Lake response modeling using biologically available phosphorus

Abstract

Biologically available phosphorus (BAP) was de termined monthly for a year in Lake Sammamish, Wash, and its principal inflow stream, to improve on previously developed re lationships between TP from increased urban runoff and lake response (chlorophyll a and transparency). Relationships were developed between bioassay-determined BAP and a combination of soluble reactive P and NaOH-extractable P. Relationships were consistent whether from Lake Sammamish monthly samples plus summer samples from 29 other lakes (r2 = 0.80) or from the inflow stream (r2 = 0.82). Seasonal changes in BAP were predicted slightly more reliably than TP, using a mass balance model and the 10-year data set. Also, a linear, arithmetic relationship between spring BAP and summer chlorophyll a represented the best fit of past data (r2 = 0.84, n = 11) and is more reliable than published log-log, TP-chlorophyll a relationships for predicting the specific response of Lake Sammamish to increased urban runoff. / Water Pollut. Control Fed., 60, 1663 (1988).