Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions

Abstract

It is hypothesized that stronger adsorption of Pb 2+ to the aquifer sediments causes the Pb-EDTA complex to disassociate to a greater degree than the Cu-EDTA complex. The mass of dissolved Zn-EDTA increased during the first 175 days of the tracer test to 140% of the mass injected, with the increase due to desorption of sewage-derived Zn. Dissolved Ni-EDTA mass remained nearly constant throughout the tracer test, apparently only participating in reversible adsorption reactions. The results of the field experiment provide a chemically complex data set that can be used in the testing of reactive transport models of flow coupled with chemical reactions.

Radionuclide-Chelating Agent Complexes in Low-Level Radioactive Decontamination Waste; Stability, Adsorption and Transport Potential

“…The combination of all these reactions leads to rather complicated breakthrough curves that would require more detailed study. An excellent methodology for studying the transport of ETDA-transition metal complexes has recently been published [Davis et al 2000]. A more quantitative analyses of our results would be possible using the Davis et al 2000 approach.…”

“…The other area that warrants more work is the quantitative determination of the adsorption properties of sediments and soils for picolinate-metal complexes using the "generalized surface complexation modeling approach" that is explained in Davis (2001), and Davis et al (2000). Using this adsorption construct one would develop adsorption constants for particular soils that are akin to thermodynamic stability constants.…”

“…After such systematic studies have been performed on a few representative soils, all the parameters would be available to build a coupled chemical reaction transport model that can predict the migration of picolinate-metal/radionuclide wastes through aquifer sediments much like Davis et al (2000) have performed for EDTA-transition metal complexes at a field site at Cape Cod, Maine.…”

“…Available research on the adsorption of EDTA, oxalate and citrate and their metal complexes to soils and specific soil components, such as hydrous oxides were reviewed in the previous project (Seine et al 1996) and more recently in Davis et al (2000). The following summary was mainly extracted from Serne et al (1996).…”

The influence of groundwater chemistry on arsenic concentrations and speciation in a quartz sand and gravel aquifer

“…Concentrations of dissolved Mn below an altitude of 11 m were 2 to 3 M ͑data not shown͒, typical of values in the suboxic zone at this distance ͑approximately 300 m͒ downgradient of the sewage-disposal beds. 37,38 Previous comparisons between total dissolved phosphorus concentrations ͑determined by ICPAES͒ and dissolved reactive phosphate concentrations ͑determined colorimetrically͒ have shown that phosphate accounts for all of the dissolved phosphorus, within analytical error. 42,43 The groundwater-chemical features shown in Fig.…”