Keywords: cadmium, hyperaccumulation, immobilisation, mycorrhiza, phytoextraction, phytostabilisation, transgenic plants, soil contamination, environmental pollution, human health risks, plant uptake, soil remediation, biomass, organic acids
Cadmium in soil-plant systems: an overview
High concentrations of cadmium in soils represent a potential threat to human health because it is incorporated in the food chain mainly by plant uptake. The behaviour of cadmium in soils depends on several factors related to both soil and plant characteristics. This paper provides an overview of such factors as well as of the most environmentally friendly in situ soil remediation techniques in development in recent years. These include chemical inactivation by means of soil amendments and phytoremediation approaches. Among phytoremediation approaches, phytostabilisation technologies are more economic and have been proven to be more realistic than phytoextraction on highly contaminated sites. Concerning phytoextraction, two plant species are well recognised as hyperaccumulator plants, Thlaspi caerulescens and Arabidopsis halleri. Nevertheless, recent investigations have been focused on the use of high biomass plants using chemical agents to improve Cd phytoextraction; the application of organic acids appears as the best option.