Heavy Metals in Liquid Waste Disposal: Water-Sediment Interactions

Abstract

Water and sediment samples taken from an area near the discharge of the Galveston Sewage Treatment Plant were analyzed for copper, nickel, lead and zinc. Two twenty-four hour sampling periods were conducted at four hour intervals: the first on 16-17 September 1978 and the second on 3-4 November 1978. The sewage treatment plant was found to discharge all four metal ions into the surrounding area. Lead and nickel ions appeared to also be brought into the area by the tides. An accumulation of silt-sized sediment and organic particulates was found in an area less than 100 m from the discharge. High concentrations of metal ions were also found in the same area. A high correlation (greater than 0.90) between the particulates and metal ions indicates that adsorption and incorporation into the sediments is probably occurring. Storm activity between September and November may have carried the accumulated particulates and metal ions out into the bay. Cause for concern exists because metal ions in the sediments can enter the food chain and concentrate in some commercial species (blue crabs, brown shrimp, and oysters).