Measuring Nutrient Spiralling in Streams

Nutrient cycling in streams involves some downstream transport before the cycle is completed. Thus, the path traveled by a nutrient atom in passing through the cycle can be visualized as a spiral. As an index of the spiralling process, we introduce spiralling length, defined as the average distance associated with one complete cycle of a nutrient atom. This index provides a measure of the utilization of nutrients relative to the available supply from upstream. Using 32 P as a tracer, we estimated a spiralling length of 193 m for phosphorus in a small woodland stream.Key words: downstream transport, nutrient cycling, phosphorus, spiralling, stream