Effects Of Biosolids Addition On The Total and Plant Available Copper In The Contaminated Stamp Sands Of Torch Lake: An Incubation Study.

Stamp sands in the Torch Lake site in Upper Peninsula, Michigan are heavily contaminated with copper (Cu) owing to extensive mining activities in the past. To develop a vegetative cover for reducing erosion of stamp sands into the Torch Lake, it is important to understand the geochemically labile pool of Cu under plant-growing conditions. Since stamp sands are poor in nutrients for plant growth, the addition of environmentally-friendly green amendments such as biosolids is necessary. Here, we report the effects of biosolids addition on the geochemical speciation of copper (Cu) in a laboratory incubation study, in which different rates of biosolids (0, 0.8, 1.6, and 3.2 g biosolids/ kg soil) were added to 100 g of stamp sand and incubated for 60 days.  These incubation mixtures were kept moist by adding water periodically to 70% water holding capacity. Samples were collected periodically after 0, 15, 30, and 60 days and analyzed for total-Cu and Cu in the different fractions according to a sequential extraction procedure. Results indicated that only minor fraction of Cu partitioned in the soluble/ available fraction.