title: Methylmercury Mass Budgets and Distribution Characteristics in the Western Pacific Ocean.
abstract: Methylmercury (MeHg) accumulation in marine organisms poses serious ecosystem and human health risk, yet the sources of MeHg in the surface and subsurface ocean remain uncertain. Here, we report the first MeHg mass budgets for the Western Pacific Ocean estimated based on cruise observations. We found the major net source of MeHg in surface water to be vertical diffusion from the subsurface layer (1.8-12 nmol m-2yr-1). A higher upward diffusion in the North Pacific (12 nmol m-2yr-1) than in the Equatorial Pacific (1.8-5.7 nmol m-2yr-1) caused elevated surface MeHg concentrations observed in the North Pacific. We furthermore found that the slope of the linear regression line for MeHg versus apparent oxygen utilization in the Equatorial Pacific was about 2-fold higher than that in the North Pacific. We suggest this could be explained by redistribution of surface water in the tropical convergence-divergence zone, supporting active organic carbon decomposition in the Equatorial Pacific Ocean. On the basis of this study, we predict oceanic regions with high organic carbon remineralization to have enhanced MeHg concentrations in both surface and subsurface waters.
authors.affiliation: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea.
authors.forename: Hyunji
authors.initials: H
authors.lastname: Kim
authors.affiliation: Department of Environmental Science and Analytical Chemistry, Stockholm University , Stockholm SE-11418, Sweden.
authors.forename: Anne L
authors.identifier: 0000-0002-8490-8600
authors.initials: AL
authors.lastname: Soerensen
authors.affiliation: Department of Environment and Energy, Sejong University , Seoul 143-747, Republic of Korea.
authors.forename: Jin
authors.initials: J
authors.lastname: Hur
authors.affiliation: Aix Marseille Université, CNRS/INSU, Université de Toulon, IRD, Mediterranean Institute of Oceanography (MIO) UM 110, 13288 Marseille, France.
authors.forename: Lars-Eric
authors.initials: LE
authors.lastname: Heimbürger
authors.affiliation: Department of Oceanography, Pusan National University , Busan 46241, Republic of Korea.
authors.forename: Doshik
authors.initials: D
authors.lastname: Hahm
authors.affiliation: Korea Polar Research Institute , Incheon 406-840, Republic of Korea.
authors.forename: Tae Siek
authors.initials: TS
authors.lastname: Rhee
authors.affiliation: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea.
authors.forename: Seam
authors.initials: S
authors.lastname: Noh
authors.affiliation: School of Earth Sciences and Environmental Engineering, Gwangju Institute of Science and Technology (GIST) , Gwangju 500-712, Republic of Korea.
authors.forename: Seunghee
authors.identifier: 0000-0002-3284-0106
authors.initials: S
authors.lastname: Han
mesh_terms: D004784:Environmental Monitoring; D008767:Methylmercury Compounds; D009792:Oceans and Seas; D010140:Pacific Ocean; D014872:Water Movements
chemical_list: D008767:Methylmercury Compounds