## 4 Results and Discussion  
The statistical parameters for the concentrations of Ni, Sn, and Li, as well as the major components of the total of 957 records (or composite samples), are listed in Table 2. The concentrations of Ni, Sn, and Li range from 8.3 \(\upmu\)g/g to 4580 \(\upmu\)g/g, 1 \(\upmu\)g/g to 9.3 \(\upmu\)g/g, and 7.8 \(\upmu\)g/g to 105 \(\upmu\)g/g, respectively. The contents of SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and TF\({}_{2}\)O\({}_{3}\) range from 37.4% to 68.1%, 3.6% to 13.2%, and 1.7% to 5.0%, respectively, which indicates that these samples are mainly silicate components. The contents of K\({}_{2}\)O, Na\({}_{2}\)O, CaO, and MgO range from 0.3% to 2.3%, 0.1% to 0.6%, 0.1% to 1.0%, and 0.3% to 1.4%, respectively, which indicates that these stream samples have undergone a chemical weathering process. The lgNi, lgSn, and lgLi values for the 957 records from the Mojiang area are shown in Figure 2a-c as histograms with their box plots. The box plots are used to display the cumulative frequency. To eliminate outliers, the mean \(\pm\) 3 SD (standard deviation) method was employed [11]. In this method, when the data of lgNi, lgSn, and lgLi fell outside the range of mean \(\pm\) 3 Std, they were excluded. This process to exclude values is repeated until no outliers are identified. The lgNi, lgSn, and lgLi data without outliers are presented in Figure 2d-f, and their statistical parameters are also listed in Table 2.  
Although the statistical parameters are also listed in Table 2, they are not discussed further because the methods used on geochemical map (the 19-level fixed-value method) and geochemical anomaly map (the seven levels classification method) are irrelevant to the distribution of the data. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c c c c} \hline \hline
**Level** & **No.** & **1** & **2** & **3** & **4** & **5** & **6** & **7** & **8** & **9** & **10** & **11** & **12** & **13** & **14** & **15** & **16** & **17** & **18** & **19** & **References** \\ \hline Ni & 2 & 6 & 10 & 18 & 25 & 32 & 39 & 48 & **60** & 70 & 100 & 190 & 245 & 495 & 1000 & 1260 & 1590 & 2000 & \(\geq\)2000 & This & & \\ lgNi & 0.301 & 0.778 & 1.000 & 1.255 & 1.389 & 1.505 & 1.591 & 1.681 & 1.778 & 1.845 & 2.000 & 2.279 & 2.389 & 2.695 & 3.000 & 3.100 & 3.201 & 3.301 & - & & \\ AlgNi & - & 0.477 & 0.222 & 0.255 & 0.143 & 0.107 & 0.086 & 0.090 & 0.097 & 0.067 & 0.155 & 0.279 & 0.110 & 0.305 & 0.305 & 0.100 & 0.101 & 0.00 & - & & \\ \hline Sn & 1 & 1.3 & 1.8 & 2.7 & 3.4 & 4.3 & 6.0 & 7.9 & 10 & 13 & 17 & 28 & 50 & 100 & 200 & 400 & 600 & 1000 & \(\geq\)1000 & [11] \\ Li & 5 & 8 & 17 & 29 & 34 & 40 & 50 & 62 & 70 & 78 & 88 & 99 & 132 & 175 & 232 & 460 & 930 & 1858 & \(\geq\)1586 & [12] \\ Mo & 0.3 & 0.37 & 0.45 & 0.55 & 0.68 & 1 & 1.43 & 2.07 & 3 & 3.8 & 4.8 & 6.1 & 9.1 & 20 & 100 & 144 & 208 & 300 & \(\geq\)300 & [14] \\ \hline \hline \end{tabular} Note: The concentration unit of Ni, Sn, Li, and Mo is \(\upmu\)g/g; the 1 st level corresponds to the detection limit of each element in the RGNR and NMPRGS project, and the 19 th level corresponds to the cutoff grade of each element.  
\end{table} 
Table 1: The information of the Ni geochemical map on the 19-level fixed-value method along with those of Sn, Li, and Mo. Figure 2: Histograms and boxplots (**a**–**c**) and (**d**–**f**) of sediment samples in the Mojiang area with and without outliers, including lgNi, lgSn, and lgLi.