FY 1983

The effect of sewage effluents on the flocculation of major and trace elements in a stratified estuary

Feely, R.A., G.J. Massoth, and M.F. Lamb

Chapter 4 in Trace Metals in Sea Water, C.S. Wong, E.A. Boyle, K.W. Bruland, J.D. Burton, and E.D. Goldberg (eds.), Plenum Publishing Corp., New York, 227–244 (1983)

In order to study the effects of sewage effluents on the flocculation of trace elements in a stratified estuary, water samples were collected from the Duwamish River Estuary at stations located above and below the Renton Sewage Disposal Site. The water samples were filtered through 0.2-µm pore size Nuclepore filters, the filtrate mixed with various amounts of filtered sea water from Elliott Bay, and the products refiltered onto 0.2-µm filters and analyzed for major and minor elements by x-ray secondary emission spectrometry. The results show that the downstream samples produced two to three times more flocculated material and three to five times more P, Ca, Fe, Ni, Cu and Zn than the upstream samples. In contrast, little differences were found for Al and Ti. Similar experiments utilizing the effluent from the Renton Sewage Treatment Plant also showed the same trends, suggesting that the sewage effluent enhanced the flocculation of these elements in the estuary. Major element analysis of the flocculated material indicates that it is mainly composed of organic material.