Beryllium uptake by excised barley roots

The uptake of beryllium by excised barley roots from a solutioncontaining 111 µM beryllium and 500 µM calcium wasstudied. The exchange-adsorbed portion was 15% of the totalBe uptake after 30 min of exposure. The total Be content couldbe reduced to 55% of the control in 1 hr with demineralizedwater. At pH levels above 6, Be uptake was increased dramatically.A Q₁₀ of 1.2 was found to exist between 1 and 23°C. Mg (111µM) did not influence Be absorption while Zn and Al atthe same concentration reduced it, possibly competitively, 27and 62% of the control, respectively. Dinitro-phenol (500 µM),cyanide (500µM), azide (500 µM) and m-chlorocarbonylcyanidephenylhydrazone (100 µM) at least doubled it indicatingthe existence of a possible metabolic barrier to beryllium entrywhich was disrupted by these compounds. Absorption kineticsover an external beryllium concentration range of 11 to 444µM suggested a number of binding sites. Above 444 µMa scattering effect was noted due possibly to its toxic effect. ¹Pesticide Programs, Environmental Protection Agency (P.S. -769),Washington, D.C. 20460, U.S.A. (Received August 13, 1979; )