Variations in stable isotope ratios of trace metals are increasingly used to address fundamental challenges to air, water and soil quality. In this talk I will focus on our ongoing work at Imperial College London to better understand mechanisms of micronutrient efficiency and sources of air pollution. I will first introduce the field of ‘non-traditional stable isotopes’ and the analytical challenges associated with the accurate and precise measurement of isotope ratios in environmental matrices. I then will show how we developed the first isotope fractionation model for zinc and copper in the soil-plant environment and discuss implications regarding a possible zinc efficiency mechanism in rice. Finally, I will present recent evidence from studies in London, Barcelona, Zaragosa and Sao Paolo that suggest that Zn and Cu isotopes can be used to trace these critical pollutants in the urban aerosols, offering a unique tool for source apportionment.