In this experiment, the effect of sulfate concentration on the biosorption rate of lead by lemna minor (common duckweed) was studied. Lead is a hazardous environmental contaminant and can cause harm to living organisms. Sulfate is another pollutant common in freshwater sources and was expected to have a negative effect on the biosorption rate of lead by the biomass. Lemna minor was placed in contaminated water of varying lead and sulfate concentrations. The concentration of lead in solution was measured at several time intervals using atomic absorption spectroscopy. Sulfate concentration was found to have no effect on the biosorption rate of lead by lemna minor.