# Spatial Variation of Water Chemistry in Aries River Catchment, Western Romania
###### Abstract  
This study aims to investigate the quality and vulnerability of surface water (Aries River catchment) in order to identify the impact of past mining activities. For this purpose, the pollution and water quality indices, Piper and Durov plots, as well vulnerability modeling maps were used. The obtained results indicate that the water samples were contaminated with As, Fe, Mn, Pb and have relatively high concentrations of SO\({}_{4}\)\({}^{2-}\), HCO\({}_{3}\)\({}^{-}\), TDS, Ca, K, Mg and high values for the electrical conductivity. Possible sources of the high content of chemicals could be the natural processes or the inputs of the mine drainage. Generally, according to the pollution indices, which were correlated to high concentrations of heavy metals, especially with Pb, Fe and Mn, the water samples were characterized by heavy metals pollution. The water quality index classified the studied water samples into five different classes of quality, namely: unsuitable for drinking, poor, medium, good and excellent quality. Similarly, medium, high and very high vulnerability classes were observed. The Durov and Piper plots classified the waters into Mg-HCO\({}_{3}\)\({}^{-}\) and Ca-Cl\({}^{-}\) types. The past and present mining activities clearly change the water chemistry and alter the quality of the Aries River, with the water requiring specific treatments before use.  
water quality; mining areas; pollution indices; Piper diagram; HCA +
Footnote †: journal: Applied Sciences  
0000-0001-5000-0001-5000]M.A.A.M.M.  
cancer cases in the area of the \"Black Town\", Copsa-Mica) [7].Since the disaster of Baia Mare area, the mining activities still continued with major impacts on groundwater and surface waters. The Aries River presents a higher vulnerability due to mining activities [8]. The main pollutants of the Aries River are Cu, Pb, Zn and cyanides, due to the acid mine drainage in the mining centers situated along the Aries River [8; 9; 10]. Different studies on the Aries River catchment revealed that the areas near the mining centers are still highly polluted and implicitly affected [9; 10; 11; 12]. Moreover, the areas crossed by the Aries River represent a petrographic mosaic where the karst landscape is dominant in the upper and middle river catchment (e.g., Bihor Mountains and Muntele Mare areas).  
Hence, information regarding the current status of the Aries River is still considered to be essential in order to define and process a suitable decontamination treatment before using the water for drinking purposes, agricultural practices and industrial usages. A part of the water sources monitoring is represented by different and efficient tools such as the water quality indices Appl. to specific points of the water bodies. Two of the most common methods are theHeavy Metal Pollution Index (HPI) and the Heavy Metal Evaluation Index (HEI), used to establish the pollution status of water ecosystems, considering the heavy metals content [13; 14; 15]. In order to evaluate the water quality regarding different types of physico-chemical characteristics, [PERSON] proposed the Water Quality Index (WQI) [16]. The WQI is widely used to characterize all types of water bodies. [PERSON] et al. [17], [PERSON] et al. [18] and [PERSON] et al. [19] assessed the quality of various water systems (in Nanganur, South India and in different areas of China and Turkey) by using the WQI.The results were useful in order to assess the quality of surface water resources as an alternative drinking water possibility.  
The aim of this study was: (1) to obtain new and valuable data regarding the current quality status and vulnerability of the Aries River, which is situated near the mining areas; (2) to study the impact of historical mining centers on the surface water quality in all the catchment areas, by determining the physico-chemical properties of waters; and (3) to assess the water quality using various heavy metal pollution indexes.