Economic evaluation of cadmium phytoextraction: Comparing accumulators using cost-efficiency indicators and scenario...

The existing efficiency indicators for phytoremediation cannot fully characterise the economic costs and application potential of remediation plants. In this study, we proposed a new strategy for selecting remediation plants based on economic indicators (cost per unit of heavy metal removal). Based on field experiments and data collection, we conducted cost-benefit analyses under various scenarios to compare the application prospects of four cadmium (Cd)-accumulators (Hylotelephium spectabile, Sedum alfredii, Sedum plumbizincicola and tobacco) on slightly Cd-contaminated farmland soil. Utilizing the current screening strategy, which prioritized remediation indicators only, we found that in Cd-contaminated soil, S. plumbizincicola exhibited the best ability to uptake Cd (250 g ha^-1). However, applying the new strategy that combined economic and remediation indicators, the Monte Carlo simulations results showed that tobacco showed the lowest cost per gram of Cd uptake (546 RMB g^-1). Combining scenario simulation and cost-benefit analysis, tobacco achieved the earliest positive net present value benefit, indicating a higher application potential in slightly Cd-contaminated soil. Additionally, the spatial distribution and optimal temperature range for tobacco cultivation were found to be superior to those of the other three accumulators, which was consistent with the assessment results of the new screening strategy. The indicator proposed in this study, namely, the cost per unit of heavy metal removal, considers both the remediation efficiency and economic cost. This holds significant value for selecting remediation plants with application potential and provides a crucial basis for decision-making in the development of future phytoremediation strategies and the implementation of large-scale applications.