Phosphorus Distribution in the Sediments of the Hooghly (Ganges) Estuary, India

The dissolved reactive phosphorus concentration in the Hooghly Estuary is maintained at a near constant value of 40 μg l-1. Sediments act as a major sink for the high dissolved phosphate input into the estuary from the Ganges River. The distribution of various forms of P and their association with other sediment components were determined in the Hooghly estuarine sediments. Total P concentration ranges from 250 to 500 μg g-1 in the surface sediments of the estuary; organic and inorganic P average 35 and 400 μg g-1 respectively; P bound to Ca is the dominant form of sediment inorganic P (70%) and occluded P constitutes 24%, whereas non-occluded P makes up 6% of inorganic P. Non-occluded and occluded P are strongly correlated with Fe, Al, Mn and the organic matter content in the surficial sediments. There are no significant changes in inorganic and organic P in the top 50-100 cm of the sediment cores.