## 3 Results
### Tracers
\begin{table}
\begin{tabular}{c c c c c c c} \hline
**Piezometer** & **Distance \({}^{*}\) (m)** & **Uranine (DL = 0.001)** & **Sulforhodamine B** & **AGA** & **Lithium** & **Bromide** \\  & & **(DL = 0.001)** & **(DL = 0.050)** & **(DL = 0.100)** & **(DL = 0.5)** & **(DL = 0.5)** \\ \hline PZ1 & \(-\)20 & 0.0 & 0.0 & 0.0 & 2.0 \({}^{*}\) & 2.8 \({}^{*}\) \\ PZ2 & 0 & 10.2 & 4.1 & 23.9 & 22.0 & 3.1 \\ PZ2 BIS & \(+\)5 & 19.8 & 21.1 & 30.0 & 148.1 & 45.7 \\ PZ3 & \(+\)10 & 1.2 & 0.3 & 0.0 & 3.4 & 5.0 \\ PZ4 & \(+\)20 & 0.5 & 0.1 & 0.0 & 2.7 & 1.1 \({}^{*}\) \\ PZ5 & \(+\)30 & 0.3 & 0.0 & 0.0 & 2.0 \({}^{*}\) & 0.5 \({}^{*}\) \\ PZ6 & \(+\)60 & 0.0 & 0.0 & 0.0 & 1.8 \({}^{*}\) & 0.9 \({}^{*}\) \\ \hline \end{tabular} Legend: Distance = Distance from injection well in the downstream direction (positive values) and upstream direction (negative value), DL = Detection Limit, AGA = Amino G Acid, \({}^{*}\) background noise.  
\end{table} 
Table 6: Maximum net tracer concentration per piezometer (in \(\mu\)g\(\cdot\)L\({}^{-1}\)). \begin{table}
\begin{tabular}{c c c c c c} \hline
**Tracer** & **Uranine** & **Sulforhodamine B** & **Amino G Acid** & **Li** & **Br** \\ \hline Method & ICP-MS & ICP-MS & ICP-MS & IC & IC \\ DL (\(\mu\)g\(\cdot\)L\({}^{-1}\)) & 0.001 & 0.05 & 0.05 & 1 & 1 \\ \hline \end{tabular} Legend: ICP-MS = Inductively Coupled Plasma-Mass Spectrometry; IC = Ionic chromatography; DL = Detection Limit).  
\end{table} 
Table 5: Analytical methods and detection thresholds for the analyzed tracers. From the PZ3 piezometer, 10 m downstream of the injection well, it is no longer possible to fit the data on a single curve because the recovery is bimodal. The first peak reflects a rapid arrival of the tracer by a preferential path (fissured zone?) while the second peak corresponds to a slower propagation within the matrix aquifer. In Figure 11, two distinct fits were therefore applied to each first peak (dashed curves) and second peak (solid curves). Table 7 shows that the porosity obtained is fairly uniform around the mean value of \(5.97\times 10^{-2}\) m\(\cdot\)s\({}^{-1}\) regardless of the piezometer or tracer studied, but that the permeability varies more strongly around the mean value of \(4.11\times 10^{-3}\) m\(\cdot\)s\({}^{-1}\) depending on the adjustment made. These values are also significantly higher than those obtained at PZ2 BIS, which is interpreted as resulting from an environment with multiple porosity, of both matrix and fissure type, once a larger aquifer volume is involved. As before, we observe a faster propagation of the plume at PZ4 (3.9 m\(\cdot\)d\({}^{-1}\)) than at PZ3 (1.6 m\(\cdot\)d\({}^{-1}\)): however, these speeds are 2 to 3 times lower than during the tracing test carried out in 2012 (10 m\(\cdot\)d\({}^{-1}\) and 3 m\(\cdot\)d\({}^{-1}\), respectively), which seems to be due to a low groundwater table which started exceptionally early this year. It should also be noted that this speed artificially reached 104 m\(\cdot\)d\({}^{-1}\) during the injection, at the PZ2 BIS which is a piezometer directly influenced by the injection conditions. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Peak** & **First Peak (With PZ2 BIS)** & **Second Peak (Without PZ2 BIS)** & **Average** \\ \hline
**Tracer** & **Lithium** & **Uranine** & **Lithium** & **Uranine** & \\ \hline Porosity (\(-\)) & \(4.85\times 10^{-2}\) & \(6.35\times 10^{-2}\) & \(5.67\times 10^{-2}\) & \(7.00\times 10^{-2}\) & \(5.97\times 10^{-2}\) \\ Permeability (m\(\cdot\)s\({}^{-1}\)) & \(4.47\times 10^{-3}\) & \(1.11\times 10^{-2}\) & \(3.03\times 10^{-4}\) & \(5.86\times 10^{-3}\) & \(4.11\times 10^{-3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Average hydrodynamic characteristics resulting from the calibration of the recovery curves. Figure 10: Evolution of uranine (green curve) and lithium (purple curve) concentrations at the nearest downstream piezometer (PZ2 BIS). (**a**) Detail of the 3 first days.