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Vertical transport of anthropogenic mercury in the ocean
Author(s) -
Strode Sarah,
Jaeglé Lyatt,
Emerson Steven
Publication year - 2010
Publication title -
global biogeochemical cycles
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.512
H-Index - 187
eISSN - 1944-9224
pISSN - 0886-6236
DOI - 10.1029/2009gb003728
Subject(s) - particulates , mercury (programming language) , flux (metallurgy) , environmental science , sorption , environmental chemistry , atmospheric sciences , deposition (geology) , oceanography , geology , chemistry , sediment , geomorphology , organic chemistry , adsorption , computer science , programming language
We investigate the vertical transport of mercury (Hg) within the ocean using a simple box diffusion model to represent vertical water transport coupled with a particulate Hg flux. The particulate flux assumes that the Hg content of marine particles is proportional to the Hg concentration of surface waters via a sorption equilibrium constant, K d . The model is forced with the observed factor of 3 increase in atmospheric Hg deposition over the industrial era. The modeled vertical profile of oceanic Hg shows a subsurface maximum at ∼500 m depth due to remineralization of Hg bound to sinking organic particles, consistent with observations. Model results indicate that surface (top 100 m) concentrations of Hg have increased by 150% since preindustrial times. Over the past 150 years, 280 Mmol of anthropogenic Hg have accumulated in the ocean, representing a 18% increase in the total oceanic Hg content. We find that 36% of the anthropogenic Hg occurs in the top 400 m and only 7% occurs below 1500 m. Over the industrial era, we find that 14% of cumulative anthropogenic emissions have accumulated in the ocean. Our model results show that half of the accumulation of anthropogenic Hg in the ocean is due to sinking on particulates. A sensitivity analysis indicates that the model results are most dependent on the value of K d .