Metal availability in heavy metal-contaminated open burning and open detonation soil: assessment using soil enzymes, earthworms, and chemical extractions.
The effects of heavy metal contamination on soil enzyme activity and earthworm health (bioaccumulation and condition) were studied in contaminated soils collected from an formerly open burning and open detonation (OBOD) site. Soil extraction methods were also evaluated using CaCl(2) and DTPA solutions as surrogate measures of metal bioavailability and ecotoxicity. Total heavy metal content of the soils ranged from 0.45 to 9.68 mg Cd kg(-1), 8.96 to 5103 mg Cu kg(-1), 40.21 to 328 mg Pb kg(-1), and 56.61 to 10,890 mg Zn kg(-1). Elevated metal concentrations are assumed to be primarily responsible for the reduction in enzyme activities and earthworm health indices. We found significant negative relationships between CaCl(2)- and DTPA-extractable metal content (Cd, Cu, and Zn) and soil enzyme activity (P<0.01). Therefore, it could be concluded that soil enzyme activity and metal bioaccumulation by earthworms can be used as an ecological indicator of metal availability. Furthermore, CaCl(2) and DTPA extraction methods are proved as promising, precise, and inexpensive surrogate measures of Cd, Cu, Pb, and Zn bioavailability from heavy metal-contaminated soils.
Lee
Sang-Hwan
SH
Technology Research Center, Mine Reclamation Corporation, Seoul 110-727, Republic of Korea.
Kim
Eul-Young
EY
Hyun
Seunghun
S
Kim
Jeong-Gyu
JG
D000818:Animals; D002122:Calcium Chloride / Q000737:chemistry; D004784:Environmental Monitoring / Q000379:methods*; D004798:Enzymes; D017745:Incineration; D019216:Metals, Heavy / Q000032:analysis*; D009835:Oligochaeta / Q000737:chemistry; D004369:Pentetic Acid / Q000737:chemistry; D012987:Soil / Q000032:analysis*; D012989:Soil Pollutants / Q000032:analysis*
D004798:Enzymes; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D004369:Pentetic Acid; D002122:Calcium Chloride