Date of Award

Winter 2010

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Ocean/Earth/Atmos Sciences

Committee Director

John R. Donat

Committee Member

Gregory A. Cutter

Committee Member

Peter N. Sedwick

Committee Member

Paula A. Mazzer

Committee Member

William M. Landing

Abstract

Dissolved and suspended particulate samples collected during the Intergovernmental Oceanographic Commission 2002 Contaminant Baseline Survey were analyzed to determine the surface and vertical distributions of Cd, Co, Cu, Mn, Ni Zn and Pb across the western and central North Pacific.

Dissolved trace metal concentrations were measured using a novel isotope dilution-ICP-MS method after extraction over an 8-hydroxyquinoline resin column and validated through the use of the SAFe consensus reference materials. Filtered suspended particulate matter was digested using an HCl/HNO3/HF mixture and analyzed by HR-ICP-MS to obtain total particulate concentrations for the trace metals and other tracer elements such as Al, Ti and P.

Particulate Mn, Fe and Al distributions reveal the importance of margin-derived material to the North Pacific. Redox-mobilization and resuspension processes were identified through particulate distributions and elemental ratios (i.e., Mn/Fe and Mn/Al). Further comparison with the hydrography of the western North Pacific revealed an extensive intermediate water mass transport system capable of advecting material beyond the immediate continental shelf. Elevated particulate Mn and Fe concentrations originating from the Kuril-Kamchatka margin are found in the central North Pacific as well as across the Kuroshio-Oyashio front.

Dissolved trace metal concentrations in the surface waters of the Western Subarctic Gyre (WSAG) are as much as 100 times higher than in typical open-ocean surface waters. Upwelling of trace-metal enriched deep waters is a significant source for some metals (Ni, Cu, Cd and Zn) while inputs from the nearby shelf sediments supply additional Mn and Co to the WSAG. Comparisons of particulate trace metal distributions with lithogenic (Al, Ti) and biogenic (P) tracers reveal the close association of Cd and P, while particulate Co is associated with both biogenic and authigenic (Mn-oxide) particles.

Dissolved and particulate Pb distributions are distinct from the other trace metals. Higher dissolved concentrations in surface and mode waters are well-correlated with the Kuroshio Current/Extension. Furthermore, vertical profiles of particulate Pb near Japan suggest subsurface inputs in addition to atmospheric inputs. A possible source for this Pb is the East China Sea, a marginal sea heavily influenced by anthropogenic inputs.

DOI

10.25777/adrh-gy41

ISBN

9781124458649

Share

COinS