Phosphorus Spiralling in a Woodland Stream: Seasonal Variations

作者：Patrick J. Mulholland, J. Denis Newbold, Jerry W. Elwood, Leigh Ann Ferren, Jackson R. Webster · 发表于：Ecology · 年份：1985 · DOI：10.2307/1940562 · 被引用次数：260 · 研究领域：Soil and Water Nutrient Dynamics、Fish Ecology and Management Studies、Freshwater macroinvertebrate diversity and ecology

Four radiotracer releases were performed over an annual period in 1981—1982 to determine seasonal variation in indices and pathways of phosphorus spiralling in Walker Branch, a small woodland stream in eastern Tennessee, USA. Each release consisted of an addition of °370 MBq each of carrier—free 32PO4 and 3H2O over a 1—h period during baseflow. Concentrations of 32P and 3H dissolved in stream water were measured intensitively at several stations downstream for the radiotracer input during and immediately following each release. Activity of 32P in coarse particulate organic matter (CPOM), fine particulate organic matter (FPOM), and aufwuchs was measured 2—3 h after each release and at various intervals for 7 wk. Total biomass of CPOM, FPOm, and aufwuchs at the time of each release was also measured. Uptake of 32PO4 from the water was greatest in November and lowest in August, Uptake length (Sw) of phosphorus, defined as the average distance travelled by a PO4 ion dissolved in water, varied from 22 m in November to 97 m in August. Uptake of 32PO4 by CPOM was generally greatest, with °50% of total uptake, while that by aufwuchs was lowest, with <15% of the total. CPOM abundance was the major determinant of whole—steam PO4 uptake rate and Sw. Turnover length (Sp) of phosphorus, defined as the average distance traveled by an atom of P taken up by particulate material, was short compared to Sw, varying from 1 m in November to 3 m in January. Consequently total spiralling length (S)...