Waters were sampled by first drilling through the ice and then lowering a Go-Flo bottle to the indicated depths. Retrieved samples were then spit into separate containers for analysis. Following the sampling of water, a shallow gravity corer with plastic lining was  attached to steel cable  and lowered through the ice hole and down to the lake bottom. The corer was dropped the final 3 meters. Core recovery ranged from only a few centimeters to 25 centimeters. Once recovered, the sediments were stoppered and transported vertically to Crary Laboratory at McMurdo station. Sediment was separated along several intervals of each core and sediment and pore waters were separated by centrifugation.  

 

Chloride was determined through ion chromatography according to methods described in Welch, K.A., Lyons, W.B., Graham, E., Neumann, K., Thomas, J.M., and D. Mikesell. 1996. Determination of major element chemistry in terrestrial waters from Antarctica by ion chromatography. Journal of Chromatography A 739: 257-263. Kathy Welch carried out the chloride determinations at the Crary Laboratory, McMurdo Station.

 

Alkalinity was determined by titration of samples with hydrochloric acid at Crary Laboratory, McMurdo Station. The methods  used for alkalinity determinations are described in  Gieskes, J.M., Gamo, T.,Brumsack, H.,1991. Chemical Methods for Intersitital water analysis aboard JOIDES Resolution, ODP Tech. Note 15, Texas AandM University, 60 pp.

 

 Samples were diluted then analyzed for I-127 and Br-79 using ICP-MS. Replicate analyses were carried out at the ICP-MS facility of Cin-Ty Lee at Rice University, as well as the ICP-MS facility of Yasuyuki Muramatsu at  Gakushuin University, Tokyo. Methods for analysis are described in: Schnetger, B., and Muramatsu, Y., Determination of the halogens, with special reference to iodine, in geological and biological samples using pyrohydrolysis for preparation of inductively coupled plasma mass spectrometry and ion chromatography for measurement, Analyst, 121:1627-1631.

 

Chloride was extracted from the samples as purified AgCl. Likewise, iodine was extracted as purified AgI using methods described in Snyder, GT and  Fabryka-Martin, JT  (2007). 129-I and 36-Cl in dilute hydrocarbon waters: Marine-cosmogenic, in situ, and anthropogenic sources. In: G.T. Snyder and J.E. Moran (Eds.), special issue: "The halogens and their isotopes in marine and terrestrial aqueous systems", Applied Geochemistry, 22 , 692-704. The purified chloride and iodide targets were sent to PRIME Laboratory at Purdue University for AMS (accelerator mass spectrometry)  analysis of Cl-36 and I-129.