The activity of bacteria colonizing a metallic surface impacts the physical and chemical properties of materials and leads to Microbial Induced Corrosion (MIC), affecting a wide range of industrial sectors such as nuclear and oil & gas industries [1]. Sulfato-Reducing Bacteria (SRB) are known to cause the most severe damage due to the production of H_2S species leading to the formation of sulfide corrosion products. The biological origin of the formation and growth of sulfide is still difficult to demonstrate unambiguously. However it is known that SRBs produce sulfide with a different sulfur isotopic ratio (~(34)S/~(32)S) than the natural distribution [2] due to a faster process for the lighter isotope. In this work, we used the ToF-SIMS to measure the ~(34)S/~(32)S intensity ratio on sulfide corrosion products. A ratio close to natural abundance is measured on the chemically formed sulfide, whereas a lower ratio is measured on the biologically prepared sulfide. Thus, this new approach opens the way to the identification of the biological origin of sulfide corrosion products, provided that analytical problems such as (i) the high mass resolution to separate ~(32)S and O_2, and (ii) the selective sputtering of lighter isotope, can be resolved. This will be discussed in the presentation.
展开▼
