Temporal evolution of emerging contaminants, priority substances and heavy metals most frequently detected in reclaimed water and grounwater in a volcanic aquifer

CEST2013 – Athens, Greece Ref no: 0624 Please do not use page numbers TEMPORAL EVOLUTION OF EMERGING CONTAMINANTS, PRIORITY SUBSTANCES AND HEAVY METALS MOST FREQUENTLY DETECTED IN RECLAIMED WATER AND GROUNDWATER IN A VOLCANIC AQUIFER E. ESTÉVEZ1, M.C. CABRERA1, J.R. FERNÁNDEZ-VERA2, A. MOLINA-DÍAZ3, J.R. ROBLES-MOLINA3 and M.P. PALACIOS-DÍAZ4 1 University of Las Palmas de Gran Canaria, Department of Physics, 2 Laboratorio Agroalimentario y Fitopatológico (Cabildo de Gran Canaria) 3 University of Jaén, Analytical Chemistry Research Group, Department of Physical and Analytical Chemistry,4 University of Las Palmas de Gran Canaria, Department of Animal Pathology, 35017, Canary Islands, Spain, [email protected], EXTENDED ABSTRACT The presence of emerging contaminants has been previously described in reclaimed water and groundwater of Gran Canaria (Spain). Despite of the environmental risk associated to irrigation with reclaimed water (R), this practice is necessary considering sustainability of the hydrological cycle in semiarid zones, especially regarding agricultural activity. The aim of this study was: i) to analyse the evolution during two years of contaminants of emerging concern, priority substances (2008/105/EC) and heavy metals in reclaimed water (R) and in a volcanic aquifer in the NE of Gran Canaria where a golf course has been irrigated with R since 1976 and ii) to relate this presence with physicochemical water properties and hydrogeological media. Reclaimed water and groundwater (GW) were monitoring quarterly from July 2009 to September 2011. Sorption and degradation processes in soil account for more compounds being detected in R. Diazinon and chlorfenvinphos were detected always in R and terbuthylazine, terbutryn and diuron at 90% of frequency. Considering all the samples, the most frequent compounds were chlorpyrifos ethyl, fluorene, phenanthrene and pyrene. Although their concentrations were frequently below 50 ngL-1, some contaminants, were occasionally detected at higher concentrations. Chlorpyrifos ethyl and diuron are priority substances detected frequently and at high concentrations so they must be included in monitoring studies. Geology and location seem to be related to the emerging compounds presence due to occasional contamination events (not related to R irrigation) and therefore not to an existence of a dangerous diffuse contamination level. Thus, it is preferable to select wells with less stable chemical water quality, in order to monitor the risk of emerging compounds presence. Considering the relationship between contaminant presence, chemical water quality, seasonal variation, hydrogeological characteristics and wells location we can conclude that chlorpyrifos ethyl and diuron were the most dangerous priority substances in terms of GW quality so they must be included in all of the monitoring studies, at least in Canary Islands. Keywords: emerging contaminants, priority substances, heavy metals, reclaimed water, groundwater, irrigation, volcanic zone. 1. INTRODUCTION Reclaimed water reuse offers a guaranteed supply and contributes to mitigate the shortage of natural water resources, especially, in semiarid zones, where reclaimed water constitutes an important source of irrigation water (Kumar et al., 2005; Kinney et al., 2006). In Gran Canaria (Spain), this practice has been used for more than thirty years (Marrero and Palacios, 1996), and reclaimed water currently represents 8% of water resources (Palacios et al., 2008). Nowadays, advances in treatment processes result in acceptable reclaimed water qualities. In the study area, effluent quality has been improved due to the installation of new infrastructures, highlighting a desalination system of the secondary effluent since 2002. Aquifers integrate recharge water (natural or from irrigation returns) from different times, especially in semiarid zones and if groundwater table head is deep. The main sources of emerging organic compounds in groundwater are related to wastewater effluents or reuse, septic tanks, livestock activities and hospital effluents (Lapworth et al., 2012). The main processes controlling emerging contaminants during migration through the soil, unsaturated zone and aquifer are sorption mainly to organic matter and clay minerals, ion exchange, and microbial degradation or transformations. Indeed, the contaminant properties as well as transit time through the unsaturated zone and groundwater residence time, redox conditions and total loading will be important in determining presence and persistence in groundwater. In volcanic materials, the presence of preferential paths in the unsaturated zone can favour a rapid recharge, so emergent contaminants can reach the aquifer in relative short times. The presence of emerging contaminants has been previously identified and described in reclaimed water used for irrigate a golf course and in groundwater of the NE of Gran Canaria (Estévez et al., 2012). This study monitors 183 contaminants of emerging concern and priority substances (2008/105/EC) since July 2009 to May 2010. The most frequent compounds were caffeine, nicotine (stimulants), chlorpyrifos ethyl (organophosphate insecticide), fluorene, phenanthrene and pyrene (PAHs). Concentrations were always below 50 ngL-1, although some pharmaceuticals and one pesticide, chlorpyrifos ethyl, were occasionally detected at higher concentrations. This paper points to more entry routes apart from reclaimed water irrigation: agricultural practices, septic tanks leaks and sewerage breaks, and mentions the importance of adsorption, degradation and preferential flows phenomena. However, temporal variations of the contaminants concentration had not been observed and a longer sampling period was recommended. One of the aims of our study was to analyse the temporal evolution 36 contaminants of the total detected by Estévez et al. (2012), also including the results of an extended period until September 2011 and the results of 20 compounds non detected in the first study. A secondary objective was to relate their presence with chemical water properties and hydrogeological conditions. Results of analyses of heavy metals in the whole period are also presented. 2. MATERIAL AND METHODS 2.1. Location and description of the study area The Bandama Golf Course is located in the NE of the Gran Canaria Island in the central part of the Las Goteras basin, between 400 m and 500 m high. The Las Goteras basin is included in the N4 zone of the Gran Canaria Water Administration Plan (CIAGC, 1999), which is represented in Figure 1. Average precipitation in the area is 300 mm per year, the average annual temperature is 19°C, and the range of humidity is from 78% to 85%. Since 1976, the Bandama Golf Course has been irrigated with reclaimed water from the Wastewater Treatment Plant of Las Palmas de Gran Canaria, where tertiary treatment installed since 2002, consisted in desalination and disinfection (Estevez et al., 2010). Figure 1. Location and geology of the study area (modified from Balcells et al., 1990), situation of the main ravines, the Bandama Caldera, the golf course and monitoring points (reclaimed water: R, wells: W0-W6 and the El Culatón water gallery) and piezometry for January 2009 (Cabrera et al., 2009, modified). The study area is next to the quaternary Bandama volcanic complex, and includes a volcanic caldera. Fresh basaltic and basanitic lavas and pyroclastic materials (2,000 years old) outcrop in the area (Hansen and Moreno, 2008). These materials overlie fractured basanitic lava flows and landslide breccias, which cover Miocene phonolites. Interbedded alluvial conglomerates outcrop inside the Bandama Caldera (Fig. 1). The island has a low permeability “core” with successive covers of younger, more permeable materials where groundwater flow concentrates (Custodio, 2003; SPA-15, 1975). Previous hydrogeological studies in the area (Cabrera et al., 2009) have shown that the groundwater flows from summits to coast follow a preferential flow line through the Las Goteras ravine and that there is a groundwater flow from the golf course to the ravine. The groundwater table head is located 250 m below the Bandama Golf Course. The aquifer system in the study area is exploited by shaft wells of 2.5-3 m in diameter (“canarian” wells) and 15-300 m depths. These irrigating wells, described in Table 1, exploit mainly the fractured Miocene phonolites with equivalent continuous yields lower than 1 Ls-1 per day. Cabrera et al. (2010) demostrated that groundwater salinity increases from summit to shore and that hydrogeochemistry changes from sodium bicarbonate (occasionally with an endogenous gas supply) to chloride sodium bicarbonate in the middle area and to sodium chloride on the coastal fringe. Also, nitrate contents increase from summit to shore (up to 180 mgL-1), exceeding normative thresholds (Directive 91/676 EEC) so it is designed as a vulnerable zone by the Regional Canary Islands Government. The mentioned study concluded that the water from the El Culatón water gallery: G (Figure 1 and Table 1), about 40 m long and located 60 m below the golf course, drains a perched aquifer with a constant flow rate of 0.05 Ls-1 and receives water from different sources, including golf course leachates. The water gallery hydrogeochemistry differs slightly from the groundwater sampled in the wells located at the bottom of the Las Goteras ravine (Cabrera et al., 2009). Table 1. Description of groundwater sampling stations (1: Depth (m), 2: Bottom elevation (m), 3: Exploited Formation, 4: Hydrochemical groundwater type) and chemical parameters of the monitoring network points presenting mean (x) and standard deviation (sd). W0 W1 W2 W3 W4 W5 W6 G R x sd x sd x sd x sd x sd x sd x sd x sd x sd 1 208 133 32 158 34 70 96 40** 2 504 168 183 27 76 205 57 430 3 Roque Nublo Phonolites Recent Basalts Recent Basalts - Phonolites Phonolites Phonolites Recent Basalts - Phonolites Roque Nublo Slipped breccia 4 HCO3-Na Cl-HCO3Na Cl-Na HCO3-Na Cl-Na Cl-SO4-Na Cl-Na Cl-Na pH 7.8b 0.3 7.6b 0.2 7.9b 0.3 6.6a 0.2 7.7b 0.2 8.0b 0.2 7.7b 0.0 7.7b 0.2 7.7b 0.2 EC 0.5a 0.0 1.6b 0.1 2.4c 0.1 3.0d 0.2 3.5e 0.2 1.6b 0.2 3.0d 0.1 1.7b 0.1 0.4a 0.1 NO3 - 7.2a 2.5 38.6b 4.3 117.0d 5.8 64.6c 18.3 185.0e 12.0 76.2c 13.5 133.0d 1.4 59.3c 7.9 8.1a 3.1 Na+ 50a 1.0 200bc 2.9 252cd 22.4 590f 57.7 468e 33.5 183b 10.1 436e 24.7 304d 5.7 49a 28.2 K+ 10.3bc 0.5 13.1c 0.7 17.8d 1.3 37.8f 4.4 41.9g 2.5 12.3c 1.0 33.0e 1.4 7.6ab 0.7 3.8a 1.8 Ca2+ 22.8b 0.5 51.9cd 5.0 99.3e 11.5 39.4c 6.8 107.7e 7.2 56.6d 8.0 62.0d 5.7 8.0a 0.4 11.6ab 1.6 Mg2+ 15.7ab 0.5 43.8c 5.2 76.5d 9.6 23.8b 4.5 88.6e 7.0 51.4c 7.1 76.0d 5.7 9.4a 0.6 8.7a 1.8 Cl31.3a 2.9 236.6b 7.0 412.0e 54.5 324.1c 18.6 676.5e 65.8 224.9b 17.0 624.0e 32.5 328.9c 10.3 58.4a 27.5 SO4 27.9a 1.9 155.2b 9.6 232.1c 24.5 371.0d 45.7 335.5d 14.7 233.6c 29.5 251.5c 6.4 130.0b 4.1 17.2a 6.9 HCO3246bc 14 310cd 14 275cd 15 839e 127 346d 21 181ab 11 303cd 29 132a 12 93a 19 SiO2 89.5d 0.6 66.4c 1.3 40.2b 2.5 67.3c 4.4 48.8b 2.0 69.1c 5.0 72.0c 4.2 64.8c 4.2 28.3a 5.7 P 0.09a 0.0 0.09a 0.1 0.24bc 0.1 0.12ab 0.1 0.11ab 0.1 0.10a 0.1 0.25c 0.1 0.42d 0.0 0.13abc 0.1 B 0.06a 0.0 0.23ab 0.0 0.46ab 0.1 1.07b 0.1 0.83ab 0.1 0.18a 0.0 0.56ab 0.0 0.53ab 0.0 0.34ab 0.2 Fe 0.00a 0.0 0.00a 0.0 0.00a 0.0 0.00a 0.0 0.00a 0.0 0.01a 0.0 0.00a 0.0 0.00a 0.0 0.09b 0.1 Mn 0.01a 0.0 0.00a 0.0 0.03a 0.1 0.32b 0.1 0.01a 0.0 0.01a 0.0 0.00a 0.0 0.00a 0.0 0.02a 0.0 W represents the 3 m-diameter wells, G: water gallery and R: reclaimed irrigation water. Electric conductivity (EC). *: Data with the same letter are not significantly different at 0.05. **: Length of the water gallery. Depth from the golf course to the water gallery: 60m 2.2. Monitoring network In the monitoring network carried out until September 2011 were sampled the golf course irrigation water (R), the El Culatón water gallery (G) and the same wells considered in Estévez et al. (2012): W1, W2, W3 and W4, adding a control well located at the highest altitude and two wells: W5 (nearer the golf course) - W6 (between W3 and W4). Samples were taken in amber glass bottles with Teflon caps (1L) to analyse organic compounds and in PE-LD bottles (250 ml and 500 ml) to analyse heavy metals and chemical parameters respectively. All samples were immediately stored in an insulated container chilled with ice packs to be dispatched by express delivery to the laboratory. All the samples were taken on the same date and were dispatched within 48h. Irrigation water was sampled directly from a water outlet located in a fairway of the golf course, water gallery samples were taken from a pipe discharging directly from it, and well samples were taken after pumping a minimum of 15 minutes. This paper presents the results of the occurrence of 65 emerging contaminants and priority substances (2008/105/EC) in nine quarterly campaigns conducted from July 2009 to September 2011. Only R and G were sampled in all the dates. In the rest of the monitoring points the number of available data is: 4 (W0), 6 (W1), 8 (W2), 7 (W3 and W4), 3 (W5) and 2 (W6). 2.3. Methods of analysis The analysis of organic compounds and heavy metals was conducted by the Laboratory of Analytical Chemistry at the University of Jaén by using two different analytical methods (Table 2). The sample pre-treatment applied for the isolation and pre-concentration of non-polar and semi-polar volatile compounds was a liquid-liquid extraction (LLE) with nhexane (Robles-Molina et al., 2010), followed by gas chromatography coupled with mass spectrometry analysis (GC-MS). The instrument used was a CP-3800 gas chromatograph coupled with a 300-MS triple quadrupole mass spectrometer (Varian Inc. Walnut Creek, California, USA). This methodology was satisfactorily validated and obtained good recovery rates, as well as the RDS (%) for most compounds. The methods’ limits of detection, together with the rest of validation parameters for those compounds found in the samples were presented in Estévez et al. (2012). Heavy metals were determined by mass spectrometer with inductively coupled plasma (ICP-MS, Agilent Technologies 7500 Series) after vacuum filtration of the samples. The rest of the chemical parameters were determined in the Laboratory of the Council of Gran Canaria (Laboratorio Agroalimentario y Fitopatológico Laboratorio del Cabildo de Gran Canaria): pH and EC; cations, SiO2, P and B by ICP coupled by Optical emission spectrophotometer (OES) and anions by ionic chromatography except carbonates and bicarbonates (Potentiometric Determination). Table 2. Analytical methods employed in this work together with the detected and nondetected compounds which were classified into the following groups: pesticides, Polycyclic Aromatic Hydrocarbons (PAH), pharmaceuticals and heavy metals. GC-MS method Pre-treatment Extraction method Analytical Method  No filtration  pH adjustment (3-4)  Liquid-Liquid Extraction (LLE)  Solvent: n-Hexane  Gas Chromatography coupled to Triple Quadrupole Mass Spectrometry (GC-TQMS). Operation mode: MRM.  Column: Varian FactorFour VF-5-ms (30m x 0.25mm i.d. x 0.25 µm) GC-MS: non detected compounds GC-MS: detected compounds Pesticides: alachlor, ametryn, aldrin, atrazine desethyl, deltamethrin, dieldrin, endosulfan sulphate, ethion, endrin, heptachlor, isodrin, iprodione, parathion, parathion methyl, trifluralin, α-HCH, β-endosulfan, βHCH, δ-HCH. Pesticides: 4,4’-DDE, 4,4’-DDT, atrazine, chlorfenvinphos, chlorotoluron, chlorpyrifos ethyl, diazinon, diuron, hexachlorobutadiene, hexachlorobenzene, isoproturon, metoxychlor, oxyfluorfen, parathion ethyl, pentachlorobenzene, procymidone, propazine, simazine, terbuthylazine, terbutryn*, α -cypermethrin, α-endosulfan, γ-HCH. Pharmaceuticals: acetaminophen, antipyrine. PAH: acenaphtylene, anthracene, benzo(a)anthracene, benzo(a)pyrene,benzo(b)fluoranthene, benzo(g,h,i)perylene, benzo(k)fluoranthene, chrysene, dibenzo(a,h)anthracene, fluorene, indene(1,2,3-cd)pyrene, phenanthrene, pyrene. ICP-MS method Pre-treatment Analytical Method  Vacuum Filtration  Mass spectrometer with inductively coupled plasma. Babington nebulizer, spray chamber double refrigerated (2 º C) of Peltier quartz and Agilent I-AS autosampler.  RF power: 1500 W, plasma gas flow of 15 Lmin-1; nebulizer gas flow: 1 Lm-1; auxiliary gas flow: 0.9 min-1; suction velocity of the sample: 0.25mLmin -1. ICP-MS: non detected compounds ICP-MS: detected compounds Heavy metals: Hg, Sn, Pt and Pd Heavy metals: Cd, Cu , Ni, Pb, Zn and Tl. Priority substances (2008/105/EC) are in cursive. 3. RESULTS 3.1. Hydrogeochemical characterization. Figure 2 presents Schoeller-Berkaloff and Stiff diagrams obtained with the last analytical results (September 2011). As it was described by Cabrera et al. (2010) GW quality remains constant over time, since similar diagrams had been depicted. Figure 2. Schoeller-Berkaloff and Stiff diagrams for the groundwater monitoring points obtained for September 2011. As it was expected, W0 represents sodium bicarbonate low mineralized groundwater, similar than the water recharge in this area. This groundwater coincides significantly in terms of most of the chemical parameters with R (Table 1), except with higher contents for K+, HCO3-, SiO2 and Fe, resulting from the volcanic rocks hydrolysis. W3 water is sodium bicarbonated with significantly larger content of Na+. Its low pH and high content of HCO3indicates that groundwater is been enriching by endogenous CO2 gas contributions. It coincides just with the well that exploits the aquifer more deeply. The water pumped from W4 is significantly different from the rest of the wells in many of the chemical parameters (EC, NO3-, SO4-2, Cl-2, Na+, K+, Ca+2, Mg+2) except of SiO2 (Table 1). W4 represents groundwater near the discharge area (the coast), where groundwater quality is the result of the progressive mineralization through the groundwater flow direction, the influence of saline recharge water due to aridity in coastal areas and anthropogenic activities. The chlorided sodic water from the water gallery presents a deficit of Ca+2, Mg+2 and HCO3-, an excess of NO3and the highest P content detected. This fact would be related with preferential flow phenomena. Comparing with R, G is more concentrated and seems to receive also alternative water sources. 3.1. Priority substances and Contaminants of Emerging Concern Table 3 shows the frequency, mean and maximum concentration for the monitoring network results. In the previous study (Estévez et al., 2012) the pesticides and PAH presenting a 100% of frequency were: chlorpyrifos ethyl, fluorene, phenanthrene and pyrene. However, once the period of time was extended and the monitoring points were increased, the frequency of chlorpyrifos ethyl detection decreased to 80% (Table 3). The concentration of this priority substance (2008/105/CE) is in a range of 10 ngL-1 (bellow the 30 ngL-1 AA-EQS), although 20% of samples were over this value, exceeding in the 5% of the results the European threshold limit in groundwater (100 ngL-1) (2006/118/CE). These exceeding values were always detected in summer, although in summer 2010 it was only detected in three samples and bellow 10 ngL-1 (Figure 3). The widespread presence of this chlorinated organophosphate insecticide, acaricide and nematicide is related to its broad spectrum and use in agricultural practices, golf courses, cattle and urban media. The continued use of this pesticide poses a risk to farmworkers and their families therefore the EPA is seeking to end agricultural use of chlorpyrifos. Although its soil persistence may depend on the formulation, rate of application, soil type, climate and other conditions (Roberts et al., 1999) chlorpyrifos is stable in soils with reported halflives ranging between 7 and 120 days (Christensen et al., 2009). As chlorpyrifos does not partition easily from soil to water its presence in runoff water is likely a result of soil-bound from eroding soil, rather than from dissolved chlorpyrifos (EPA, 1999). The high frequency and concentration of this adsorbable compound detected in the Las Goteras aquifer are consistent with the preferential flow transport described in volcanic aquifers. In this sense, the highest values obtained in groundwater coincided with higher EC or nitrate contents. Hence, its presence in high concentrations seems to correspond to occasional contamination events (not related to RW irrigation) and not to an existence of a dangerous diffuse contamination level. On April 15, 2009, EPA included chlorpyrifos ethyl in the initial list of chemicals to be screened for their potential effects on the endocrine system (EPA, 2009), which aims to cover all pesticide chemicals, as well as substances that may occur in sources of drinking water to which a substantial population may be exposed. Nowadays, EPA is reviewing test order responses and making available the status or test order responses (EPA, 2013). As occurred in our previous study, fluorene, phenanthrene and pyrene (PAH compounds) were detected with frequencies of 100%. These compounds are included in the list of the 30 most frequently detected compounds reported in the UK Environmental Agency Groundwater Micropollutant Database (Stuart et al., 2012). The range concentration of fluorene is less than 7 ngL-1. Phenanthrene and pyrene (Figure 4) concentration were always below 25 ngL-1 in GW, except for the anomalous maximum values described in Estevez et al., (2012) (close to 60 ngL-1). Non seasonal variation was observed (Figure 4) for those PAHs. Table 3. Concentration (µgL-1: heavy metals, ngL-1: rest of substances) and frequency of detection per sample (irrigation water: R, water gallery: G and wells: W0W6), for those compounds detected at least once in the whole period (July 2009 – September 2011). Nº: Compound Number ordered by group (pesticides: 1-23, PAH: 24-36, heavy metals: 37-42 and pharmaceuticals: 43-44) and by frequency of detection, X: mean concentration, Max: maximum concentration, nt: total number of analysis, nd: number of detections, %T: total frequency (GW and R), %R: reclaimed water frequency and %GW: groundwater frequency. R G W0 W1 W2 W3 W4 W5 W6 Nº X Max X Max X Max X Max X Max X Max X Max X Max X Max Frequency nt = 9 nt = 9 nt = 4 nt = 6 nt = 8 nt = 7 nt = 7 nt = 3 nt = 2 % T % R %GW 1 5.9 27.2 4.2 9.3 1.3 2.9 2.3 4.1 2.4 9.9 5.3 13.4 3.1 6.8 2.4 4.4 3.6 5.6 nd/n t 6/9 6/9 4/4 5/6 8/8 6/7 6/7 3/3 2/2 83.3 66.7 86.7 2* 6.8 18.1 10 39 3.3 5.3 62 223 52 294 7.7 28.2 51 262 3 6.3 5.2 nd/n t 6/9 7/9 3/4 5/6 6/8 7/7 6/7 3/3 1/2 79.6 66.7 82.2 3* 9.8 42.3 2.8 4.6 2.6 9.3 13.8 8 25 4.8 7.6 131 624 3 3.7 nd/n t 8/9 5/9 1/4 4/6 5/8 4/7 5/7 2/3 61.1 88.9 55.6 4* 6.2 18 1.7 2.8 1 3.8 8.1 2.8 6.3 2 2.6 68 195 0.5 nd/n t 8/9 3/9 1/4 5/6 6/8 4/7 3/7 1/3 55.6 88.9 48.9 5 1.8 3.2 2.7 7.6 1.6 2.4 4.5 11.7 2.3 3.4 2.4 7.3 1.3 1.5 0.9 1.6 3.2 nd/n t 5/9 4/9 3/4 3/6 5/8 4/7 3/7 2/3 1/2 53.7 55.6 53.3 6 12 36.1 1.8 0.7 1.3 0.9 0.9 0.8 nd/n t 9/9 1/9 2/6 4/8 3/7 2/7 38.9 100 26.7 7* 4.1 11.3 1.6 1 2.9 4 5.5 1.7 3.9 126 250 nd/n t 8/9 1/9 1/4 2/6 1/8 3/7 2/7 33.3 88.9 22.2 8* 0.4 0.7 0.8 1.9 14 34.5 14 36 164 325 nd/n t 1/9 2/9 1/4 3/6 3/8 2/7 22.2 11.1 24.4 9* x 35 191 101 nd/n t 9/9 1/7 18.5 100 2.2 10* 1.3 2.5 9.1 13.8 4 6.7 2.8 4.3 242 484 nd/n t 1/9 1/9 2/6 2/8 1/7 2/7 18.5 11.1 20 11* 2.2 0.2 2.5 4.4 2.8 1.6 2.3 109 217 nd/n t 1/9 1/9 2/6 1/8 2/7 2/7 16.7 11.1 17.8 12 0.4 1.2 1.7 1.6 0.4 0.5 0.3 0.4 0.3 1.0 nd/n t 1/9 2/9 1/6 2/8 2/7 1/7 1/3 14.8 11.1 15.6 13 0.8 1.3 2.1 2.8 2.8 6.4 11 nd/n t 1/9 2/6 1/8 1/7 2/7 13 0 15.6 14 0.4 1.2 0.5 5.1 nd/n t 1/9 1/9 1/4 1/6 9.3 11.1 8.9 15 8 14.7 1.5 1.8 nd/n t 2/9 2/4 7.4 22.2 4.4 16 0.1 0.2 0.5 nd/n t 1/9 1/7 1/2 5.6 0 6.7 17 6.5 9 8 42 nd/n t 1/9 1/4 1/6 1/7 5.6 0 6.7 18 0.2 0.2 1.5 nd/n t 1/9 1/6 1/8 5.6 0 6.7 19 3 3 nd/n t 2/9 3.7 22.2 0 20 0.3 0.8 nd/n t 1/6 1/8 3.7 0 4.4 21 20 nd/n t 1/9 1.9 11.1 0 22 0.9 nd/n t 1/8 1.9 0 2.2 23 12 nd/n t 1/6 1.9 0 2.2 24 8.1 60 1.2 3.1 1 2.2 1.3 3.2 1.9 6.5 1.7 5.6 1.4 2.1 0.7 1.4 1.6 1.8 nd/n t 9/9 9/9 4/4 6/6 8 7/7 7/7 3/3 2/2 100 100 100 25 6 18.7 5.7 18 6.4 14 13 57 6.9 18.9 5.8 9.8 2.7 5.8 9.4 13 nd/n t 9/9 9/9 4/4 8/8 7/7 7/7 3/3 2/2 100 100 100 26 4.9 17.6 3.9 8.9 4.4 6.7 4.5 6.9 9.4 23 2.5 5 7.1 11 nd/n t 9/9 9/9 4/4 6/6 7/7 3/3 2/2 100 100 100 27 1 1.6 0.5 0.6 0.4 0.5 0.4 0.7 0.5 0.8 0.4 0.5 0.4 nd/n t 2/9 3/9 1/4 1/6 3/8 3/7 2/7 1/2 27.8 22.2 28.9 28 2.3 6.2 2.7 9.3 0.5 0.9 1.2 4.8 12 11 21.4 8.5 17 nd/n t 3/9 4/9 1/4 2/6 3/8 2/7 2/7 25.9 11.1 28.9 29 0.2 0.2 0.3 0.4 0.3 0.4 0.4 0.2 0.4 0.2 0.3 nd/n t 5/9 2/9 1/6 2/8 3/7 2/7 24.1 33.3 22.2 30 0.3 0.3 0.3 0.4 0.3 0.4 0.4 0.8 0.5 0.7 0.2 0.2 nd/n t 2/9 2/9 2/6 3/8 2/7 2/7 24.1 22.2 24.4 31 0.7 1.2 0.7 0.9 0.5 0.6 0.6 0.6 1.2 1.8 1.3 nd/n t 3/9 2/9 2/6 2/8 2/7 1/7 22.2 33.3 20 32 0.3 0.4 0.5 0.8 1.2 1.4 0.4 0.6 0.4 nd/n t 1/9 2/9 1/6 2/8 2/7 1/7 16.7 11.1 17.8 33 0.2 0.3 0.4 0.6 1.1 1.2 0.3 0.4 0.4 nd/n t 1/9 2/9 1/6 2/8 2/7 1/7 16.7 11.1 17.8 34 0.8 0.9 0.3 0.4 0.3 0.4 0.3 0.4 nd/n t 2/9 2/9 2/6 2/7 14.8 22.2 13.3 35* 7.7 14 0.5 105 0.5 nd/n t 1/9 1/9 1/8 1/7 1/3 9.3 11.1 8.9 36 0.3 18 0.5 nd/n t 1/9 1/4 1/8 5.6 11.1 4.4 37* 425 811 351 1022 280 396 381 1006 292 532 362 563 377 610 216 353 282 317 nd/n t 9/9 9/9 3/4 6/6 7/8 7/7 7/7 3/3 2/2 98.1 100 97.8 38* x 347 1732 5.6 24 2.2 3.7 29 140 8.6 34 3.8 6.9 5.4 18 1.2 2 4,3 4,7 nd/n t 9/9 8/9 3/4 6/6 6/8 7/7 6/7 2/3 2/2 81.5 100 77.8 39 10 24.7 4.4 15 4.5 5.6 4.9 12.6 15 35.3 10 19 2.5 3,3 6,9 11 nd/n t 7/9 9/9 2/4 6/6 7/7 7/7 3/3 2/2 81.5 77.8 82.2 40 0.2 0.4 0.2 0.4 0.2 0.5 0.2 0.3 0.2 0.4 0.1 nd/n t 4/9 4/9 4/6 4/8 3/7 1/3 37 44.4 35.6 41 0.3 0.6 0 0.1 0.1 0.1 0.7 0.4 2.7 nd/n t 3/9 5/9 1/4 1/6 5/7 1/7 1/3 16.7 33.3 13.3 42 0.05 0.007 0.007 1.1 0.9 0.007 nd/n t 1/9 1/9 1/8 1/7 1/3 2/2 13 11.1 13.3 43 51 92 nd/n t 5/9 9.3 55.6 0 44 x 1832 35 nd/n t 1/9 1/4 3.7 11.1 2.2 *: Compounds etected at least once in the groundwater (G or W0 - W6) at a concentraction higher than 0.1 µgL-1. x: detected at least once in the reclaimed water (R) at a concentration higher than 0.1 µgL-1. Nº = Compound Number ordered by group (Pesticides: 123, PAH: , Pharmaceuticals: and heavy metals: ) and frequency of detection. PESTICIDES: 1: hexachlorobenzene, 2*: chlorpyrifos ethyl, 3*: terbuthylazine, 4*: diuron, 5: oxyfluorfen, 6: chlorfenvinphos, 7*: terbutryn, 8*: procymidone, 9* x: diazinon, 10*: atrazine, 11*: propazine, 12: pentachlorobenzene, 13: simazine,14:chlorotoluron, 15: γ-HCH, 16: 4,4’-DDT, 17: α-endosulfan, 18: 4,4’-DDE, 19: isoproturon, 20: hexachlorobutadiene, 21: α-cypermethrin, 22: metoxychlor, 23: parathion ethyl. PAH: 24: fluorene, 25: phenanthrene, 26: pyrene, 27:acenaphtylene, 28: chrysene, 29: benzo(b)fluoranthene, 30:benzo(a)anthracene, 31: benzo(ghi)perylene, 32: indene(1,2,3-cd)pyrene, 33: dibenzo(a,h)anthracene, 34: benzo(k)fluoranthene, 35*: anthracene, 36: benzo(a)pyrene. HEAVY METALS: 37*: Zn, 38 x: Cu, 39: Ni, 40: Cd, 41: Pb and 42: Tl. PHARMACEUTICALS: 43: antipyrine, 44 x: acetaminophen.