# Spatial Variation of Water Chemistry in Aries River Catchment, Western Romania
## 4 Discussion  
On a global scale, acid mine drainage is an important source of surface water pollution. [PERSON] et al. (2009) reported the effects of mine drainage to a hydrographic river catchment in an area characterized by an abundance of sulfide ore bodies from Portugal [45].  
The degree of the mineralization process could be reflected by the EC and TDS, which showed variations. The EC and TDS were positively correlated. In the case of samples A7, A8 and A13, the EC and TDS values were in the range of 901-1348 \(\upmu\)S/cm and 712-952 mg/L, respectively. Similar results of pH, TDS and EC were reported in the surface water resources nearby the gold mining areas in Tongon--an open-pit gold mine  
Figure 8: Spatial variation of the water quality index (WQI).  
that produced between 2012 and 2015 about 1.356 \(\times\) 107 tons of ores, located in Cote d'Ivoire Region, Africa [58]. In different parts of Europe (Georgia, Spain and Turkey), comparable results were obtained for Coruh and EI Avenue Rivers with pH variation from 4.50 to 9.07, and EC from 114 to 1200 \(\upmu\)S/cm [53; 54].  
In general, the sources of high amounts of heavy metals are industrial and mining activities [53; 54]. Recent studies from Turkey and Georgia show relatively high amounts of heavy metals in surface waters, such as 0.33-2.88 \(\upmu\)S/L Cd; 0.7-17.2 \(\upmu\)S/L Co; 0.13-2.02 \(\upmu\)S/L Cr; 0.06-895 \(\upmu\)S/L Cu; 53.3-3140 \(\upmu\)S/L Fe; 5.8-402 \(\upmu\)S/L Mn; 1.4-21.0 \(\upmu\)S/L Ni; 0.1-73.0 \(\upmu\)S/L Pb and 7.6-537 \(\upmu\)S/L Zn [53]. While in Spain (El Avenue River), the heavy metal content varied between 0.01 and 1.00 mg/L Cd, 0.01 and 0.15 mg/L Cu, 0.01 and 0.25 mg/L Pb, and 0.01 and 450 mg/L Zn [54].  
In surface water in China, mining activities influenced the quality of water as well, by increasing the level of metals, the studied waters being characterized by relatively high concentrations of As (0.0-6.90 \(\upmu\)S/L), Cr (0.95-42.9 \(\upmu\)S/L), Cu (1.20-19.0 \(\upmu\)S/L), Mn (2.65-168 \(\upmu\)S/L), Ni (1.69-164 \(\upmu\)S/L), Pb (0.91-28.2 \(\upmu\)S/L) and Zn (2.74-490 \(\upmu\)S/L) [59].  
HPI results were ranging from 68.4 to 412, as indicated in Table 5, showing some pollution levels with the studied heavy metals. The spatial distribution of HPI results is presented in Figure 7a. The mean value of HPI results was 132, indicating a concerning risk of pollution with the analyzed heavy metals in the study area, more specifically with Pb, Mn and Fe. Different studies from Serbia (Ugljesnica River) and India (Bokaro River) indicated no heavy metal pollution with Cd, Cu, Fe, Mn, Pb, Zn with HPI scores. ranging from 66 to 90 and 2.0 to 26 [14; 15] although the rivers are located nearby mining areas. In Nigeria (Commodore channel) and China (Houjing River), the HPI results ranged between 985 and 5995, and 100 and 230, indicating high amounts of heavy metals due to industrial (wastewaters, landfill leachate) and household activities [60; 61].  
\begin{table}
\begin{tabular}{c c c c} \hline  & **HPI** & **HEI** & **WQI** \\ \hline A1 & 91.4 & 3.50 & 17.9 \\ A2 & 100 & 3.72 & 18.4 \\ A3 & 109 & 4.38 & 22.6 \\ A4 & 96.2 & 3.53 & 17.7 \\ A5 & 87.7 & 3.48 & 18.8 \\ A6 & 7