Comparison of the DGGE profiles in both sample types and their detected Hgt concentrations in each sample showed that there was no relationship between the bacterial groups and HgT concentrations. For example, the sediment samples collected from sites: ST1, ST2 and SK were clustered in the same group (Fig. 3B and Table 3), but the Hgt concentrations (ug/kg dry sediment weight) were totally different as in PT (391.60), ST1 (367.68), ST2 (183.22) and SK (59.52) Moreover, the Hgt concentration in RN1 (140.21 Hg/kg dry sediment weight) was very close to that of RN2 (135.22 Hg/kg dry sediment weight), but the RN1 site had no detectable pufM gene. This was similar for the water samples, as the DGGE profiles in KT2 site, with the highest concentrations of HgT (0.030 ug/L was grouped with the TPI and ST1-3 with the lowest concentration of Hgr (