Sammendrag
In situ deployments of diffusive gradients in thin films (DGT) can
provide direct information on complex dissociation rates in natural waters. Recent
advances in understanding the dynamics of the interactions of metal complexes within
DGT devices have highlighted the characteristics of the binding layer, but there are
few data to complement these theoretical developments. In this work the penetration
into the Chelex binding layer of complexes of Ni with nitrilotriacetic (NTA) and
Suwannee River fulvic and humic acids (FA and HA) in solution at pH 7 was
investigated by deployment of DGT devices with two sequential binding layers, a
“front” and a “back” layer. In Ni−NTA experiments, the masses of Ni bound by the
front and back binding layers were similar, as predicted for slowly dissociating
complexes. For Ni−FA/HA solutions, a higher mass of Ni was taken up by the front
binding layer, consistent with fast dissociation from a high proportion of the binding
sites. The ratio of Ni in the front to back binding layers was significantly lower (p
Vis fullstendig beskrivelse