1. Environmental Chemistry Laboratory, University of Bologna, Via dell’Agricoltura 5, 48100 Ravenna, Italy
2. Department of Chemistry “G. Ciamician”, Alma Mater Studiorum University of Bologna, Via Selmi 2, 40126 Bologna, Italy, Fax: (internat.) + 39‐051‐2099456
3. Department of Biology, University of Trieste, Via Weiss 2, Trieste, Italy