## 3 Results
### Microbial Mineralization  
The degradation kinetics of \({}^{14}\)C-metolachlor in non-sterilized soils incubated under both aerobic and anaerobic conditions in Catlin, Flanagan, and Drummer soils are depicted in Figure 2a-c, while Figure 2d-f illustrates the microbial mineralization pattern of metolachlor, measured as the amount of \({}^{14}\)CO\({}_{2}\) evolved. Under both soil incubation treatments, there was a lag phase of at least 8 weeks before the evolution of mineralized \({}^{14}\)CO\({}_{2}\). About 8-11% of the applied herbicide was mineralized in the soils maintained under aerobic incubation, whereas 13-16% of the metolachlor was converted to \({}^{14}\)CO\({}_{2}\) in the anaerobic microcosm after 140 days of incubation (Table 4). No significant evolution of \({}^{14}\)CO\({}_{2}\) was  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Soil**} & \multicolumn{2}{c}{\(k\) **(day–1)**} & \multicolumn{2}{c}{**T\({}_{1/2}\) (days)**} & \multicolumn{2}{c}{**\(R^{2}\)**} & \multicolumn{2}{c}{**Degradation \(\ddagger\)**} & \multicolumn{2}{c}{**Mineralization \#**} \\ \cline{2-11}  & **Aer** & **An** & **Aer** & **An** & **Aer** & **An** & **Aer** & **An** \\ \hline Catlin & 0.0048 & 0.0093 & 144 b\({}^{\dagger\ddagger}\) & 75 d & 0.88 & 0.89 & 42.19 & 20.20 & 8.8 & 13.1 \\  & (0.0018) * & (0.0017) & (388) & (415) & (0.85) & (0.88) & (67.99) & (69.96) & (ND) & (ND) \\ Flanagan & 0.0045 & 0.0088 & 154 a  & 79 d & 0.92 & 0.93 & 43.05 & 22.14 & 9.1 & 14.2 \\  & (0.0014) & (0.0010) & (487) & (675) & (0.57) & (0.81) & (74.02) & (78.4) & (ND) & (ND) \\ Drummer & 0.0059 & 0.0107 & 117 c  & 65 e  & 0.82 & 0.95 & 31.00 & 19.92 & 11.0 & 16.5 \\  & (0.0022) & (0.0024) & (314) & (288) & (0.86) & (0.88) & (66.30) & (62.01) & (ND) & (ND) \\ \hline \hline \end{tabular} \(k\) = rate constant, T\({}_{1/2}\) = degradation half-life, \(R^{2}\) = goodness of fit for first-order degradation model. \(\ddagger\) Percent of applied herbicide remaining after 140 days of incubation. # Percent of applied herbicide evolved as \({}^{14}\)CO\({}_{2}\) after 140 days of incubation. * Values in the parentheses in each column represent the corresponding values for sterilized soil control. \(\dagger\) Mean values followed by the same letter superscripts are not significantly different (\(p<0.05\)). ND = not detected.  
\end{table}
Table 4: Degradation (first-order kinetics) and mineralization of \({}^{14}\)C-metolachlor in different soil types under aerobic (Aer) and anaerobic (An) environmental conditions.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Soil**} & \multicolumn{2}{c}{\(K_{des}\)} & \multicolumn{2}{c}{**1/\(n_{des}\)**} & \multicolumn{2}{c}{\(R^{2}\)**} \\ \cline{2-7}  & **Aer** & **An** & **Aer** & **An** & **Aer** & **An** \\ \hline Catlin & 3.11 e\({}^{\dagger\ddagger}\) (\(\pm\)0.04) * & 2.75 e\({}^{\dagger}\) (\(\pm\)0.03) & 0.21 (\(\pm\)0.002) & 0.30 (\(\pm\)0.004) & 0.94 & 0.90 \\ Flanagan & 7.63 e\({}^{\ddagger}\) (\(\pm\)0.03) & 5.52 d\({}^{\ddagger}\) (\(\pm\)0.03) & 0.21 (\(\pm\)0.006) & 0.16 (\(\pm\)0.011) & 0.92 & 0.85 \\ Drummer & 11.13 a  (\(\pm\)0.04) & 9.95 b\({}^{\ddagger}\) (\(\pm\)0.03) & 0.16 (\(\pm\)0.002) & 0.09 (\(\pm\)0.028) & 0.92 & 0.80 \\ \hline \hline \end{tabular}  
\(K_{des}\) = Freundlich desorption coefficient, \(1/n_{des}\) = desorption isotherm slope, \(R^{2}\) = goodness of fit for Freundlich model. \(\dagger\) Mean values followed by the same letter superscripts are not significantly different (\(p<0.05\)). * Values in the parentheses are the 95% confidence intervals.  
\end{table}
Table 3: Desorption (Freundlich model) of \({}^{14}\)C-metolachlor in different soil types under aerobic (Aer) and anaerobic (An) environmental conditions.  
measured in any of the sterilized control soils. Among the three soil types, Drummer exhibited the highest mineralization rate under both aerobic and anaerobic conditions.