Measuring acid volatile sulphide in floodplain lake sediments: effect of reaction time, sample size and aeration.

For the routine measurement of acid volatile sulphide (AVS) in floodplain lake sediments, an earlier published diffusion method was adapted and optimised. We evaluated the effect of reaction time, sample weight and passive sample aeration on AVS recovery, and determined the method's reproducibility. The optimal reaction time was 4 h. Losses of AVS due to sample aeration did not occur within 15 min of sample-air contact. Relative standard deviation was <2.5% for known sulphide solutions, was between 10% and 15% for AVS concentrations in sediments and <12% for SEM concentrations in sediments, generally. Sediment samples with known SEM and AVS content were used to compare results of the developed method with the purge-and-trap method. There is a good agreement with the purge-and-trap method for SEM concentrations. AVS concentrations measured with the diffusion method are higher than with the purge-and-trap method. We conclude that the adapted diffusion method is well suited for the routine measurement of AVS concentrations in floodplain sediments.