Abstract

Radon-222 and 226Ra activities were measured in the waters and sediment of the southeastern Bering Sea shelf to evaluate the use of radon as a tracer of gas exchange, water column mixing and sediment-water exchange. Cross-shelf distributions of 222Rn and 226Ra are presented. Gas transfer coefficients were estimated using near-surface 222Rn deficiency measurements. A statistically significant linear relationship between averaged wind speed and transfer coefficient was found. Vertical eddy diffusivities were evaluated by applying a one-dimensional model to near-bottom excess 222Rn distributions; these diffusivities were compared to independently determined values. The one-dimensional model applied to the near-bottom 222Rn data was found to be inadequate and a two-dimensional model was applied to improve the fit between model and data. Exchange across the sediment-water interface was computed from the deficiency of 222Rn measured in sediment cores, standing crop estimates of excess 222Rn in the water column and 222Rn production rates of sediment surface grab samples. Biological irrigation of the sediments appeared to be the primary exchange mechanism between the sediment and water columns. Distributions in the water column showed finestructure reported previously and suggested biological removal of 226Ra. © 1987.