The measurement of sediment irrigation rates: A comparison of the Br? tracer and 222Rn/226Ra disequilibrium techniques Academic Article uri icon

abstract

  • We have carried out a series of experiments designed to allow comparison of sediment irrigation rates determined simultaneously using two methods: the measurement of super(222)Rn/ super(226)Ra disequilibrium in pore waters, and the measurement of distributions of a tracer, Br super(-), which was added to the water overlying sediments at the start of incubation experiments. The experiments were carried out on fine-grained sediments from Buzzards Bay, MA. We made irrigation rate measurements on sediments in their natural state, as well as on sediments that had been treated to alter macrofaunal abundance and diversity. The range of irrigation rates measured was similar for both tracers, and was similar to rates measured at the study site previously by Martin and Sayles (1987). Furthermore. the two tracers gave similar patterns of irrigation rate variability between cores and with depth below the sediment-water interface. On the other hand, comparisons of individual cores showed significant differences in the absolute rates measured using the different tracers; in particular, the super(222)Rn/ super(226)Ra disequilibrium method yielded more rapid irrigation rate estimates at depths exceeding 10 cm below the sediment-water interface.

publication date

  • February 1, 1992