Tracking Zinc In The Environment

Researchers at the University of Paris Diderot, in France, have used zinc isotopes to follow zinc-bearing pollution as it travels through the environment (Environ. Sci. Technol., DOI: 10.1021/es800725z). Dissolved zinc works nicely as a tracer because biological activity does not degrade its isotopic signature as it moves through water and soil. Jiubin Chen and colleagues sampled water from locations in the Seine River Basin in France between 2004 and 2007. They measured ⁶⁶Zn/⁶⁴Zn ratios by an inductively coupled plasma mass spectrometry technique. Because each natural or anthropogenic source of zinc has a particular isotopic signature, the researchers determined that approximately 90% of the dissolved zinc in the Seine originates from anthropogenic sources. For example, the team traced a large percentage of contamination back to zinc leached by rain from roofing material in Paris and carried to the river in storm runoff. The researchers say that the absence of distinctive signatures of fertilizer, compost, or rainwater from rural areas suggests that soils there retain zinc.