Predicting metal sensitivities and metal mixture interactions for species within each trophic level is essential to understand the effects of metals at the ecosystem level. The present study was set up to explore the correlations of metal sensitivities among species and if these sensitivities or metal mixture interactions are related to growth or morphological traits. The toxicity of Ni, Cu, and Zn on algal growth was tested for 8 freshwater algal species when dosed singly and in combinations in phosphorus-limiting static systems. The metal sensitivities on specific growth rate (10% effect concentrations expressed as free ion activities) varied 2 to 3 orders of magnitude among species depending on metal. These sensitivities were unrelated (p > 0.05) to their specific growth rate (0.7-1.8 d -1 ) or cell volume (10 0 -10 3 m 3 cell -1 ). Species-specific differences in one or more toxicokinetic and/or toxicodynamic (TKTD) processes are likely at the basis of this variation. The logtransformed metal sensitivities positively correlated (p < 0.1) among the species in all 3 binary combinations (Ni-Cu, Ni-Zn, and Cu-Zn), suggesting that species have correlated TKTD rates for these metals. Furthermore, they would also predict stronger effects of metal mixtures on algal community biodiversity than what would be expected without a positive correlation. Low-level metal mixture effects varied similarly, largely among species and mixture interactions that were highly variable: ranging from synergistic to antagonistic relative to independent action during exponential growth, whereas mixture interactions at 10% effect shifted toward additivity/synergism relative to concentration addition at carrying capacity. Some evidence was found for stronger synergistic mixture effects in smaller species. Overall, the present study highlights the importance of incorporating more species in sensitivity distributions and accounting for mixture toxicity in risk assessment.

Mineral phosphate (P) fertilisers are the main suspected sources of uranium (U) and cadmium (Cd) input to agricultural soils. This study was set up to survey the general long‐term impact of P fertilisers on concentrations of Cd, U and other trace metals in European soils. A total of 218 soil samples was collected from 15 long‐term (3–78 years, median 18 years) P trials at 11 locations with a pairwise comparison of topsoil composition between the fertilised and corresponding unfertilised soils. Aqua regia soil extraction detected the effects of fertilisation more sensitively than the HF (real total) soil extraction. Statistically significant differences in aqua regia soluble metals due to fertiliser application were detected more frequently for U (10 of 15 trials) than for Cd (4 of 15 trials). The concentrations of U and Cd in soil linearly increased with cumulative applied P across all soils and sites; a total addition of 1 ton P ha−1 increased the mean topsoil (23 cm depth) concentrations by 0.11 mg U kg−1 soil (0.09–0.12 mg U kg−1, 95% CI) and 0.03 (0.02–0.04) mg Cd kg−1 soil. These results correspond with mass balance predictions (1 ton P ha−1; +0.15 mg U kg−1 soil and +0.02 mg Cd kg−1 soil) based on previously determined average trace element concentrations in European fertilisers. Data thus suggests that, on average among trials, losses of Cd from soil are undetectable. In contrast, about 30% of the theoretical U input from fertilisers is lost in the same trials. This study provides data to better evaluate the modelled trace metal accumulations in soil and to evaluate the prevailing metal limits in mineral fertilisers. Highlights U and Cd accumulation in agricultural soils correlates with cumulative mineral P‐fertiliser dose. Accumulation of fertiliser‐derived U is more often detectable compared to Cd. Due to its accumulation potential, U accumulation should be monitored. Aqua regia soluble concentrations better detect metal accumulation in soil than real total concentrations.

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