Validating the chronic Pb algae bioavailability model at high pH : single-species evaluation : final report, 12 June 2017

Abstract

We investigated toxicity of Pb to Pseudokirchneriella subcapitata using the standard 72h-growth inhibition assays at 2 pH levels (pH 7.2 & pH 8.4) and 2 P (P 10 ug/L & P 100 ug/L) levels, i.e. at 4 treatments in total. This was done to test whether an existing algae Pb bioavailability model developed for pH≤8.0, can be used at higher pH>8.0. The algae Pb bioavailability model calibrated on Pb toxicity at pH 7.2 (P 100 µg/L) predicted filtered Pb toxicity(EC50 and EC20) at pH 8.4 (P 100 µg/L) with reasonable accuracy, i.e. within 2-fold error. Although the slope of the linear relationship between pH and log10(EC50 as Pb2+ acitivity) for the pH range between 7.2 and 8.4 (present study) was slightly lower than that of the pH range between 6 and 8 (existing model), our study suggests that the chronic algae Pb bioavailability model can be extrapolated to predict Pb toxicity up to pH 8.4