplankton may produce TDS. We pres ent results from preliminary culture studies which demonstrate that ph ytoplankton produce TDS and particulate acid-volatile sulfide (pAVS). The phylogenetic order of TDS + pAVS production (per unit cell volume) for the oceanic species examined is Synechococcus sp. > Emiliania hux leyi almost-equal-to Pyramimonas obovata > Thalassiosira oceanica. Mor eover, TDS and pAVS production increases when the concentrations of un complexed trace metals in culture media are also increased, suggesting metal detoxification via the formation of metal sulfide complexes.