Figure 3

Tracer test breakthrough curves, (a) Specific conductance (SpC) in microsiemens per centimeter (μS/cm) and pH.Expected arrival time of the tracers, calculated assuming spherical symmetry of the injected tracer cloud and an effective porosity of 0.39, and the end of the injection are indicated, (b) Concentrations of phosphorus, total dissolved arsenic (AsT), arsenic(III) [As(III)], and arsenic(V) [As(V)] in micromoles per liter (μM). Bars show error limits for measured As(V) concentrations. Sampling 14.5 h after completing the injection showed 0.078 μM As(V), 435 μM phosphorus, and a pH of 5.91.