ldentifying areas of potential pollution risk in the Turia River through a cumulative index

Trabajo presentado en NET-SCARCE International Conference, celebrada en Barcelona (España) del 15 al 16 de noviembre de 2016The use of river water quality indices as a tool to assess water quality status at certain times and locations have been adopted by many organizations and agencies, but there is no worldwide accepted methodology in developing a water quality index. In this paper, we test the applicability of a cumulative index to river waters, based in the calculation proposed by Gredilla et al (2014), to identify the areas of highest concern in the Turia River, classifying them in a relative scale from 0 to 10. The parameters used here were chosen to represent a number of key environmental issues that have global relevance, including organic pollution, nutrient pollution (eutrophication), and salinization. After the selection of parameters, we calculate four sub-indices related to four categories of contamination indicators: (1) metals and metalloids, (2) pesticides, (3) polycyclic aromatic hydrocarbons (PAHs), and (4) nutrients and salinization. Index aggregation is performed after the assignment of weights to obtain the final index value. The trace metal concentrations were measured by ICP/OES after samples microwave acid digestion (American Public Health Association, 2012, Method 3030K). The 16 priority EPA PAHs were determined after SPE extraction with dicloromethane-metanol mixture and analysed by GC-MS according Martínez et al. (2004) method. The pesticides were determined by liquid chromatography tandem mass spectrometry (LC-MS/MS) after their extraction of water samples by SPE (Ccanccapa et al., 2016). The other watrer chemical paramenters were measured at field sampling points (n=22) with the meter PCD 650 (Eutech Instruments). Results show that the cumulative index, that considers the concomitance of different contaminats (inorganic and organics) affecting the Turia River water quality, is a useful tool to sort and classify the sampling points from the studied area according to the concnetrations of the contaminats selected. The index lowest values correspond at the headwaters, whereas their higesht values appear in three areas: (1) around Teruel city due to the highest levels of heavy metals and nutriet loads; (2) Benagéber reservoir, with highest values of PAHs and nutrient loads, related to the wildfire that affected this area in the year of sampling, and (3) the final area of the river, close to Valencia city, with the higesht loads of pesticides as well as nutrients, related to the dominant agricultural activity in the Turia alluvial plain.This work has been supported by the Project CGL2011-29703-C02-01, financed by the Spanish Ministerio de Ciencia e Innovación and Projects Eco2TOOLS and Eco2SUPPORT financed by the Spanish Ministerio de Economía y Competitividad (CGL2015-64454-C2).Peer reviewe