In situ tracer studies of solute transport across the sedimentwater interface at the Bermuda Time Series site

In situ tracer experiments have been utilized to assess the rates of transport of solutes across the sediment-water interface in the deep sea at the Bermuda Time Series site. The site lies some 83 km southeast of Bermuda, an environment considered to be representative of an oligotrophic gyre. Transport has been evaluated on the basis of release of NaBr into benthic chambers and determinations of Br losses from the chambers as well as Br− profiles and inventories in the sediments recovered in the chambers. The experiments provide no evidence of transport across the sediment-water interface in excess of that expected for diffusion alone. The sensitivity of our analysis to variations in transport rate places a limit on non-diffusive transport of ≤25% of diffusive transport.