Zinc isotopic variation of water and surface sediments from the German Elbe River.

•Zn isotope-amount ratios as a potential tracer for anthropogenic Zn emissions.•Analysis of water and sediment samples from the Elbe River and its tributaries.•MC ICP-MS analysis with low blank levels and double spike calibration.•Enrichment of heavier isotopes in selected anthropogenically impacted tributaries.•Influence of natural fractionation processes on Zn isotopic composition in water.