Sulfide concentration
Methane oxidation

CHEMISTRY

Sulfide concentration

Dissolved sulfide in the water column comprises the forms H₂S and HS^-. Water is sampled immediately from the CTD-rosette bottles using a plastic tubing and avoiding contact with air.

A 50 ml water sample is transferred to a 50 ml serum bottle and 4 ml of the appropriately mixed diamine reagent

Diamine-reagent: dissolve N,N-dimethyl-p-phenylenediamine sulfate and ferric chloride (see table) in 500 ml cool 50 % (v/v) reagent grade hydrochloric acid.

The serum cap is replaced promptly to reduce volatilization of the H2S, and the solution is mixed gently.

After 20 min the absorbance at = 670 nm is determined spectrophotometrically in the appropriate cuvette.

The concentration of sulfide in the sample is calculated from C = F (A-Ab)

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