Opal (Zn/Si) ratios as a nearshore geochemical proxy in coastal Antarctica
Figure S2: Plots of Al versus trace metal intensities for cleaned opal during a series of dissolution experiments. (52.39Mb)
Figure S3: Yield experiments for Si, showing 100% yield and no loss of Si through the production of volatile compounds. (27.92Mb)
Figure S5a: Within-analysis external reproducibility of ratio method assessed by simulating a run by measuring a reference standard (31.58Mb)
Figure S5b: Long-term external reproducibility assessed by measuring a reference standard at intervals throughout a period of a year. (30.81Mb)
Text S1: Operating conditions for the Q-ICP-MS, blank and sample intensities, and standard concentrations. (8.224Kb)
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During the last 50 years, the Antarctic Peninsula has experienced rapid warming with associated retreat of 87% of marine and tidewater glacier fronts. Accelerated glacial retreat and iceberg calving may have a significant impact on the freshwater and nutrient supply to the phytoplankton communities of the highly productive coastal regions. However, commonly used biogenic carbonate proxies for nutrient and salinity conditions are not preserved in sediments from coastal Antarctica. Here we describe a method for the measurement of zinc to silicon ratios in diatom opal, (Zn/Si)opal, which is a potential archive in Antarctic marine sediments. A core top calibration from the West Antarctic Peninsula shows (Zn/Si)opal is a proxy for mixed layer salinity. We present down-core (Zn/Si)opal paleosalinity records from two rapidly accumulating sites taken from nearshore environments off the West Antarctic Peninsula which show an increase in meltwater input in recent decades. Our records show that the recent melting in this region is unprecedented for over 120 years.
Author Posting. © American Geophysical Union, 2008. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Paleoceanography 23 (2008): PA2218, doi:10.1029/2007PA001576.