Understanding various biocorrosion mechanisms requires direct measurement of chemical concentrations and profiles within thin biofilms or discrete biodeposits. A gold-based mercury microelectrode was developed for simultaneous measurement of dissolved O2, Mn, Fe, S(–II), and low pH using square wave voltammetry. It was constructed by electroreducing Hg(II) on a gold wire of 25-μm diameter encased in glass. By mounting the electrode on a computerized micromanipulator, vertical microprofiles of the key redox species were measured with 10-μm depth resolution across marine biofilms formed on metal coupons. Various interfering factors and experimental parameters of the voltammetric measurements were reviewed. Results revealed the heterogeneous nature of the biofilm and complex microbially mediated heavy metal (Mn and Fe) cycles within the film system. Data interpretation provided further insight into the mechanism of microbiologically influenced metal corrosion.

Subject
Electric current, Microelectrodes, Metal surfaces, Waves, Seawater, Acidity, Biofilms, Mercury, Maritime, Oxygen, Risk reduction, Electrodes, Electrode potential
Keywords:
biocorrosion, biofilm, gold, microbiologically influenced corrosion, microelectrode, microprofile, redox species, square wave voltammetry
NACE International
1998
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