Quantitative ICP-OES Analysis of Cadmium and Lead Accumulation in Hydroponic Phytoremediation Systems

Abstract

Heavy metal contamination of water resources by cadmium (Cd) and lead (Pb) poses significant ecological and human health risks due to the persistence and non-biodegradable nature of these toxic elements. Phytoremediation in hydroponic systems represents a sustainable strategy for removing dissolved contaminants from aqueous media. However, comparative data on whole-plant bioconcentration of Cd versus Pb as solitary contaminants in controlled hydroponic environments remain limited, particularly under conditions where the absence of soil-based buffering alters metal bioavailability and plant stress responses. This study quantifies and compares whole-plant Cd and Pb accumulation to evaluate sequestration capacity when each metal is present as a solitary contaminant.

Plants were initially established in a soil substrate before being transferred to isolated single-metal hydroponic systems spiked with starting concentrations of 5 mg/L of Cd or Pb. Total metal accumulation was quantified using inductively coupled plasma optical emission spectroscopy (ICP-OES) following whole-plant acid digestion. Results indicated that both metals were successfully sequestered, with plants exposed to Cd reaching a mean digestate solution concentration of 0.145 mg/L and plants exposed to Pb reaching 0.123 mg/L. These results indicate comparable uptake efficiencies under identical exposure conditions, with Cd accumulation 17.9% higher than Pb.