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.
Department of Environmental Science, University of Lancaster, Lancaster LA1 4YQ, United Kingdom.
Emily R
ER
Unsworth
Kent W
KW
Warnken
Hao
H
Zhang
William
W
Davison
Frank
F
Black
Jacques
J
Buffle
Jun
J
Cao
Rob
R
Cleven
Josep
J
Galceran
Peggy
P
Gunkel
Erwin
E
Kalis
David
D
Kistler
Herman P
HP
Van Leeuwen
Michel
M
Martin
Stéphane
S
Noël
Yusuf
Y
Nur
Niksa
N
Odzak
Jaume
J
Puy
Willem
W
Van Riemsdijk
Laura
L
Sigg
Erwin
E
Temminghoff
Mary-Lou
ML
Tercier-Waeber
Stefanie
S
Toepperwien
Raewyn M
RM
Town
Liping
L
Weng
Hanbin
H
Xue
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