High resolution mass spectrometry (HRMS) determination of drugs in wastewater and wastewater based epidemiology in Cadiz Bay (Spain).

Multi-residue methods for the determination of the myriad of compounds of emerging concern (CECs) entering in the environment are key elements for further assessment on their distribution and fate. Here, we have developed an analytical protocol for the simultaneous analysis of 195 prescription, over-the-counter, and illicit drugs by using a combination of solid phase extraction (SPE) and determination by liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS). The method was applied to the analysis of influent sewage samples from 3 wastewater treatment plants (WWTPs) from Cadiz Bay (SW Spain), enabling the quantification of more than 100 pharmaceuticals, 19 of them at average concentrations higher than 1 µg L-1, including caffeine (92 µg L-1), paracetamol (72 µg L-1), and ibuprofen (56 µg L-1), as well as several illicit drugs (e.g., cocaine). Wastewater based epidemiology (WBE) was applied for 27 of the detected compounds to establish their consumption in the sampling area, which has been never attempted before. Caffeine, naproxen, and salicylic acid stood out because of their high consumption (638, 51, and 20 g d-1·1000pop-1, respectively). Regarding illicit drugs, cocaine showed the highest frequency of detection and we estimated an average consumption of 3683 mg d-1·1000pop-1 in Cadiz Bay. The combination of new HRMS methods, capable of discriminating thousands of chemicals, and WBE will allow for a more comprehensive characterization of chemical substances and their consumption in urban environments in the near future.

Passive Samplers vs Sentinel Organisms: One-Year Monitoring of Priority and Emerging Contaminants in Coastal Waters.

Temporal monitoring of pollutants in aquatic systems impacted by human activities is mandatory for a correct assessment on their environmental impact and later management. The aim of this work was to study the suitability of using silicone rubber passive samplers and caged organisms (Ruditapes philippinarum), simultaneously, to examine the spatial and temporal variability of priority and emerging contaminants in a coastal environment (Cadiz Bay, SW Spain) over the course of an entire year. Seasonal trends were observed for some classes of compounds, such as UV filters and fragrances, and attributed to fluctuations in their sources and changes in the hydrodynamic conditions, respectively. Up to 42 out of 48 (in seawater) and 27 out of 37 (in biota) target analytes were detected, the highest concentrations being observed for synthetic fragrances and UV filters in both biota (136.9-159 ng g-1) and the dissolved phase (3322.2-265.7 ng L-1). Conversely, spatiotemporal differences in the concentrations of target contaminants in clam tissues were minimal. Higher field bioaccumulation factors (log BAF > 5) were found for priority substances. Overall, silicone rubber passive samplers proved to be more sensitive than sentinel organisms for monitoring spatiotemporal changes in the dissolved aqueous concentrations of contaminants, whereas the latter allowed for a more realistic evaluation of the potential uptake and bioaccumulation of each compound.

Evaluation of the anaerobic biodegradation of linear alkylbenzene sulfonates (LAS) using OECD 308 water/sediment systems.

Linear alkylbenzene sulfonates (LAS) are the most widely used anionic surfactants in household detergents and cleaning products. We have evaluated LAS anaerobic degradation in sediments following OECD 308 guidelines. Four different classes of sediments were collected from non-polluted areas and tested to check the influence of: fine and coarse texture, low and high organic carbon content, and freshwater and marine origin. The concentrations of LAS and possible degradation metabolites in sediment and water phases were monitored by high resolution mass spectrometry over an incubation period of 160 days. LAS removal was between 0 and 63%, depending on the sediment used, and it was accompanied by formation of sulfophenyl carboxylic acids (SPCs). The best results were observed for marine sediments having low organic carbon and silt + clay contents (0.5% and 13%, respectively), whereas degradation was negligible in freshwater sediments. The large differences in degradation observed across the sediments tested were attributed to their physicochemical properties influencing LAS bioavailability and the heterogeneity of microbial communities. Further research is also needed to address some shortcomings observed during the application of the OECD 308 and to ensure that test results obtained with these guidelines model anaerobic biodegradation under realistic environmental conditions.

Occurrence and spatial distribution of legacy and emerging organic pollutants in marine sediments from the Atlantic coast (Andalusia, SW Spain).

Contamination of aquatic systems by no longer used but very persistent compounds (e.g., organochlorine pesticides) and newly detected chemicals, such as personal care products (PCPs), represents a raising concern. In this study, we carried out one of the first comparisons of both types of contaminants, legacy and emerging, in two coastal systems (Cadiz Bay and Huelva Estuary). A wide range of analytes were selected to this end, including hydrocarbons, UV filters, fragrances, and antimicrobials. Analysis of surface sediments revealed the occurrence of 46 out of 97 target analytes, most of them predominantly accumulated in depositional areas with high organic carbon content. Polycyclic aromatic hydrocarbons (PAHs), fragrances (e.g., octahydrotetramethyl acetophenone or "OTNE"), UV filters (e.g., octocrylene), and nonylphenol had the highest concentrations (up to 1098, 133.5, 72 and 575ngg-1, respectively). Several inputs were detected, from atmospheric deposition after combustion to wastewater discharges and recreational activities. However, an environmental risk assessment performed for those chemicals for which ecotoxicological data were available, indicated that legacy compounds still pose the highest potential risk towards benthonic organisms (individual hazard quotients up to 580 for dichlorophenyldichloroethylene or "DDE") compared to PCPs.

Effects of extreme rainfall events on the distribution of selected emerging contaminants in surface and groundwater: The Guadalete River basin (SW, Spain).

This study is focused on the Guadalete River basin (SW, Spain), where extreme weather conditions have become common, with and alternation between periods of drought and extreme rainfall events. Combined sewer overflows (CSOs) occur when heavy rainfall events exceed the capacity of the wastewater treatment plants (WWTP), as well as pollution episodes in parts of the basin due to uncontrolled sewage spills and the use of reclaimed water and sludge from the local WWTP. The sampling was carried out along two seasons and three campaigns during dry (March 2007) and extreme rainfall (April and December 2010) in the Guadalete River, alluvial aquifer and Jerez de la Frontera aquifer. Results showed minimum concentrations for synthetic surfactants in groundwater (<37.4µg·L-1) during the first campaign (dry weather conditions), whereas groundwater contaminants increased in December 2010 as the heavy rainfall caused the river to overflow. In surface water, surfactant concentrations showed similar trends to groundwater observations. In addition to surfactants, pharmaceuticals and personal care products (PPCPs) were analyzed in the third campaign, 22 of which were detected in surface waters. Two fragrances (OTNE and galaxolide) and one analgesic/anti-inflammatory (ibuprofen) were the most abundant PPCPs (up to 6540, 2748 and 1747ng·L-1, respectively). Regarding groundwater, most PPCPs were detected in Jerez de la Frontera aquifer, where a synthetic fragrance (OTNE) was predominant (up to 1285ng·L-1).

Degradation kinetics of pharmaceuticals and personal care products in surface waters: photolysis vs biodegradation.

Poor removal of many pharmaceuticals and personal care products (PPCPs) in sewage treatment leads to their discharge into the receiving waters, where they may cause negative effects. Their elimination from the water column depends of several processes, including photochemical and biological degradation. We have focused this research on comparing the degradation kinetics of a wide number (n=33) of frequently detected PPCPs considering different types of water, pH and solar irradiation. For those compounds that were susceptible of photodegradation, their rates (k) varied from 0.02 to 30.48h-1 at pH7, with the lowest values for antihypertensive and psychiatric drugs (t1/2>1000h). Modification of the pH turned into faster disappearance of most of the PPCPs (e.g., k=0.072 and 0.066h-1 for atenolol and carbamazepine at pH4, respectively). On the other hand, biodegradation was enhanced by marine bacteria in many cases, for example for mefenamic acid, caffeine and triclosan (k=0.019, 0.01 and 0.04h-1, respectively), and was faster for anionic surfactants. Comparing photodegradation and biodegradation processes, hydrochlorothiazide and diclofenac, both not biodegradable, were eliminated exclusively by irradiation (t1/2=0.15-0.43h and t1/2=0.14-0.17h, respectively). Salicylic acid and phenylbutazone were efficiently photo (t1/2<3h) and biodegraded (t1/2=116-158h), whereas some compounds such as ibuprofen, carbamazepine and atenolol had low degradation rates by any of the processes tested (t1/2=23-2310h), making then susceptible to persist in the aquatic media.

Photolysis of Antibiotics under Simulated Sunlight Irradiation: Identification of Photoproducts by High-Resolution Mass Spectrometry.

There is growing concern regarding the widespread use of antibiotics and their presence in the aqueous environment. Their removal in the water column is mediated by different types of degradation processes for which the mechanisms are still unclear. This research is focused on characterizing the photodegradation kinetics and pathways of two largely employed antibiotics families: sulfonamides (9 SDs) and fluoroquinolones (6 FQs). Degradation percentages and rates were measured in pure water exposed to simulated natural sunlight at a constant irradiance value (500 W m-2) during all the experiments, and the main photoproducts formed were characterized through accurate mass measurement using ultraperformance liquid chromatography-quadrupole-time-of-flight-mass spectrometry (UPLC-QToF-MS). Over 200 different phototransformation products were identified for SDs and FQs, 66% of them, to the best of our knowledge, have not been described before. Their sequential formation and disappearance over the course of the experiments reveals the existence of several pathways for the degradation of target antibiotics. Occurrence of new photoproducts derived from desulfonation and/or denitrification, as well as hydroxylation of photo-oxidized heterocyclic rings, have been identified during photodegradation of SDs, whereas a new pathway yielding oxidation of the benzene ring after the cleavage of the piperazine ring (e.g., CIP product with m/z 280) is described for FQs.

Determination of silicone rubber and low-density polyethylene diffusion and polymer/water partition coefficients for emerging contaminants.

There is a growing interest in assessing the concentration and distribution of new nonregulated organic compounds (emerging contaminants) in the environment. The measurement of freely dissolved concentrations using conventional approaches is challenging because of the low concentrations that may be encountered and their temporally variable emissions. Absorption-based passive sampling enables the estimation of freely dissolved concentrations of hydrophobic contaminants of emerging concern in water. In the present study, calibration was undertaken for 2 polymers, low-density polyethylene (LDPE) and silicone rubber for 11 fragrances, 5 endocrine-disrupting compounds, 7 ultraviolet (UV) filters, and 8 organophosphate flame retardant compounds. Batch experiments were performed to estimate contaminant diffusion coefficients in the polymers (Dp ), which in general decreased with increasing molecular weight. The values for fragrances, endocrine-disrupting compounds, and UV filters were in ranges similar to those previously reported for polycyclic aromatic hydrocarbons, but were 1 order of magnitude lower for organophosphate flame retardant compounds. Silicone rubber had higher Dp values than LDPE and was therefore selected for further experiments to calculate polymer/water partition coefficients (KPW ). The authors observed a positive correlation between log KPW and log octanol/water partition coefficient values. Field testing of silicone rubber passive samplers was undertaken though exposure in the River Alna (Norway) for an exposure time of 21 d to estimate freely dissolved concentration. Some fragrances and UV filters were predominant over other emerging and regulated contaminants, at levels up to 1600 ng L(-1) for galaxolide and 448 ng L(-1) for octocrylene. Environ Toxicol Chem 2016;35:2162-2172. © 2016 SETAC.

In-cell clean-up pressurized liquid extraction and gas chromatography-tandem mass spectrometry determination of hydrophobic persistent and emerging organic pollutants in coastal sediments.

The main goal of this work was to develop, optimize and validate a multi-residue method for the simultaneous determination of 97 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organophosphorus flame retardants, and several types of pesticides in marine sediment samples. Extraction and cleanup were integrated into the same step using pressurized liquid extraction (PLE) with in-cell clean-up (1g of alumina). The extraction was performed using dichloromethane at 100 °C, 1500 psi and 3 extraction cycles (5 min per cycle). Extracts were derivatized with N-(tert-butyldimethylsilyl)-N-methyltrifluoroacetamide (MTBSTFA) to improve the signal and sensitivity of some target compounds (i.e., triclosan, 2-hydroxybenzophenone). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to tandem mass spectrometry. Under optimal conditions, the optimized protocol showed good recovery percentages (70-100%), linearity (>0.99) and limits of detection below 1 ng g(-1) for all compounds. Finally, the method was applied to the analysis of sediment samples from different coastal areas from Andalusia (Spain), where occurrence and distribution of emerging contaminants in sediments is very scarce. Twenty five compounds out of 98 were detected in all samples, with the endocrine disruptor nonylphenol and the fragrance galaxolide showing the highest concentrations, up to 377.6 ng g(-1) and 237.4 ng g(-1), respectively.

Anaerobic degradation of alcohol ethoxylates and polyethylene glycols in marine sediments.

This research is focused on alcohol polyethoxylates (AEOs), nonionic surfactants used in a wide variety of products such as household cleaners and detergents. Our main objective in this work was to study the anaerobic degradation of these compounds and their main aerobic degradation products and precursors (polyethylene glycols, PEGs, which are also used for many other applications) in marine sediments, providing the first data available on this topic. First, we observed that average AEO sediment-water partition coefficients (Kd) increased towards those homologs having longer alkyl chains (from 257 L/kg for C12 to 5772 L/kg for C18),which were less susceptible to undergo biodegradation. Overall, AEO and PEG removal percentages reached up to 99.7 and 93%, respectively, after 169 days of incubation using anaerobic conditions in sediments ([O2] = 0 ppm, Eh = -170 to -380 mV and T = 30 °C). Average half-life was estimated to be in a range from 10 to 15 days for AEO homologs (C12AEO8-C18AEO8), and 18 days for PEGEO8.Methanogenic activity proved to be intense during the experiment, confirming the occurrence of anaerobic conditions. This is the first study showing that AEOs and PEGs can be degraded in absence of oxygen in marine sediments, so this new information should be taken into account for future environmental risk assessments on these chemicals.

Distribution of anionic and nonionic surfactants in a sewage-impacted Mediterranean coastal lagoon: inputs and seasonal variations.

In this work we have monitored the seasonal inputs, occurrence and distribution of the world's most widely used surfactants (linear alkylbenzene sulfonates, LAS, nonylphenol polyethoxylates, NPEOs, and alcohol polyethoxylates, AEOs) in Mar Menor lagoon (SE Spain) and its main tributary (El Albujón) for the first time. Concentration of target compounds was determined in both surface waters and sediments after solid phase extraction and pressurized liquid extraction, respectively, followed by liquid chromatography-mass spectrometry (LC-MS). There were significant differences in surfactant fluxes from El Albujón towards Mar Menor depending on the season and the day of the week, with maximum estimated annual inputs being detected for LAS (406 kg) and their metabolites, sulfophenyl carboxylic acids (482 kg). Average concentrations of surfactants in the lagoon were between 44 and 1665 µg/kg in sediment, and between 0.3 and 63 µg/L in water. These levels were significantly higher for samples collected near the shore than for those measured inside the lagoon itself. Overall, the occurrence and distribution of surfactants in the system could be explained due to a combination of different sources (surface and groundwater inputs, treated and untreated wastewater effluents, towns, ports, etc.) and simultaneous in-situ physicochemical and biological processes, with an special emphasis on degradation during warmer months.

Occurrence and spatial distribution of emerging contaminants in the unsaturated zone. case study: Guadalete River basin (Cadiz, Spain).

Irrigation with reclaimed water is becoming a common practice in arid- and semi-arid regions as a consequence of structural water resource scarcity. This practice can lead to contamination of the vadose zone if sewage-derived contaminants are not removed properly. In the current work, we have characterized soils from the Guadalete River basin (SW Spain), which are often irrigated with reclaimed water from a nearby wastewater treatment plant and amended using sludge. Physico-chemical, mineralogical and hydraulic properties were measured in soil samples from this area (from surface up to 2 m depth). Emerging contaminants (synthetic surfactants and pharmaceutically active compounds, or PhACs) were also determined. Synthetic surfactants, widely used in personal care products (PCPs), were found in a wide range of concentrations: 73-1300 µg kg(-1) for linear alkylbenzene sulfonates (LAS), 120-496 µg kg(-1) for alkyl ethoxysulfates (AES), 19-1090 µg kg(-1) for alcohol polyethoxylates (AEOs), and 155-280 µg kg(-1) for nonylphenol polyethoxylates (NPEOs). The presence of surfactant homologues with longer alkyl chains was predominant due to their sorption capacity. A positive correlation was found between LAS and AEOs and soil organic carbon and clay content, respectively. Out of 64 PhACs analyzed, only 7 were detected occasionally (diclofenac, metoprolol, fenofibrate, carbamazepine, clarithromycin, famotidine and hydrochlorothiazide), always at very low concentrations (from 0.1 to 1.3 µg kg(-1)).

Atmospheric pressure gas chromatography-time-of-flight-mass spectrometry (APGC-ToF-MS) for the determination of regulated and emerging contaminants in aqueous samples after stir bar sorptive extraction (SBSE).

This work presents the development, optimization and validation of a multi-residue method for the simultaneous determination of 102 contaminants, including fragrances, UV filters, repellents, endocrine disruptors, biocides, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and several types of pesticides in aqueous matrices. Water samples were processed using stir bar sorptive extraction (SBSE) after the optimization of several parameters: agitation time, ionic strength, presence of organic modifiers, pH, and volume of the derivatizing agent. Target compounds were extracted from the bars by liquid desorption (LD). Separation, identification and quantification of analytes were carried out by gas chromatography (GC) coupled to time-of-flight (ToF-MS) mass spectrometry. A new ionization source, atmospheric pressure gas chromatography (APGC), was tested. The optimized protocol showed acceptable recovery percentages (50-100%) and limits of detection below 1ngL(-1) for most of the compounds. Occurrence of 21 out of 102 analytes was confirmed in several environmental aquatic matrices, including seawater, sewage effluent, river water and groundwater. Non-target compounds such as organophosphorus flame retardants were also identified in real samples by accurate mass measurement of their molecular ions using GC-APGC-ToF-MS. To the best of our knowledge, this is the first time that this technique has been applied for the analysis of contaminants in aquatic systems. By employing lower energy than the more widely used electron impact ionization (EI), AGPC provides significant advantages over EI for those substances very susceptible to high fragmentation (e.g., fragrances, pyrethroids).

Partitioning of alcohol ethoxylates and polyethylene glycols in the marine environment: field samplings vs laboratory experiments.

Nowadays, alcohol ethoxylates (AEOs) constitute the most important group of non-ionic surfactants, used in a wide range of applications such as household cleaners and detergents. Significant amounts of these compounds and their degradation products (polyethylene glycols, PEGs, which are also used for many other applications) reach aquatic environments, and are eliminated from the water column by degradation and sorption processes. This work deals with the environmental distribution of AEOs and PEGs in the Long Island Sound Estuary, a setting impacted by sewage discharges from New York City (NYC). The distribution of target compounds in seawater was influenced by tides, consistent with salinity differences, and concentrations in suspended solid samples ranged from 1.5 to 20.5 µg/g. The more hydrophobic AEOs were mostly attached to the particulate matter whereas the more polar PEGs were predominant in the dissolved form. Later, the sorption of these chemicals was characterized in the laboratory. Experimental and environmental sorption coefficients for AEOs and PEGs showed average values from 3607 to 164,994 L/kg and from 74 to 32,862 L/kg, respectively. The sorption data were fitted to a Freundlich isotherm model with parameters n and log KF between 0.8-1.2 and 1.46-4.39 L/kg, respectively. AEO and PEG sorptions on marine sediment were also found to be mostly not affected by changes in salinity.

Global metabolite profiling reveals transformation pathways and novel metabolomic responses in Solea senegalensis after exposure to a non-ionic surfactant.

Alcohol polyethoxylate (AEO) surfactants are widely used in household and industrial products, but the health effects arising from short-term exposure to sublethal concentrations are unknown. A metabolomic approach was used to investigate the biotransformation and effects of exposure to sublethal concentrations of hexaethylene glycol monododecylether (C12EO6) in juvenile sole, Solea senegalensis. After 5 days, C12EO6 was rapidly metabolized in the sole by oxidation, glucuronidation, and ethoxylate chain shortening. C12EO6 exposure at either 146 or 553 µg L(-1) resulted in significant metabolite disruption in liver and blood samples, including an apparent fold increase of >10(6) in the circulating levels of C24 bile acids and C27 bile alcohols, disturbance of glucocorticoid and lipid metabolism, and a 470-fold decrease in levels of the fatty acid transport molecule palmitoyl carnitine. Depuration resulted in rapid elimination of the surfactant and normalization of metabolites toward pre-exposure levels. Our findings show for the first time the ability of metabolomic analyses to discern effects of this AEO on metabolite homeostasis at exposure levels below its no effect concentrations for survival and reproduction in juvenile fish. The pronounced alteration in levels of liver metabolites, phospholipids, and glucocorticoids in S. senegalensis in response to surfactant exposure may indicate that this contaminant could potentially impact a number of health end points in fish.

Reactivity and fate of secondary alkane sulfonates (SAS) in marine sediments.

This research is focused on secondary alkane sulfonates (SAS), anionic surfactants widely used in household applications that access aquatic environments mainly via sewage discharges. We studied their sorption capacity and anaerobic degradation in marine sediments, providing the first data available on this topic. SAS partition coefficients increased towards those homologues having longer alkyl chains (from up to 141 L kg(-1) for C14 to up to 1753 L kg(-1) for C17), which were those less susceptible to undergo biodegradation. Overall, SAS removal percentages reached up to 98% after 166 days of incubation using anoxic sediments. The degradation pathway consisted on the formation of sulfocarboxylic acids after an initial fumarate attack of the alkyl chain and successive ß-oxidations. This is the first study showing that SAS can be degraded in absence of oxygen, so this new information should be taken into account for future environmental risk assessments on these chemicals.

Occurrence, distribution and partitioning of nonionic surfactants and pharmaceuticals in the urbanized Long Island Sound Estuary (NY).

This work deals with the environmental distribution of nonionic surfactants (nonylphenol and alcohol ethoxylates), their metabolites (NP, nonylphenol; NPEC, nonylphenol ethoxycarboxylates; and PEG, polyethylene glycols) and a selection of 64 pharmaceuticals in the Long Island Sound (LIS) Estuary which receives important sewage discharges from New York City (NYC). Most target compounds were efficiently removed (>95%) in one wastewater treatment plant monitored, with the exception of NPEC and some specific drugs (e.g., hydrochlorothiazide). Concentrations of surfactants (1.4-4.5 µg L(-1)) and pharmaceuticals (0.1-0.3 µg L(-1)) in seawater were influenced by tides and sampling depth, consistent with salinity differences. Surfactants levels in suspended solids samples were higher than 1 µg g(-1), whereas only most hydrophobic or positively charged pharmaceuticals could be found (e.g., tamoxifen, clarithromycin). Maximum levels of target compounds in LIS sediments (PEG at highest concentrations, 2.8 µg g(-1)) were measured nearest NYC, sharply decreasing with distance from major sewage inputs.

Determining the distribution of triclosan and methyl triclosan in estuarine settings.

We have developed a method for the analysis of two sewage-derived contaminants: triclosan (TCS), an antibacterial agent, and methyl triclosan (MTCS), a TCS metabolite. For solid samples (4 g), extraction and cleanup were integrated into the same step using pressurized liquid extraction (PLE) with in-cell-clean-up (1g of florisil). The extraction was performed using dichloromethane at 100 °C, 1500 psi and 3 static extraction cycles of 5 min each. For water samples (100mL), stir bar sorptive extraction-liquid desorption (SBSE-LD) was used. Bars were stirred for 10h and analytes were later desorbed using acetonitrile. Finally, MTCS and a silylated derivative of TCS were determined by gas chromatography-mass spectrometry (GC-MS). Recovery experiments in water and sediments were performed and the results ranged from 67% to 78%. Limits of detection (LODs) were 5 ng L(-1) for TCS and 1 ng L(-1) for MTCS, in water samples, and 0.1 ng g(-1) for TCS and MTCS in solid samples. The method was applied then to determine the levels of these compounds in the estuary of Guadalete River (SW Spain). TCS and MTCS concentrations up to 9.6 ng g(-1) in sediments and 310 ng L(-1) in water were measured. Their distribution was strongly influenced by the presence of wastewater sources, treated and untreated, along the sampling area, where maximum concentrations were detected. Highest values were reached in the water column during low tides as the water volume in the estuary becomes lower.

Vertical distribution profiles and diagenetic fate of synthetic surfactants in marine and freshwater sediments.

This manuscript deals with the presence and degradation of the most commonly-used surfactants, including anionic (linear alkylbenzene sulfonates, LAS, and alkyl ethoxysulfates, AES) and non-ionic (alcohol polyethoxylates, AEOs, and nonylphenol polyethoxylates, NPEOs) compounds, in sediments and pore water from several aquatic environments (Southwest, Spain). Different vertical distributions were observed according to the respective sources, uses, production volumes and physicochemical properties of each surfactant. Levels of nonionics (up to 10 mg kg(-1)) were twice as high as anionics in industrial areas and harbors, whereas the opposite was found near urban wastewater discharge outlets. Sulfophenyl carboxylic acids (SPCs), LAS degradation products, were identified at anoxic depths at some sampling stations. Their presence was related to in situ anaerobic degradation of LAS in marine sediments, whereas the occurrence of these metabolites in freshwater sediments was attributed to the existence of wastewater sources nearby. No significant changes in the average length of AEO and NPEO ethoxylated chains were observed along the sediment cores, suggesting that their biodegradation was very limited in the sampling area. This may be directly related to their lower bioavailability, as their calculated sediment-pore water distribution coefficients (log K(sw)), which showed that non-ionic surfactants examined in this study had greater sorption affinity than the anionic surfactants (e.g., 2.3±0.3 for NPEOs).

Analysis of alcohol polyethoxylates and polyethylene glycols in marine sediments.

Alcohol polyethoxylates (AEOs) are the most commercially important type of nonionic surfactants, used in a wide variety of products such as household cleaning detergents, industrial cleaners, textiles, adjuvants in pesticides, wetting and dispersing agents, and emulsifiers. Our main objective in this work was to develop a methodology for the extraction, isolation and analysis of these compounds and their main degradation products and precursors (polyethylene glycols, PEGs) in solid environmental matrices. First, analytes were extracted by pressurized liquid extraction (PLE) using methanol at 120°C as solvent and 3 cycles (5 min per cycle). Clean-up and concentration of the extracts were carried out by solid-phase extraction (SPE), using Oasis HLB cartridges and a mixture dicloromethane/methanol 1:1 as eluting solvent. Recovery percentages were usually between 54% and 106% for most compounds. Identification and quantification of analytes were performed using a liquid chromatography-mass spectrometry (LC-MS) system equipped with an electrospray interface (ESI) operating in positive ionization mode. Water content, cone voltage and adduct formation were optimized to this end. Limits of detection were usually below 50 ng g(-1), being higher for some shorter ethoxymers (>100 ng g(-1)) because of poor ionization. Finally, the protocol proposed here was applied to the determination of the concentration of AEOs and PEGs in selected surface sediment samples collected in Mar Menor Lagoon (Murcia, Spain). In this sense, this paper presents some of the first data relative to the occurrence of these analytes in coastal sediments, showing relatively high concentrations of PEGs (up to 9000 ng g(-1)) compared to those measured for AEOs (<100 ng g(-1)).