Enric Vázquez-Suñé

Emerging organic contaminants in groundwater in Spain: A review of sources, recent occurrence and fate in a European context

This paper reviewed the presence of emerging organic contaminants (EOCs) that have been found in the groundwater in Spain in both, rural and urban areas. The list of compounds included pesticides, pharmaceutical active compounds (PhACs), selected industrial compounds, drugs of abuse (DAs), estrogens, personal care products and life-style compounds. The main sources of pollution and possible pathways have been summarised in this review. EOCs are likely to enter to the aquifer mainly through the effluents of waste water treatment plants (WWTPs) and are present in groundwater at concentrations of ng/L to μg/L. The most studied compounds in Spanish groundwater were pesticides followed by industrial compounds and PhACs. It is important to mention that compared to other water bodies, such as rivers, groundwater is considerably less contaminated, which may be indicative of the natural attenuation capacity of the aquifers. However, some EOCs have sometimes been detected at higher concentration levels in the aquifer than in the rivers, indicating the need for further research to understand their behaviour in the aquifers. For a wide array of compounds, their maximum concentrations show values above the European groundwater quality standard for individual pesticides (0.1 μg/L). Therefore, to preserve groundwater quality against deterioration it is necessary to define environmental groundwater thresholds for the non-regulated compounds.

Occurrence of 95 pharmaceuticals and transformation products in urban groundwaters underlying the metropolis of Barcelona, Spain

The present paper presents the occurrence of 72 pharmaceuticals and 23 transformation products (TPs) in groundwaters (GWs) underlying the city of Barcelona, Spain. Thirty-one samples were collected under different districts, and at different depths. Aquifers with different geologic features and source of recharge were included, i.e., natural bank filtration, infiltration from wastewater and water supply pipes, rainfall recharge, etc. Antibiotics were the most frequently found compounds detected at levels reaching 1000 ng L(-1). Natural bank filtration from the river that receives large amounts of effluents from waste water treatment plants (WWTPs), turned out being the most influencing source of contamination, thus GW showed high range of compounds and concentrations as high as or even higher than in the river itself. In general, TPs were found at lower concentrations than the corresponding parent compounds, with some exceptions, such as 4OH propranolol and enalaprilat.

Urban groundwater contamination by residues of UV filters

The occurrence and fate of UV filters (UV F) in an urban aquifer in correlation with (1) the spatial distribution of UV F in Barcelonas groundwater, (2) the depth of the groundwater sample, (3) the physicochemical properties of the target compounds, (4) the recharge sources, and (5) the redox conditions of the Barcelona aquifers, were studied for the first time. The highest groundwater concentrations and the largest number of detected UV F were observed in an aquifer recharged by a polluted river (around 55 ng/L in SAP-4). In contrast, the urbanized areas had lower concentrations (around 20 ng/L in MPSP-1). Two pathways can be identified for UV F to enter the aquifers: (1) leakage of row sewage from the sewage network in urbanized areas and (2) wastewater treatment plant (WWTP) effluents discharged into the river. Measured concentrations of UV F were significantly much lower than those estimated from the waste water proportion in groundwater samples suggesting that UV F might undergo transformation processes in both reducing and oxidizing conditions.

Drugs of abuse in urban groundwater. A case study: Barcelona

This study is concerned with drugs of abuse (DAs) and their metabolites in urban groundwater at field scale in relation to (1) the spatial distribution of DAs in Barcelonas groundwater, (2) the depth of the groundwater samples, (3) the presence of DAs in recharge sources, and (4) the assessment of the fate of DAs in Barcelona aquifers. To this end, 37 urban groundwater samples were collected in the city of Barcelona and a total of 21 drugs were analyzed including cocainics, amphetamine-like compounds, opioids, lysergics and cannabinoids and the prescribed drugs benzodiazepines. Overall, the highest groundwater concentrations (around 200 ng/L in SAP-4) and the largest number of detected DAs were found in zones basically recharged by a river that receives large amounts of effluents from waste water treatment plants (WWTPs). In contrast, the urbanized areas yielded not only lower concentrations but also a much smaller number of drugs, which suggests a local origin. In fact, cocaine and its metabolite were dominant in more prosperous neighborhoods, whereas the cheaper MDMA was the dominant DA in poorer districts. Measured concentrations were consistently smaller than those estimated from the waste water fraction in groundwater samples, suggesting that DAs undergo removal processes in both reducing and oxidizing conditions.

High-resolution seismic characterization in an urban area: Subway tunnel construction in Barcelona, Spain

Traveltime seismic tomography used to aid subway tunnel drilling in Barcelona, Spain, provides a detailed characterization of the shallow subsurface, including a complex network of faults and dikes. We encountered many difficulties while working in this urban setting, such as cultural noise and the inability to deploy instruments along much of the tunnel trace because of the street layout. Furthermore, the shallow subsurface is highly heterogeneous (because of gas and water lines, building foundations, and the sewage system), obscuring deeper structures. We acquired seismic data using a 10-s vibroseis sweep that provided relatively good signal-to-noise (S/N) ratio. First-arrival traveltime tomography proved to be a key tool to differentiate rock vol-umes characterized by different physical properties — in particular, the contact between the weathered upper layer and the more competent rock below. We interpreted the seismic results using surface geologic observations and borehole cores. Low seismic velocit...

Occurrence of carbamazepine and five metabolites in an urban aquifer

This paper deals with urban groundwater contaminated with carbamazepine (CBZ) and five of its human metabolites in Barcelona. Groundwater samples were accordingly collected in the aquifers of Poble Sec and Besòs River Delta. Higher concentrations and more compounds were found in the Besòs River Delta aquifer, which is recharged by a river contaminated with treated effluent from numerous treatment plants. By contrast, the urban area of Poble Sec presented lower concentrations and fewer compounds. The results showed that CBZ could be attenuated in the Poble Sec aquifer since concentrations in groundwater were lower than those evaluated from mixing of the recharge sources. Conversely, CBZ and its human metabolites were not removed under the reducing conditions of the Besòs River Delta aquifer probably because of the short residence time in this aquifer.

The use of GIS-based 3D geological tools to improve hydrogeological models of sedimentary media in an urban environment

A software platform was developed to facilitate the development of 3D geological models of sedimentary media for hydrogeological modelling, especially for urban environments. It is composed by a geospatial database and a set of tools that enable the user to perform an accurate stratigraphic analysis. The geospatial database is used for the management of a large amount of different data types coming from different sources (geophysical logs, borehole logs, hydraulic tests, etc.). Its structure allows us to store accurate and very detailed geological borehole-log description that can be straightforwardly generalized and further upscaled. The set of stratigraphic analysis instruments, working within a Geographical Information System (GIS) environment, has been set up to facilitate the geological data interpretation. Detailed stratigraphic columns of the selected boreholes can be generated using customized queries. Creating automatically a geological profile is further possible by displaying the boreholes lithological columns and the geophysical and geotechnical field-tests’ results together with the defined stratigraphic units. Based on an interactive analysis environment is created, where the user is able to analyze and to define the possible existing correlation surfaces, units, and faults. The obtained information represented by the geological units/subunits can be then converted within a 3D environment. The resulted 3D features could be used within the same GIS environment or by external software packages for further stochastic analysis or to build up 3D geological and hydrogeological models. Starting from an accurate and very detailed geological description, the software allows us to represent in three dimensions (3D) the heterogeneity of the sedimentary media and their spatial distribution. Thus, it shows how connectivity implemented into hydrogeological models among the different sedimentary bodies plays an important role. Results are shown consisting in a case study located in the Besòs River Delta, in the metropolitan area of Barcelona, on the Mediterranean coast in NE Spain.

Using EMMA and MIX analysis to assess mixing ratios and to identify hydrochemical reactions in groundwater.

This study presents a methodology using an end-member mixing analysis (EMMA) and MIX to compute mixing ratios and to identify hydrochemical reactions in groundwater. The methodology consists of (1) identifying the potential sources of recharge, (2) characterising recharge sources and mixed water samples using hydrogeochemistry, (3) selecting chemical species to be used in the analysis and (4) calculating mixing ratios and identification of hydrochemical reactions in groundwater. This approach has been applied in the Besòs River Delta area, where we have collected 51 groundwater samples and a long data register of the hydrogeochemistry of the Besòs River created by the Catalan Water Agency is also available. The EMMA performed in the Besòs River suggests that 3 end-members are required to explain its temporal variability, accounting for the species chloride, sulphate, sodium, bicarbonate, calcium, magnesium, potassium, ammonium, total nitrogen, and electrical conductivity. One river end-member is from the wet periods (W1), and two are from dry periods (D1 and D2). These end-members have been used to compute mixing ratios in groundwater samples because the Besòs River is considered the main recharge source for the aquifer. Overall, dry season end-members dominated over the wet season end-member, in a proportion of 4:1. Moreover, when departures from the mixing line exist, geochemical processes might be identified. Redox processes, carbonate dissolution/precipitation and ion exchange processes may occur in Besòs Delta aquifer.

Occurrence, fate and risk assessment of personal care products in river–groundwater interface

This work presents the occurrence and fate of selected personal care products (PCPs) in the urban river-groundwater interface. To this end, urban river and groundwater samples were collected in Sant Adrià del Besòs (NE of Spain) and a total of 16 PCPs were analyzed including benzophenone derivatives, camphor derivatives, p-aminobenzoic acid derivatives, triazoles and parabens in three different campaigns (from May 2010 to July 2014). These compounds reach the aquifer through the recharge of Besòs River that receives large amounts of effluents from waste water treatment plants. Results have shown that most of the compounds were not or barely detected (maximum concentrations around 200ng/L) in groundwater samples during the different sampling campaigns. Only two triazoles, namely benzotriazole (BZT) and methyl benzotriazol (MeBZT) were found at high concentrations in groundwater samples (maximum concentration around 2000ng/L). The fate of PCPs in the aquifer was assessed using mixing analysis considering the seasonal variability of the Besòs River. Overall, measured groundwater concentrations were significantly much lower than those estimated by the mixing of the river water. This observation suggested that most of the PCPs are naturally removed when river water infiltrates the aquifer. However, some compounds were more persistent in the aquifer. These compounds were in descending order: the triazoles BZT and MeBZT followed by the camphor derivative 4MBC and the paraben MePB. The measured concentrations allowed us to assess the environmental risk posed by the selected UV-filters and parabens in the river and groundwater samples. Hazard Quotients (HQs) for different aquatic species were calculated in order to characterize the ecotoxicity potential of the studied compounds in the river-groundwater interface. HQ values were always below 1 indicating that at the concentrations observed in the surface or aquifer water of Besòs River these compounds pose no risk to the selected aquatic organisms.

Influence of releases from a fresh water reservoir on the hydrochemistry of the Tinto River (SW Spain)

The Tinto River is an extreme case of pollution by acid mine drainage (AMD), with pH values below 3 and high sulphate, metal and metalloid concentrations along its main course. This study evaluates the impact of releases from a freshwater reservoir on the Tinto River, identifying the metal transport mechanisms. This information is needed to understand the water quality evolution in the long term, and involves the comprehension of interactions between AMD sources, freshwaters, particulate matter and sediments. This work proposes a methodology for quantifying the proportions in which the different sources are contributing. The method is based on the mass balance of solutes and accounts for the uncertainty of end-members. The impact of the releases from the Corumbel Reservoir on the hydrochemistry of the Tinto River was significant, accounting up to a 92% of river discharge. These releases provoked a sharp decrease in dissolved metal concentrations, especially for Fe (approximately 1000 fold) due to dilution and precipitation. Cadmium, Zn, Cu, Co, Ni and Al suffered a dilution to a 12-16 fold decrease while Ca, Sr, Na, Pb and Si were less affected (2-4 folds decrease). However, these releases also gave rise to an increase in particulate transport, mainly Fe, As, Cr, Ba, Pb and Ti, due to sediment remobilisation and Fe precipitation. Aluminium, Li, K, Si, Al, Ni and Sr, together with Cu were present in the particulate phase during the discharge peak. The proposed 2-component mixing model revealed the existence of non-conservative behaviour for Al, Ca, Li, Mn, Ni and Si as a consequence of the interactions between the acidic Tinto waters and the clay-rich reservoir sediments during the bottom outlet opening. These results were improved by a 3-component mixing model, introducing a new end-member to account the chemical dissolution of clay-rich sediments by acidic Tinto waters.