Trace Element Contaminants and Radioactivity from Phosphate Fertiliser

A risk ranking model was developed to provide a systematic evaluation of the range and quantity of 28 elemental contaminants applied to land in New Zealand and applied to mineral P fertilisers. The methodology is transparent, flexible and robust and allows contamination issues to be ranked according to their real or potential impact. The quantitative ranking model is based on the relative importance of each element in relation to accumulation in soil, transfer to water or uptake by plants, toxicity to soil organisms, plants and people, and the contribution of any radioactive isotopes. The highest risk score for potential environmental significance of P fertiliser borne trace element contaminants was found for uranium, followed (in decreasing order) by cadmium, mercury, boron, fluoride, selenium, arsenic, silver and rare earth elements. The lowest score (rank 28) was attributed to strontium.