Influence of variable chemical conditions on EDTA-enhanced transport of metal ions in mildly acidic groundwater.

Adsorption of Ni and Pb on aquifer sediments from Cape Cod, Massachusetts, USA increased with increasing pH and metal-ion concentration. Adsorption could be described quantitatively using a semi-mechanistic surface complexation model (SCM), in which adsorption is described using chemical reactions between metal ions and adsorption sites. Equilibrium reactive transport simulations incorporating the SCMs, formation of metal-ion-EDTA complexes, and either Fe(III)-oxyhydroxide solubility or Zn desorption from sediments identified important factors responsible for trends observed during transport experiments conducted with EDTA complexes of Ni, Zn, and Pb in the Cape Cod aquifer. Dissociation of Pb-EDTA by Fe(III) is more favorable than Ni-EDTA because of differences in Ni- and Pb-adsorption to the sediments. Dissociation of Ni-EDTA becomes more favorable with decreasing Ni-EDTA concentration and decreasing pH. In contrast to Ni, Pb-EDTA can be dissociated by Zn desorbed from the aquifer sediments. Variability in adsorbed Zn concentrations has a large impact on Pb-EDTA dissociation.

[1]  D. Kent,et al.  Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions , 2000 .

[2]  J. Zachara,et al.  Adsorption-Dissolution Reactions Affecting the Distribution and Stability of CoIIEDTA in Iron Oxide-Coated Sand. , 1994, Environmental science & technology.

[3]  B. Nowack,et al.  Influence of Natural and Anthropogenic Ligands on Metal Transport during Infiltration of River Water to Groundwater , 1997 .

[4]  J. L. Young,et al.  Subsurface cobalt-60 migration from a low-level waste disposal site. , 1984, Environmental science & technology.

[5]  C.A.J. Appelo,et al.  User's guide to PHREEQC - a computer program for speciation,batch-reaction, one-dimensional transport, and inversegeochemical calculations. , 1999 .

[6]  James A. Davis,et al.  Pb2+ and Zn2+ adsorption by a natural aluminum- and iron-bearing surface coating on an aquifer sand , 1995 .

[7]  P. Jardine,et al.  UNSATURATED TRANSPORT PROCESSES IN UNDISTURBED HETEROGENEOUS POROUS MEDIA.I: INORGANIC CONTAMINANTS , 1993 .

[8]  L Sigg,et al.  Speciation of EDTA in Natural Waters: Exchange Kinetics of Fe-EDTA in River Water. , 1995, Environmental science & technology.

[9]  J. M. Cleveland,et al.  Characterization of plutonium in maxey flats radioactive trench leachates. , 1981, Science.

[10]  D. Freyberg,et al.  A natural gradient experiment on solute transport in a sand aquifer: 1. Approach and overview of plume movement , 1986 .

[11]  D. Kent,et al.  Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions, Cape Cod, Massachusetts: Dispersive transport of bromide and nickel , 2002 .

[12]  J. A. Davis,et al.  Simulation of the mobility of metal-EDTA complexes in groundwater: the influence of contaminant metals. , 2002, Environmental science & technology.

[13]  E. Sudicky.  A natural gradient experiment on solute transport in a sand aquifer: Spatial variability of hydraulic conductivity and its role in the dispersion process , 1986 .

[14]  Tammo S. Steenhuis,et al.  MOBILITY AND SOLUBILITY OF TOXIC METALS AND NUTRIENTS IN SOIL FIFTEEN YEARS AFTER SLUDGE APPLICATION , 1997 .

[15]  C. Fuller,et al.  Characterization of metal adsorption variability in a sand and gravel aquifer, Cape Cod, Massachusetts, U.S.A , 1996 .

[16]  J. A. Davis,et al.  Modeling the movement of a pH perturbation and its impact on adsorbed zinc and phosphate in a wastewater‐contaminated aquifer , 2007 .

[17]  D. Sedlak,et al.  Sources and Environmental Fate of Strongly Complexed Nickel in Estuarine Waters: The Role of Ethylenediaminetetraacetate , 1999 .

[18]  D. Crerar,et al.  Migration of Radioactive Wastes: Radionuclide Mobilization by Complexing Agents , 1978, Science.

[19]  D. Taylor,et al.  Reactive transport of EDTA-complexed cobalt in the presence of ferrihydrite , 1996 .

[20]  D. L. Parkhurst,et al.  Reactive-Transport Simulation of Phosphorus in the Sewage Plume at the Massachusetts Military Reservation, Cape Cod, Massachusetts , 2003 .

[21]  Steven C. Smith,et al.  ADSORPTION AND DISSOCIATION OF CO-EDTA COMPLEXES IN IRON OXIDE-CONTAINING SUBSURFACE SANDS , 1995 .

[22]  L. Sigg,et al.  Dissolution of Fe(III) (hydr) oxides by metal-EDTA complexes , 1997 .

[23]  Janet G. Hering,et al.  Principles and Applications of Aquatic Chemistry , 1993 .

[24]  R. Keil,et al.  Geochemical changes along a river-groundwater infiltration flow path: Glattfelden, Switzerland , 1988 .

[25]  D. Kent,et al.  Effect of adsorbed metal ions on the transport of Zn- and Ni-EDTA complexes in a sand and gravel aquifer , 2002 .

[26]  J. McCarthy,et al.  Mobilization of transuranic radionuclides from disposal trenches by natural organic matter , 1998 .

[27]  James A. Davis,et al.  Modeling the influence of variable pH on the transport of zinc in a contaminated aquifer using semiempirical surface complexation models , 2000 .

[28]  A. Ulrich,et al.  Behavior of Heavy Metals, Nutrients, and Major Components during Roof Runoff Infiltration , 1999 .