As the name suggests, the SRD test provides an estimate of the rate of in situ sulfate reduction activity. In the lab, a small amount of 35S-sulfate is added to a sample and incubated at temperatures close to field conditions. After the short incubation period, reduced inorganic sulfides are extracted, 35S-sulfides are measured and the sulfate reduction rate is calculated.
SULFATE REDUCTION ACTIVITY (SRD) ADVANTAGES:
The SRD test provides conclusive evidence for sulfate reduction activity – not just for the potential for sulfate reduction/sulfide production.
The SRD test provides an estimate of the in situ rate of sulfate reduction in units of mmoles/L/day.
SENSITIVE AND ACCURATE
Since the SRD test uses a small amount of radiolabeled sulfate which does not significantly change the size of the endogenous sulfate pool, the results are accurate and sensitive even in systems with high background sulfate concentrations.
The incubation period for the SRD test is typically between 5 and 7 days.
HOW TO USE SRD:
Use the SRD estimate of the sulfate reduction rate as part of a multiples lines of evidence approach in assessing the threat of MIC and reservoir souring. Data interpretation should emphasize comparisons of SRD results for select locations or time points to answer specific questions.
Use SRD to help answer…
- Is sulfate reduction occurring at specific locations?
- Was biocide treatment effective?
- Was nitrate treatment effective?
- Did sulfate reduction activity decrease after treatment?