Metal uptake in maize, willows and poplars on impoldered and freshwater tidal marshes in the Scheldt estuary

Foliar Cd and Zn concentrations in Salix, Populus and Zea mays grown on freshwater tidal marshes were assessed. Soil metal concentrations were elevated, averaging 9.7 mg Cd kg-1 dry soil, 1100 mg Zn kg-1 dry soil and 152 mg Cr kg-1 dry soil. Cd (1.1-13.7 mg kg-1) and Zn (192-1140 mg kg-1) concentrations in willows and poplars were markedly higher than in maize on impoldered tidal marshes (0.8-4.8 mg Cd kg -1 and 155-255 mg Zn kg-1). Foliar samples of maize were collected on 90 plots on alluvial and sediment-derived soils with variable degree of soil pollution. For soil Cd concentrations exceeding 7 mg Cd kg -1 dry soil, there was a 50% probability that maize leaf concentrations exceeded public health standards for animal fodder. It was shown that analysis of foliar samples of maize taken in August can be used to predict foliar metal concentrations at harvest. These findings can therefore contribute to anticipating potential hazards arising from maize cultivation on soils with elevated metal contents. © 2006 British Society of Soil Science.