Lead, zinc and cadmium accumulation from two metalliferous soils with contrasting calcium contents in heavy metal-hyperaccumulating and non-hyperaccumulating metallophytes: a comparative study

Aims and background

We previously compared metallicolous (M) and non-metallicolous (NM) populations of Noccaea (=Thlaspi) caerulescens, Silene vulgaris, and Matthiola flavida for their abilities to tolerate and (hyper)-accumulate lead (Pb) in hydroponics. In the present study we aimed 1) to check the hyperaccumulation and tolerance abilities of these populations in controlled experiments using metalliferous soils, 2) to test the M. flavida M population for Zn and Cd hypertolerance in hydroponics.

Methods

Plants were grown in hydroponics and fertilized metalliferous substrates, collected from a Zn/Pb smelter sinter deposit near Plombières, Belgium (low pH, low Ca), and a tailing of the Irankouh Zn/Pb mine, Iran (high pH, high Ca). Metal tolerance was assessed from root growth inhibition in hydroponics, or mortality, stunting or chlorosis in the experiments with soil.

Results

Metallicolous M. flavida did not show hypertolerance or hyperaccumulation of Cd or Zn in hydroponics. Only one of the N. caerulescens M populations and the native S. vulgaris M population were able to grow in Plombières soil, whereas the others stopped growing or died within 40?days. All the populations survived and maintained growth for 40?days in Irankouh soil. When grown in Irankouh soil, the M population of M. flavida hyperaccumulated Pb. N. caerulescens hyperaccumulated Zn from Plombières soil, but not from Irankouh soil.

Conclusions

The M. flavida M population is non-Pb-hypertolerant. It hyperaccumulates Pb from Irankouh soil, but not from Pb-amended nutrient solution. N. caerulescens does not hyperaccumulate Zn from the calcareous Irankouh soil.