Temporal and spatial distribution of beryllium-7 in the sediments of Chesapeake Bay

The sediment inventory of 7Be was determined at six stations in the main stem of Chesapeake Bay nine times between April, 1986, and September, 1987. The inventories ranged from < 0·20−7·32 dpm cm −2. Comparison to the atmospherically supported 7Be inventory (range 2–4 dpm cm −2) showed significant focusing of 7Be in the sediments in the zone of the turbidity maximum during the summer, and suggested that the spatial distribution of 7Be in the sediments of the lower Bay was determined largely by horizontal redistribution of bottom sediments. The processes causing this redistribution of 7Be in the lower Bay apparently had a recurrence frequency greater than the sampling frequency in this investigation. The temporal pattern of 7Be accumulation at the six stations over the first year of this investigation allowed estimation of sedimentation rates, which suggested that the processes governing the distribution of 7Be in Chesapeake Bay sediments were similar to the processes determining sedimentation patterns over about the past 100 years.