Fast analysis of 4-tertoctylphenol, pentachlorophenol and 4-nonylphenol in river sediments by QuEChERS extraction procedure combined with GC-QqQ-MS/MS

Human health ambient water quality criteria and risk assessment of pentachlorophenol in Poyang Lake Basin, China

Pentachlorophenol (PCP) has been widely used as an insecticide for killing oncomelania (the intermediate host of schistosome) in China and leads to severe environmental contamination. Poyang Lake, as the largest freshwater lake and bird habitat in China, was once a schistosomiasis epidemic area. In this study, the concentrations of PCP in water and aquatic products from Poyang Lake were determined and analyzed, and then the human health ambient water quality criteria (AWQC) was derived based on native parameters of Poyang Lake basin. Finally, a comprehensive analysis of the health risks of drinking water and different types of aquatic products consumption was carried out. The results showed that PCP concentrations were ranged from 0.01 to 0.43 μg/L in surface water and 3.90 to 85.95 μg/kg in aquatic products. Due to the carcinogenicity of PCP, the human health AWQC for PCP are 0.02 μg/L for consumption of water and organisms and 0.03 μg/L for consumption of organisms only. Deterministic and probabilistic risk analysis indicated that the non-carcinogenic risk of PCP were acceptable in Poyang Lake, while the carcinogenic risk cannot be ignored. The health risks of PCP caused by aquatic products consumption were higher than that by drinking water. The percentages of acceptable risk for the population in Poyang Lake Basin were 99.95% at acceptable level of 10^-4. Based on the sensitivity analysis, the impact of PCP concentrations on health risk values ranged from 53 to 82%. The study provided valuable information for regional water quality criteria development and water quality assessment.

Simultaneous detection of multiple phenolic compounds in fish by gas chromatography-mass spectrometry following a modified QuEChERS cleanup

Phenolic compounds can cause health problems in humans through the food chain. Considering that fish play an important role in human diets, we established a rapid, simple and high-throughput method for the determination of 18 phenolic compounds in fish based on a modified QuEChERS sample preparation method combined with GC-MS. The average recovery of the 18 phenolic compounds was 81.3-116% at 3 spiked levels, and the relative standard deviations, RSD_r and RSD_wR, were in the range of 1.1-11.3% and 1.5-12.2%, respectively. The limit of detection was 2.0-10.1 μg/kg. Satisfactory linear relationships (R² > 0.998) were observed for the phenolic compounds in their corresponding concentration ranges. Moreover, the established method exhibited a high sensitivity, good stability, and reliability. The development of this method has an important theoretical and practical significance for establishing standards and to control the residue levels of phenolic compounds in fish.

Oxidative dehalogenation of trichlorophenol catalyzed by a promiscuous artificial heme-enzyme

The miniaturized metalloenzyme Fe(iii)-mimochrome VI*a (Fe(iii)-MC6*a) acts as an excellent biocatalyst in the H₂O₂-mediated oxidative dehalogenation of the well-known pesticide and biocide 2,4,6-trichlorophenol (TCP). The artificial enzyme can oxidize TCP with a catalytic efficiency (k_cat/K^TCP_m = 150 000 mM⁻¹ s⁻¹) up to 1500-fold higher than the most active natural metalloenzyme horseradish peroxidase (HRP). UV-visible and EPR spectroscopies were used to provide indications of the catalytic mechanism. One equivalent of H₂O₂ fully converts Fe(iii)-MC6*a into the oxoferryl-porphyrin radical cation intermediate [(Fe(iv) Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> O)por˙⁺], similarly to peroxidase compound I (Cpd I). Addition of TCP to Cpd I rapidly leads to the formation of the corresponding quinone, while Cpd I decays back to the ferric resting state in the absence of substrate. EPR data suggest a catalytic mechanism involving two consecutive one-electron reactions. All results highlight the value of the miniaturization strategy for the development of chemically stable, highly efficient artificial metalloenzymes as powerful catalysts for the oxidative degradation of toxic pollutants.

The artificial metalloenzyme FeMC6*a is able to perform the H₂O₂-mediated dechlorination of 2,4,6-trichlorophenol with unrivalled catalytic efficiency, highlighting its potential application for the removal of toxic pollutants.

Simultaneous determination of tetra-, penta- and hexachlorobutadienes in shellfish by gas chromatography-triple quadrupole mass spectrometry

Polychloro-1,3-butadienes (polyCBDs) are attracting increasing concern due to their high toxicity. However, research on multiple polyCBDs in aquatic biota is still extremely limited. In this study, a sensitive method for simultaneous determination of nine polyCBD (Cl₄-Cl₆) congeners, including six tetrachlorobutadiene (TeCBD) isomers, two pentachlorobutadiene (PeCBD) isomers, and hexachlorobutadiene (HCBD), in shellfish was developed based on accelerated solvent extraction (ASE), solid-phase extraction (SPE) clean-up and gas chromatography-triple quadrupole mass spectrometry (GC-QqQ-MS/MS). Low method limits of detection (MDLs) in the range 0.03-0.21 ng/g dry weight for target analytes with satisfactory recoveries (47.7 %-70.6 %) were achieved. The valid method was then applied to analyze nine polyCBDs congeners in 42 shellfish and 11 fish samples collected from markets in eight coastal cities, China. Trace HCBD was detected in 14 samples, while TeCBDs and PeCBDs were under the MDLs in all the samples, indicating little contamination of these pollutants in the marketed shellfish and fish in China. Multiple polyCBDs especially TeCBDs and PeCBDs were firstly involved in the proposed method and investigation here, which lay the groundwork for future research on the environmental behavior and exposure risks of polyCBDs in aquatic biotas.

Typical pesticides diffuse loading and degradation pattern differences under the impacts of climate and land-use variations

Riverine sediment can reconstruct the history of organic pollution loads and can provide reliable temporal information for pesticide metabolite dynamics in watershed. Sediment core samples were collected from two riverine sections of a cold watershed base in the presence land use change under agricultural development, and the vertical concentrations of four pesticides (atrazine, prometryn, isoprothiolane, and oxadiazon) and two atrazine metabolites (deisopropyl-atrazine and deethyl-atrazine) were determined by gas chromatography-mass spectrometry. The presence of pesticides and metabolites was detected at different depths (11-17 cm) at 1-cm intervals along the two sediment cores, and the flux was calculated with a constant rate of supply model based on the observed concentrations and ²¹⁰Pb isotope radioactivity chronology. By comparing the concentrations and fluxes of pesticides between the two sediment sections, significant differences in accumulation under different land-use patterns were found. Redundancy analysis further indicated that temporal watershed farmland variance was the dominant factor for pesticide loading. The lower concentration of atrazine and the higher concentration of the other pesticides in the estuarine sediment was closely related to the decreasing upland in the upstream area and the increase in paddy fields in the downstream area. The analysis of atrazine and the metabolites indicated that atrazine is more likely degraded to deethyl-atrazine and the metabolites have similar migration processes in the sediments, which can easily migrate downward. Moreover, the ratio of metabolites to atrazine showed that atrazine degradation was intensive during the transport process, but the metabolites efficiency was lower in this area due to the cold temperature. The results provide insights for the management of pesticide pollution control in watersheds and the potential effects of low temperature on the degradation of pesticides.

Facile and efficient 3-chlorophenol sensor development based on photolumenescent core-shell CdSe/ZnS quantum dots

Quantum dots (QDs) are semiconducting inorganic nanoparticles, tiny molecules of 2-10 nm sizes to strength the quantum confinements of electrons. The QDs are good enough to emit light onto electrons for exciting and returning to the ground state. Here, CdSe/ZnS core/shell QDs have been prepared and applied for electrochemical sensor development in this approach. Flat glassy carbon electrode (GCE) was coated with CdSe/ZnS QDs as very thin uniform layer to result of the selective and efficient sensor of 3-CP (3-chlorophenol). The significant analytical parameters were calculated from the calibration plot such as sensitivity (3.6392 µA µM-1 cm-2) and detection limit (26.09 ± 1.30 pM) with CdSe/ZnS/GCE sensor probe by electrochemical approach. The calibration curve was fitted with the regression co-efficient r2 = 0.9906 in the range of 0.1 nM ∼ 0.1 mM concentration, which denoted as linear dynamic range (LDR). Besides these, it was performed the reproducibility in short response time and successfully validated the fabricated sensor for 3-CP in the real environmental and extracted samples. It is introduced as a noble route to detect the environmental phenolic contaminants using CdSe/ZnS QDs modified sensor by electrochemical method for the safety of healthcare and environmental fields at broad scales.

Environmental Water Pollution, Endocrine Interference and Ecotoxicity of 4-tert-Octylphenol: A Review

4-tert-Octylphenol is a degradation product of non-ionic surfactants alkylphenol polyethoxylates as well as raw material for a number of industrial applications. It is a multimedia compound having been detected in all environmental compartments such as indoor air and surface waters. The pollutant is biodegradable, but certain degradation products are more toxic than the parent compound. Newer removal techniques from environmental waters have been presented, but they still require development for large-scale applications. Wastewater treatment by plant enzymes such as peroxidases offers promise in total removal of 4-tert-octylphenol leaving less toxic degradation products. The pollutant's endocrine interference has been well reported but more in oestrogens than in any other signalling pathways through which it is believed to exert toxicity on human and wildlife. In this paper we carried out a review of the activities of this pollutant in environmental waters, endocrine interference and relevance to its toxicities and concluded that inadequate knowledge of its endocrine activities impedes understanding of its toxicity which may frustrate current efforts at ridding the compound from the environment.

Simultaneous analysis of multiclass contaminants of emerging concern in sediments by liquid chromatography with tandem quadrupole mass spectrometry

A quick, easy, cheap, effective, rugged, and safe (QuEChERS)-based extraction and simultaneous dispersive solid-phase extraction (dSPE) clean-up method was developed for contaminants of emerging concern (CECs) in sediment samples. Hydration with a phosphate buffer (pH 2.0) and salting out with NaCl and MgSO₄ facilitated the extraction and liquid-liquid portioning of the aqueous and organic phases. Cleanup of the extracts was achieved by florisil and C18 (1:1) sorbents in dSPE with minimal compromise of the analytes. The extracts were clean enough for determination by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The procedure was validated for preservatives, blood lipid regulators, analgesics and anti-inflammatory drugs, plasticizers, and other classes of CECs in sediment matrix spiked at 6 levels between 1- and 40-fold concentrations for CECs of varying analytical sensitivities. The recovery values were generally between approximately 27 and 120% and the relative standard deviation (%RSD) values were below 20% at 10- , 20- , and 40-fold spiking levels, albeit the recoveries for some analytes dropped at low spike concentrations. The method showed high sensitivity where the method detection limits (MDLs) were at low ppb levels for the majority of the analytes that ranged between 0.002 and 1.93 µg/kg. The method performance was also compared with well-established US Environmental Protection Agency (USEPA) Method 1694 by analyzing sediment samples collected from Yundang Lagoon (Xiamen, China) with field-incurred CEC residues. The sediment samples were detected with residues of parabens, gemfibrozil, ketoprofen, naproxen, fenoprofen, diclofenac, miconazole, carbamazepine, benzophenon-3, glibenclamide, sildinafil citrate, and some bisphenol analogues. Environ Toxicol Chem 2019;38:1409-1422. © 2019 SETAC.

Biochar Immobilizes and Degrades 2,4,6-Trichlorophenol in Soils

Soil contamination by chlorophenol compounds, such as 2,4,6-trichlorophenol (2,4,6-TCP), is of great concern because they are environmentally persistent, are difficult to degrade, and can lead to cancer. Thus, means of degrading these compounds in situ are desperately needed. Biochar was investigated as a material to sequester, reduce downward transport, and aid in soil 2,4,6-TCP degradation. In 2 column studies, wheat straw (Triticum aestivum L.)-derived biochar (pyrolyzed at 450 °C) application to soil (up to 5% by wt) improved soil water and soil organic carbon content. Biochar reduced 2,4,6-TCP downward transport, likely attributable to improved soil water mobility and retention, allowing 2,4,6-TCP to be more easily transported and sorbed to organic functional groups on biochar, leading to enhanced degradation. The 2,4,6-TCP was rapidly degraded into a combination of benzene derivatives and low-molecular weight organic compounds in the first 2 mo following biochar application. The present study provides evidence that biochars can be used to improve environmental quality by lessening the downward transport and enhancing the degradation of organochlorine compounds such as 2,4,6-TCP. Environ Toxicol Chem 2019;38:1364-1371. © 2019 SETAC.

Biotoxin Tropolone Contamination Associated with Nationwide Occurrence of Pathogen Burkholderia plantarii in Agricultural Environments in China

Tropolone, a biotoxin produced by the agricultural pathogen Burkholderia plantarii, exerts cytotoxicity toward a wide array of biota. However, due to the lack of quantitative and qualitative approach, both B. plantarii occurrence and tropolone contamination in agricultural environments remain poorly understood. Here, we presented a sensitive and reliable method for detection of B. plantarii in artificial, plant, and environmental matrices by tropolone-targeted gas chromatography-triple-quadrupole tandem mass spectrometry analysis. Limits of detection for B. plantarii and tropolone were 10 colony-forming units (CFU)/mL and 0.017 μg/kg, respectively. In a series of simulation trials, we found that B. plantarii from 10 to 10⁸ CFU/mL produced tropolone between 0.006 and 107.8 mg/kg in a cell-population-dependent manner, regardless of habitat. Correlation analysis clarified a reliable reflection of B. plantarii density by tropolone level with R² values from 0.9201 to 0.9756 ( p < 0.01). Through a nationwide pilot study conducted in China, tropolone contamination was observed at 0.014-0.157 mg/kg in paddy soil and rice grains, and subsequent redundancy analysis revealed soil organic matter to be a dominant environmental factor, having a positive correlation with tropolone contamination. In this context, our results imply that potential ecological and dietary risks posed by long-term exposure to trace levels of tropolone contamination are of concern.

Dissipation, occurrence and risk assessment of a phenylurea herbicide tebuthiuron in sugarcane and aquatic ecosystems in South China

In this study, a modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) method coupled with UPLC-QqQ-MS/MS analysis was developed to detect tebuthiuron in sugarcane fields and the surrounding aquatic ecosystems. Methodological validation showed the method developed was of favorable sensitivity, reproducibility and accuracy. For assessment of its dietary and ecological risks, dissipation and occurrence of tebuthiuron in situ were further investigated through a supervised field trial and an aquatic environment monitoring carried out in six dominant sugarcane production regions in South China. After application at the range of recommended dose, tebuthiuron dominantly distributed in soil, and then dissipated in accordance with the first-order rate model with the half-lives of 12.2-21.5 d. At pre-harvest intervals (PHI), occurrence of tebuthiuron was found to be 0.718-1.366 mg/kg and 0.016-0.034 mg/kg, in sugarcane and soil, respectively. The supervised trials median residue (STMR) of tebuthiuron in sugarcane was thus 0.024 mg/kg and the dietary Risk Quotient (RQ_d) was accordingly calculated as 2.34 × 10^-4, indicating safety on long-term consumption of sugarcane with tebuthiuron residues. Yet high risks of tebuthiuron towards soil ecosystems was noticed as it possessed maximum ecological Risk Quotient (RQ_e) at 1.97 to earthworms. In sugarcane field-surrounding aquatic environment, distribution of tebuthiuron was found to range from 0.007 mg/L to 0.022 mg/L, leading to high risk towards the aquatic ecosystem due to the maximum RQ_e at 440 to algae, irrespective of its low risks to invertebrate and fish. Taken together, our approach serve as an effective tool for monitoring residual tebuthiuron environmentally and also advance in-depth understanding of dietary and ecological risks posed by the phenylurea herbicide.

Determination of pentachlorophenol by anodic electrochemiluminescence of Ru(bpy)32+ based on nitrogen-doped graphene quantum dots as co-reactant

A novel ultrasensitive Ru(bpy)₃²⁺-based anodic ECL sensor using NGQDs as co-reactant was developed for PCP detection.