MEROMIXIS IN HYPERSALINE MONO LAKE, CALIFORNIA .3. BIOGEOCHEMICAL RESPONSE TO STRATIFICATION AND OVERTURN

Mono Lake is a terminal, saline lake that became ectogenically meromic tic in 1982-1983 and remained stratified until November 1988. During t his period, the monimolimnion remained anoxic and nearly isothermal, w hile the upper mixolimnion was well oxygenated and exhibited a seasona l thermal regime. Dissolved sulfide and methane increased in the monim olimnion as a result of diffusive flux from the sediments. Winter mixi ng down to the chemocline distributed sulfide and methane throughout t he mixolimnion. Lakewide inventories of dissolved sulfide and methane reflected the balance between increased concentrations and decreased m onimolimnion volume over time. At overturn, the entire water column wa s isothermal and anoxic. Dissolved sulfide (380 x 10(6) mol) was oxidi zed in 1 week by molecular oxygen. Methane (12 x 10(6) mol) was remove d more slowly by microbial oxidation and ventilation across the air-wa ter interface.