DOI: 10.1016/j.epsl.2020.116676
论文题名: Limited iodate reduction in shipboard seawater incubations from the Eastern Tropical North Pacific oxygen deficient zone
作者: Hardisty D.S. ; Horner T.J. ; Evans N. ; Moriyasu R. ; Babbin A.R. ; Wankel S.D. ; Moffett J.W. ; Nielsen S.G.
刊名: Earth and Planetary Science Letters
ISSN: 0012821X
出版年: 2021
卷: 554 语种: 英语
中文关键词: iodate reduction
; iodine paleoredox proxy
; iodine speciation
; iodine-to-calcium ratios
; oxygen deficient zone
英文关键词: Biochemical oxygen demand
; Dissolved oxygen
; Mixing
; Oceanography
; Offshore oil well production
; Ships
; Superconducting tapes
; Tracers
; Tropics
; Biological productivity
; Conservative tracers
; Dissolved oxygen concentrations
; Oxygen concentrations
; Redox transformations
; Relative abundance
; Variable precision
; Water mass analysis
; Iodine compounds
; calcium
; concentration (composition)
; iodine
; paleogeography
; redox conditions
; reduction
; seawater
; shipping
; Pacific Ocean
; Pacific Ocean (North)
英文摘要: The relative abundance of the inorganic iodine species, iodide and iodate, are applied to characterize both modern and ancient marine oxygen deficient zones (ODZs). However, the rates and mechanisms responsible for in situ iodine redox transformations are poorly characterized, rendering iodine-based redox reconstructions uncertain. Here, we provide constraints on the rates and mechanisms of iodate reduction in the Eastern Tropical North Pacific (ETNP) offshore ODZ using a shipboard tracer–incubation method. Observations of iodate reduction from incubations were limited to the top of the oxycline (σθ∼25.2kgm−3) where native oxygen concentrations were low, but detectable (≈11 μM). Incubations from additional depths below the oxycline—where O2 was <2 μM—yielded no detectable evidence of iodate reduction despite hosting the lowest iodate concentrations. These experiments place an upper limit of iodate reduction rates of generally <15 nM day−1 but as low as <2.3 nM day−1, which are based on variable precision of individually incubated replicates between experiments. Experimental inferences of limited or slow iodate reduction in the ODZ core relative to that observed in the oxycline are generally consistent with iodate persistence of up to 70 nM and low biological productivity in this zone. We also compare dissolved iodine and oxygen concentrations between variable water masses of the ETNP and globally distributed open ocean ODZs. Consistent with sluggish reduction rates, comparison of iodate concentrations with previously published water mass analyses within the ETNP ODZ (σθ=26-27kgm−3; O<27μM) demonstrate iodate as a semi-conservative tracer at least partially reflecting regional water mass mixing. A compilation of iodate and dissolved oxygen concentrations from global ODZs generally supports that at least some iodate variations in both vertical and lateral transects largely reflect variable combinations of relatively slow reduction and mixing of iodate reduction signals generated in adjacent regions—as opposed to solely rapid in situ processes. In this context, the variations in iodine speciation inferred for the ancient and modern ocean represent a combination of in situ processes and regional mixing between water masses that retain variable spatially and temporally integrated redox histories. © 2020 Elsevier B.V. Citation statistics:
资源类型: 期刊论文
标识符: http://119.78.100.158/handle/2HF3EXSE/165497
Appears in Collections: 气候变化与战略
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作者单位: Department of Earth and Environmental Sciences, Michigan State University, East Lansing, MI, United States; Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, United States; Department of Biological Sciences, University of Southern California, Los Angeles, CA, United States; Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States; Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, United States
Recommended Citation:
Hardisty D.S.,Horner T.J.,Evans N.,et al. Limited iodate reduction in shipboard seawater incubations from the Eastern Tropical North Pacific oxygen deficient zone[J]. Earth and Planetary Science Letters,2021-01-01,554