Surface arsenic, antimony speciation, and alkaline phosphatase activity along with US GEOTRACES North Atlantic Transect from the R/V Knorr KN199-04, KN199-05 cruises in the subtropical N. Atlantic during 2010 (U.S. GEOTRACES NAT project) (NCEI Accession 0291624)

Change History:
Data were updated 3 January 2013

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Acquisition Description:
Filtered (0.4 µm) water samples from the Geotraces surface tow-fish taken at discrete times into 500 mL Teflon FEP bottles, refrigerated, and analyzed within 24 hours of collection. Arsenic and antimony speciation determined using selective hydride generation, liquid nitrogen-cooled trapping, and then revolatilization and determination with gas chromatography/photoionization detection (Cutter et al., 1991; Cutter and Cutter, 2006). Calibration performed daily via the standard additions method, with a minimum of 4 additions of AsIII, AsV, MMAs, or DMAs depending on the analyses. The slope from the linear fit to these data was then applied to all samples for that day. Detection limits were 25 pmol/L for As(III) and As(III+V), and 50 pmol/L for MMAs and DMAs. Precision was better than 8% (relative standard deviation) for all As species. Alkaline phosphatase enzyme activity was measured using the fluorescence method of Ammerman (1993).