Endocrine disrupting chemicals (EDCs) can be released to coastal waters and affect the endocrine system of marine organisms. To monitor their levels in seawaters, a simple, robust passive sampling ...method, the diffusive gradients in thin-films (DGT) technique, was developed with XDA-1 resin as a binding agent. Six EDCs (including three estrogens, two pesticides and bisphenol A) were used to assess the performance of the DGT. The XDA-1 binding gel showed adequate ability for adsorbing EDCs in seawaters. The DGT sampler exhibited linear accumulation for the EDCs during a 15-day deployment and diffusion coefficients and sampling rates were calculated. The DGT measurement was independent of pH in the range 7.0–9.0 and ionic strength in the range 0.4–0.8 M. Field applications of this DGT in a coast of Dalian (China) showed comparable results to those from grab sampling. Five EDCs were detected with concentrations ranging from 0.7 to 19.4 ng L−1. This study is a first attempt to apply DGT sampler for determining EDCs in seawaters.
•XDA-DGT was developed for determining EDCs in seawaters.•XDA-DGT is suitable for a range of pH (7–9) and ionic strength (0.4–0.8 M).•XDA-DGT showed good linear uptakes for EDCs over 15 d in artificial seawater.
Sulfonamide antibiotics (SAs) are increasingly detected as aquatic contaminants and exist as different dissociated species depending on the pH of the water. Their removal in sunlit surface waters is ...governed by photochemical transformation. Here we report a detailed examination of the hydroxyl radical (•OH) and singlet oxygen (1O2) mediated photooxidation of nine SAs: sulfamethoxazole, sulfisoxazole, sulfamethizole, sulfathiazole, sulfamethazine, sulfamerazine, sulfadiazine, sulfachloropyridazine and sulfadimethoxine. Both •OH and 1O2 oxidation kinetics varied depending on the dominant protonated states of the SA in question (H2SAs+, HSAs0 and SAs−) as a function of pH. Based on competition kinetic experiments and matrix deconvolution calculations, HSAs0 or SAs− (pH ∼5–8) were observed to be more highly reactive towards •OH, while SAs− (pH ∼8) react the fastest with 1O2 for most of the SAs tested. Using the empirically derived rates of reaction for the speciated forms at different pHs, the environmental half-lives were determined using typical 1O2 and •OH concentrations observed in the environment. This approach suggests that photochemical 1O2 oxidation contributes more than •OH oxidation and direct photolysis to the overall phototransformation of SAs in sunlit waters. Based on the identification of key photointermediates using tandem mass spectrometry, 1O2 oxidation generally occurred at the amino moiety on the molecule, whereas •OH reaction experienced multi-site hydroxylation. Both these reactions preserve the basic parent structure of the compounds and raise concerns that the routes of phototransformation give rise to intermediates with similar antimicrobial potency as the parent SAs. We therefore recommend that these phototransformation pathways are included in risk assessments concerning the presence and fate of SAs in waste and surface waters.
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•Aquatic photooxidation of sulfonamides (SAs) via reactive oxygen species is important.•The kinetics depend on pH and separate reactivities of H2SAs+, HSAs0 and SAs−.•1O2 plays a key role in aquatic fate of SAs compared with •OH and direct photolysis•Different primary pathways and multiple intermediates occur for the three reactions.
As coastal waters in many regions of the world have been polluted by organic micro-pollutants such as antibiotics that can promote the development of resistance genes, it is of importance to monitor ...the levels of antibiotics in coastal waters. For this purpose, a reliable and robust sampling approach based on diffusive gradients in thin films (DGT) was developed in this study. The DGT measurement can provide a time weighted average concentration of pollutants. A binding material (resin XDA-1) with a high adsorption capacity for antibiotics, which can resist the pH and ionic strength of seawaters, was selected. The DGT sampler exhibited linear accumulation for 20 antibiotics during a 12h deployment. The antibiotic measurement by the sampler was not affected by pH in the range of 7.3 to 8.9 and ionic strength in the range of 0.5 to 0.8M. After an 8-hour in situ DGT sampling, 10 antibiotics were detected in Dalian coastal seawaters with the concentrations ranging from 2.6 to 44.8ngL−1, which was comparable to the results measured by an active sampling method. This study can be a first attempt to construct DGT sampler for determining antibiotics in seawaters.
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•A novel DGT device was developed for sampling antibiotics in seawaters.•XDA-1 resin was selected as the binding material from eight resins.•10 antibiotics were detected by the developed DGT in a coast of Dalian, China.
The light-absorbing organic aerosol referred to as brown carbon (BrC) affects the global radiative balance. The linkages between its molecular composition and light absorption properties and how ...environmental factors influence BrC composition are not well understood. In this study, atmospheric dissolved organic matter (ADOM) in 55 aerosol samples from Guangzhou was characterized using Fourier transform ion cyclotron resonance mass spectrometry and light absorption measurements. The abundant components in ADOM were aliphatics and peptide-likes (in structure), or nitrogen- and sulfur-containing compounds (in elemental composition). The light absorption properties of ADOM were positively correlated with the levels of unsaturated and aromatic structures. Particularly, 17 nitrogen-containing species, which are identified by a random forest, characterized the variation of BrC absorption well. Aggregated boosted tree model and nonmetric multidimensional scaling analysis show that the BrC composition was largely driven by meteorological conditions and anthropogenic activities, among which biomass burning (BB) and OH radical were the two important factors. BrC compounds often accumulate with elevated BB emissions and related secondary processes, whereas the photolysis/photooxidation of BrC usually occurs under high solar radiance/•OH concentration. This study first illuminated how environmental factors influence BrC at the molecular level and provided clues for the molecular-level research of BrC in the future.
It is essential to monitor pesticides in the environment to help ensure water and soil quality. The diffusive gradients in thin-films (DGT) technique can measure quantitative in situ labile ...(available) concentrations of chemicals in water, soil, and sediments. This study describes the systematic development of the DGT technique for nine current pesticides, selected to be representative of different classes with a wide range of properties, with two types of resins (HLB (hydrophilic-lipophilic-balanced) and XAD 18) as binding layer materials. The masses of pesticides accumulated by DGT devices were proportional to the deployment time and in inverse proportion to the thickness of the diffusive layer, in line with DGT theoretical predictions. DGT with both resin gels were tested in the laboratory for the effects of typical environmental factors on the DGT measurements. DGT performance was independent of the following: pH in the range of 4.7–8.2; dissolved organic matter concentrations <20 mg L–1; and ionic strength from 0.01 to 0.25 M, although it was slightly affected at 0.5 M in some cases. This confirms DGT as a sampler suitable for controlled studies of environmental processes affecting pesticides. Field applications of DGT to measure pesticides in situ in waters and controlled laboratory measurements on five different soils (prepared at fixed soil/water ratios) demonstrated DGT is a suitable tool for environmental monitoring in waters and for investigating chemical processes in soils.
Recent industrial relocation in China causes lots of environment concerns including risks of emerging contaminants (ECs). Herein, the occurrence, fate, removal and ecological risks of 34 per- and ...polyfluoroalkyl substances (PFAS), 17 endocrine disrupting chemicals (EDCs), 16 phthalate esters (PAEs), and 23 polycyclic aromatic hydrocarbons (PAHs) were investigated in two textile WWTPs (conventional and Fenton-modified) from a large textile industrial park in Southwest China. Totally 50 ECs were identified and the levels followed the order of PAEs > EDCs > PFAS ≈ PAHs. The EDCs predominated in textile washing and rinsing wastewater whereas the PAEs did in desizing wastewater. Biphasic correlations of log Kd and log P, molecular weight, and numbers of rings (r2 = 0.63–0.66, p < 0.01) were observed for PAHs, suggesting that hydrophobicity might not facilitate adsorption of super-hydrophobic PAHs onto activated sludge. 63–69% of detected ECs were effectively removed by two textile WWTPs with removal efficiencies ≥ 80%, which were much higher than previous reports. Fenton processing enhanced the removal efficiencies for long-chain PFAS rather than short-chain PFAS. The PAEs and EDCs posed a medium-to-high risk to aquatic organisms and were screened as the priority ECs. To date, such a comprehensive investigation for ECs has not been previously conducted in textile WWTPs and this study provides basic information about regional chemical emission inventory of ECs.
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•50 ECs were detected in textile WWTPs with levels of PAEs > EDCs > PFAS ≈ PAHs.•Significant co-occurrence patterns were observed for the PAEs, EDCs, and PAHs.•Over 60% of detected ECs were efficiently removed by the textile WWTPs.•Fenton oxidation process enhanced removal efficiencies of long-chain PFAS.•The residual PAEs and EDCs posed a medium-to-high risk to aquatic organisms.
•Distinct photochemistry of two dissociated FQs (H2FQs+, HFQs0 and FQs−) was reported.•HFQs0 had the highest apparent photolytic efficiency and ·OH oxidation reactivity.•Relevance and pathways of ...these reactions were clarified based on key photoproducts.•Antibacterial activity of GAT to E. coli. persisted even after notable photolysis.
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Fluoroquinolone antibiotics (FQs) are ubiquitous and ionisable in surface waters. Here we investigate gatifloxacin (GAT) and balofloxacin (BAL), two widely used FQs, and determine the photochemical reactivity of their respective dissociation species that arise at different pH to understand the relevance and pathways of phototransformation reactions. Simulated-sunlight experiments and matrix calculations showed that neutral forms (HFQs0) of the two antibiotics had the highest apparent photolytic efficiency and hydroxyl-radical oxidation reactivity. Based on the pH-dependent photochemical reactivities, the solar apparent photodegradation half-lives (t1/2) in sunlit surface waters ranged from 14.5–169min and was 1–2 orders of magnitude faster than hydroxyl-radical induced oxidation (t1/2=20.9–29.8h). The corresponding pathways were proposed based on the identification of key intermediates using HPLC-ESI-MS/MS. The apparent photodegradation induced defluorination, decarboxylation, and piperazinyl oxidation and rearrangement, whereas hydroxyl-radical oxidation caused hydroxylated defluorination and piperazinyl hydroxylation. The photomodified toxicity of GAT and BAL was examined using an Escherichia coli activity assay. E. coli activity was not affected by BAL, but was significantly affected by the photo-modified solutions of GAT, indicating that primary photo-degradates have a comparable or higher antibacterial activity than the parent GAT. In fresh water and seawater this antibacterial activity remained high for up to 24h, even after GAT had undergone significant photodegradation (>1 half-life), indicating the potential impact of this chemical on microbial communities in aquatic systems.
A novel passive water sampler (diffusive gradients in thin-films for organics, o-DGT) was previously developed and successfully tested in the laboratory, but has not yet been validated in the field. ...Here, o-DGT samplers were deployed in the influent and effluent of a typical UK wastewater treatment plant (WWTP); the influent was also sampled with a conventional automatic sampler (Auto) and by grab (Grab) sampling. All the samples were analyzed by LC-MS/MS for 40 target antibiotics (including 16 sulfonamides (SAs), 12 fluoroquinolones, 6 macrolides, 2 ionophores, 2 diaminopyimidines, 1 aminocoumarin, and 1 lincosamide). The diffusion coefficients (D) of these antibiotics in o-DGT, measured in the laboratory, ranged from 0.58 × 10–06 to 6.24 × 10–06 cm2 s–1. The derived surface area normalized sampling rates (R S/A, 0.54–5.74 mL d–1 cm–2) were comparable with those for another passive sampler called POCIS. Fourteen antibiotics were detected in the actively sampled water samples, with 10 of the 14 detected in o-DGT devices deployed for more than 7 days. Most of the antibiotics detected in o-DGT, except sulfapyridine, were continually accumulated by o-DGT for ∼10 days. Deployment for 7 days is recommended to integrate ambient concentrations over time, without risks of reaching capacity and significant biofouling. Diffusive boundary layer (DBL) thickness had less effect on the o-DGT measurement than reported for other passive samplers. The comparison between o-DGT and Auto and Grab samplings showed that o-DGT was more efficient in terms of cost, time, and labor. This study demonstrates for the first time in a real environment that o-DGT is an effective tool for the routine monitoring of antibiotics in wastewaters and provides a powerful approach to studying their occurrence, fate, and behavior in the environment.
•Juvenile brown trout were exposed to n-TiO2, PCB77, and n-TiO2-PCB77 mixtures via the diet.•The presence of n-TiO2 in the test diet affected PCB77 availability.•Dietary co-exposure to n-TiO2 and ...PCB77 led to combination effects on intestinal tight junction protein (zo-1) expression.•An object resembling n-TiO2 was imaged inside the Space of Disse of a liver sinusoid suggesting NP transport to the liver.•n-TiO2 had a potentiating effect on PCB77-induced biomarker responses in the liver.
Titanium dioxide nanoparticles (n-TiO2) are among the man-made nanomaterials that are predicted to be found at high concentrations in the aquatic environment. There, they likely co-exist with other chemical pollutants. Thus, n-TiO2 and other chemical pollutants can be taken up together or accumulate independently from each other in prey organisms of fish. This can lead to dietary exposure of fish to n-TiO2-chemical pollutant mixtures. In this study, we examine if simultaneous dietary exposure to n-TiO2 and 3,3’,4,4’-Tetrachlorobiphenyl (PCB77) –used as a model compound for persistent organic pollutants with dioxin-like properties– can influence the uptake and toxicological response elicited by the respective other substance. Juvenile brown trout (Salmo trutta) were fed custom-made food pellets containing n-TiO2, PCB77 or n-TiO2+PCB77 mixtures for 15 days. Ti and PCB77 concentrations in the liver were measured by ICP-MS and GC–MS, respectively. Besides, n-TiO2 uptake was assessed using TEM. Combination effects on endpoints specific for PCB77 (i.e., cytochrome P450 1A (CYP1A) induction) and endpoints shared by both PCB77 and n-TiO2 (i.e., oxidative stress-related parameters) were measured in intestine and liver using RT-qPCR and enzyme activity assays. The results show that genes encoding for proteins/enzymes essential for tight junction function (zo-1) and ROS elimination (sod-1) were significantly upregulated in the intestine of fish exposed to n-TiO2 and PCB77 mixtures, but not in the single-substance treatments. Besides, n-TiO2 had a potentiating effect on PCB77-induced CYP1A and glutathione reductase (GR) expression/enzyme activity in the liver. This study shows that simultaneous dietary exposure to nanomaterials and traditional environmental pollutants might result in effects that are larger than observed for the substances alone, but that understanding the mechanistic basis of such effects remains challenging.
Widespread use of organic chemicals in household and personal care products (HPCPs) and their discharge into aquatic systems means reliable, robust techniques to monitor environmental concentrations ...are needed. The passive sampling approach of diffusive gradients in thin-films (DGT) is developed here and demonstrated to provide in situ quantitative and time-weighted average (TWA) measurement of these chemicals in waters. The novel technique is developed for HPCPs, including preservatives, antioxidants and disinfectants, by evaluating the performance of different binding agents. Ultrasonic extraction of binding gels in acetonitrile gave good and consistent recoveries for all test chemicals. Uptake by DGT with HLB (hydrophilic–lipophilic-balanced) as the binding agent was relatively independent of pH (3.5–9.5), ionic strength (0.001–0.1 M) and dissolved organic matter (0–20 mg L–1), making it suitable for applications across a wide range of environments. Deployment time and diffusion layer thickness dependence experiments confirmed DGT accumulated chemicals masses are consistent with theoretical predictions. The technique was further tested and applied in the influent and effluent of a wastewater treatment plant. Results were compared with conventional grab-sampling and 24-h-composited samples from autosamplers. DGT provided TWA concentrations over up to 18 days deployment, with minimal effects from biofouling or the diffusive boundary layer. The field application demonstrated advantages of the DGT technique: it gives in situ analyte preconcentration in a simple matrix, with more quantitative measurement of the HPCP analytes.
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