Water Analysis: Emerging Contaminants and Current Issues

Database and review of disinfection by-products since 1974: Constituent elements, molecular weights, and structures

Since trihalomethanes were discovered in 1974, disinfection by-products (DBPs) in drinking water have attracted extensive attention. In 2011, more than 600 known DBPs were compiled; however, newly reported DBPs have not been integrated. The rapid development of mass spectrometry has led to a significant increase in the number of DBPs, therefore, there is a need to develop a database of all DBPs and their properties. Herein, a database including 6310 DBPs (651 confirmed, 1478 identified and 4142 proposed) reported between 1974 and 2022 was constructed and made available for public use at https://dbps.com.cn/main. This database can be a tool in screening new DBPs, comprehensively reviewing, and developing predictive models. In this paper, to demonstrate the functions of the database and provide useful information for this area, the origin of the collected DBPs was presented, and some basic information, including elemental composition, molecular weight, functional groups, and carbon frameworks, were comparatively analyzed. The results showed that the proportion of DBPs verified by standard compounds and frequently detected in real water is less than 7.0%, and most of DBPs remained to be identified. Approximately 88% of DBPs contain halogens, and brominated -DBPs occupied a similar ratio to chlorinated -DBPs in real water. Acids were the main functional groups of DBPs, aliphatic and aromatic compounds are the two major carbon frameworks, and the molecular weights of most DBPs ranged from 200 to 400 Da. In addition, 4142 proposed DBPs as obtained using high-resolution mass spectrometry, were characterized based on the modified van Krevelen diagram and adjusted indexes with halogens. Most of the proposed DBPs featured lignin and tannin structures, and phenolic/highly unsaturated DBPs account for the majority.

A mechanothermal approach for the synthesis of Fe3O4 nanoparticles as dopant on mesoporous TiO2 for electrochemical determination of catechol

The subject of water contamination and how it gets defiled to the society and humans is confabulating from the past decades. Phenolic compounds widely exist in the water sources and it is emergent to determine the toxicity in natural and drinking water, because it is hazardous to the humans. Among these compounds, catechol has sought a strong concern because of its rapid occurrence in nature and its potential toxicity to humans. The present work aims to develop an effective electrochemical sensing of catechol using mesoporous structure of Fe₃O₄-TiO₂ decorated on glassy carbon (GC) electrode. The creation of pure TiO₂ using the sol-gel technique was the first step in the synthesis protocol for binary nanocomposite, which was then followed by the loading of Fe₃O₄ nanoparticles on the surface of TiO₂ using the thermal decomposition method. The resultant Fe₃O₄-TiO₂ based nanocomposite exhibited mesoporous structure and the cavities were occupied with highly active magnetite nanoparticles (Fe₃O₄) with high specific surface area (90.63 m²/g). When compared to pure TiO₂, catechol showed a more prominent electrochemical response for Fe₃O₄-TiO₂, with a significant increase in anodic peak current at a lower oxidation potential (0.387 V) with a detection limit of 45 μM. Therefore, the prepared magnetite binary nanocomposite can serve as an efficient electroactive material for sensing of catechol, which could also act as a promising electrocatalyst for various electrocatalytic applications.

Nitrogen-rich based conjugated microporous polymers for highly efficient adsorption and removal of COVID-19 antiviral drug chloroquine phosphate from environmental waters

Chloroquine phosphate (CQP) has been suggested as an important and effective clinical reliever medication for the 2019 coronavirus (COVID-19). Nevertheless, its excessive use will inevitably cause irreparable damage to the entire ecosystem, thereby posing a considerable environmental safety concern. Hence, the development of highly-efficient methods of removing CQP from water pollution sources, e.g., effluents from hospitals and pharmaceutical factories is significant. This study reported the fabrication of novel C—N bond linked conjugated microporous polymers (CMPs) (BPT–DMB–CMP) with multiple nitrogen-rich anchoring sites for the quick and efficient removal of CQP from aqueous solutions. The irreversible covalent C—N bond linked in the internal framework of BPT–DMB–CMP endowed it with good chemical stability and excellent adsorbent regeneration. With its predesigned functional groups (i.e., rich N—H bonds, triazine rings, and benzene rings) and large area surface (1,019.89 m²·g⁻¹), BPT–DMB–CMP demonstrated rapid adsorption kinetics (25 min) and an extraordinary adsorption capacity (334.70 mg·g⁻¹) for CQP, which is relatively higher than that of other adsorbents. The adsorption behavior of CQP on BPT–DMB–CMP corresponded with Liu model and mixed-order model. Based on the density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS), and adsorption comparisons test, the halogen bonding, and hydrogen bonding cooperates with π − π, C — H···π interactions and size-matching effect in the CQP adsorption system on BPT–DMB–CMP. The excellent practicability for the removal of CQP from real wastewater samples verified the prospect of practical application of BPT–DMB–CMP. BPT–DMB–CMP exhibited the application potentials for the adsorption of other antiviral drugs. This work opens up an efficient, simple, and high adsorption capacity way for removal CQP.

Polyurethane/Vermiculite Foam Composite as Sustainable Material for Vertical Flame Retardant

Rigid polyurethane foams were prepared by the one-step expandable foam method using casting molding followed by forming clay-based composites. Polyurethane/vermiculite foam composites (PU/VMT) were controlled based on adding the percentage of clay in the formulation. The effects of composite modifications were evaluated by X-ray diffraction (XRD), thermogravimetric analysis (TG/DTG), and scanning electron microscopy (SEM/EDS) applied to the flame retardancy explored by the vertical burn test. The results indicated that adding clay controlled the particle size concerning polyurethane (PU) foams. However, they exhibited spherical structures with closed cells with relatively uniform distribution. XRD analysis showed the peaks defined at 2θ = 18° and 2θ = 73° relative to the crystallinity in formation and interaction of rigid segments were identified, as well as the influence of crystallinity reduction in composites. In the flame test, the flame retardant surface was successful in all composites, given the success of the dispersibility and planar orientation of the clay layers and the existence of an ideal content of vermiculite (VMT) incorporated in the foam matrix.

Detection and remediation of chiral pharmaceuticals from wastewater: A review

Chiral organic pollutants including pharmaceuticals, pesticides, herbicides, flame retardants, and polycyclic musk cause significant risks to both the environment and human health. Chiral pharmaceuticals (CPs) are among the significant class of pseudo-persistent substances that have been observed in the concentration level from nanomolar to micromolar quantities and cause bad impacts on nontargeted species and direct or indirect human health issues due to water and foodborne contamination. The CPs may contain one or more chiral centers in their structural framework and thus enantiomers of CPs often possess different distribution, fate, bioaccumulation potential, and toxicity. The enantioselective chromatographic techniques have been extensively applied to detect drug enantiomers during the last few years. Bioremediation techniques offer unique characteristics above conventional remediation procedures as these could be cost-effective and accomplish total organic pollutant decomposition without causing collateral damage to the site material or native flora and fauna. This review describes the impacts of chiral pharmaceuticals on the environment; detection technologies (particularly liquid chromatography), and important remedial measures for safer disposal of such pollutants.

Hybrid Inorganic-Organic Visible-Light-Driven Microrobots Based on Donor-Acceptor Organic Polymer for Degradation of Toxic Psychoactive Substances

Light-driven microrobots based on organic semiconductors have received tremendous attention in the past few years due to their unique properties, such as ease of reactivity tunability, band-gap modulation, and low cost. However, their fabrication with defined morphologies is a very challenging task that results in amorphous microrobots with poor motion efficiencies. Herein, we present hybrid inorganic-organic photoactive microrobots with a tubular shape and based on the combination of a mesoporous silica template with an active polymer containing thiophene and triazine units (named as Tz-Th microrobots). Owing to their well-defined tubular structure, such Tz-Th microrobots showed efficient directional motion under fuel-free conditions. Depending on the accumulation of the polymer coating, these microdevices also exhibited stand-up and rotation motion. As a proof-of-concept, we use these hybrid microrobots for the capture and degradation of toxic psychoactive drugs commonly found in wastewater effluents such as methamphetamine derivatives. We found that the microrobots were able to decompose the drug into small organic fragments after 20 min of visible light irradiation, reaching total intermediates removal after 2 h. Therefore, this approach represents a versatile and low-cost strategy to fabricate structured organic microrobots with efficient directional motion by using inorganic materials as the robot chassis, thereby maintaining the superior photocatalytic performance usually associated with such organic polymers.

Occurrence, spatial distribution, and fate of polycyclic musks in sediments from the catchment of Chaohu Lake, China

Twenty-nine surface sediments from Chaohu Lake in China and from its six main tributaries were sampled to investigate the concentrations of two important polycyclic musks (PCMs), 1,3,4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran (galaxolide, HHCB) and 7-acetyl-1,1,3,4,4,6-hexamethyl-1,2,3,4-tetrahydronaphthalene (tonalide, AHTN), as well as the concentration of 4,6,7,8-hexahydro-4,6,6,7,8,8-hexamethylcyclopenta(g)-2-benzopyran-1-one (galaxolidon, HHCB-lactone), which is the main degradation product of HHCB. Except for the high concentrations of AHTN and HHCB measured in the Nanfei River (879 ng/g dw and 5,513 ng/g dw, respectively), the levels of AHTN and HHCB in the river sediments were 7.08-44.9 ng/g dw and 20.6-268 ng/g dw, respectively, which are slightly lower than those documented in various areas worldwide. The concentrations of AHTN and HHCB in the sediments of Chaohu Lake were one or two orders of magnitude lower than those in the tributary rivers and showed a clear regional distribution. The concentrations of HHCB-lactone were comparable to those of HHCB and presented a significant positive correlation with the concentrations of HHCB, suggesting that the HHCB-lactone originated directly from the degradation of HHCB in wastewater treatment plants (WWTPs) or in the natural environment. The diagnostic ratios of HHCB/AHTN and HHCB-lactone/HHCB and the enantiomeric fractions (EFs) of these PCMs showed that the direct origins of the target PCMs in the study area were municipal and industrial wastewaters discharged from adjacent cities or point sources and that the HHCB-lactone in sediment originated from the natural degradation of HHCB in the rivers and the lake. The results of the risk assessment showed that the PCMs in the watershed sediments were unlikely to pose a threat to aquatic species. However, the effluents of industrial and municipal wastewaters that are discharged into the Nanfei River should be investigated in future research.

Ultrasensitive mercury ion and biothiol detection based on Dansyl-His-Pro-Gly-Asp-NH2 fluorescent sensor

Mercury is an environmental contaminant, which is highly toxic even at extremely low concentrations. Long-term accumulation of mercury in human body will damage the central nervous system or digestive tract system. Here, a new fluorescent chemical sensor Dansyl-His-Pro-Gly-Asp-NH₂ (D-P4) was synthesized for the determination of Hg²⁺. The D-P4 sensor exhibits excellent selectivity and sensitivity to Hg²⁺ in aqueous solution with a 'turn-off' fluorescence response. Furthermore, D-P4-Hg system displays a good 'turn-on' fluorescence response to biothiols. The calculated binding constant for the 1:1 complex of D-P4 with Hg^{2 +} is 1.07 × 10⁵ M^-1, which also confirms the high affinity of D-P4 for Hg²⁺. Results indicate that the detection limit of D-P4 for Hg²⁺ is 61.0 nM, and that of D-P4-Hg system for Cys is as low as 80.0 nM.

Recent development of chromogenic and fluorogenic chemosensors for the detection of arsenic species: Environmental and biological applications

Due to biological and environmental significance of highly toxic arsenic species, the design, synthesis and development of chemosensors for arsenic species has been a very active research field in recent times. In this review, we summarize recent works on the sensing mechanisms employed by fluorometric/colorimetric chemosensors and their applications in arsenic detection. Various types of sensing strategies can be categorized into six types including (i) chemosensors based on hydrogen bonding interactions; (ii) aggregation induced emission (AIE) based chemosensors; (iii) chemodosimetric approach (reaction-based chemosensors); (iv) metal coordination-based sensing strategy; (v) chemosensors based on metal complex displacement approach and (vi) metal complex as chemosensor. All these sensing strategies are very much simple and sensitive for use in the design of arsenic selective chromogenic and fluorogenic probes.

Occurrence and Fate of Emerging Pollutants in Water Environment and Options for Their Removal

Emerging pollutants (EPs) are chemicals known to cause major impacts on the terrestrial, aquatic life and human health as a result of their chronic and acute toxicity. Although lots of studies on EPs behavior in the aquatic environment are currently available in literature, an urgent requirement exists to complete toxicological studies and develop and implement efficient and ecological methods for their removal. This paper raises some relevant problems related to water environment pollution with EPs, the risks they can generate for aquatic life and humans and opportunities to reduce the effects of pollution by EPs removal. Categories of emerging chemicals of concern in the environment, their sources, fate and impacts, with some examples are discussed. Organic UV filters are shortly presented as a relative new EPs category, with a focus on the need to develop extensive experimental studies on their environmental occurrence, fate and removal. Furthermore, sources for the aquatic environment resulting from discharging EPs directly into rivers from wastewater treatment plants are examined. The incidence of environmental and human health risks related to EPs is also considered. The removal of EPs from the environment as a solution to risk mitigation is addressed, with emphasis on several non-conventional processes involving biological removal of EPs. The paper provides a critical look at the current challenges posed by the presence of emerging pollutants in the aquatic environment, with critical comments and recommendations for further research to reduce the impact of EPs on water and human health and improve the performance of developed methods for their removal.

Removal of Drugs in Polluted Waters with Char Obtained by Pyrolysis of Hair Waste from the Tannery Process

The presence and final destination of pharmaceutical compounds in waters constitute one of the emerging events in current environmental chemistry. Two widely consumed compounds have been evaluated in this study, amoxicillin (AMOX) and diclofenac (DFC), at a concentration of 200 mg L-1. The presence of both in wastewater has been verified, generating problems in ecosystems and human health. Pyrolysis of hair waste from a tannery process was performed in a fixed-bed reactor. Char was obtained at different operating temperatures (300, 350, 400, and 450 °C), which underwent a characterization of heavy metals and elemental composition. An activation process was applied to the char obtained at 450 °C by means of physicochemical processes and with two chemical agents (KOH and K2CO3). For the removal of drugs, two separate tests were performed, one for 28 days and the other one for 4 h, to assess the efficiency and the percentage of removal. It was found that the char obtained at 450 °C is the one that removes most of both compounds: more than 90% of AMOX and more than 80% of DFC.

A comparative study of UV/H2O2 and UV/PDS for the degradation of micro-pollutants: kinetics and effect of water matrix

Organic micro-pollutants such as pesticides and endocrine disruptors cause serious harm to human health and aquatic ecosystem. In this study, the potential degradation of atrazine (ATZ), triclosan (TCS), and 2,4,6-trichloroanisole (TCA) by UV-activated peroxydisulfate (UV/PDS) and UV-activated H₂O₂ (UV/H₂O₂) processes were evaluated under different conditions. Results showed that UV/PDS process was more effective than UV/H₂O₂ under the same conditions. Increasing oxidant dosage or decreasing the initial ATZ, TCS, and TCA concentrations promoted the degradation rates of these three compounds. The presence of natural organic matter (NOM) could effectively scavenge sulfate radical (SO₄•^-) and hydroxyl radical (HO•) and reduced the removal rates of target compounds. Degradation rates of ATZ and TCA decreased with pH increasing from 5.0 to 9.0 in UV/PDS process, while in UV/H₂O₂ process, the increase of solution pH had little effect on ATZ and TCA degradation. In the UV/PDS and UV/H₂O₂ oxidation process, when the solution pH increased from 5 to 8, the removal rates of TCS decreased by 19% and 1%, while when the solution pH increased to 9, the degradation rates of TCS increased by 23% and 17%. CO₃^2-/HCO₃^- had a small inhibitory effect on ATZ and TCA degradation by UV/H₂O₂ and UV/PDS processes but promoted the degradation of TCS significantly (> 2 mM). Cl^- had little effect on the degradation of ATZ, TCA, and TCS in UV/H₂O₂ process. Cl^- significant inhibited on the degradation of ATZ and TCS, but the influence of Cl^- on the degradation of TCA was weak in UV/PDS process. Based on these experimental results, the various contributions of those secondary radicals (i.e., carbonate radical, chlorine radical) were discussed. This study can contribute to better understand the reactivities when UV/PDS and UV/H₂O₂ are applied for the treatment of micro-pollutant-containing waters.

Isotope analysis method for the herbicide bromoxynil and its application to study photo-degradation processes

Bromoxynil is an increasingly applied nitrile herbicide used for post-emergent control of annual broadleaved weeds. Compound-specific isotope analysis (CSIA) of the compound is of interest for studying its environmental fate, yet is challenging following its polar nature. We present a CSIA method for bromoxynil that includes offline thin-layer chromatography purification followed by an elemental analyzer isotope ratio mass spectrometer (EA-IRMS). This method was shown to be accurate and precise for δ¹³C and δ¹⁵N analysis of the compound (standard deviation of replicate standards <0.5‰). The method was applied to photodegraded samples, either radiated under laboratory condition with a UV lamp, or exposed to sunlight under environmental conditions. Dominating degradation products were similar in both cases. Nevertheless, isotope effects differed, presenting a strong inverse carbon isotope effect (εC = 4.74 ± 0.82‰) and a weak inverse nitrogen isotope effect (εN = 0.76 ± 0.12‰) for the laboratory experiment, and an insignificant carbon isotope effect (εC = 0.34 ± 0.44‰) and a normal nitrogen isotope effect (εN = -3.70 ± 0.30‰) for the natural conditions experiment. The differences in δ¹³C vs. δ¹⁵N enrichment trends suggest different mechanism for the two processes. Finally, the obtained dual isotope trend for natural conditions provide the basis for studying the dominance of photodegradation as a degradation route in the environment.

Enhanced Thermometric Sensor for Arsenate Analysis Based on Dual Temperature Readout Signaling Strategy

New methods for portable detection of arsenate are still in urgent need. Herein, we explored a simple but sensitive thermometric strategy for arsenate determination without complex instruments and skilled technicians. Cobalt oxyhydroxide (CoOOH) nanoflakes, can ingeniously decompose hydrogen peroxide into oxygen in a sealed reaction vessel, accompanied by marked pressure and significant temperature increase due to the exothermic reaction effect (ΔH = -98.2 kJ/mol). The increased pressure then compelled a certain amount of H₂O overflowing from the drainage device into another vessel, leading to a significant temperature decrease due to the preloaded ammonium nitrate (NH₄NO₃) and its good dissolution endothermic effect (ΔH = 25.4 kJ/mol). In the presence of arsenate, the catalytic activity of CoOOH nanoflakes for H₂O₂ decomposition was inhibited dramatically, resulting in an obvious decrease of the pressure, weighting water and temperature response. The two temperature responses with increasing and decreasing feature were easily measured through a common thermometer, and exhibited an effective signaling amplification via coupling both "signal-on" and "signal-off" temperature readout elements. The obtained dual superimposing temperature readout exhibits a good linear with the concentration of arsenate with a lower detection limit (51 nM, 3.8 ppb). Compared to the inductively coupled plasma mass spectrometry, this enhanced thermometric strategy provides a simple, rapid, convenient, low cost, and portable platform for sensing arsenate in real environmental water.

Removal process of antibiotics during anaerobic treatment of swine wastewater

High concentrations of antibiotics in swine wastewater pose potentially serious risks to the environment, human and animal health. Identifying the mechanism for removing antibiotics during the anaerobic treatment of swine wastewater is essential for reducing the serious damage they do to the environment. In this study, batch experiments were conducted to investigate the biosorption and biodegradation of tetracycline and sulfonamide antibiotics (TCs and SMs) in anaerobic processes. Results indicated that the removal of TCs in the anaerobic reactor contributed to biosorption, while biodegradation was responsible for the SMs' removal. The adsorption of TCs fitted well with the pseudo-second kinetic mode and the Freundlich isotherm, which suggested a heterogeneous chemisorption process. Cometabolism was the main mechanism for the biodegradation of SMs and the process fitted well with the first-order kinetic model. Microbial activity in the anaerobic sludge might be curtailed due to the presence of high concentrations of SMs.

Sucralose and acesulfame as an indicator of domestic wastewater contamination in Wuhan surface water

Artificial sweeteners (ASs) are applied widely as sucrose substitutes in food, pharmaceuticals, and personal-care products, which results in their release into surface water. The occurrence of ASs in aquatic environments in China has rarely been reported. In this study, we determined the concentration of seven ASs in surface water and sediment samples from 16 lakes in Wuhan. The sum of the ASs concentration ranged from 0.89 to 20.6 μg/L in the surface water, with a mean value of 4.96 ± 5.16 μg/L. The most abundant AS was sucralose (SUC), with a concentration from 0.33 to 18.0 μg/L, followed by acesulfame (ACE) (0.40-2.78 μg/L), saccharin (SAC) (<MDL to 1.86 μg/L), and cyclamate (CYC) (<MDL to 2.22 μg/L). SUC and ACE accounted for 90% ± 8% of the total ASs in the surface water. The Σ₄ ASs sediment concentrations ranged from 1.71 to 6.49 ng/g of the dry weight (dw, mean value 3.03 ± 1.03 ng/g dw). SAC, CYC, and ACE were detected in sediments (<MDL to 4.17 ng/g dw), with SAC as the dominant AS. In surface water, the Σ₄ ASs concentrations of Hanyang station were higher than those of Hankou, while the Σ₄ ASs concentrations in sediment samples from different regions showed no significant difference. The ASs concentrations in the surface water and sediment in winter were significantly higher than those in summer. Relatively higher concentrations and detected frequencies of SUC and ACE were found in surface water samples, whereas these two ASs were absent in background samples, which indicates that SUC and ACE can be used as potential indicators of wastewater contamination in Wuhan, China.

Bioaccumulation behavior and spatiotemporal trends of per- and polyfluoroalkyl substances in Indo-Pacific humpback dolphins from the Pearl River Estuary, China

Sixteen per- and polyfluoroalkyl substances (PFASs) were measured in liver (n = 52) and kidney (n = 18) tissues of Indo-Pacific humpback dolphins (Sousa chinensis) stranded in the Pearl River Estuary (PRE) of China between 2004 and 2016. The average concentrations of perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and most of other PFASs in the liver samples were respectively greater than any records previously reported in cetaceans globally. PFOS levels in 46% of dolphin liver samples exceeded the hepatic toxicity threshold in cetaceans. For the first time, we found a U-shaped trend for the distribution pattern of perfluorinated carboxylic acids (PFCAs) between liver and kidney with increasing carbon chain lengths (C5-C16), whereas a descending trend (C4-C10) was found for perfluoroalkane sulfonic acids (PFASs), which may be explained by binding efficiencies of PFAS analogues to proteins. Dolphins with the highest levels of ∑PFASs (age-corrected) were clustered near the river outlets in Lingdingyang area, which agrees with the spatial distribution of PFASs in the environment. Significant temporal trends were observed for many PFASs. Concentrations of PFOA, perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA) and perfluoroheptanoic acid (PFHpA) all peaked in year 2011, followed by a decreasing trend, while a consistently descending trend was shown for perfluoroundecanoic acid (PFUdA) and perfluorodecane sulfonate (PFDS). Our findings contribute to the knowledge of tissue distribution and spatiotemporal trends of PFASs in the PRE dolphins, which are valuable for us to understand the PFASs exposure risk and their industrial emission in Southern China.

Evaluating gas chromatography with a halogen-specific detector for the determination of disinfection by-products in drinking water

The occurrence of disinfection by-products (DBPs) in drinking water has become an issue of concern during the past decades. The DBPs pose health risks and are suspected to cause various cancer forms, be genotoxic, and have negative developmental effects. The vast chemical diversity of DBPs makes comprehensive monitoring challenging. Only few of the DBPs are regulated and included in analytical protocols. In this study, a method for simultaneous measurement of 20 DBPs from five different structural classes (both regulated and non-regulated) was investigated and further developed for 11 DBPs using solid-phase extraction and gas chromatography coupled with a halogen-specific detector (XSD). The XSD was highly selective towards halogenated DBPs, providing chromatograms with little noise. The method allowed detection down to 0.05 μg L^-1 and showed promising results for the simultaneous determination of a range of neutral DBP classes. Compounds from two classes of emerging DBPs, more cytotoxic than the "traditional" regulated DBPs, were successfully determined using this method. However, haloacetic acids (HAAs) should be analyzed separately as some HAA methyl esters may degrade giving false positives of trihalomethanes (THMs). The method was tested on real water samples from two municipal waterworks where the target DBP concentrations were found below the regulatory limits of Sweden.

Legacy and emerging pollutants in the Gulf of Gdańsk (southern Baltic Sea) - loads and distribution revisited

Coastal marine areas of densely populated countries are exposed to a wide array of human activities having an impact on their ecological status. The Baltic Sea is particularly susceptible to pollution by hazardous substances (limited water exchange, shallowness, and large catchment area). Polish media regularly reports ecological catastrophes in the Gulf of Gdańsk area caused by eg. shipwrecks leaking. Thus, there is a need of a broad scientific based report on recent contaminant loads and distribution. In this review paper, we report loads of contaminants from different obvious and non-obvious sources. We also gather data on legacy and new emerging contaminant concentrations measured in the Gulf of Gdańsk within the last decade (2008-2018). The paper also includes available biological effect measurements performed recently as well as a summary of needs and gaps to be filled for the development of reliable risk assessment.

Contamination patterns and attenuation of pharmaceuticals in a temporary Mediterranean river

The contamination patterns and fate of pharmaceutically active compounds (PhACs) were investigated in the Evrotas River (Southern Greece). This is a temporary river with differing levels of water stress and water quality impairment in a number of its reaches. Three sampling campaigns were conducted in order to capture different levels of water stress and water quality. Four sampling sites located on the main channel of the Evrotas River were sampled in July 2015 (moderate stream flow), and June and September 2016 (low stream flow). Discharge of urban wastewater has been determined as the main source of pollution, with PhACs, nutrients and other physicochemical parameters considerably increasing downstream the wastewater treatment plant (WWTP) of Sparta city. Due to the pronounced hydrological variation of the Evrotas River, generally, the highest concentrations of PhACs have been detected during low flow conditions. Simultaneously, low flow resulted in an increased water travel time and consequently longer residence time that accounted for the higher attenuation of most PhACs. The average decrease in total concentration of PhACs within the studied waterbody segment (downstream of Sparta city) increased from 22% in July 2015 to 25% in June 2016 and 77% in September 2016. The PhACs with the highest average concentration decrease throughout the sampling campaigns were hydrochlorothiazide, followed by sotalol, carbamazepine, valsartan, and naproxen.

Marine environment pollution: The contribution of mass spectrometry to the study of seawater

The study of marine pollution has been traditionally addressed to persistent chemicals, generally known as priority pollutants; a current trend in environmental analysis is a shift toward "emerging pollutants," defined as newly identified or previously unrecognized contaminants. The present review is focused on the peculiar contribution of mass spectrometry (MS) to the study of pollutants in the seawater compartment. The work is organized in five paragraphs where the most relevant groups of pollutants, both "classical" and "emerging," are presented and discussed, highlighting the relative data obtained by the means of different MS techniques. The hyphenation of MS and separative techniques, together with the development of different ion sources, makes MS and tandem MS the analytical tool of choice for the determination of trace organic contaminants in seawater. © 2016 Wiley Periodicals, Inc. Mass Spec Rev 37:492-512, 2018.

Degradation kinetics of organic chloramines and formation of disinfection by-products during chlorination of creatinine

Organic chloramines can interfere with the measurement of effective combined chlorine in chlorinated water and are potential intermediate products of highly toxic disinfection by-products (DBPs). In order to know more about the degradation and transformation of organic chloramines, a typical organic chloramine precursor creatinine was selected for investigation and a corresponding individual organic chloramine chlorocreatinine was prepared in this study. The preparation condition of chlorocreatinine by chlorination was established as chlorine/creatinine = 1 M/M, reaction time = 2 h and pH = 7.0. Then the degradation kinetics of chlorocreatinine during further chlorination was studied, and a second-order rate constant of 1.16 (±0.14) M^-1 s^-1 was obtained at pH 7.0. Solution pH significantly influenced the degradation rate, and the elementary rate constants of chlorocreatinine with HOCl+H⁺, HOCl, OCl^- and chlorocreatinine^- with OCl^- were calculated as 2.43 (±1.55) × 10⁴ M^-2 s^-1, 1.05 (±0.09) M^-1 s^-1, 2.86 (±0.30) M^-1 s^-1 and 3.09 (±0.24) M^-1 s^-1, respectively. Besides, it was found that chlorocreatinine could be further converted into several C-DBPs (chloroform and trichloroacetone) and N-DBPs (dichloroacetonitrile (DCAN) and trichloronitromethane (TCNM)) during chlorination. The total yield of DBPs increased obviously with increasing pH, especially for TCNM. In addition, the presence of humic acid in creatinine solution could increase the formation of DCAN obviously during chlorination. Based on the UPLC-Q-TOF-MS analysis, the conversion pathways of chlorocreatinine were proposed. Several kinds of intermediate products were also identified as organic chloramines and some of them could even exist stably during the further chlorination.

Impact of urban chemical pollution on water quality in small, rural and effluent-dominated Mediterranean streams and rivers

The impact and occurrence of wastewater (treated and untreated) derived pharmaceutically active compounds (PhACs) have been investigated in small, rural and effluent-dominated tributaries of the lower Ebro River located in the North-Eastern Spain (Catalonia). We have observed the predominant effect of stream flow and consequently dilution factor on the concentration levels of detected PhACs that combined with the absence of wastewater treatment plants (WWTP) resulted in 12 times higher concentrations in streams with direct discharge of untreated wastewater. Non-steroidal anti-inflammatory drugs (NSAIDs) were the most ubiquitous compounds, in terms of both individual concentration and frequency of detection. In the sites impacted by raw wastewater, acetaminophen and ibuprofen showed the highest concentrations among all analyzed PhACs, reaching concentrations up to 7.78μgL^-1 and 2.66μgL^-1, respectively. However, PhACs detected in the sites impacted by treated wastewater showed generally lower concentration levels and frequencies of detection. Also, effluent-dominated streams showed higher concentration levels of PhACs due to a generally lower stream flows and small dilution factors. However, concentration levels of detected PhACs were dependent on the hydraulic travel time and distance from the discharge point and related with the in-stream attenuation. As a result, this study highlights the combined impact of hydrological and chemical stressors on the water quality of the rural Mediterranean aquatic ecosystems.

Detection and discrimination of Zn2+ and Hg2+ using a single molecular fluorescent probe

A new fluorescent probe (SAPH) has been introduced which shows specific sensing towards Zn²⁺ and Hg²⁺ at two different wavelength maxima at physiological pH.

Chlorate origin and fate in shallow groundwater below agricultural landscapes

In agricultural lowland landscapes, intensive agricultural is accompanied by a wide use of agrochemical application, like pesticides and fertilizers. The latter often causes serious environmental threats such as N compounds leaching and surface water eutrophication; additionally, since perchlorate can be present as impurities in many fertilizers, the potential presence of perchlorates and their by-products like chlorates and chlorites in shallow groundwater could be a reason of concern. In this light, the present manuscript reports the first temporal and spatial variation of chlorates, chlorites and major anions concentrations in the shallow unconfined aquifer belonging to Ferrara province (in the Po River plain). The study was made in 56 different locations to obtain insight on groundwater chemical composition and its sediment matrix interactions. During the monitoring period from 2010 to 2011, in June 2011 a nonpoint pollution of chlorates was found in the shallow unconfined aquifer belonging to Ferrara province. Detected chlorates concentrations ranged between 0.01 and 38 mg/l with an average value of 2.9 mg/l. Chlorates were found in 49 wells out of 56 and in all types of lithology constituting the shallow aquifer. Chlorates concentrations appeared to be linked to NO₃^-, volatile fatty acids (VFA) and oxygen reduction potential (ORP) variations. Chlorates behaviour was related to the biodegradation of perchlorates, since perchlorates are favourable electron acceptors for the oxidation of labile dissolved organic carbon (DOC) in groundwater. Further studies must take into consideration to monitor ClO₄^- in pore waters and groundwater to better elucidate the mass flux of ClO₄^- in shallow aquifers belonging to agricultural landscapes.

Fate of the sunscreen compound oxybenzone in Cyperus alternifolius based hydroponic culture: Uptake, biotransformation and phytotoxicity

Oxybenzone (OBZ), a common ingredient in sunscreens and personal care products, has been frequently detected in effluents from municipal wastewater treatment plants and also in surface waters. OBZ is an emerging contaminant due to its adverse impacts on marine/aquatic ecosystems. To investigate the removal and degradation capacity of phytotreatment for OBZ, the common wetland plant species Cyperus alternifolius L. was exposed to this compound at 5, 25 and 50 μM for 120 h, respectively. Continuous uptake by roots and accumulation in plant tissues was observed over the exposure time, and depletion of spiked OBZ from the aqueous medium exceeded 73.9 ± 9.1% after 120 h. Similar to its fate in mammalian cells, OBZ is activated in a phase I reaction resulting in the hydroxylated metabolite 2,4-dihydroxybenzophenone (DHB). Independently, two phase II metabolites were identified as oxybenzone-glucoside (OBZ-Glu) and oxybenzone-(6-O-malonyl)-glucoside (OBZ-Mal-Glu) by LC-MS/MS. Formation of these metabolites increased over the experimental period. To our knowledge this is the first time that DHB, OBZ-Glu and OBZ-Mal-Glu are shown to be formed in higher plant tissues. Furthermore, plant defense systems-antioxidative enzymes (SOD, CAT, APOX and POX) were found to be elevated to counteract stress caused by exposure to OBZ. This study presents the huge potential of aquatic plants to cope with benzophenone type UV filters in contaminated water bodies.

Contamination sources and distribution patterns of pharmaceuticals and personal care products in Alpine rivers strongly affected by tourism

Knowledge regarding the impact of tourism on the emergence of pharmaceuticals and personal care products (PPCPs) in Alpine river waters is limited and scarce. Therefore, a study on the occurrence patterns and spatiotemporal variability of 105 PPCPs in an Alpine river basin located in the Trentino-Alto Adige region (North-Eastern Italy) has been conducted. We observed that the total concentration of analyzed PPCPs was generally higher in all sampling sites during winter than in the summer. The analysis of tourist data revealed that during both sampling campaigns the number of tourists was lower in the downstream sites in comparison with the upstream area of the basin (Val di Sole). Particularly, sampling sites located near important tourist resorts have shown the highest abundance of the PPCPs during winter, being analgesics/anti-inflammatories, antihypertensives and antibiotics the most abundant pharmaceutically active compounds (PhACs). Diclofenac showed the highest concentration amongst PhACs, reaching concentrations up to 675ngL^-1 in the sampling site situated downstream of the Tonale wastewater treatment plant (WWTP). Antihypertensives were found at concentrations >300ngL^-1, while antibiotics were quantified up to 196ngL^-1, respectively. Amongst personal care products (PCPs), the most abundant compound was octyl-dimethyl-p-aminobenzoic acid (ODPABA) with concentrations reaching up to 748ngL^-1 in the sampling site situated within the Rotaliana district. In general, concentrations and detection frequencies were higher in water than in the sediment samples. The most frequently detected PhACs in sediments from both sampling campaigns were antibiotics, while amongst PCPs in sediments, octocrylene (OC) showed the highest concentration in both sampling campaigns. As a result, this study highlights the potential impact of tourism on the water quality of the Alpine aquatic ecosystems.

A "Turn-On" thiol functionalized fluorescent carbon quantum dot based chemosensory system for arsenite detection

Carbon quantum dots (CQDs) have emerged out as promising fluorescent probes for hazardous heavy metals detection in recent past. In this study, water soluble CQDs were synthesized by facile microwave pyrolysis of citric acid & cysteamine, and functionalized with ditheritheritol to impart thiol functionalities at surface for selective detection of toxic arsenite in water. Microscopic analysis reveals that the synthesized CQDs are of uniform size (diameter ∼5nm) and confirmed to have surface SH groups by FT-IR. The functionalized probe is then demonstrated for arsenite detection in water by "Turn-On" read out mechanism, which reduces the possibility of false positive signals associated with "turn off' probes reported earlier. The blue luminescent functionalized CQDs exhibit increase in fluorescence intensity on arsenite addition in 5-100ppb wide detection range. The probe can be used for sensitive detection of arsenite in environmental water to a theoretical detection limit (3s) of 0.086ppb (R²=0.9547) with good reproducibility at 2.6% relative standard deviation. The presented reliable, sensitive, rapid fCQDs probe demonstrated to exhibit high selectivity towards arsenite and exemplified for real water samples as well. The analytical performance of the presented probe is comparable to existing organic & semiconductor based optical probes.

Integrated Evaluation Concept to Assess the Efficacy of Advanced Wastewater Treatment Processes for the Elimination of Micropollutants and Pathogens

A multidisciplinary concept has been developed to compare advanced wastewater treatment processes for their efficacy of eliminating micropollutants and pathogens. The concept is based on (i) the removal/formation of selected indicator substances and their transformation products (TPs), (ii) the assessment of ecotoxicity via in vitro tests, and (iii) the removal of pathogens and antibiotic resistant bacteria. It includes substances passing biological wastewater treatment plants regulated or proposed to be regulated in the European Water Framework Directive, TPs formed in biological processes or during ozonation, agonistic/antagonistic endocrine activities, mutagenic/genotoxic activities, cytotoxic activities, further activities like neurotoxicity as well as antibiotics resistance genes, and taxonomic gene markers for pathogens. At a pilot plant, ozonation of conventionally treated wastewater resulted in the removal of micropollutants and pathogens and the reduction of estrogenic effects, whereas the in vitro mutagenicity increased. Subsequent post-treatment of the ozonated water by granular activated carbon (GAC) significantly reduced the mutagenic effects as well as the concentrations of remaining micropollutants, whereas this was not the case for biofiltration. The results demonstrate the suitability of the evaluation concept to assess processes of advanced wastewater treatment including ozonation and GAC by considering chemical, ecotoxicological, and microbiological parameters.

The application of a G-quadruplex based assay with an iridium(iii) complex to arsenic ion detection and its utilization in a microfluidic chip

In this work, the iridium(iii) complex 1 was synthesized and employed in constructing an assay which is based on a G-quadruplex for detecting arsenic ions in aqueous solution.

A chemosensor for micro- to nano-molar detection of Ag+ and Hg2+ ions in pure aqueous media and its applications in cell imaging

The synthesis and characterization of a simple thiourea-based Ag⁺ and Hg²⁺ sensor is reported.

A Demonstration of the Uncertainty in Predicting the Estrogenic Activity of Individual Chemicals and Mixtures From an In Vitro Estrogen Receptor Transcriptional Activation Assay (T47D-KBluc) to the In Vivo Uterotrophic Assay Using Oral Exposure

In vitro estrogen receptor assays are valuable tools for identifying environmental samples and chemicals that display estrogenic activity. However, in vitro potency cannot necessarily be extrapolated to estimates of in vivo potency because in vitro assays are currently unable to fully account for absorption, distribution, metabolism, and excretion. To explore this issue, we calculated relative potency factors (RPF), using 17α-ethinyl estradiol (EE2) as the reference compound, for several chemicals and mixtures in the T47D-KBluc estrogen receptor transactivation assay. In vitro RPFs were used to predict rat oral uterotrophic assay responses for these chemicals and mixtures. EE2, 17β-estradiol (E2), benzyl-butyl phthalate (BBP), bisphenol-A (BPA), bisphenol-AF (BPAF), bisphenol-C (BPC), bisphenol-S (BPS), and methoxychlor (MET) were tested individually, while BPS + MET, BPAF + MET, and BPAF + BPC + BPS + EE2 + MET were tested as equipotent mixtures. In vivo ED50 values for BPA, BPAF, and BPC were accurately predicted using in vitro data; however, E2 was less potent than predicted, BBP was a false positive, and BPS and MET were 76.6 and 368.3-fold more active in vivo than predicted from the in vitro potency, respectively. Further, mixture ED50 values were more accurately predicted by the dose addition model using individual chemical in vivo uterotrophic data (0.7-1.5-fold difference from observed) than in vitro data (1.4-86.8-fold). Overall, these data illustrate the potential for both underestimating and overestimating in vivo potency from predictions made with in vitro data for compounds that undergo substantial disposition following oral administration. Accounting for aspects of toxicokinetics, notably metabolism, in in vitro models will be necessary for accurate in vitro-to-in vivo extrapolations.

Characterization of pharmaceutically active compounds in Dongting Lake, China: Occurrence, chiral profiling and environmental risk

Twenty commonly used pharmaceuticals including eight chiral drugs were investigated in Dongting Lake, China. The contamination level was relatively low on a global scale. Twelve pharmaceuticals were identified. The most abundant compound was caffeine followed by diclofenac, DEET, mefenamic acid, fluoxetine, ibuprofen and carbamazepine with mean concentrations from 2.0 to 80.8ngL(-1). Concentrations between East and West Dongting Lake showed spatial difference, with the West Dongting Lake less polluted. The relatively high ratio of caffeine versus carbamazepine (over 50) may indicate there was possible direct discharge of domestic wastewater into the lake. This is the first study presenting a survey allowing for comprehensive analysis of multiclass achiral and chiral pharmaceuticals including beta-blockers, antidepressants and anti-inflammatory drugs in freshwater lake. The enantiomeric compositions presented racemic to weakly enantioselective, with the highest enantiomeric fraction (EF) of 0.63 for fluoxetine. Meanwhile, venlafaxine was identified and evaluated the environment risk in surface water in China for the first time. The results of risk assessment suggested that fluoxetine, venlafaxine and diclofenac acid might pose a significant risk to aquatic organisms in Dongting Lake. The resulting data will be useful to enrich the research of emerging pollutants in freshwater lake and stereochemistry for environment investigations.

The Occurrence of Veterinary Pharmaceuticals in the Environment: A Review

It is well known that there is a widespread use of veterinary pharmaceuticals and consequent release into different ecosystems such as freshwater bodies and groundwater systems. Furthermore, the use of organic fertilizers produced from animal waste manure has been also responsible for the occurrence of veterinary pharmaceuticals in agricultural soils. This article is a review of different studies focused on the detection and quantification of such compounds in environmental compartments using different analytical techniques. Furthermore, this paper reports the main challenges regarding veterinary pharmaceuticals in terms of analytical methods, detection/quantification of parent compounds and metabolites, and risks/toxicity to human health and aquatic ecosystems. Based on the existing literature, it is clear that only limited data is available regarding veterinary compounds and there are still considerable gaps to be bridged in order to remediate existing problems and prevent future ones. In terms of analytical methods, there are still considerable challenges to overcome considering the large number of existing compounds and respective metabolites. A number of studies highlight the lack of attention given to the detection and quantification of transformation products and metabolites. Furthermore more attention needs to be given in relation to the toxic effects and potential risks that veterinary compounds pose to environmental and human health. To conclude, the more research investigations focused on these subjects take place in the near future, more rapidly we will get a better understanding about the behavior of these compounds and the real risks they pose to aquatic and terrestrial environments and how to properly tackle them.