Elevated Fe(II) and Dissolved Fe in Hypoxic Shelf Waters off Oregon and Washington: An Enhanced Source of Iron to Coastal Upwelling Regimes
Maeve C. Lohan
Kenneth W. Bruland
10.1021/es800144j.s001
https://acs.figshare.com/articles/journal_contribution/Elevated_Fe_II_and_Dissolved_Fe_in_Hypoxic_Shelf_Waters_off_Oregon_and_Washington_An_Enhanced_Source_of_Iron_to_Coastal_Upwelling_Regimes/2917561
There has been a growing interest in the cause and impact of hypoxic regions known as “dead zones” that have increasingly appeared along the west coast of the United States and have caused widespread destruction to the crab and fishing industry in this upwelling region. Here, we present results that demonstrate that the hypoxic conditions in the water column over the continental shelf result in a marked increase in iron(II) concentrations, which contribute to elevated dissolved and labile particulate iron concentrations. These elevated dissolved iron(II) concentrations result from two factors: (1) the hypoxic water column allows extremely elevated iron(II) concentrations in reducing porewaters to exist close to the sediment water interface, leading to an increased flux of iron(II) from the sediments; (2) the low oxygen, low pH, and low temperatures within the bottom boundary layer act in concert to markedly slow down the oxidation rate of Fe(II). During upwelling conditions, this process can result in a greatly enhanced source of Fe available to upwell to surface waters, potentially increasing phytoplankton productivity, which can, in turn, lead to enhanced export flux, driving the system further into hypoxic or suboxic conditions.
2008-09-01 00:00:00
suboxic conditions
hypoxic conditions
hypoxic water column
Hypoxic Shelf Waters
fishing industry
Enhanced Source
sediment water interface
export flux
west coast
oxidation rate
shelf result
United States
hypoxic regions
phytoplankton productivity
bottom boundary layer act
iron concentrations
Coastal Upwelling RegimesThere
upwelling conditions
surface waters
Dissolved Fe
upwelling region
water column