Immobilization Heavy Metals In Soils Polluted By Lead Smelting In Henan Province

In recent years, the lead smelting made a rapid development in Henan Province, whichresulted in severe heavy metals pollution in soil near the smelters. These polluted soils aremainly calcareous soils. However, fewer efforts have been made on the remediation ofcalcareous soils polluted by lead smelting. In this work, lead smelting polluted soils fromHenan Province was remediated with different amendments, the main results include,i) A lead-smelting polluted calcareous soil was amended with monopotassiumphosphate (MPP), monocalcium phosphate (MCP), or MPP and calcium nitrate (CN), orMCP and CN and incubated. The results indicated that, amendment with CN resulted inlower DTPA-Pb, DTPA-Zn and DTPA-Cd (1.1%to5.8%), the concentration of DTPA-Pbof soil amended with MPP and CN was significantly lower than that only amended withMPP (P<0.05). Amendment with CN also resulted in lower Olsen-P concentration(P<0.05), Olsen-P concentration of MPP+CN decreased more than that of MCP+CN.ii) The above lead smelting polluted soil was amended with apatite powder, or sludge,hay or apatite and hay, apatite and sludge. The results indicated that, concentrations ofDTPA-Pb decreased1.99%to19.7%, compared with the control, statistical differenceexisted between all the treatments and the control (P<0.05), except that amended only withapatite. Sole amendment with sludge resulted in higher DTPA-Cd concentration, comparedwith the control (P<0.05), amendment with sludge or sludge and apatite resulted in higherDTPA-Zn than the control (P<0.05). Compared with the amendments with only sludge orhay, combined amendment with apatite resulted in lower DTPA-Pb, Zn and Cdconcentrations, while the amendment of sludge with apatite had significantly lowerDTPA-Cd concentration (P<0.05).iii) The above lead smelting polluted soil was amended with original honeycombbriquette combustion residue (OHBCR), water-washed HBCR (WHBCR) or dilute acidwashed HBCR (AHBCR) at the rates of1%,2%or4%. After incubation, analysis of samples found that, the DTPA-Cd concentration of the soils decreased as the rate ofOHBCR increased, at the4%rate, the DTPA-Cd concentration decreased13.1%(P<0.05),except this rate, the soil DTPA-Pb concentration also decreased. For the WHBCR amendedsoils, soil DTPA-Pb and Cd also decreased with increasing rates. Concentrations ofDTPA-Pb decreased7.7%-10.4%, compared with the control (P<0.05), while thedifference of DTPA-Cd was not significant (P>0.05). The DTPA-Cd concentrationsincreased with the increasing rates of the WHBCR, while the concentration of DTPA-Pbfirst decreased then increased with the increasing rates, at the rate of2%, the DTPA-Pbconcentration decreased6.5%(P<0.05)The results of this work suggest that, for the remediation of the calcareous soilspolluted by lead smelting in Henan Province, we can use amendments of soluble phosphateand calcium nitrate, or combined amendment with insoluble phosphate and hay, oramendment with water washed honeycomb briquette combustion residue to immobilize Pb,Cd and Zn in the soil.