EVIDENCE OF OLD CARBON IN THE DEEP-WATER COLUMN OF THE PANAMA BASIN FROM NATURAL-RADIOCARBON MEASUREMENTS

Radiocarbon (Delta(14)C) analyses were performed on sinking and suspen ded particulate matter, dissolved inorganic carbon (DIC), sediment and sediment fluff from a deep-water station in the Panama Basin. Delta(1 4)C signatures for sinking particulate inorganic and organic carbon (P IC, POC) collected at 3354 meters depth were lower than surface DIC De lta(14)C values, and higher than the inorganic and organic carbon from the sediment (SIC, SOC). We compare these data with those obtained fo r other Pacific and Atlantic sites and show that the gradient between surface DIC Delta(14)C and deep suspended POC Delta(14)C is the same i rrespective of distance from the coast. This indicates that: 1) resusp ended SOC is an equally important contributor to deep POC at locations close to and far from continental slopes, and/or 2) DOC sorption is a significant contributor for causing low Delta(14)C values of deep POC .