In vivo accumulation of radioactive polonium by the giant kelp Macrocystis pyrifera

The in vivo accumulation rate of ²¹⁰Po by Macrocystis pyrifera (L) Ag. has been determined by the tagging of specific parts of young, growing lamina in La Jolla kelp beds and their subsequent collection for ²¹⁰Po analysis. The rates of accumulation for observed and growth-corrected data were, respectively, 0.78x10^-9 pCi/cm² sec (1.73x10^-9 dpm/cm² sec) and 1.17x10^-9 pCi/cm² sec (2.60x10^-9 dpm/cm² sec). Invert, but biologically foulable, glass-slide surfaces exposed to the kelp bed environment yielded ²¹⁰Po accumulation rates of 0.64x10^-9 pCi/cm² sec (1.42x10^-9 dpm/cm² sec), slightly less than those of M. pyrifera. Distinction is made between observed net accumulation rate and gross rates or total flux. Several factors contributing to the final net accumulation rate are discussed.