Trace elemental distribution in soil and compost-derived humic acid molecular fractions and colloidal organic matter in municipal wastewater by flow field-flow fractionation-inductively coupled plasma mass spectrometry (flowFFF-ICP-MS)
D. Amarasiriwardena et al., Trace elemental distribution in soil and compost-derived humic acid molecular fractions and colloidal organic matter in municipal wastewater by flow field-flow fractionation-inductively coupled plasma mass spectrometry (flowFFF-ICP-MS), J ANAL ATOM, 16(9), 2001, pp. 978-986
Humic acids (HA) are heterogeneous, dark-colored, organic macromolecules fo
und in soil and aquatic systems that play a crucial role in complexation, t
ransportation and cycling of trace elements in ecosystems. Flow field-flow
fractionation-inductively coupled plasma mass spectrometry (flow FFF-ICP-MS
) is applied to study trace metals complexed to soil-, peat- and compost-de
rived HA and colloidal organic matter (COM) in municipal wastewater. Monomo
dal elemental fractograms with different polydispersities demonstrate that
Cu, Fe. Mn, Pb and Zn are bound to a broad range of HA molecular size fract
ions. Molecular weights (M-p) and diffusion coefficients (D-p) at peak maxi
mum for HA or various origins were determined by flow FFF. The average M-p
of nine replicate measurements of investigated HA ranged from 3950 to 3790
Da while their diffusion coefficients varied from 1.72 x 10(-6) cm(2) s(-1)
for peat-derived HA to 1.66 x 10(-6) cm(2) s(-1) for compost-derived HA, i
ndicating very small variations among the HA under investigation. Elemental
fractograms were also obtained for aqueous COM in municipal wastewater aft
er on-line preconcentration. Fractograms clearly showed the gradual reducti
on of COM content for primary through secondary treatment. Elemental COM fr
actograms also demonstrated that the bulk of Al, Cu, Fe, Pb, Mn and Zn was
complexed to organic macromolecules while a fraction of Al, Zn, Mn and halo
gens (Cl, Br and I) was present as dissolved ionic species. Copper, Fe and
Zn signals decreased during wastewater treatment. This investigation demons
trate,,, precipitation and Subsequent removal of metal ions that are associ
ated with COM as Sludge.