3 research outputs found
Regulating the mobility of Cd, Cu and Pb in an acid soil with amendments of phosphogypsum, sugar foam, and phosphoric rock
11 pages, figures, and tables statistics.When acid soil has been contaminated by metals as a result of industrial discharges, accidental spills, or
acid mine drainage it may be desirable to retain the metals in the soil rather than allow them to leach
away. We have investigated the potential of phosphogypsum (PG), sugar foam (SF), and phosphoric
rock (PR) to regulate the availability and mobility of Pb, Cd and Cu. We have also identified changes in
attenuation during incubation for 1 year and the effect of aging on metal speciation in amended soils. We
studied miscible displacement in columns of undisturbed soil previously treated with solutions of the
amendments and soluble metals and, subsequently, single and sequential chemical metal extractions. All
amendments increased the soil’s metal retention capacity. This, in turn, increased the amount of metal
extractable by diethylenetriaminepentaacetic acid (DTPA). However, over time the amounts of DTPAextractable
metal decreased, particularly for Cu and Pb. Both Cu and Cd were held preferentially within
the acetic acid-extractable fraction (operationally defined exchangeable fraction – EX fraction), whereas
Pb was associated mainly with the hydroxylammonium-extractable fraction (operationally defined bound
to Fe and Al hydroxides – OX fraction). Both Pb and Cu in the oxide and organic fractions increased in
the PG- and SF-treated soils. In general, the distribution of metal did not change in the PR-treated
columns after the incubation. Finally, scanning electron microscopy in back-scattered electron mode
(SEM–BSE) showed the formation of Al-hydroxy polymers which provides the soils with additional
cation sorption capacity. In the PG- and PR-treated columns, P and S were associated with these
formations. The three metals were associated with the Al polymers, probably through direct coordination
or the formation of ternary complexes with the inorganic ligands phosphate and sulphate.This research was supported by the Spanish Ministry of
Science and Technology within the framework of the research
project AGL2002-04545-C03-01. We are especially grateful to
Laura Barrios for her assistance in the statistical treatment of
the data, to Fertiberia, S.A. and Azucarera Ebro, S.L. for
supplying us with samples of phosphogypsum and sugar
foam, respectively, and to Guoping Lu, anonymous referees
and the Editors for their review and comments.Peer reviewe
Regulating the mobility of Cd, Cu and Pb in an acid soil with amendments of phosphogypsum, sugar foam, and phosphoric rock
11 pages, figures, and tables statistics.When acid soil has been contaminated by metals as a result of industrial discharges, accidental spills, or
acid mine drainage it may be desirable to retain the metals in the soil rather than allow them to leach
away. We have investigated the potential of phosphogypsum (PG), sugar foam (SF), and phosphoric
rock (PR) to regulate the availability and mobility of Pb, Cd and Cu. We have also identified changes in
attenuation during incubation for 1 year and the effect of aging on metal speciation in amended soils. We
studied miscible displacement in columns of undisturbed soil previously treated with solutions of the
amendments and soluble metals and, subsequently, single and sequential chemical metal extractions. All
amendments increased the soil’s metal retention capacity. This, in turn, increased the amount of metal
extractable by diethylenetriaminepentaacetic acid (DTPA). However, over time the amounts of DTPAextractable
metal decreased, particularly for Cu and Pb. Both Cu and Cd were held preferentially within
the acetic acid-extractable fraction (operationally defined exchangeable fraction – EX fraction), whereas
Pb was associated mainly with the hydroxylammonium-extractable fraction (operationally defined bound
to Fe and Al hydroxides – OX fraction). Both Pb and Cu in the oxide and organic fractions increased in
the PG- and SF-treated soils. In general, the distribution of metal did not change in the PR-treated
columns after the incubation. Finally, scanning electron microscopy in back-scattered electron mode
(SEM–BSE) showed the formation of Al-hydroxy polymers which provides the soils with additional
cation sorption capacity. In the PG- and PR-treated columns, P and S were associated with these
formations. The three metals were associated with the Al polymers, probably through direct coordination
or the formation of ternary complexes with the inorganic ligands phosphate and sulphate.This research was supported by the Spanish Ministry of
Science and Technology within the framework of the research
project AGL2002-04545-C03-01. We are especially grateful to
Laura Barrios for her assistance in the statistical treatment of
the data, to Fertiberia, S.A. and Azucarera Ebro, S.L. for
supplying us with samples of phosphogypsum and sugar
foam, respectively, and to Guoping Lu, anonymous referees
and the Editors for their review and comments.Peer reviewe