Multispecies reactive tracer test in an aquifer with spatially variable chemical conditions, Cape Cod, Massachusetts: Dispersive transport of bromide and nickel

摘要: [1] Dispersive transport of groundwater solutes was investigated as part a multispecies reactive tracer test conducted under spatially variable chemical conditions in an unconfined, sewage-contaminated sand and gravel aquifer on Cape Cod, Massachusetts. Transport the nonreactive bromide (Br) reflected physical hydrologic processes. nickel (Ni) complexed with organic ligand (NiEDTA) varied response to pH other within aquifer. A loss about 14% Ni mass calculated from distribution tracers through time. This is consistent reversible adsorption NiEDTA onto iron aluminum oxyhydroxide coatings sediments. The consistently lagged behind Br retardation coefficient 1.2. Longitudinal dispersivities reached constant values 2.2 1.1 m for Ni, respectively, by at least 69 travel. smaller dispersivity possibly due nonlinear or variant NiEDTA. In upper, uncontaminated zone aquifer, longitudinal dispersion greater than that early result general, transverse were much (horizontal: 1.4–1.5 × 10−2 m; vertical: 0.5–3.8 10−3 m) dispersivities. results are similar those eight years earlier, suggesting parameters stationary scale 300 covered overlapping tests. significant difference between two tests travel distance (69 26 needed reach dispersivity.