"Photoremineralization" of carbon accompanies previously reported "photodissolution" of particulate organic carbon (POC) from resuspended estuarine and deltaic bottom sediments. Irradiations of suspensions of bottom sediments from Atchafalaya Bay, LA were conducted in a solar simulator. Dissolved oxygen, POC, dissolved organic carbon (DOC), and dissolved inorganic carbon (DIC) were measured before and after every irradiation. Dissolved oxygen levels did not change in dark controls but decreased in irradiated suspensions in proportion to POC loss, with one mole O₂ consumed for every 2-3 moles OC "photodissolved". Photodissolved organic carbon was recovered as a combination of DOC and DIC. In sediments, DIC photoproduction accounted for O₂ typically consumed during irradiation. For comparison, "fresh" POC (membranes of disrupted Tetraselmis cells) was also irradiated. Photochemical O₂ consumption, normalized to initial POC, mirrored that of sediments, but normalized photoproduction of DIC was 2.5 times smaller. This implies generation of photoproducts other than DIC. Whereas 20% of POC is susceptible to photodissolution, only 1-5% is photooxidized; given previous estimates that 15% of DOC is photooxidized, we suggest that remineralization follows POC photodissolution.