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Chemical Immobilization of Lead, Zinc, and Cadmium in Smelter‐Contaminated Soils Using Biosolids and Rock Phosphate
Author(s) -
Basta N.T.,
Gradwohl R.,
Snethen K.L.,
Schroder J.L.
Publication year - 2001
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2001.3041222x
Subject(s) - biosolids , environmental chemistry , chemistry , cadmium , environmental remediation , bioavailability , lime , soil contamination , soil water , phosphorite , extraction (chemistry) , zinc , soil ph , contamination , phosphate , environmental engineering , environmental science , soil science , metallurgy , ecology , bioinformatics , materials science , organic chemistry , chromatography , biology
ABSTRACT Chemical immobilization, an in situ remediation method where inexpensive chemicals are used to reduce contaminant solubility in contaminated soil, has gained attention. We investigated the effectiveness of lime‐stabilized biosolid (LSB), N‐Viro Soil (NV), rock phosphate (RP), and anaerobic biosolid (AB) to reduce extractability and plant and gastrointestinal (GI) bioavailability in three Cd‐, Pb‐, and Zn‐contaminated soils from smelter sites. Treated (100 g kg −1 soil) and control soils were incubated at 27°C and −0.033 MPa (−0.33 bar) water content for 90 d. The effect of soil treatment on metal extractability was evaluated by sequential extraction, on phytoavailability by a lettuce bioassay ( Lactuca sativa L.), on human GI availability of Pb from soil ingestion by the Physiologically Based Extraction Test. The largest reductions in metal extractability and phytoavailability were from alkaline organic treatments (LSB and NV). Phytotoxic Zn [1188 mg Zn kg −1 extracted with 0.5 M Ca(NO 3 ) 2 ] in Blackwell soil (disturbed soil) was reduced by LSB, NV, and RP to 166, 25, and 784 mg Zn kg −1 , respectively. Rock phosphate was the only treatment that reduced GI‐available Pb in both gastric and intestinal solutions, 23 and 92%, respectively. Alkaline organic treatments (LSB, NV) decreases Cd transmission through the food chain pathway, whereas rock phosphate decreases risk from exposure to Pb via the soil ingestion pathway. Alkaline organic treatments can reduce human exposure to Cd and Pb by reducing Zn phytotoxicity and revegetation of contaminated sites.