Concentrations of 17 neuro-active pharmaceuticals and their major metabolites (bupropion, hydroxy-bupropion, erythro-hydrobupropion, threo-hydrobupropion, carbamazepine, ...10,11,-dihydro-10,11,-dihydroxycarbamazepine, 10-hydroxy-carbamazepine, citalopram, N-desmethyl-citalopram, fluoxetine, norfluoxetine, gabapentin, lamotrigine, 2-N-glucuronide-lamotrigine, oxcarbazepine, venlafaxine and O-desmethyl-venlafaxine), were measured in treated wastewater and receiving surface waters from 24 locations across Minnesota, USA. The analysis of upstream and downstream sampling sites indicated that the wastewater treatment plants were the major source of the neuro-active pharmaceuticals and associated metabolites in surface waters of Minnesota. Concentrations of parent compound and the associated metabolite varied substantially between treatment plants (concentrations±standard deviation of the parent compound relative to its major metabolite) as illustrated by the following examples; bupropion and hydrobupropion 700±1000ngL−1, 2100±1700ngL−1, carbamazepine and 10-hydroxy-carbamazepine 480±380ngL−1, 360±400ngL−1, venlafaxine and O-desmethyl-venlafaxine 1400±1300ngL−1, 1800±2300ngL−1. Metabolites of the neuro-active compounds were commonly found at higher or comparable concentrations to the parent compounds in wastewater effluent and the receiving surface water. Neuro-active pharmaceuticals and associated metabolites were detected only sporadically in samples upstream from the effluent outfall. Metabolite to parent ratios were used to evaluate transformation, and we determined that ratios in wastewater were much lower than those reported in urine, indicating that the metabolites are relatively more labile than the parent compounds in the treatment plants and in receiving waters. The widespread occurrence of neuro-active pharmaceuticals and metabolites in Minnesota effluents and surface waters indicate that this is likely a global environmental issue, and further understanding of the environmental fate and impacts of these compounds is warranted.
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•Neuro-active pharmaceuticals and their associated major metabolites were measured.•We evaluated wastewater and receiving rivers from 24 locations across Minnesota.•We utilized liquid chromatography time-of-flight mass spectrometry.•Metabolites generally are found at higher concentrations than parent compounds
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•Frac waters from the same formation can have vast differences in water quality.•Metal salts (5ppm) can reduce turbidity and hydrocarbon levels of frac waters.•Powder activated carbon ...can sorb PEGs and hydrocarbons in frac waters.•Coagulation-adsorption can reduce turbidity, DOC, PEGs, and TPH in frac waters.
Waters produced from fracturing operations in the oil and gas industry are a complex mixture of fracturing fluids and formation water. Closing the water cycle loop in this industry depends on the effective reuse of these wastewaters, and therefore treatment. This study investigated the application of chemical coagulants and powdered activated carbon (PAC) to reduce turbidity, dissolved organic carbon (DOC), total petroleum hydrocarbons (TPH), and polyethylene glycols (PEGs) in four hydraulic fracturing wastewaters. Jar tests were performed to evaluate both the PAC and coagulants. Treatment goals were operationally defined targeting 90% reduction of turbidity, PEGs, and TPH. PAC was found to be effective at removing both PEGs and TPH from the wastewaters, but would not settle without the addition of a coagulant. Ferric chloride achieved a 90% reduction in turbidity at a lower dose than aluminum chlorohydrate, in the presence and absence of PAC. The optimized coagulant dose by itself had little to no effect upon concentrations of DOC and PEGs, while greater than 80% removal of TPH, a minor component of DOC, was observed in three of the waters. PAC at 1000mgL−1 achieved greater than 80% reductions of the total ion chromatogram, while DOC removals were from 9.5 to 48.3%. These results suggest that coagulation with ferric chloride at doses as low as 5mgL−1 is an effective process for turbidity and TPH reduction in hydraulic fracturing wastewaters, and when coupled with PAC can also remove DOC and targeted organic contaminants such as PEGs.
Granular activated carbon (GAC) adsorption of 30 environmentally relevant micropollutants (MP) from four surface waters was investigated at the pilot-scale with empty bed contact times (EBCTs) of 7 ...and 15 min. An increase in background dissolved organic matter resulted in more and earlier MP breakthrough. Compared to an EBCT of 7 min, MP breakthrough at an EBCT of 15 min demonstrated 52% later breakthrough on average for five MPs on a throughput basis. A regression model was developed with data from three waters to predict MP throughput in bed volumes to 10% breakthrough (BV10%) based on the influent dissolved organic carbon concentration and the MP pH-dependent octanol–water partition coefficient, polarizability, and molecular volume. The regression model over predicted full-scale BV10% values when applied to a wastewater-water impacted water source and to GAC with a larger particle diameter, for which a particle size adjustment was able to account for most of the difference.
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•The 30 organic micropollutants studied broke though after DOC did in all five waters.•For the three runs with coagulated DOM and the same GAC, higher DOC0 caused earlier MP breakthrough.•A relationship for BV10% was developed with DOC0, MP log D, MP polarizability, and MP molecular volume.•Observed BV10% values in an anthropogenic impacted water were lower than predicted.
•Straightforward method to overcome matrix effects of produced water•Mass spectrometric detection enhanced with use of polymeric sorbents•Desalting and volumetric concentration both contribute to ...enhancement of signal•Polymeric sorbents are preferential for extraction of fracturing fluid additives•Solid-phase extraction enriches common fluid additives in raw and dilute samples
This work describes the development of a solid-phase extraction method capable of detecting common fracturing fluid additives in flowback and produced water with mass spectrometry. Dissolved organic carbon (DOC) was used as a bulk measurement to investigate the retentive capacity of seven sorbents and to determine a loading volume. Conductivity was used to determine rinse volume. Based on this, four sorbents (HLB, PPL, Carbon, and C-18) were selected for further investigation of their ability to recover common fluid additives. Enrichment factors were calculated for poly(ethylene) glycols (PEGs), PEG-amines, and their metabolites PEG-carboxylates and PEG-carboxylate-amines, poly(propylene) glycols (PPGs), and linear alkyl ethoxylates (LAEs). The sorbent HLB gave the greatest enrichment for all of these compounds, with an average of 8.0× for PEGs, 11.9× for PEG-amines, 4.9× for PEG-carboxylates, and 21.6× for LAEs, though enrichment was highly dependent on sample composition. The effect was more pronounced for higher molecular weight compounds and enabled detection of some compounds in saltier samples. Then, HLB was used to recover these additives from 1:200 and 1:1000 dilutions in groundwater, illustrating the ability of solid-phase extraction to detect these compounds at low levels (<100 ppb) and highlighting the utility of desalting. This method was used to identify ethoxylated amines in flowback and produced waters from across the country.
To simulate the effects of wildfire on the combustion process in soils and their potential to leach organic compounds into streams and groundwater, mineral soil samples were heated at temperatures of ...150–550 °C. Then, the soils were leached with deionized water, filtered, and analyzed for dissolved organic carbon. The water extract was concentrated by both XAD-8 and XAD-4 resins and analyzed by C-13 nuclear magnetic resonance and liquid chromatography time-of-flight mass spectrometry. Approximately 15–20% of the water-extractable organic carbon was identified as benzene dicarboxylic acids, tricarboxylic acids, and tetracarboxylic acid isomers, commonly called BPCAs. Also identified were isomers of pyridine dicarboxylic acids and tricarboxylic acids (PCAs). The conversion of soil organic carbon to BPCAs occurs at 250 °C and reaches a maximum between 350 and 450 °C. At higher temperatures (>450 °C), the BPCA concentrations decrease, suggesting decarboxylation and conversion to carbon dioxide and water. This is the first report of BPCAs and PCAs in water-extractable organic carbon from thermally altered soil and suggest that these compounds are possible candidates for further water-quality studies in watersheds affected by wildfire. Finally, BPCAs and PCAs could contribute to the black carbon and nitrogen in seawater and are worthy of future investigation.
•We used fragmentation patterns to identify NDMA precursors in environmental samples.•Two diagnostic fragments were found to be specific to representative NDMA precursors.•We identified 16 NDMA ...precursors in isolates of 12 drinking water supplies.•We identified 5 new NDMA precursors, of which, 3 were metabolites of pharmaceuticals.
N-Nitrosodimethylamine (NDMA) is carcinogenic in rodents and occurs in chloraminated drinking water and wastewater effluents. NDMA forms via reactions between chloramines and mostly unidentified, N-containing organic matter. We developed a mass spectrometry technique to identify NDMA precursors by analyzing 25 model compounds with LC/QTOF-MS. We searched isolates of 11 drinking water sources and 1 wastewater using a custom MATLAB® program and extracted ion chromatograms for two fragmentation patterns that were specific to the model compounds. Once a diagnostic fragment was discovered, we conducted MS/MS during a subsequent injection to confirm the precursor ion. Using non-target searches and two diagnostic fragmentation patterns, we discovered 158 potential NDMA precursors. Of these, 16 were identified using accurate mass combined with fragment and retention time matches of analytical standards when available. Five of these sixteen NDMA precursors were previously unidentified in the literature, three of which were metabolites of pharmaceuticals. Except methadone, the newly identified precursors all had NDMA molar yields of less than 5%, indicating that NDMA formation could be additive from multiple compounds, each with low yield. We demonstrate that the method is applicable to other disinfection by-product precursors by predicting and verifying the fragmentation patterns for one nitrosodiethylamine precursor.
This work describes the discovery of amino-poly(ethylene glycol)s, amino-poly(ethylene glycol) carboxylates, and amino-poly(ethylene glycol) amines in 20 produced water samples from hydraulic ...fracturing in the western United States. These compounds, with masses in the range of m/z 120–986, were identified using solid-phase extraction and liquid chromatography/quadrupole time-of-flight mass spectrometry. The polymeric sorbent, Oasis HLB, gave good recovery for all three ethoxylated surfactants and desalted the samples, which significantly reduced suppression of the mass spectral signal allowing detection and identification. The Kendrick mass defect, mass spectra, fragmentation pathways, and pure standards were used for confirmation. Finally, because these compounds are not explicitly listed in FracFocus reports, rather they are categorized as a proprietary surfactant blend; their identification is an important step in understanding the chemistry, treatment, and possible toxicity of hydraulic fracturing wastewater.
Ash and surface water samples collected after wildfires in four different geographical locations (California, Colorado, Kansas and Alberta) were analyzed. The ash samples were leached with deionized ...water, and leachates were concentrated by solid phase extraction and analyzed by liquid chromatography/time-of-flight mass spectrometry. In addition, three surface water samples and a lysimeter water sample were collected from watersheds recently affected by fire in California and Colorado, and analyzed in similar fashion. A suite of benzene polycarboxylic acids (BPCAs), with two and three carboxyl groups and their corresponding isomers were identified for the first time in both ash leachates and water samples. Also found was a pyridine carboxylic acid (PCA), 3,5-pyridine dicarboxylic acid. Furthermore, putative identifications were made for other carboxylated aromatic acids: quinolinic, naphthalenic, and benzofuranoic acid carboxylates. The wildfire ashes, a controlled wood ash, and post-fire surface water samples suggest that burned woody material, along with surface plant-material and heated o-horizon soil organic matter, contribute to both BPCAs and PCAs in runoff. This study is the first of its kind to identify this suite of aromatic acids in wildfire ash and surface water samples. These data make an important contribution to the nature of dissolved organic matter from wildfire and are useful to better understand the impact of wildfire on water quality and drinking water sources.
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•Aromatic polycarboxylic acids are present in wildfire ash and surface water.•Woody materials are an important source of BPCAs and PCAs in ash and water.•Other families of aromatic acids were identified by HRMS MS2 analysis.•New families include: quinoline, naphthalene and benzofuran polycarboxylates.
In-stream attenuation was determined for 14 neuro-active pharmaceuticals and associated metabolites. Lagrangian sampling, which follows a parcel of water as it moves downstream, was used to link ...hydrological and chemical transformation processes. Wastewater loading of neuro-active compounds varied considerably over a span of several hours, and thus a sampling regime was used to verify that the Lagrangian parcel was being sampled and a mechanism was developed to correct measured concentrations if it was not. In-stream attenuation over the 5.4-km evaluated reach could be modeled as pseudo-first-order decay for 11 of the 14 evaluated neuro-active pharmaceutical compounds, illustrating the capacity of streams to reduce conveyance of neuro-active compounds downstream. Fluoxetine and N-desmethyl citalopram were the most rapidly attenuated compounds (t 1/2 = 3.6 ± 0.3 h, 4.0 ± 0.2 h, respectively). Lamotrigine, 10,11,-dihydro-10,11,-dihydroxy-carbamazepine, and carbamazepine were the most persistent (t 1/2 = 12 ± 2.0 h, 12 ± 2.6 h, 21 ± 4.5 h, respectively). Parent compounds (e.g., buproprion, carbamazepine, lamotrigine) generally were more persistent relative to their metabolites. Several compounds (citalopram, venlafaxine, O-desmethyl-venlafaxine) were not attenuated. It was postulated that the primary mechanism of removal for these compounds was interaction with bed sediments and stream biofilms, based on measured concentrations in stream biofilms and a column experiment using stream sediments.
A rapid screening method for the detection of nontargeted compounds in surface water samples was developed using MS-MS high-resolution mass spectrometry and data-dependent acquisition. The key ...parameters for the acquisition method were optimized using five model compounds with diverse chemical characteristics. The parameter selection required optimization between the total number of precursor ions that could be selected in an LC-MS run, the quality of each MS (full range) spectrum, and the quality of each MS-MS fragmentation spectrum. After the acquisition method was optimized, 18 surface water samples from rivers, reservoirs, and effluents from wastewater treatment plants were analyzed, generating 41625 MS-MS spectra in about 14 h. The raw data were then converted into two generic formats using the open-access program MSConvert. A combinatorial approach, similar partition searching (SPS), was then used to putatively identify analytes from the accurate mass of each analyte (adjusted for the adduct mass) and the corresponding MS-MS spectra were obtained. In this approach, the structures of about 250000 common compounds, stored in a large database as mathematical partitions of their exact mass, were compared directly to each MS-MS spectrum. Compounds with a similar mass and retention time were grouped together and labeled as "Analytes", using an Excel Add-In. The isotope ratio data from the MS spectrum, the corresponding MS-MS spectra, and the putative identifications were then imported into an Access relational database to facilitate sorting, searching, filtering, and querying the results. This allowed final inspection to assess confidence of the identifications made through the nontargeted screening.
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