The dissolved Hg analyses were performed at sea, by both WHOI and Wright State personnel.

See Hg Cook Book for full methodology (PDF)
Detailed method descriptions can be found in Lamborg et al., 2012, Hammerschmidt & Bowman, 2012, Bowman et al., 2015
Sample collection: Cutter & Bruland, 2012
- TMR - trace metal rosette
- FISH – trace-metal clean, surface towed pump system
Sample bottles/cleaning: Hammerschmidt et al., 2012
All analyses were performed at sea aboard the ship.
HgT analysis were all performed by analysts from WHOI:
- Fitzgerald & Gill, 1979, Bloom & Fitzgerald, 1988, Bloom, 1989
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 0.03 pM
- Procedural duplicates: 7 ± 9% (n = 29)
- Recovery of known additions: 97 ± 2% (n = 5)
Hg0 analysis were all performed by analysts from WHOI:
- Fitzgerald & Gill, 1979, Bloom & Fitzgerald, 1988, Bloom, 1989
- Tekran Model 2500 CVAFS Detector
- Detection limit: 0.01 pM
- Procedural duplicates: 20 ± 15%, n = 27
- Recovery of known additions: N/A
MMHg analysis were all performed by analysts from Wright State:
- Bowman & Hammerschmidt, 2011, Tseng et al., 2004, Munson et al., 2014
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 0.02 pM
- Procedural duplicates: 35 ± 22% (n = 6)
- Recovery of known additions: 84 ± 12% (n =3)
DMHg analysis were all performed by analysts from Wright State:
- Bowman & Hammerschmidt, 2011, Tseng et al., 2004, Baya et al., 2013
- Tekran Model 2500 CVAFS Mercury Detector
- Detection limit: 0.002 pM
- Procedural duplicates: 27 ± 20% (n = 17)
- Recovery of known additions: N/A

“lt_DL” indicates that a sample was below the method detection limit.

Sample volumes were used to calculate picomolar concentrations of different mercury species.

Related References:

Baya, P.A., Hollinsworth, J.L. and Hintelmann, H., 2013. Evaluation and optimization of solid adsorbents for the sampling of gaseous methylated mercury species. Anal. Chim. Acta, 786, 61–69.

Bloom, N. 1989. Determination of picogram levels of methylmercury by aqueous phase ethylation, followed by cryogenic gas-chromatography with cold vapor atomic fluorescence detection. Can. J. Fish. Aquat. Sci. 46, 1131–1140.

Bloom, N.S., Fitzgerald, W.F. 1988. Determination of volatile mercury species at the picogram level by low-temperature gas chromatography with cold-vapor atomic fluorescence detection. Anal. Chim Acta 208, 151–161.

Bowman, K.L., Hammerschmidt, C.R. 2011. Extraction of monomethylmercury from seawater for low-femtomolar determination. Limnol. Oceanogr.: Methods 9, 121–128.

Bowman, K.L., Hammerschmidt, C.R., Lamborg, C.H. and Swarr, G., 2015. Mercury in the North Atlantic Ocean: The U.S. GEOTRACES zonal and meridional sections. Deep-Sea Res. Pt. II. 116, 251–261.

Cutter, G.A., Bruland, K.W. 2012. Rapid and noncontaminating sampling system for trace elements in global ocean surveys. Limnol. Oceanogr.: Methods 10, 425–436.

Fitzgerald, W.F., Gill, G.A. 1979. Subnanogram determination of mercury by two-stage gold amalgamation applied to atmospheric analysis. Anal. Chem. 51, 1714–1720.

Hammerschmidt, C.R., Bowman, K.L. 2012. Vertical methylmercury distribution in the subtropical North Pacific Ocean. Mar. Chem. 132, 77–82.

Hammerschmidt, C.R., Bowman, K.L., Tabatchnick, M.D., Lamborg, C.H. 2011. Storage bottle material and cleaning for determination of total mercury in seawater. Limnol. Oceanogr.: Methods 9, 426–431.

Lamborg, C.H., Hammerschmidt, C.R., Gill, G.A., Mason, R.P., Gichuki, S. 2012. An intercomparison of procedures for the determination of total mercury in seawater and recommendations regarding mercury speciation during GEOTRACES cruises. Limnol. Oceanogr.: Methods, 10, 90-100.

Munson, K.M., Babi, D. and Lamborg, C.H., 2014. Determination of monomethylmercury from seawater with ascorbic acid-assisted direct ethylation. Limnol. Oceanogr.-Meth. 12, 1–9.

Tseng, C.-M., Hammerschmidt, C.R., Fitzgerald, W.F. 2004. Determination of methylmercury in environmental matrixes by on-line flow injection and atomic fluorescence spectrometry. Anal. Chem. 76, 7131–7136.