Effects of regulatory agent on the heavy metal stability in tidal sediments

The object of this work was to evaluate the feasibility of calcium nitrate-regulatory agent for the stabilization of heavy metals in tidal sediments. The pilot-scale treatment was deployed in a section of the urban river in Ronggui, Foshan, which was heavily contaminated with Cu, Zn, Pb and Cr. For the remediation of the contaminated sediment, chemical speciation and stability of four elements were studied. The results indicated that: a)the percentage of four elements associated with reducible fraction and oxidizable fraction was decreased with the treatment of regulatory agent; b) the regulatory agent could effectively promote Cu, Zn, Pb, and Cr in sediment distributing in the residual fraction, which were increased by 4% , 20% , 21% and 23% after being treated by dosing regulatory agent for 22 days, with lower bioavailability in environment; c) the concentration of acid soluble fraction of Cu, Pb and Cr was increased except Zn. In general, the effect of stabilization for heavy metals Cu, Zn, Pb and Cr by regulatory agent is not ideal except Zn which has a certain effect, but the effect is not obvious.