Using isotopic dilution to assess chemical extraction of labile Ni, Cu, Zn, Cd and Pb in soils.
Chemosphere
; 155: 534-541, 2016 Jul.
Article
in En
| MEDLINE
| ID: mdl-27153236
ABSTRACT
Chemical extractants used to measure labile soil metal must ideally select for and solubilise the labile fraction, with minimal solubilisation of non-labile metal. We assessed four extractants (0.43 M HNO3, 0.43 M CH3COOH, 0.05 M Na2H2EDTA and 1 M CaCl2) against these requirements. For soils contaminated by contrasting sources, we compared isotopically exchangeable Ni, Cu, Zn, Cd and Pb (EValue, mg kg(-1)), with the concentrations of metal solubilised by the chemical extractants (MExt, mg kg(-1)). Crucially, we also determined isotopically exchangeable metal in the soil-extractant systems (EExt, mg kg(-1)). Thus 'EExt - EValue' quantifies the concentration of mobilised non-labile metal, while 'EExt - MExt' represents adsorbed labile metal in the presence of the extractant. Extraction with CaCl2 consistently underestimated EValue for Ni, Cu, Zn and Pb, while providing a reasonable estimate of EValue for Cd. In contrast, extraction with HNO3 both consistently mobilised non-labile metal and overestimated the EValue. Extraction with CH3COOH appeared to provide a good estimate of EValue for Cd; however, this was the net outcome of incomplete solubilisation of labile metal, and concurrent mobilisation of non-labile metal by the extractant (MExtKey words
Full text:
1
Database:
MEDLINE
Main subject:
Soil
/
Soil Pollutants
/
Metals, Heavy
/
Environmental Pollution
/
Solid Phase Extraction
Country/Region as subject:
Europa
Language:
En
Year:
2016
Type:
Article