title: Decline of trace metal pollution in the bottom sediments of the Barcelona City continental shelf (NW Mediterranean).
abstract: The evolution of trace metal pollution on the Barcelona city continental shelf during the last few decades was studied by analyzing the historical records of trace metals in sediment cores and surface sediment samples taken at the same locations in 1987 and in 2008. Polluted surface samples taken in 1987 reached enrichment factors of up to 490 for Hg, about 40 for Pb and Cd, and about 17 for Zn, Cr and Cu. The data show a decline of up to one order of magnitude in the trace metal content of surface sediments during the last few decades, with maximum enrichment factors of between 20 and 30 for Hg and Cd and between 5 and 12 for Zn, Cr, Pb and Cu. Although present-day pollution is still significant, it is evident that environmental regulations that are in place, including the operation since 1979 of wastewater treatment plants built in the Besòs River watershed, have drastically reduced the pollution levels in this highly populated and industrialized Mediterranean area. However, water discharge during heavy rain events exceeds the treatment capacity of the existing facilities, leading to the maintenance of still high levels of metals in sediments of the Barcelona city shelf.
authors.affiliation: Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003, Spain. Electronic address: albertp@icm.csic.es.
authors.forename: Albert
authors.initials: A
authors.lastname: Palanques
authors.affiliation: Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Lopez
authors.affiliation: Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: Guillén
authors.affiliation: Institute of Marine Sciences (CSIC), Passeig Maritim de la Barceloneta, 37-49, Barcelona 08003, Spain.
authors.forename: Pere
authors.initials: P
authors.lastname: Puig
authors.affiliation: Departament de Física and Institut de Ciència i Tecnologia Ambientals, Universitat Autònoma de Barcelona, Bellaterra 08193, Spain; School of Science, Centre for Marine Ecosystems Research, Edith Cowan University, Joondalup, WA 6027, Australia; The University of Western Australia Oceans Institute, University of Western Australia, 35 Stirling Highway, Crawley, WA 6009, Australia.
authors.forename: Pere
authors.initials: P
authors.lastname: Masqué
keywords: Barcelona; Environmental regulations; Historical evolution of pollution; Mediterranean Sea; Sediment pollution record; Trace metals