Two related factors affect the vertical distribution and inventory of 7Be (53-day half life) in salt marsh sediments: (1) the movement of pore water, and (II) the vegetation. Infiltration of rainwater into unsaturated sediment distributes 7Be over several centimeters depth without disturbing the sediment fabric. The sediment inventory of 7Be expected from its atmospheric flux could only be accounted for in vegetated areas where foliage traps 7Be from rainfall and surface flow. These factors lead to hetero-geneous vertical and lateral distributions of 7Be throughout the marsh, and may also affect the sediment distribution of the other trace substances, such as 210Pb, 137Cs, and heavy metals.