Using isotopes to trace freshly applied cadmium through mineral phosphorus fertilization in soil-fertilizer-plant systems

• DOI: 10.1016/j.scitotenv.2018.08.127
• Publication Date: 2018-08-14T03:59:26Z
• Authors: Matthias Wiggenha...; Moritz Bigalke; Martin Imseng; Armin Keller; Mark Rehkämper; Wolfgang Wilcke; Emmanuel Frossard
• Keywords: Geography & travel; 910; 01 natural sciences; Cadmium Radioisotopes; MD Multidisciplinary; Soil Pollutants; Source tracing; info:eu-repo/classification/ddc/910; Fertilizers; Cadmium; Mineral P fertilizer; Radio isotopes; Source tracing; Stable isotopes; Wheat; Pot experiment; Mineral P fertilizer; Triticum; Stable isotopes; 0105 earth and related environmental sciences; 2. Zero hunger; Pot experiment; Phosphorus; 04 agricultural and veterinary sciences; ddc:910; Radio isotopes; Crop Production; Wheat; 0401 agriculture, forestry, and fisheries; Environmental Sciences; Cadmium

Applications of mineral phosphorus (P) fertilizer can lead to cadmium (Cd) accumulation in soils and can increase Cd concentrations in edible crop parts. To determine the fate of freshly applied Cd, a Cd source tracing experiment was conducted in three soil-fertilizer-wheat systems by using a mineral P fertilizer labeled with the radio isotope 109Cd and by exploiting natural differences in Cd stable isotope compositions (δ114/110Cd). Source tracing with stable isotopes overestimated the proportion of Cd in plants derived from the P fertilizer, because the isotope ratios of the sources were not sufficiently distinct from those of the soils. Despite indistinguishable extractable Cd pools between control and treatments, the addition of P fertilizer resulted in a more negative apparent isotope fractionation between soil and wheat. Overall, the radio isotope approach provided more robust results and revealed that 6.5 to 15% of the Cd in the shoot derived from the fertilizer. From the introduced Cd, a maximum of 2.2% reached the wheat shoots, whilst 97.8% remained in the roots and soils. The low recoveries of the fertilizer derived Cd suggest that continuous P fertilizer application in the past decades can lead to a build-up of a residual Cd pool in soils.