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Irrigation with reclaimed water (R) is necessary to guarantee the sustainability of semi-arid areas. Results obtained during a two years monitoring network (2009-2011) in Gran Canaria are presented, including the analysis of chemical parameters, N and S isotopes, priority substances (2008/105/EC, 2013/39/EU), other organic contaminants and heavy metals in groundwater and R used to irrigate a golf course. The aims of this work are to evaluate the contamination in a volcanic aquifer, relate the presence of organic contaminants and heavy metals with the hydrogeochemistry and identify pollution sources in the area. No priority substance exceeded the EU thresholds for surface water, although seventeen were detected in R. The most frequent compounds were hexachlorobenzene, chlorpyrifos ethyl, fluorene, phenanthrene and pyrene. These compounds were detected at low concentration, except chlorpyrifos. Chlorpyrifos ethyl, terbuthylazine, diuron, terbutryn, procymidone, atrazine and propazine exceeded the European threshold concentration for pesticides in groundwater (100ngL(-1)). Therefore, the priority substances chlorpyrifos ethyl and diuron must be included in monitoring studies. The priority pesticides chlorfenvinphos and diazinon were always detected in R but rarely in groundwater. Besides, the existence of contaminants not related to the current R irrigation has been identified. Absence of environmental problems related to heavy metals can be expected. The relationship among contaminant presence, hydrogeochemistry, including the stable isotopic prints of δ(18)O, δ(15)N and δ(34)S and preferential recharge paths has been described. The coastal well shows high values of EC, nitrate, a variable chemistry, and 50% of organic contaminants detected above 100ngL(-1). The well located in the recharge area presents a stable hydrochemistry, the lowest value of δ(15)N and the lowest contaminants occurrence. The area is an example of a complex volcanic media with several sources of contaminants such as leakages from septic tanks and sewerage, agriculture practices, irrigation with reclaimed water or urban runoff., (Copyright © 2016 Elsevier B.V. All rights reserved.)

In semiarid regions, reclaimed water can be an important source of emerging pollutants in groundwater. In Gran Canaria Island, reclaimed water irrigation has been practiced for over thirty years and currently represents 8% of water resources. The aim of this study was to monitor contaminants of emerging concern and priority substances (2008/105/EC) in a volcanic aquifer in the NE of Gran Canaria where the Bandama Golf Course has been sprinkled with reclaimed water since 1976. Reclaimed water and groundwater were monitoring quarterly from July 2009 to May 2010. Only 43% of the 183 pollutants analysed were detected: 42 pharmaceuticals, 20 pesticides, 12 polyaromatic hydrocarbons, 2 volatile organic compounds and 2 flame retardants. The most frequent compounds were caffeine, nicotine, chlorpyrifos ethyl, fluorene, phenanthrene and pyrene. Concentrations were always below 50 ng L(-1), although some pharmaceuticals and one pesticide, cholrpyrifos ethyl, were occasionally detected at higher concentrations. This priority substance for surface water exceeded the maximum threshold (0.1 μg L(-1)) for pesticide concentration in groundwater (2006/118/EC). Sorption and degradation processes in soil account for more compounds being detected in reclaimed water than in groundwater, and that some contaminants were always detected in reclaimed water, but never in groundwater (flufenamic acid, propyphenazone, terbutryn and diazinon). Furthermore, erythromycin was always detected in reclaimed water (exceeding occasionally 0.1 μg L(-1)), and was detected only once in groundwater. In contrast, some compounds (phenylephrine, nifuroxazide and miconazole) never detected in reclaimed water, were always detected in groundwater. This fact and the same concentration range detected for the groups, regardless of the water origin, indicated alternative contaminant sources (septic tanks, agricultural practices and sewerage breaks). The widespread detection of high adsorption potential compounds, and the independence of concentration with origin and depths, indicates the existence of preferential flows phenomena as potential contamination route in volcanic fractured materials., (Copyright © 2012 Elsevier B.V. All rights reserved.)