Model predictions of metal speciation in freshwaters compared to measurements by in situ techniques.
Measurements of trace metal species in situ in a softwater river, a hardwater lake, and a hardwater stream were compared to the equilibrium distribution of species calculated using two models, WHAM 6, incorporating humic ion binding model VI and visual MINTEQ incorporating NICA-Donnan. Diffusive gradients in thin films (DGT) and voltammetry at a gel integrated microelectrode (GIME) were used to estimate dynamic species that are both labile and mobile. The Donnan membrane technique (DMT) and hollow fiber permeation liquid membrane (HFPLM) were used to measure free ion activities. Predictions of dominant metal species using the two models agreed reasonably well, even when colloidal oxide components were considered. Concentrations derived using GIME were generally lower than those from DGT, consistent with calculations of the lability criteria that take into account the smaller time window available forthe fluxto GIME. Model predictions of free ion activities generally did not agree with measurements, highlighting the need for further work and difficulties in obtaining appropriate input data.
Unsworth
Emily R
ER
Department of Environmental Science, University of Lancaster, Lancaster LA1 4YQ, United Kingdom.
Warnken
Kent W
KW
Zhang
Hao
H
Davison
William
W
Black
Frank
F
Buffle
Jacques
J
Cao
Jun
J
Cleven
Rob
R
Galceran
Josep
J
Gunkel
Peggy
P
Kalis
Erwin
E
Kistler
David
D
Van Leeuwen
Herman P
HP
Martin
Michel
M
Noël
Stéphane
S
Nur
Yusuf
Y
Odzak
Niksa
N
Puy
Jaume
J
Van Riemsdijk
Willem
W
Sigg
Laura
L
Temminghoff
Erwin
E
Tercier-Waeber
Mary-Lou
ML
Toepperwien
Stefanie
S
Town
Raewyn M
RM
Weng
Liping
L
Xue
Hanbin
H
D001578:Benzopyrans / Q000032:analysis; D002254:Carbonates / Q000032:analysis; D004784:Environmental Monitoring / Q000379:methods*; D005544:Forecasting; D006812:Humic Substances / Q000032:analysis; D008670:Metals / Q000032:analysis*; D008954:Models, Biological; D015203:Reproducibility of Results; D045483:Rivers / Q000737:chemistry*; D012680:Sensitivity and Specificity; D014874:Water Pollutants, Chemical / Q000032:analysis*
D001578:Benzopyrans; D002254:Carbonates; D006812:Humic Substances; D008670:Metals; D014874:Water Pollutants, Chemical; C005023:fulvic acid