title: Historic and Industrial Lead within the Northwest Pacific Ocean Evidenced by Lead Isotopes in Seawater.
abstract: We report the continued lead (Pb) contamination of the Northwest Pacific Ocean in 2002 and present the first comprehensive Pb isotope data set for that region. In the upper ocean, a Pb concentration maxima (64-113 pmol kg-1) extended throughout the entire North Pacific Subtropical Gyre (NPSG). We determined most of the Pb in this feature was from industrial emissions by many nations in the 1980s and 1990s, with the largest contributions from leaded gasoline emissions. In contrast, the deep water (>1000 m) Pb concentrations were lower (6-37 pmol kg-1), and constituted a mix of background (natural) Pb and anthropogenic Pb inputs from preceding decades. Deep water below the Western Subarctic Gyre (WSAG) contained more industrial Pb than below the NPSG, which was attributed to a calculated 60-fold greater flux of particulate Pb to abyssal waters near the Asian continent. Assuming Pb isotope compositions in the North Pacific Ocean were homogeneous prior to large-scale 20th century anthropogenic inputs, this evidence suggests a relatively faster change in Pb isotope ratios of North Pacific deep water below the WSAG versus the NPSG.
authors.affiliation: WIGS, Environmental Toxicology, University of California Santa Cruz , 1156 High Street, Santa Cruz, California 95064, United States.
authors.forename: Cheryl M
authors.identifier: 0000-0002-6109-427X
authors.initials: CM
authors.lastname: Zurbrick
authors.affiliation: Institute of Marine Sciences, University of California Santa Cruz , 1156 High Street, Santa Cruz California 95064, United States.
authors.forename: Céline
authors.initials: C
authors.lastname: Gallon
authors.affiliation: WIGS, Environmental Toxicology, University of California Santa Cruz , 1156 High Street, Santa Cruz, California 95064, United States.|Institute of Marine Sciences, University of California Santa Cruz , 1156 High Street, Santa Cruz California 95064, United States.
authors.forename: A Russell
authors.initials: AR
authors.lastname: Flegal
mesh_terms: D004784:Environmental Monitoring; D007554:Isotopes; D007854:Lead; D010140:Pacific Ocean; D012623:Seawater
chemical_list: D007554:Isotopes; D007854:Lead