Methylmercury Mass Budgets and Distribution Characteristics in the Western Pacific Ocean

详细信息    查看全文

• 作者：Hyunji Kim ; Anne L. SoerensenJin Hur ; Lars-Eric Heimbürger ; Doshik Hahm ; Tae Siek Rhee ; Seam Noh ; Seunghee Han
• 刊名：Environmental Science & Technology
• 出版年：2017
• 出版时间：February 7, 2017
• 年：2017
• 卷：51
• 期：3
• 页码：1186-1194
• 全文大小：530K
• ISSN：1520-5851

文摘

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^–2 yr^–1). A higher upward diffusion in the North Pacific (12 nmol m^–2 yr^–1) than in the Equatorial Pacific (1.8–5.7 nmol m^–2 yr^–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.