Sediment status of the Hooghly and Haldi estuaries at Haldia industrial area with special reference to trace metals

Sediment quality of Hooghly and Haldi estuaries at Haldia industrial area, West Bengal was studied in the present investigation. The trace metal (Cd, Cu, Mn, Pb and Zn) content in sediment phase and the possible impact due to anthropogenic activities in the zone were also evaluated. The seasonal influences were prominent on sediment specific conductance, CaCO₃, primary particles distribution, available nitrogen and also on the content of the trace metals viz., Cu, Mn and Zn. Specific conductance was basically related with headwater discharge and tidal influence. The industrial effluents significantly increased the level of organic carbon. Higher levels of specific conductance, available nitrogen and trace metals (Cu, Mn and Zn) were also recorded in the area influenced by township, although the increase was not statistically significant. Relatively more variations were noticed in the content of Mn and Cu in the out-fall zone due to industrial effluents. Correlation studies revealed that organic carbon and available phosphate were positively correlated with clay (r = 0.24, p=0.04). Among the trace metals, Zn and Pb also exhibited good correlation with clay (r = 0.33, p=0.004 and r = 0.27, p=0.025, respectively). Organic carbon showed positive correlation with Cu (r = 0.31, p=0.007). Factor analysis technique yielded 4 factors expressing 96% variability of the observed parameters. Levels of Cd (sampling site averages 1.69 to 2.09 mg kg⁻¹) and Cu (sampling site averages 16.75 to 36.56 mg kg⁻¹) observed in the present study were higher than the previous reports on river Ganga. At the same time, the observed levels of Cu and Mn were found to be much lower than those reported for the other river systems of India. The study would be of immense help in sequencing of trace metals in similar Indian estuarine sediments.