Fate of Metals Applied in Sewage to Land Wastewater Disposal Sites.

This study investigated the fate of copper, zinc, cadium, nickel, and lead contaminants in secondary treated sewage effluent for four different soils. Five large undisturbed monoliths of each soil were enclosed in drainage lysimeters. In addition field plots of two of the soils were treated similarly. The effluent was spiked with 1 ppm of each of the metals and applied at a rate which averaged 2.7 cm per week for one year. Natural rainfall was excluded from the plots to facilitate continuous application. Samples of the Bermuda grass, soil samples at a series of depths, and samples of water in the root zone area from the bottom of the lysimeter were periodically collected and analyzed for heavy metals. The total metal content of the soil samples was determined as well as the soluable, exchangeable and organic bond fractions. The majority of the applied metal accumulated in the top 12-12-cm of soil, with the greatest concentrations at the surface. Downward movement of the metals in the profile was slow and no metals were in any of the soils. Only very small portions of the applied metals were taken up by the vegetation during the study.