The Feasibility of Using Dredged Bottom Sediments as an Agricultural Soil

Abstract

<p>The utilization of contaminated bottom sediments as agricultural soil was investigated as a new approach of the dredged sediment disposal.</p> <p>Bottom sediments collected from Hamilton Harbour~ Humber Bay Port Stanley~ Detroit River Mouth~ and Lake St. Clair were used for the determination of chemical, physical and biological properties considered important for the evaluation of bottom sediments as agricultural soil.</p> <p>It was proved in leaching experiments and lysimeters that the concentrations of elements, released from the bottom sediments dispersed in water ~ were Imver than those recommended for water for public use with the exception of manganese and nickel. (Cd < 0.001 mg/I, Cr < 0.2 mg/l, Cu 0.08 mg/l, Fe 0.08 mg/l, pb < 0.001 mg/I, Mn 2.9 mg/l, Hg < 0.05 mg/l, Ni 0.07 mg/l, Zn 1.1 mg/l). The suitability of contaminated bottom sediments from Hamilton Harbour, Humber Bay and Detroit River as agricultural soil was verified in greenhouse experiment by -planting tomatoes and corn with a good crop yield. The crop yield of the Humber Bay tomato plants was best, follmved by those of Hamilton Harbour and Detroit River.</p> <p>Tomato plants and corn did not take up various elements in the proportions in which the elements occurred in the sediments, but exerted a selective action, absorbing greater amounts of some elements than others. Tomato plants took up nutrients and trace elements only to a certain limiting concentration characteristic for individual plant organs. The concentrations were comparable with those found by soil scientists studying the uptake of elements from soils.</p> <p>Following maximum concentrations were determined for tomato fruit grown in Humber Bay sediment: K 37,000 mg/kg, Mg 2,100 mg/kg, Ca 1,750 mg/kg, Zn 40 mg/kg, Sr 30 mg/kg, Cu 23 mg/kg, Pb 12 mg/kg, Co 7 mg/kg, Cd 2 mg/kg - Arsenic, molybdenum, manganese, chromium, nlckel and mercury were below the levels of detection.</p>