http://www.revistadechimie.ro REV.CHIM.(Bucharest)♦68♦No. 8 ♦2017 1732 Water Quality Index, a Useful Tool for Evaluation of Danube River Raw Water IULIANA PAUN 1 *, FLORENTINA LAURA CHIRIAC 1 , NICOLETA MIRELA MARIN 1 , LILIANA VALERIA CRUCERU 1 , LUOANA FLORENTINA PASCU 1 , CAROL BLAZIU LEHR 1 , CORINA ENE 2 1 National Research and Development Institute for Industrial Ecology ECOIND, 71-73 Drumul Podu Dambovitei Str., 060652, Bucharest, Romania 2 Petroleum-Gas University of Ploiesti, Faculty of Economic Sciences, 39 Bucharest Blvd., 100680, Ploiesti, Romania The Danube River is the major source of drinking water supply for the cities in the southern part of Romania. The study was a descriptive-analytical one and lasted for 9 month. Samples were taken monthly between March 2016 and November 2016. Six sampling sites were selected to evaluate the spatial and temporal changes of water quality along the river. The samples were analyzed based on the standard methods for the following parameters: pH, conductivity (EC), NH 4 + , NO 3 - , Cl - , suspended solids, PO 4 3- , SO 4 2- , metals (Fe, Cd, Cr, Pb, Ni, Hg, As, Zn, Cu, Mn). The obtained values were compared with those imposed by the Romanian environmental legislation. An efficient and simplified method to express the quality of water used for consumption is provided by the Water Quality Index (WQI). WQI reflects the quality of water in a single value by comparing data obtained from the investigation of a number of physico-chemical parameters to the existing limits. The evaluation of water quality was performed using the Water Quality Index of the Canadian Council of Ministries of the Environment (CCME WQI). Water quality indices were classified as: excellent, good, medium, bad and very bad. The results indicated the water quality classification as “good” in all six sampling selected sites. Keywords: drinking water quality, Danube River, physico-chemical parameters, raw water, WQI Water is the most important natural resource of the ecosystem, having an important role both as drinking supply and for economic sectors. Water sources may be mainly in the form of rivers, lakes, glaciers, rain water or ground water. The availability and quality of either surface or ground water have been deteriorated by increasing population, industrialization and urbanization. The Danube is the second longest river of Europe (after the Volga) and is the only European river that flows from West to East. The Danube hydrological regime is characterized by the existence of significant variations of the level and flow during the year and over the time [1]. Being a relevant resource for several water uses [2], Danube River is one of the main sources of drinking water for many surrounding cities/villages (for more than 700000 inhabitants) [3]. Given that for some areas it is the only drinking water source (for example: Danube Delta area) [4], an important issue related to the drinking water quality is associated with the pollution of raw water [5]. In Romania, the role of the Danube River as local and European waste water collector makes it an important source of pollution in the Black Sea [6], as the river receives discharges from agricultural, industrial and urban sources [7, 8]. Growing concern for Danube water quality is mainly determined by the fact that it is an important source of drinking water for riparian population, in some cases without being subjected to any process of drinking water abstraction [9]. The study of the surface water as a complex multi- component system depends on the knowledge and application of facts, principles, and methods from chemistry, physics, geology, hydrology, meteorology, mathematics and other sciences for the purpose of solving the essential ecological problems. The particularity and * e m a il: iuliana.paun@incdecoind.ro; Phone: + (40) 722.437.605 complexity of the surface water chemical composition and of quality indicators (representing the effects of various dissolved substances such as mineral and organic matter, gases, colloids, suspended particles, and microorganisms present in water through natural or artificial processes) stress the importance of applying quality index methods for their assessment by identifying a mutual factor that emphasizes quality as a whole [10]. Traditionally, drinking water quality status is professionally communicated by comparing the individual physical, chemical and biological parameters with guideline values. The limits of those parameters that are harmful to human health have been established at national or international level (WHO, EPA, MECC) by various laws, regulations, normatives. The water quality index aims at assessing the quality of water on the basis of one system which converts all the individual parameters and their concentrations - present in a sample - into a single value. Numerous water quality indices (National Sanitation Foundation Water Quality Index (NSFWQI), Canadian Council of Ministers of the Environment Water Quality Index (CCMEWQI), British Columbia Water Quality Index (BCWQI), Oregon Water Quality Index (OWQI)) have been formulated all over the world, allowing to easily assess the overal water quality within a particular area promptly and efficiently [11 -15]. The Canadian Council of Ministers of the Environment Water Quality Index (CCME WQI) provides an overall measure of the suitability of water bodies to support aquatic life at selected monitoring sites in Canada. The indicator is based on applications of the Water Quality Index (WQI). Given that aquatic life can be influenced by the presence of hundreds of both natural and anthropogenic substances present in water, the WQI provides a useful tool that allows