During the International Commission on Tracers workshop HW07, at Gothenburg, the presentations covered many branches of hydrology.

They included reports on the tracer approaches and studies in Japan, China and some European countries, as well as an overview of how tracer techniques contribute to the understanding and quantification of water dynamics and pollutant origin, applying new methods for water-age estimation using data from simultaneous measurements of different environmental tracers, 3-D mathematical modelling of lowand transport processes, mathematical modelling and quantifying of the heterogeneity of water flux in the unsaturated zone by using artificial tracers in lysimeter experiments.

Dr Martin Elsner, from Germany, in his invited talk, presented extremely interesting new aspects of using tracer methods: the application of compound-specific isotope values of groundwater pollutants to understand biodegradation processes and their quantification.

In total, there were three oral and one poster session. The oral presentations represented only two continents (Asia 7 and Europe 9); most were from Japan (5) and Germany (3).

Based on the experience of this workshop, the ICT commission decided to propose one workshop for the IAHS General Assembly in Prague 2015 titled: Tracer methods for understanding response of hydrological systems to transient contamination inputs.

Piotr Maloszewski, Convener