Pan-European survey on the occurrence of selected polar organic persistent pollutants in ground water

Occurrence and removal of benzotriazole and benzothiazole in drinking water treatment plants

The occurrence and removal of four benzotriazoles (BTRs) and five benzothiazoles (BTHs) in drinking water treatment plants (DWTPs) and bottled water were investigated. The mean total BTR and BTH concentrations were 390 and 117 ng/L in raw water, 51.2 and 66.5 ng/L in treated water, and 0.758 and 48.4 ng/L in bottled water, respectively. Different distribution patterns were observed according to the water type, with the dominant BTR being 1H-BTR (mean: 57.8%) in raw water and a predominance of BTH in bottled water (mean: 84.6%). In the DWTPs, the mean removal of BTRs (90.9%) was better than that of BTHs (29.3%). The BTRs were efficiently removed in DWTPs, and in particular during adsorption processes. 5Cl-BTR had a high removal efficiency (75.7%) in the adsorption processes, followed by 5M-BTR (70.0%), 5,6-di-MeBTR (58.4%), and 1H-BTR (50.1%). By contrast, BTHs were not efficiently removed in DWTPs, although relatively high removal efficiencies were achieved with an ozonation process (43.1%) compared to other treatment processes. In treated drinking and bottled water, the hazard quotients (HQs) of the representative BTRs and BTHs were acceptable (defined as HQ < 1), with a safety margin of 2-5 orders of magnitude.

Pesticides monitoring in surface water of a subsistence agricultural catchment in Uganda using passive samplers

Pesticides are intensely used in the agricultural sector worldwide including smallholder farming. Poor pesticide use practices in this agronomic setting are well documented and may impair the quality of water resources. However, empirical data on pesticide occurrence in water bodies of tropical smallholder agriculture is scarce. Many available data are focusing on apolar organochlorine compounds which are globally banned. We address this gap by studying the occurrence of a broad range of more modern pesticides in an agricultural watershed in Uganda. During 2.5 months of the rainy season in 2017, three passive sampler systems were deployed at five locations in River Mayanja to collect 14 days of composite samples. Grab samples were taken from drinking water resources. In these samples, 27 compounds out of 265 organic pesticides including 60 transformation products were detected. In the drinking water resources, we detected eight pesticides and two insecticide transformation products in low concentrations between 1 and 50 ng/L. Also, in the small streams and open fetch ponds, detected concentrations were generally low with a few exceptions for the herbicide 2,4-D and the fungicide carbendazim exceeding 1 ug/L. The widespread occurrence of chlorpyrifos posed the largest risk for macroinvertebrates. The extensive detection of this compound and its transformation product 3,4,5-trichloro-2-pyridinol was unexpected and called for a better understanding of the use and fate of this pesticide.

Aquatic environmental fates and risks of benzotriazoles, benzothiazoles, and p-phenylenediamines in a catchment providing water to a megacity of China

Wearing of vehicle parts could release many chemical additives into the environment, such as benzotriazoles (BTRs), benzothiazoles (BTHs), and p-phenylenediamines (PPDs), which are potentially toxic to wildlife and humans. This study investigated the occurrence, source, and risks of BTRs, BTHs, and PPDs in a source catchment providing water to Guangzhou, a megacity in South China, covering groundwater, surface water, and stormwater. The results showed that BTRs and BTHs were predominant in surface water and groundwater. Unexpectedly, the BTR and BTH concentrations were lower in surface water than groundwater in a third of the paired samples. For the first time, 6PPD-quinone, a toxic ozonation product of N-(1,3-dimethylbutyl)-N'-phenyl-1,4-phenylenediamine (6PPD), was extensively detected in source waters. Stormwater decreased the BTR concentrations but increased the 6PPD-quinone concentrations in surface water owing to their affiliation to suspended particles. From natural to urban segments of Liuxi river, a downstream increasing trend in BTR and BTH concentrations was observed, confirming that they are indicative of urban anthropogenic activities. Strong correlations between industrial activities and BTR or BTH concentrations in surface water indicated that industrial activities were their main sources. Six compounds were prioritized as potentially persistent, mobile, and toxic (PMT) chemicals, combing our monitoring results and REACH criterion. This study improves our understanding of the environmental fates and risks of water-soluble tire-wear chemicals, which provides important information for chemical management, and indicates attention should be paid to the risk posed by 6PPD-quinone in the source water.

Degradation of seven pesticides and two metabolites before and during aquifer storage transfer and recovery operation

Degradation of 7 common pesticides (bentazon, boscalid, chloridazon, fluopyram, flutolanil, imidacloprid, and methoxyfenozide) and 2 metabolites of chloridazon (desphenyl-chloridazon, and methyl-desphenyl-chloridazon) was studied in an anoxic and brackish sandy aquifer before and during Aquifer Storage Transfer and Recovery (ASTR) operation. Fresh tile drainage water was injected and stored for later re-use as irrigation water. We hypothesized that electron acceptors (O₂, NO₃), dissolved organic carbon (∼24.7 mg/L), nutrients (NO₃: ∼14.1 mg/L, NH₄: ∼0.13 mg/L, PO₄: ∼5.2 mg/L), and biodegrading bacteria in tile drainage water could stimulate degradation of the pesticides and metabolites (ranging between 0.013 and 10.8 μg/L) introduced in the aquifer. Pesticide degradation was studied at 6 depths in the aquifer using push-pull tests lasting ±18 days before the onset of ASTR operation. Degradation was too limited to quantify and/or could not be assessed because of the potential occurrence of pesticide retardation. Utilizing push-pull tests to obtain degradation constants should only be considered in future studies for non-retarding pesticides with relative low half-lives (here <20 days). During ASTR operation, pesticide degradation was studied at the same depths during 3 storage periods equally spread over 1.5 years of ASTR operation. Overall, trends of degradation were observed, although with relatively high half-lives of at least 53 days. Microbial adaptation of the aquifer and/or bioaugmentation by the injected biodegrading bacteria did not result in enhanced degradation during consecutive storage periods. Operational monitoring data over longer periods and distances yielded half-lives of at least 141 days. The slow degradation mostly agrees with previous studies. The injected tile drainage water composition did therefore not notably stimulate pesticide degradation. The relatively persistent behavior of the studied pesticides/metabolites implies that ASTR abstracted water will have generally high pesticide concentrations, and non-abstracted water may form a contamination risk for the surrounding native brackish groundwater.

Study of Photocatalytic Oxidation of Micropollutants in Water and Intensification Case Study

During the last decades, heterogenous photocatalysis has shown as the most promising advanced oxidation process for the removal of micropollutants due to degradation rate, sustainability, non-toxicity, and low-cost. Synergistic interaction of light irradiation, photocatalysts, and highly reactive species are used to break down pollutants toward inert products. Even though titanium dioxide (TiO2) is the most researched photocatalyst, to overcome shortcomings, various modifications have been made to intensify photocatalytic activity in visible spectra range among which is modification with multiwalled carbon nanotubes (MWCNTs). Therefore, photocatalytic oxidation and its intensification by photocatalyst’s modification was studied on the example of four micropollutants (diclofenac, DF; imidacloprid, IMI; 1-H benzotriazole, BT; methylene blue, MB) degradation. Compound parabolic collector (CPC) reactor was used as, nowadays, it has been considered the state-of-the-art system due to its usage of both direct and diffuse solar radiation and quantum efficiency. A commercially available TiO2 P25 and nanocomposite of TiO2 and MWCNT were immobilized on a glass fiber mesh by sol-gel method. Full-spectra solar lamps with appropriate UVB and UVA irradiation levels were used in all experiments. Photocatalytic degradation of DF, IMI, BT, and MB by immobilized TiO2 and TiO2/CNT photocatalysts was achieved. Mathematical modelling which included mass transfer and photon absorption was applied and intrinsic reaction rate constants were estimated: kDF=3.56 × 10−10s−1W−0.5m1.5, kIMI=8.90 × 10−11s−1W−0.5m1.5, kBT=1.20 × 10−9s−1W−0.5m1.5, kMB=1.62 × 10−10s−1W−0.5m1.5. Intensification of photocatalysis by TiO2/CNT was observed for DF, IMI, and MB, while that was not the case for BT. The developed model can be effectively applied for different irradiation conditions which makes it extremely versatile and adaptable when predicting the degradation extents throughout the year using sunlight as the energy source at any location.

Assessing the Persistence and Mobility of Organic Substances to Protect Freshwater Resources

Persistent and mobile organic substances are those with the highest propensity to be widely distributed in groundwater and thereby, when emitted at low-levels, to contaminate drinking water extraction points and freshwater environments. To prevent such contamination, the European Commission is in the process of introducing new hazard classes for persistent, mobile, and toxic (PMT) and very persistent and very mobile (vPvM) substances within its key chemical regulations CLP and REACH. The assessment of persistence in these regulations will likely be based on simulated half-life, t _1/2, thresholds; the assessment of mobility will likely be based on organic carbon-water distribution coefficient, K _OC, thresholds. This study reviews the use of t _1/2 and K _OC to describe persistence and mobility, considering the theory, history, suitability, data limitations, estimation methods, and alternative parameters. For this purpose, t _1/2, K _OC, and alternative parameters were compiled for substances registered under REACH, known transformation products, and substances detected in wastewater treatment plant effluent, surface water, bank filtrate, groundwater, raw water, and drinking water. Experimental t _1/2 values were rare and only available for 2.2% of the 14 203 unique chemicals identified. K _OC data were only available for a fifth of the substances. Therefore, the usage of alternative screening parameters was investigated to predict t _1/2 and K _OC values, to assist weight-of-evidence based PMT/vPvM hazard assessments. Even when considering screening parameters, for 41% of substances, PMT/vPvM assessments could not be made due to data gaps; for 23% of substances, PMT/vPvM assessments were ambiguous. Further effort is needed to close these substantial data gaps. However, when data is available, the use of t _1/2 and K _OC is considered fit-for-purpose for defining PMT/vPvM thresholds. Using currently discussed threshold values, between 1.9 and 2.6% of REACH registered substances were identified as PMT/vPvM. Among the REACH registered substances detected in drinking water sources, 24-30% were PMT/vPvM substances.

Nitrate promoted defluorination of perfluorooctanoic acid in UV/sulfite system: Coupling hydrated electron/reactive nitrogen species-mediated reduction and oxidation

A significantly accelerated defluorination of recalcitrant perfluorooctanoic acid (PFOA) was explored with the co-present nitrate (20 mg L^-1) by UV/sulfite treatment (UV/sulfite-nitrate). The deep defluorination of PFOA and complete denitrification of nitrate were simultaneously achieved in UV/sulfite-nitrate system. At the initial 30 min, PFOA defluorination exhibited an induction period, exactly corresponding to the removal of the co-existed nitrate. Upon the induction period passed, an accelerated removal of PFOA (5 mg L^-1) occurred, nearly 100% defluorination ratio reached within 2 h. Compared with those in UV/sulfite, the kinetics of PFOA decay, defluorination, and transformation product formations were greatly enhanced in UV/sulfite-nitrate system. Reactive nitrogen species (RNS) generated from e_aq^--induced reduction of nitrate were found to play significant roles on the promoted defluorination apart from e_aq^--mediated reductive defluorination. The investigations on solution pH (7.0-11.0) confirmed that the reductive defluorination of PFOA was more efficient under alkaline conditions, however, the presence of nitrate can promote the defluorination even under neutral pH. Theoretical calculations of Fukui function demonstrated that RNS could easily launch electrophilic attack toward H-rich moieties of fluorotelomer carboxylates (FTCAs, C_nF_2n+1-(CH₂)_m-COO^-), more persistent intermediates (formed via H/F exchange), and convert FTCAs into shorter-chain perfluorinated carboxylic acids, thus facilitating the deep defluorination. Along with the analysis on the denitrification products, the liberation of fluoride ions and generated intermediates, possible decomposition pathways were proposed. This work highlights the indispensable synergy from e_aq^-/RNS with integrated reduction and oxidation on PFOA defluorination and will advance remediation technologies of perfluorinated compound contaminated water.

Presence of pesticides in the environment, transition into organic food, and implications for quality assurance along the European organic food chain - A review

The use of synthetic pesticides is not allowed in organic production, but traces of synthetic pesticides are regularly detected in organic food. To safeguard the integrity of organic production, organic certifiers are obliged to investigate the causes for pesticide residues on organic food, entailing high costs to the organic sector. Such residues can have various origins, including both fraud and unintentional contamination from the environment. Because the knowledge about contamination from environmental sources is scattered, this review provides an overview of pathways for unintentional and technically unavoidable contamination of organic food with synthetic pesticides in Europe. It shows that synthetic pesticides are widely present in all environmental compartments. They originate from applications in the region, in distant areas or from historical use. Transition into the food chain has been demonstrated by various studies. However, large uncertainties remain regarding the true pesticide contamination of the environment, their dynamics and the contamination risks for the food chain. Organic operators can take certain measures to reduce the risks of pesticide contamination of their products, but a certain extent of pesticide contamination is technically unavoidable. The present paper indicates that (i) a potential risk for pesticide residues exists on all organic crops and thus organic operators cannot meet a 'zero-tolerance' approach regarding pesticide residues at the moment. (ii) Applying a residue concentration threshold to distinguish between cases of fraud and unavoidable contamination for all pesticides is not adequate given the variability of contamination. More reliable answers can be obtained with a case-by-case investigation, where evidence for all possible origins of pesticide residues is collected and the likelihood of unavoidable contamination and fraud are estimated. Ultimately, for organic certification bodies and control authorities it will remain a challenge to determine whether a pesticide residue is due to neglect of production rules or technically unavoidable.

PWC-based evaluation of groundwater pesticide pollution in the Júcar River Basin

Predicting pesticides' behavior in the environment is necessary to anticipate and minimize their adverse effects. Despite the use of pesticides in Spain is increasing, the implementation and use of predictive mathematical models is seldomly done in practice due to the lack of available data. In this original work, the Pesticide Root Zone Model version 5 (PRZM 5) mathematical model under the Pesticide in Water Concentration 1.52 (PWC) interface has been applied to model pesticide behavior in nine groundwater bodies located inside the Júcar River Basin (JRB) in Spain. Mathematical modeling allowed calculating the maximum concentration of pesticides after completing the calibration process. Bromacil, terbuthylazine, atrazine, desethyl-terbuthylazine, and terbumeton concentrations in groundwater were simulated between 2006 and 2019. Results show that the maximum pesticide concentration value on every well exceeds the current Spanish Maximum Concentration Limit (0.1 μg/L). PRZM 5 was able to reproduce pesticide concentration observations over time despite the limited amount of available data. This study contributes to assessing environmental risks caused by the use of pesticides inside the JRB and can potentially be applied in other areas of interest.

Potential and limitations for monitoring of pesticide biodegradation at trace concentrations in water and soil

Pesticides application on agricultural fields results in pesticides being released into the environment, reaching soil, surface water and groundwater. Pesticides fate and transformation in the environment depend on environmental conditions as well as physical, chemical and biological degradation processes. Monitoring pesticides biodegradation in the environment is challenging, considering that traditional indicators, such as changes in pesticides concentration or identification of pesticide metabolites, are not suitable for many pesticides in anaerobic environments. Furthermore, those indicators cannot distinguish between biotic and abiotic pesticide degradation processes. For that reason, the use of molecular tools is important to monitor pesticide biodegradation-related genes or microorganisms in the environment. The development of targeted molecular (e.g., qPCR) tools, although laborious, allowed biodegradation monitoring by targeting the presence and expression of known catabolic genes of popular pesticides. Explorative molecular tools (i.e., metagenomics & metatranscriptomics), while requiring extensive data analysis, proved to have potential for screening the biodegradation potential and activity of more than one compound at the time. The application of molecular tools developed in laboratory and validated under controlled environments, face challenges when applied in the field due to the heterogeneity in pesticides distribution as well as natural environmental differences. However, for monitoring pesticides biodegradation in the field, the use of molecular tools combined with metadata is an important tool for understanding fate and transformation of the different pesticides present in the environment.

Global groundwater vulnerability for Pharmaceutical and Personal care products (PPCPs): The scenario of second decade of 21st century

The global production of PPCPs have increased by multiple folds promoting excessive exposure of its metabolites to humans via different aquatic systems. The higher residence time of toxic precursors of these metabolites pose direct human health risk. Among the different aquatic systems, the contamination of groundwater by PPCPs is the most concerning threat. This threat is especially critical considering the lesser oxidizing potential of the groundwater as compared to freshwater/river water. A major challenge also arises due to excessive dependency of the world's population on groundwater, which is exponentially increasing with time. This makes the identification and characterization of spatial contamination hotspots highly probabilistic as compared to other freshwater systems. The situation is more vulnerable in developing countries where there is a reported inadequacy of wastewater treatment facilities, thereby forcing the groundwater to behave as the only available sequestrating sink for all these contaminants. With increased consumption of antibiotics and other pharmaceuticals compounds, these wastes have proven capability in terms of enhancing the resistance among the biotic community of the soil systems, which ultimately can become catastrophic and carcinogenic in near future. Recent studies are supporting the aforementioned concern where compounds like diclofenac (analgesic) have attained a concentration of 1.3 mgL^-1 in the aquifer systems of Delhi, India. The situation is far worse for developed nations where prolonged and indiscriminate usage of antidepressants and antibiotics have life threating consequences. It has been confirmed that certain compounds like ofloxacin (antibiotics) and bis-(2-ethylhexyl)phthalate are present in some of the most sensitive wells/springs of the United States and Mexico. The current trend of the situation has been demonstrated by integrating a comparative approach of the published literatures in last three years. This review provides first-hand information report for formulating a directive policy framework for tackling PPCPs issues in the groundwater system.

Pesticides and their metabolites in European groundwater: Comparing regulations and approaches to monitoring in France, Denmark, England and Switzerland

Pesticides, i.e. plant protection products (PPP), biocides and their metabolites, pose a serious threat to groundwater quality and groundwater dependent ecosystems. Across large parts of Europe these compounds are monitored in groundwater to ensure compliance with the European Water Framework Directive (WFD), the Groundwater Directive (GWD) and Drinking water Directive (DWD). European regulation concerning the placing of PPP on the market includes groundwater monitoring as a higher tier of the regulatory procedure. Nevertheless, the lists of compounds to be monitored vary from one directive to another and between countries. The implementation of monitoring strategies for these directives and other national drivers, differs across Europe. This is illustrated using case studies from France, Denmark (EU member states), England (part of the EU up to January 2020) and Switzerland (associated country). The collection of data (e.g. monitoring design and analytical approaches) and dissemination at national and European level and the scale of data reporting to EU is country-specific. Data generated by the implementation of WFD and DWD can be used for retrospective purposes in the context of PPP registration whereas the post-registration monitoring data generated by the product applicants are generally only directly available to the regulators. This lack of consistency and strategic coordination between thematic regulations is partly compensated by national regulations. This paper illustrates the benefits of a common framework for regulation in Europe but shows that divergent national approaches to monitoring and reporting on pesticides in groundwater makes the task of assessment across Europe challenging.

Global distributions, source-type dependencies, and concentration ranges of per- and polyfluoroalkyl substances in groundwater

A meta-analysis was conducted of published literature reporting concentrations of per- and polyfluoroalkyl substances (PFAS) in groundwater for sites distributed in 20 countries across the globe. Data for >35 PFAS were aggregated from 96 reports published from 1999 to 2021. The final data set comprises approximately 21,000 data points after removal of time-series and duplicate samples as well as non-detects. The reported concentrations range over many orders of magnitude, from ng/L to mg/L levels. Distinct differences in concentration ranges are observed between sites located within or near sources versus those that are not. Perfluorooctanoic acid (PFOA), ranging from <0.03 ng/L to ~7 mg/L, and perfluorooctanesulfonic acid (PFOS), ranging from 0.01 ng/L to ~5 mg/L, were the two most reported PFAS. The highest PFAS concentration in groundwater is ~15 mg/L reported for the replacement-PFAS 6:2 fluorotelomer sulfonate (6:2 FTS). Maximum reported groundwater concentrations for PFOA and PFOS were compared to concentrations reported for soils, surface waters, marine waters, and precipitation. Soil concentrations are generally significantly higher than those reported for the other media. This accrues to soil being the primary entry point for PFAS release into the environment for many sites, as well as the generally significantly greater retention capacity of soil compared to the other media. The presence of PFAS has been reported for all media in all regions tested, including areas that are far removed from specific PFAS sources. This gives rise to the existence of a "background" concentration of PFAS that must be accounted for in both regional and site-specific risk assessments. The presence of this background is a reflection of the large-scale use of PFAS, their general recalcitrance, and the action of long-range transport processes that distribute PFAS across regional and global scales. This ubiquitous distribution has the potential to significantly impact the quality and availability of water resources in many regions. In addition, the pervasive presence of PFAS in the environment engenders concerns for impacts to ecosystem and human health.

Harnessing plant-microbiome interactions for bioremediation across a freshwater urbanization gradient

Urbanization impacts land, air, and water, creating environmental gradients between cities and rural areas. Urban stormwater delivers myriad co-occurring, understudied, and mostly unregulated contaminants to aquatic ecosystems, causing a pollution gradient. Recipient ecosystems host interacting species that can affect each others' growth and responses to these contaminants. For example, plants and their microbiomes often reciprocally increase growth and contaminant tolerance. Here, we identified ecological variables affecting contaminant fate across an urban-rural gradient using 50 sources of the aquatic plant Lemna minor (duckweed) and associated microbes, and two co-occurring winter contaminants of temperate cities, benzotriazole and salt. We conducted experiments totalling >2,500 independent host-microbe-contaminant microcosms. Benzotriazole and salt negatively affected duckweed growth, but not microbial growth, and duckweeds maintained faster growth with their local, rather than disrupted, microbiota. Benzotriazole transformation products of plant, microbial, and phototransformation pathways were linked to duckweed and microbial growth, and were affected by salt co-contamination, microbiome disruption, and source sites of duckweeds and microbes. Duckweeds from urban sites grew faster and enhanced phytotransformation, but supported less total transformation of benzotriazole. Increasing microbial community diversity correlated with greater removal of benzotriazole, but taxonomic groups may explain shifts across transformation pathways: the genus Aeromonas was linked to increasing phototransformation. Because benzotriazole toxicity could depend on amount and type of in situ transformation, this variation across duckweeds and microbes could be harnessed for better management of urban stormwater. Broadly, our results demonstrate that plant-microbiome interactions harbour manipulable variation for bioremediation applications.

Removal of organic micropollutans by adsorptive membrane

Various emerging organic micropollutants, such as pharmaceuticals, have attracted the interest of the water industry during the last two decades due to their insufficient removal during conventional water and wastewater treatment methods and increasing demand for pharmaceuticals projected to climate change-related impacts and COVID-19, nanosorbents such as carbon nanotubes (CNTs), graphene oxides (GOs), and metallic organic frameworks (MOFs) have recently been extensively explored regarding their potential environmental applications. Due to their unique physicochemical features, the use of these nanoadsorbents for organic micropollutans in water and wastewater treatment processes has been a rapidly growing topic of research in recent literature. Adsorptive membranes, which include these nanosorbents, combine the benefits of adsorption with membrane separation, allowing for high flow rates and faster adsorption/desorption rates, and have received a lot of publicity in recent years. The most recent advances in the fabrication of adsorptive membranes (including homogeneous membranes, mixed matrix membranes, and composite membranes), as well as their basic principles and applications in water and wastewater treatment, are discussed in this review. This paper covers ten years, from 2011 to 2021, and examines over 100 published studies, highlighting that micropollutans can pose a serious threat to surface water environments and that adsorptive membranes are promising, particularly in the adsorption of trace substances with fast kinetics. Membrane fouling, on the other hand, should be given more attention in future studies due to the high costs and restricted reusability.

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) in groundwater: current understandings and challenges to overcome

Perfluoroalkyl and polyfluoroalkyl substances (PFASs) have been frequently detected in groundwater globally. With the phase-out of perfluorooctane sulfonate (PFOS) and perfluorooctanate (PFOA) due to their risk to the ecosystem and human population, various novel PFASs have been used as replacements and detected in groundwater. In order to summarize the current understanding and knowledge gaps on PFASs in groundwater, we reviewed the studies about environmental occurrence, transport, and risk of legacy and novel PFASs in groundwater published from 1999 to 2021. Our review suggests that PFOS and PFOA could still be detected in groundwater due to the long residence time and the retention in the soil-groundwater system. Firefighting training sites, industrial parks, and landfills were commonly hotspots of PFASs in groundwater. More novel PFASs have been detected via nontarget analysis using high-resolution mass spectrometry. Some novel PFASs had concentrations comparable to that of PFOS and PFOA. Both legacy and novel PFASs can pose a risk to human population who rely on contaminated groundwater as drinking water. Transport of PFASs to groundwater is influenced by various factors, i.e., the compound structure, the hydrochemical condition, and terrain. The exchange of PFASs between groundwater and surface water needs to be better characterized. Field monitoring, isotope tracing, nontarget screening, and modeling are useful approaches and should be integrated to get a comprehensive understanding of PFASs sources and behaviors in groundwater.

Effect-Directed Analysis Based on the Reduced Human Transcriptome (RHT) to Identify Organic Contaminants in Source and Tap Waters along the Yangtze River

Since a large number of contaminants are detected in source waters (SWs) and tap waters (TWs), it is important to perform a comprehensive effect evaluation and key contributor identification. A reduced human transcriptome (RHT)-based effect-directed analysis, which consisted of a concentration-dependent RHT to reveal the comprehensive effects and noteworthy pathways and systematic identification of key contributors based on the interactions between compounds and pathway effects, was developed and applied to typical SWs and TWs along the Yangtze River. By RHT, 42% more differentially expressed genes and 33% more pathways were identified in the middle and lower reaches, indicating heavier pollution. Hormone and immune pathways were prioritized based on the detection frequency, sensitivity, and removal efficiency, among which the estrogen receptor pathway was the most noteworthy. Consistent with RHT, estrogenic effects were widespread along the Yangtze River based on in vitro evaluations. Furthermore, 38 of 100 targets, 39 pathway-related suspects, and 16 estrogenic nontargets were systematically identified. Among them, diethylstilbestrol was the dominant contributor, with the estradiol equivalent (EEQ) significantly correlated with EEQ_water. In addition, zearalenone and niclosamide explained up to 54% of the EEQ_water. The RHT-based EDA method could support the effect evaluation, contributor identification, and risk management of micropolluted waters.

Screening of Contaminants of Emerging Concern in Surface Water and Wastewater Effluents, Assisted by the Persistency-Mobility-Toxicity Criteria

Contaminants of emerging concern (CECs) are compounds of diverse origins that have not been deeply studied in the past which are now accruing growing environmental interest. The NOR-Water project aimed to identify the main CECs and their sources in the water environment of Northern Portugal-Galicia (located in northwest Spain) transnational region. To achieve these goals, a suspect screening analytical methodology based on the use of liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) was applied to 29 sampling sites in two campaigns. These sampling sites included river and sea water, as well as treated wastewater. The screening was driven by a library of over 3500 compounds, which included 604 compounds prioritized from different relevant lists on the basis of the persistency, mobility, and toxicity criteria. Thus, a total of 343 chemicals could be tentatively identified in the analyzed samples. This list of 343 identified chemicals was submitted to the classification workflow used for prioritization and resulted in 153 chemicals tentatively classified as persistent, mobile, and toxic (PMT) and 23 as very persistent and very mobile (vMvP), pinpointing the relevance of these types of chemicals in the aqueous environment. Pharmaceuticals, such as the antidepressant venlafaxine or the antipsychotic sulpiride, and industrial chemicals, especially high production volume chemicals (HPVC) such as ε-caprolactam, were the groups of compounds that were detected at the highest frequencies.

Ecotoxicological aspects related to the occurrence of emerging contaminants in the Dinaric karst aquifer of Jadro and Žrnovnica springs

Karst aquifers are globally important source of drinking water and harbor specific ecosystems that are vulnerable to anthropogenic contamination. This paper provides insights into the occurrence and ecotoxicological characterization of 21 emerging contaminants (ECs) detected in the karst catchment of Jadro and Žrnovnica springs (Dinarides, Croatia). Karst springs used for water supply, surface water, and groundwater were sampled during seven campaigns. The ECs concentration levels ranged from 0.3 ng/L (tramadol in Jadro spring) to 372 ng/L (1H-benzotriazole in Cetina River). DEET was the most frequently detected ECs with an average concentration of around 50 ng/L in both surface water and groundwater. To prioritise detected ECs, their persistence (P), bioaccumulation (B), mobility (M) and toxicity (T) were assessed based on in silico strategy for PBT assessment and recently developed REACH PMT guidelines. PBT scores ranging below the threshold of 0.5, indicated non-PBT compounds of expected low concern. However, only 4 out of 21 detected ECs were not assessed as PMT/vPvM. Concerningly, 20 ECs were categorised as very mobile. Karst springs exhibited larger proportions of ECs meeting PMT/vPvM criteria than surface water. To characterise the contamination extent and estimate the incidence of adverse effects of detected ECs, a preliminary environmental risk assessment (ERA) was conducted. Most ECs posed no environmental risk with RQ values predominantly below 0.01. The total risk quotient RQ_site accentuated Cetina River as having the highest risk compared to other sampling sites. This is the first study on ECs in Croatian karst, contributing to a growing need to understand the impacts of emerging contaminants in karst aquifers, which are still largely unexplored.

Development and validation of a high resolving power absolute quantitative per- and polyfluoroalkyl substances method incorporating Skyline data processing

RATIONALE

The ability to perform absolute quantitation and non-targeted analysis on a single mass spectrometry instrument would be advantageous to many researchers studying per- and polyfluoroalkyl substances (PFAS). High-resolution accurate mass (HRAM) instrumentation (typically deployed for non-targeted work) carries several advantages over traditional triple quadrupole workflows when performing absolute quantitation. Processing this data using a vendor-neutral software would promote collaboration for these environmental studies.

METHODS

LC-MS (Orbitrap Exploris 240) was used for absolute quantitation of 45 PFAS using precursor (MS1) peak areas for quantitation, whereas isotope pattern matching and fragmentation (MS2) pattern matching were used for qualitative identification. In addition, a fluorinated chromatographic column achieved superior separation compared to the typical C18 columns typically used in PFAS analyses. This method was validated across eight different chemical classes using recommended guidelines found in EPA Method 537.1 and Skyline data processing software.

RESULTS

The validated limits of all 45 compounds, as well as metrics or accuracy and reproducibility, are reported. Most compounds achieved limits of quantitation in the range of 2-50 ng/L. Four newly released Chemours-specific compounds (PEPA, PFO3OA, PFO4DA, and PFO5DoA) were also validated. Aspects of data analysis specific to high resolving power absolute quantitation are reviewed as are the details of processing these data via Skyline.

CONCLUSIONS

This method shows the feasibility of performing reproducible absolute quantitation of PFAS on an HRAM platform and does so using an open-source vendor-neutral data processing software to facilitate sharing of data across labs and institutions.

Modeling of Bentazone Leaching in Soils with Low Organic Matter Content

The aim of this study was to estimate bentazone’s potential to leach to groundwater in the Arenosols developed from sand, Luvisols developed from loamy sand or sandy loam, and Luvisols or Cambisols developed from loess, and to identify the major factors influencing bentazone’s fate in the soils. Potato and maize cultivations were simulated using the FOCUS PELMO 5.5.3 pesticide leaching model. The amount of bentazone reaching groundwater was highly sensitive to degradation parameters, water-holding capacity, evapotranspiration, organic carbon content, and pH. The highest bentazone concentrations in percolate were noted in Arenosols. The risk of bentazone concentration exceeding 0.1 μg/L was low only in Arenosols with high organic carbon content (3.0% for topsoil or higher). In Luvisols developed from loamy sand or sandy loam, the estimated bentazone concentrations in percolate were highly dependent on the climate. In Luvisols or Cambisols developed from loess, concentrations of >0.1 μg/L were the least likely due to the high water-holding capacity and high organic carbon content of these soils. The study also revealed that the FOCUS Hamburg scenario, representing the coarsest soils in the European Union with relatively low organic carbon content, does not reflect the leaching potential of Arenosols and Luvisols.

Investigating a broad range of emerging contaminants in a set of anthropogenically impacted environmental compartments

Environmental compartments are repositories of probably thousands of emerging contaminants (ECs) released along with treated/untreated wastewater. Despite extensive studies on the detection of ECs in surface water, other environmental compartments such as sediments and groundwater are yet to be thoroughly investigated. To assess the heavy anthropogenic impact on the environment, 24 environmental samples comprising of surface water, sediment and groundwater collected from the Yamuna River basin of India were analyzed via target and suspect screening. The surface water and sediment samples were collected from upstream and downstream of densely populated cities and towns situated along the heavily contaminated river Yamuna. The groundwater samples were collected from shallow drinking water wells of the catchment. Liquid chromatography tandem mass-spectroscopy was used to quantify 10 widely consumed pharmaceuticals in the samples. The study also analyzed the potential health hazards posed by the quantified contaminants. In order to evaluate further, the surface water and groundwater samples were subjected to high resolution mass spectrometry (HRMS) screening against a library resulting in a list of 450 ECs in the surface water and 309 ECs in the groundwater. Agricultural chemicals and pharmaceuticals found abundantly in the samples and half of whom were reported first time. The risk quotient was calculated to assess the potential hazard of the target analytes.

Occurrence and distribution of Pharmaceuticals and Personal Care Products (PPCPs) in wastewater related riverbank groundwater

Pharmaceutical and personal care products (PPCPs) are among the most frequently reported groups of emerging contaminants in groundwater worldwide. PPCPs in rivers may infiltrate into groundwater through hydraulic exchange and potentially threaten drinking water safety and human health. In the present study, the occurrence and distribution of nine PPCPs in riverbank groundwater and adjacent rivers (distance up to 113 m) were investigated at four sites with different lithological features and permeabilities of aquifers in a city in North China. Seven of nine PPCPs were detectable in groundwater, ranging from <LOQ (limit of quantification) to 128 ng/L. N,N-diethyl-meta-toluamide (DEET), carbamazepine, and caffeine had the highest detection frequencies (>90%). The concentrations and major compounds in river water varied with the sampling location and water system distribution, resulting in distinct compositions of PPCPs in the groundwater at each site along with different lithology and hydrological conditions. The spatial distribution of PPCPs in riverbank groundwater was affected by the hydraulic connection between the groundwater and river and the lithology of aquifers. Direct hydraulic connection of a fine sand aquifer to the adjacent river caused a decrease in PPCPs with increasing distance. The results also suggested that sandy gravel aquifers had a lower capacity to attenuate PPCPs compared to that of fine sand. Significant correlations between PPCP concentrations and thirteen physicochemical factors of groundwater were discovered, including nitrate, potassium, and manganese. Overall, this study provides important evidence on the role of lithology and hydrological conditions on the composition, distribution, and influential physicochemical factors of PPCPs in riverbank groundwater.

Effective Electrochemiluminescence Aptasensor for Detection of Atrazine Residue

According to the chemiluminescence characteristics of the luminol-hydrogen peroxide (H₂O₂) system, this work designed a novel and effective electrochemiluminescence (ECL) aptasensor to detect atrazine (ATZ) rapidly. Silver nanoparticles (AgNPs) could effectively catalyze the decomposition of H₂O₂ and enhance the ECL intensity of the luminol-H₂O₂ system. Once ATZ was modified on the aptasensor, the ECL intensity was significantly weakened because of the specific combination between ATZ and its aptamer. Therefore, the changes in ECL intensity could be used to detect the concentration of ATZ. Under optimal detecting conditions, the aptasensor had a wide linear range from 1 × 10⁻³ ng/mL to 1 × 10³ ng/mL and a low limit of detection (3.3 × 10⁻⁴ ng/mL). The designed aptasensor had the advantages of good stability, reproducibility, and specificity. The aptasensor could be used to detect the ATZ content of tap water, soil, and cabbage and had satisfactory results. This work effectively constructs a novel, effective, and rapid ECL aptasensor for detecting ATZ in actual samples.

Structure–Biodegradability Relationship of Nonylphenol Isomers in Two Soils with Long-Term Reclaimed Water Irrigation

Nonylphenol (NP), as one of the typical endocrine disrupter chemicals (EDCs), has a high detection concentration and frequency in reclaimed water. This research focused on the degradation of NP isomers in two typical reclaimed water irrigation fields in Daxing, China, and Florida, USA. The results showed that the half-lives of NP isomer degradation in the soil of China and Florida were 2.03–8.66 d and 5.16–11.83 d, respectively. The degradation of NP isomers was structure-specific. Isomers of NP5, NP2, NP11, and NP3 had the highest degradation rates in the two soils; NP12, NP7, and NP6 were the isomers with medium degradation rates; and NP4, NP1, NP10, NP9, and NP8 had the slowest degradation rates. Steric hindrance and mean information index for the magnitude of distance (IDWbar) were found to be the better indexes for measuring the degradation of NP isomers compared with the length of the side chain, the type of the substitute, and the molecular connectivity. This study offers insights into the characteristics of NP isomers and two reliable indicators for measuring the degradation of NP isomers, which could provide data support for the environmental fate and the health risk assessment of NP in the future.

Benzotriazole Ultraviolet Stabilizers Promote Breast Cancer Cell Proliferation via Activating Estrogen-Related Receptors α and γ at Human-Relevant Levels

Benzotriazole ultraviolet stabilizers (BUVSs) are ubiquitous emerging pollutants that have been reported to show estrogenic disruption effects through interaction with the classic estrogen receptors (ERs) in the fashion of low activity. The present study aims at revealing the potential disruption mechanism via estrogen-related receptors α and γ (ERRα and ERRγ) pathways. By the competitive binding assay, we first found that BUVSs bond to ERRγ ligand binding domain (ERRγ-LBD) with Kd ranging from 0.66 to 19.27 μM. According to the results of reporter gene assays, the transcriptional activities of ERRα and ERRγ were promoted by most tested BUVSs with the lowest observed effective concentrations (LOEC) from 10 to 100 nM, which are in the range of human exposure levels. At 1 μM, most tested BUVSs showed higher agonistic activity toward ERRγ than ERRα. The most effective two BUVSs promoted the MCF-7 proliferation dependent on ERRα and ERRγ with a LOEC of 100 nM. The molecular dynamics simulation showed that most studied BUVSs had lower binding free energy with ERRγ than with ERRα. The structure-activity relationship analysis revealed that molecular polarizability, electron-donating ability, ionization potential, and softness were the main structural factors impacting the binding of BUVSs with ERRγ. Overall, our results provide novel insights into the estrogenic disruption effects of BUVSs.

Occurrence, source apportionment and potential risks of selected PPCPs in groundwater used as a source of drinking water from key urban-rural settings of Pakistan

BACKGROUND

Pharmaceuticals and personal care products (PPCPs) are emerging contaminants that have been extensively used in present time to improve the living standards. Their persistence in water resources due to various anthropogenic sources such as wastewater treatment plants, pharmaceutical industries, and runoff from agricultural and livestock farms has not only threaten aquatic life but their occurrence in groundwater has also raised concerns related to humans' wellbeing.

METHODS

Considering this as a neglected area of research in Pakistan, a systematic monitoring study was designed to investigate their occurrence, sources, and potential environmental and human health risks in groundwater from urban-rural areas of six cities. Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry (UHPLC-MS/MS) was used to analyze the collected samples preceded by solid-phase extraction.

RESULTS

Overall, 8 out of 11 selected PPCPs were detected in groundwater samples with detection frequency ranging from 5.5-65%. Their concentrations ranged from below limit of detection (<LOD) to 1961 ng/L. The overall mean concentrations of detected PPCPs were found below 100 ng/L. The highest mean concentration was reported for Ibuprofen (154 ng/L) in Rawalpindi/Islamabad. Results of PCA-MLR revealed that domestic wastewater discharge (76.4%) was the dominant source contributing to PPCPs contamination in groundwater. Followed by mixed source (pharmaceutical & hospital waste) 17.8%, and rural discharge/animal husbandry 5.8%. No appreciable risk to human health upon exposure to detected PPCPs via drinking water was anticipated. However, environmental risk assessment indicated moderate risk posed to P. subcapitata (RQ = 0.98) and D. magna (RQ = 0.2) by ibuprofen.

CONCLUSION

The current study reports the first evidence of PPCPs occurrence in groundwater in Pakistan. Reporting their occurrence in groundwater is a fundamental initial step to inform public-health decisions concerning sewage systems and drinking water quality. Hence, comprehensive monitoring programs are required to further investigate contamination of emerging contaminants in groundwater and their associated risks.

Efficient removal of PFOA with an In2O3/persulfate system under solar light via the combined process of surface radicals and photogenerated holes

The environmental persistence, high toxicity and wide spread presence of perfluorooctanoic acid (PFOA) in aquatic environment urgently necessitate the development of advanced technologies to eliminate PFOA. Here, the simultaneous application of a heterogeneous In₂O₃ photocatalyst and homogeneous persulfate oxidation (In₂O₃/PS) was demonstrated for PFOA degradation under solar light irradiation. The synergistic effect of direct hole oxidation and in-situ generated radicals, especially surface radicals, was found to contribute significantly to PFOA defluorination. Fourier infrared transform (FTIR) spectroscopy, Raman, electrochemical scanning microscope (SECM) tests and density functional theory (DFT) calculation showed that the pre-adsorption of PFOA and PS onto In₂O₃ surface were dramatically critical steps, which could efficiently facilitate the direct hole oxidation of PFOA, and boost PS activation to yield high surface-confined radicals, thus prompting PFOA degradation. Response surface methodology (RSM) was applied to regulate the operation parameters for PFOA defluorination. Outstanding PFOA decomposition (98.6%) and near-stoichiometric equivalents of fluorides release were achieved within illumination 10 h. An underlying mechanism for PFOA destruction was proposed via a stepwise losing CF₂ unit. The In₂O₃/PS remediation system under solar light provides an economical, sustainable and environmentally friendly approach for complete mineralization of PFOA, displaying a promising potential for treatment of PFOA-containing water.

Fate of sulfamethoxazole in compost, manure and soil amended with previously stored organic wastes

Application of organic wastes as soil fertilizers represents an important route of agricultural soil contamination by antibiotics such as sulfamethoxazole (SMX). Soil contamination may be influenced by the storage time of organic wastes before soil spreading. The objective of this work was to study the fate of SMX in two organic wastes, a co-compost of green waste and sewage sludge and a bovine manure, which were stored between 0 and 28 days, then incorporated in an agricultural soil that has never received organic waste and monitored for 28 days under laboratory conditions. Organic wastes were spiked with ¹⁴C-labelled SMX at two concentrations (4.77 and 48.03 mg kg^-1 dry organic waste). The fate of SMX in organic wastes and soil-organic waste mixtures was monitored through the distribution of radioactivity in the mineralised, available (2-hydroxypropyl-β-cyclodextrin extracts), extractable (acetonitrile extracts) and non-extractable fractions. SMX dissipation in organic wastes, although partial, was due to i) incomplete degradation, which led to the formation of metabolites detected by high performance liquid chromatography, ii) weak adsorption and iii) formation of non-extractable residues. Such processes varied with the organic wastes, the manure promoting non-extractable residues, and the compost leading to an increase in extractable and non-extractable residues. Short storage does not lead to complete SMX elimination; thus, environmental contamination may occur after incorporating organic wastes into soil. After addition of organic wastes to the soil, SMX residues in the available fraction decreased quickly and were transferred to the extractable and mostly non-extractable fractions. The fate of SMX in the soil also depended on the organic wastes and on the prior storage time for manure. However the fate of SMX in the organic wastes and soil-organic waste mixtures was independent on the initial spiked concentration.

Automation in quantifying phenoxy herbicides and bentazon in surface water and groundwater using novel solid phase extraction and liquid chromatography tandem mass spectrometry

The occurrence of phenoxy herbicides is a financial and regulatory concern for drinking water treatment plants. This paper presents a new method of quantification for nine phenoxy-acids and bentazon in different water samples using liquid chromatography tandem mass spectrometry (LC-MS/MS). The method is based on an automated solid phase extraction (SPE) process that applied hydrophilic modified polystyrene and divinylbenzene cartridges at low pH (<2.0). Main advantages of the presented method include the reduced consumption of organic solvent in extraction and the fully automated sample pre-concentration. The method is thus more environmentally-friendly. In the quantification step, five stable isotopically labelled analogues were used as internal standards to account for the losses during sample preparation and to calibrate the ion source response under the mass spectrometric detection. The method was optimized in terms of sample preparation and subsequent LC-MS/MS separation to obtain reliable measurement of the analyte concentration during real sample analysis. The method quantification limit was between 1.5 and 10.0 ng/L for target compounds in surface water and groundwater samples. The method was validated at three fortification levels between 10.0 and 1000 ng/L, and the results showed fit-for-purpose recovery with appropriate precision at low concentration levels. The method was also utilized to analyse thirty-two actual water samples from different sources. Forty percent of the analysed samples contained detectable level of herbicides, ranging from 1.91 to 40.5 ng/L. The concentrations of targeted herbicides in our study were comparable to those found in water samples in other regions of world.

A review on environmental occurrence, toxicity and microbial degradation of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs)

In recent years, Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) have surfaced as a novel class of pollutants due to their incomplete degradation in wastewater treatment plants and their inherent ability to promote physiological predicaments in humans even at low doses. The occurrence of the most common NSAIDs (diclofenac, ibuprofen, naproxen, and ketoprofen) in river water, groundwater, finished water samples, WWTPs, and hospital wastewater effluents along with their toxicity effects were reviewed. The typical concentrations of NSAIDs in natural waters were mostly below 1 μg/L, the rivers receiving untreated wastewater discharge have often showed higher concentrations, highlighting the importance of effective wastewater treatment. The critical analysis of potential, pathways and mechanisms of microbial degradation of NSAIDs were also done. Although studies on algal and fungal strains were limited, several bacterial strains were known to degrade NSAIDs. This microbial ability is attributed to hydroxylation by cytochrome P450 because of the decrease in drug concentrations in fungal cultures of Phanerochaete sordida YK-624 on incubation with 1-aminobenzotriazole. Moreover, processes like decarboxylation, dehydrogenation, dechlorination, subsequent oxidation, demethylation, etc. also constitute the degradation pathways. A wide array of enzymes like dehydrogenase, oxidoreductase, dioxygenase, monooxygenase, decarboxylase, and many more are upregulated during the degradation process, which indicates the possibility of their involvement in microbial degradation. Specific hindrances in upscaling the process along with analytical research needs were also identified, and novel investigative approaches for future monitoring studies are proposed.

New insight into PFOS transformation pathways and the associated competitive inhibition with other perfluoroalkyl acids via photoelectrochemical processes using GOTiO2 film photoelectrodes

The global distribution and environmental persistence of perfluoroalkyl acids (PFAAs) has been considered a critical environmental concern. In this work, we successfully fabricated a graphene oxide-titanium dioxide (GOTiO₂) photoelectrode for perfluorooctane sulfonate (PFOS) degradation in a photoelectrochemical (PEC) system. The results reveal that a 5 wt.% GOTiO₂ anode possesses the optimal PEC performance, with a band gap (E_g) of 2.42 eV, specific surface area (S_BET) of 72.6 m² g^-1 and specific capacitance (Cs) of 4.63 mF cm^-2. In the PEC system, PFOS can be efficiently removed within 4 h of reaction time, with a pseudo-first-order rate constant of 0.0124 min^-1, under the optimized conditions of current density = 20 mA cm^-2, electrode distance = 5 mm, solution pH = 5.64, [PFOS]₀= 0.5 µM and NaClO₄ electrolyte concentration = 50 mM. The electron transfer pathway, hydroxyl radicals and superoxide radicals are all responsible for PFOS decomposition/transformation. New degradation pathways were identified; a total of 25 PFOS byproducts are reported in this work; and perfluoroalkane sulfonates (PFSAs), perfluorinated aldehydes (PFALs) and hydrofluorocarbons (HFCs) were identified for the first time. PFOS degradation involves the desulfonation pathway as the first step, followed by oxidation and subsequent defluorination, decarboxylation, decarbonylation, sulfonation, defluorination and hydroxylation. The results from this work also show that the reactivity of PFAAs is related to their carbon chain length, with shorter-chain PFAAs exhibiting a lower degradation rate. In a PFAA mixture, a decline in the degradation rate was observed for the shorter-chain-length PFAAs, suggesting stronger competitive inhibition and indicating stronger environmental recalcitrance during the treatment process. Novelty statement: Although many efforts have been made to identify perfluorooctane sulfonate (PFOS) degradation byproducts, previous studies were only able to identify byproducts that are related to perfluorinated carboxylic acids (PFCAs). This is the first study to elucidate the new PFOS degradation pathway; furthermore, this is the first report to identify byproducts containing sulfonate groups (perfluoroalkane sulfonates, PFSAs), aldehyde groups (perfluorinated aldehydes, PFALs), and hydrofluorocarbons (HFCs). This study further systematically explores how perfluoroalkyl acid (PFAA) degradation may be affected in the mixture system: shorter-chain-length PFAAs suffer stronger competitive inhibition in the photoelectrochemical (PEC) system. By utilizing the graphene oxide-titanium dioxide (GOTiO₂) photoelectrode fabricated in this work, PFOS can be successfully decomposed during the PEC process for the first time.

Unravelling the impacts of perfluorooctanoic acid on anaerobic sludge digestion process

Perfluorooctanoic acid (PFOA) is a type of persistent organic pollutant that has been detected in wastewater treatment systems, subsequently entering the waste activated sludge (WAS) anaerobic digesters. Nevertheless, how PFOA affects the anaerobic digestion of WAS has never been reported till now. In this study, a series of batch digesters were set up to assess the performance of the anaerobic sludge digestion processes with exposures to different levels of PFOA. Experimental results revealed that the increased PFOA concentration (3-60 μg/g-TS) caused the 11.1-19.2% decrease in methane production than the control. Correspondingly, the relative abundances of several key microbes related to acidification (e.g., Longilinea sp.) and methanation (e.g., Methanosaeta sp.) decreased when exposed to PFOA, as demonstrated by microbial community analysis. Further investigations based on modelling and intermediate metabolites analysis confirmed the inhibition of acidification and methanation caused by PFOA, thus decreasing the methane production potential of WAS in anaerobic digestion.

A Review of the Occurrence of Pharmaceutical Compounds as Emerging Contaminants in Treated Wastewater and Aquatic Environments

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In recent years, pharmaceutical compounds have emerged as potential contaminants in the aquatic matrices of the environment. High production, consumption, and limited removal through conventional treatment processes/wastewater treatment plants (WWTPs) are the major causes for the occurrence of pharmaceutical compounds in wastewater and aquatic environments worldwide. A number of studies report adverse health effects and risks to aquatic life and the ecosystem because of the presence of pharmaceutical compounds in the aquatic environment. This paper provides a state-of-the-art review of the occurrence of pharmaceutical compounds in treated wastewater from various WWTPs, surface water and groundwater bodies. Additionally, this review provides comprehensive information and pointers for research in wastewater treatment and waterbodies management.

Detection and removal of poly and perfluoroalkyl polluting substances for sustainable environment

PFAs (poly and perfluoroalkyl compounds) are hazardous and bioaccumulative chemicals that do not readily biodegrade or neutralize under normal environmental conditions. They have various industrial, commercial, domestic and defence applications. According to the Organization for Economic Co-operation and Development, there are around 4700 PFAs registered to date. They are present in every stream of life, and they are often emerging and are even difficult to be detected by the standard chemical methods. This review aims to focus on the sources of various PFAs and the toxicities they impose on the environment and especially on humankind. Drinking water, food packaging, industrial areas and commercial household products are the primary PFAs sources. Some of the well-known treatment methods for remediation of PFAs presented in the literature are activated carbon, filtration, reverse osmosis, nano filtration, oxidation processes etc. The crucial stage of handling the PFAs occurs in determining and analysing the type of PFA and its remedy. This paper provides a state-of-the-art review of determination & tools, and techniques for remediation of PFAs in the environment. Improving new treatment methodologies that are economical and sustainable are essential for excluding the PFAs from the environment.

Biostimulation is a valuable tool to assess pesticide biodegradation capacity of groundwater microorganisms

Groundwater is the main source for drinking water production globally. Groundwater unfortunately can contain micropollutants (MPs) such as pesticides and/or pesticide metabolites. Biological remediation of MPs in groundwater requires an understanding of natural biodegradation capacity and the conditions required to stimulate biodegradation activity. Thus, biostimulation experiments are a valuable tool to assess pesticide biodegradation capacity of field microorganisms. To this end, groundwater samples were collected at a drinking water abstraction aquifer at two locations, five different depths. Biodegradation of the MPs BAM, MCPP and 2,4-D was assessed in microcosms with groundwater samples, either without amendment, or amended with electron acceptor (nitrate or oxygen) and/or carbon substrate (dissolved organic carbon (DOC)). Oxygen + DOC was the most successful amendment resulting in complete biodegradation of 2,4-D in all microcosms after 42 days. DOC was most likely used as a growth substrate that enhanced co-metabolic 2,4-D degradation with oxygen as electron acceptor. Different biodegradation rates were observed per groundwater sample. Overall, microorganisms from the shallow aquifer had faster biodegradation rates than those from the deep aquifer. Higher microbial activity was also observed in terms of CO₂ production in the microcosms with shallow groundwater. Our results seem to indicate that shallow groundwater contains more active microorganisms, possibly due to their exposure to higher concentrations of both DOC and MPs. Understanding field biodegradation capacity is a key step towards developing further bioremediation-based technologies. Our results show that biostimulation has real potential as a technology for remediating MPs in aquifers in order to ensure safe drinking production.

Carbon, hydrogen and nitrogen stable isotope fractionation allow characterizing the reaction mechanisms of 1H-benzotriazole aqueous phototransformation

1H-benzotriazole is part of a larger family of benzotriazoles, which are widely used as lubricants, polymer stabilizers, corrosion inhibitors, and anti-icing fluid components. It is frequently detected in urban runoff, wastewater, and receiving aquatic environments. 1H-benzotriazole is typically resistant to biodegradation and hydrolysis, but can be transformed via direct photolysis and photoinduced mechanisms. In this study, the phototransformation mechanisms of 1H-benzotriazole were characterized using multi-element compound-specific isotope analysis (CSIA). The kinetics, transformation products, and isotope fractionation results altogether revealed that 1H-benzotriazole direct photolysis and indirect photolysis induced by OH radicals involved two alternative pathways. In indirect photolysis, aromatic hydroxylation dominated and was associated with small carbon (ε_C = -0.65 ± 0.03‰), moderate hydrogen (ε_H = -21.6‰), and negligible nitrogen isotope enrichment factors and led to hydroxylated forms of benzotriazole. In direct photolysis of 1H-benzotriazole, significant nitrogen (ε_N = -8.4 ± 0.4 to -4.2 ± 0.3‰) and carbon (ε_C = -4.3 ± 0.2 to -1.64 ± 0.04‰) isotope enrichment factors indicated an initial N-N bond cleavage followed by nitrogen elimination with a C-N bond cleavage. The results of this study highlight the potential for multi-element CSIA application to track 1H-benzotriazole degradation in aquatic environments.

Occurrence of Pharmaceuticals and Personal Care Products in the Water Environment of Poland: A Review

The issue of pharmaceuticals and personal care products (PPCPs) in the water environment has gained increasing interest worldwide. To determine the nature and extent of this problem for Poland, this paper presents a review of research on the presence of PPCPs in Poland, looking at results for different water samples, including wastewater (before and after treatment), landfill leachate, surface water (standing water bodies and rivers), seawater, groundwater and drinking water. The review is based on over 50 scientific articles and dissertations referring to studies of PPCPs. It also briefly outlines possible sources and the fate of PPCPs in the aquatic environment. The review of Polish research has revealed that studies have previously covered at least 39 PPCP groups (270 compounds in total). These studies focused mainly on wastewater and rivers, and only a few concerned landfill leachate and seawater. They most often reported on nonsteroidal anti-inflammatory drugs and antibiotics. The highest concentrations of the analysed PPCPs were found mainly in raw wastewater (e.g., naproxen, up to 551,960 ng/L), but they were also occasionally found in surface water (e.g., azithromycin, erythromycin, irbesartan and metoprolol) and in groundwater (e.g., N,N-diethyl-meta-toluamide, known as DEET, up to 17,280 ng/L). Extremely high concentrations of bisphenol A (up to 2,202,000 ng/L) and diclofenac (up to 108,340 ng/L) were found in landfill leachate. Although numerous substances have been detected, PPCPs are still not monitored regularly, which makes it difficult to obtain a clear understanding of their incidence in the water environment.

Identification of Pesticide Transformation Products in Surface Water Using Suspect Screening Combined with National Monitoring Data

Pesticides are widespread anthropogenic chemicals and well-known environmental contaminants of concern. Much less is known about transformation products (TPs) of pesticides and their presence in the environment. We developed a novel suspect screening approach for not well-explored pesticides (n = 16) and pesticide TPs (n = 242) by integrating knowledge from national monitoring with high-resolution mass spectrometry data. Weekly time-integrated samples were collected in two Swedish agricultural streams using the novel Time-Integrating, MicroFlow, In-line Extraction (TIMFIE) sampler. The integration of national monitoring data in the screening approach increased the number of prioritized compounds approximately twofold (from 23 to 42). Ultimately, 11 pesticide TPs were confirmed by reference standards and 12 TPs were considered tentatively identified with varying levels of confidence. Semiquantification of the newly confirmed TPs indicated higher concentrations than their corresponding parent pesticides in some cases, which highlights concerns related to (unknown) pesticide TPs in the environment. Some TPs were present in the environment without co-occurrence of their corresponding parent compounds, indicating higher persistency or mobility of the identified TPs. This study showcased the benefits of integrating monitoring knowledge in this type of studies, with advantages for suspect screening performance and the possibility to increase relevance of future monitoring programs.

Use of Plant Protection Products in Lombardy, Italy and the Health Risk for the Ingestion of Contaminated Water

Pesticides used to protect agricultural crops may contaminate groundwater. This work aimed to identify the pesticides used in Lombardy, Italy, in 2016, their concentration in the groundwater and the risk for health associated with the intake of drinkable water in the adult population. The risk was evaluated for the presence of single and multiple active substances in the groundwater, calculating the hazard quotient (HQ) and the hazard index (HI), respectively. Lombardy utilises an agricultural area of 980,112 h, which is mainly cultivated with cereals (74%). Approximately 2354 pesticides (about 1.3 × 10⁷ kg), containing 410 active substances (about 4.5 × 10⁶ kg) were sold. There were groundwater contamination measurements in 158 monitoring points, which were investigated twice a year for 31 active substances, and a total of 9152 determinations. Only 17 currently used active substance were measured in the groundwater, among which three belonged to the 10 best-sold pesticides. The exceedance of the environmental quality standard was observed for about 1.5% determinations. The intake of contaminated water in the adult population resulted in a HQ typically ranging between 10⁻³ and 10⁻⁴ and a HI of about 10⁻³. Although the number of pesticides sold in 2016 in Lombardy was big, only a small fraction of active substances was monitored in the groundwater. Considering these monitored substances, the intake of contaminated groundwater in the adult general population posed an irrelevant risk for health.

Synergistic effects of contaminants in Lombardy waters

Quantifying synergistic environmental effects in water contamination is still an open issue. Here, we have analyzed geolocalized data of pollutants recorded in 2018 in surface and groundwater of Lombardy, one of the areas with the highest agricultural production rates, not only in Italy, but also in Europe. Both herbicides and insecticides are present at concentration levels above the legal limit, mainly in surface waters. Geolocalized analysis allows us to identify interesting areas particularly affected by a combination of multiple pesticides. We thus investigated possible synergistic effects of these compounds on the environment, using the alga C. reinhardtii as a biosensor. Our results show that exposure for 7 days to four compounds, that we found present together at high concentration in surface waters, was able to induce a stress in the algae, as indicated by the presence of palmelloids. Our work results in a pipeline that could easily be exported to monitor other territories in Italy and abroad.

Sensitivity of a widespread groundwater copepod to different contaminants

Groundwater is an indispensable resource for humankind and sustainable biomes functioning. Anthropogenic disturbance threatens groundwater ecosystems globally, but to which extent groundwater organisms respond to stressors remains poorly understood. Groundwater animals are rare, with small populations, difficult to find and to breed in the lab, which poses a main challenge to the assessment of their responses to pollutants. Despite the difficulties, assessing the toxicity of a large spectrum of stressors to groundwater organisms is a priority to inform towards appropriate environmental protection of these ecosystems. We tested the sensitivity to CuSO₄, diclofenac, and NaCl of a groundwater population of the copepod Diacyclops crassicaudis crassicaudis and compared its sensitivity with the model organism Daphnia magna. We ranked its sensitivity using a species sensitivity distribution (SSD) approach using the feasible data available for groundwater and surface crustaceans. Our results show that the most toxic compound was CuSO₄ for which higher amount of data was recorded and wider variability in response was observed. It was followed by diclofenac, largely lacking data for groundwater-adapted organisms, and the least toxic compound was NaCl. The differential sensitivity between D. crassicaudis and D. magna was contaminant-dependent. As a general trend D. crassicaudis was always distributed in the upper part of the SSD curves together with other groundwater-adapted organisms. Our results highlight that the widespread groundwater populations of the D. crassicaudis species complex, which can be successfully breed in the lab, may provide a reasonable approach to assess the ecological effects of anthropogenic stressors in groundwater ecosystems.

Evaluating sewer exfiltration in groundwater by pharmaceutical tracers after the 2016 Kumamoto earthquakes, Japan

In April 2016, a series of earthquakes (M 7.3 on the Japan Meteorological Agency scale) occurred in Kumamoto, Japan causing serious damage to underground sewerage networks. In this study, we evaluated sewer exfiltration in groundwater in the Kumamoto area after the earthquakes by using multiple tracers. We used 14 pharmaceuticals, including carbamazepine and crotamiton, and anthropogenic Gd as tracers, and we measured concentrations of these tracers from September 2016 to November 2017 seasonally. The detection frequency of caffeine, carbamazepine, crotamiton, ibuprofen, and anthropogenic Gd ranged from 29% to 45%, and the concentrations of the pharmaceuticals in the groundwater were lower than those in previous studies. The median of all pharmaceutical concentrations did not decrease, whereas the median of the sum of crotamiton and carbamazepine concentrations, which are quantitative sewage markers, decreased with time. The sewer exfiltration rates in September 2016 estimated using carbamazepine, crotamiton, and anthropogenic Gd were 0.59 ± 0.27%, 0.66 ± 0.47%, and 0.11 ± 0.18% of sewage dry weather flow, respectively, indicating that the effect of the earthquakes on sewer exfiltration was small, probably because the damaged sewers were quickly repaired. This study demonstrated that a multiple-tracer approach is useful for evaluating sewer exfiltration after major earthquakes.

Sorption Properties of Specific Polymeric Microspheres towards Desethyl-Terbuthylazine and 2-Hydroxy-Terbuthylazine: Batch and Column Studies

This work investigates the sorption properties of poly(divinylbenzene) modified in the Diels-Alder reaction towards persistent and mobile metabolites of terbuthylazine. The batch experiments were carried out to examine the efficiency of desethyl-terbuthylazine and 2-hydroxy-terbuthylazine adsorption on the specific adsorbent and the impact of different factors on the adsorption process. Results fit well to a pseudo-second order kinetic model. It was confirmed that hydrogen bonds play an important role in the studied systems. Five times greater sorption of 2-hydroxy-terbuthylazine than desethyl-terbuthylazine was observed. The molecular structures of both metabolites exhibit complementarity to the arrangement of functional groups in the polymer but the differences in the physicochemical properties of the desethyl derivative make it a highly mobile compound with higher affinity to the aqueous phase. The equilibrium data in the batch study fit the Freundlich isotherm for 2-hydroxy-terbuthylazine, and for desethyl-terbuthylazine the Temkin and Dubinin-Radushkevich models were better. The adsorption capacities obtained under dynamic conditions were comparable with batch results. For column adsorption modeling the Bohart-Adams, Wolborska, Thomas and Yoon-Nelson models were used. The proposed microspheres can be reused easily with no significant decrease in adsorption capacity by using ethanol as eluent in the desorption.

Disposal Practices of Unused and Leftover Medicines in the Households of Dhaka Metropolis

Background: This fact-finding study aimed to attain an overall idea and knowledge about medicine disposal practices in Dhaka Metropolitan households. Methods: This mixed study (both quantitative and qualitative) was orchestrated to inspect the household leftover medicine disposal pattern's governing status. A cross-sectional survey was conducted following a structured questionnaire and key informant interview with a household person and in-depth interviews with the top pharmaceutical and government officials. Results: Findings disclose that, for most of the key informants, the terms "drug disposal" and "drug pollution" were unknown; more precisely, 67% and 74% of key informants even did not hear these two terms. Almost all (87%) households faced undesired incidents due to the insecure storage of medicines. People disposed of excess and expired medication in regular dustbins (47%), threw out of the window (19%), flushed within commode (4%), burnt in fire (2%), and reused (4%). A good percentage of people (21%) returned unexpired drugs to the pharmacy and bought other medicines on a need basis. A total of 72% wanted a medicine take-back program, and 100% agreed on mass education on this issue. Officials of pharmaceuticals conferred mixed opinion: top-ranked pharmaceuticals will adopt leftover medicine disposal practices; middle and low-ranked pharmaceutical companies are reluctant, merely denied mentioning the less important issue. Conclusions: The absence of mass awareness and standard laws and policies may explain these existing aberrant practices.

Identification of LC-HRMS nontarget signals in groundwater after source related prioritization

Groundwater is a major drinking water resource but its quality with regard to organic micropollutants (MPs) is insufficiently assessed. Therefore, we aimed to investigate Swiss groundwater more comprehensively using liquid chromatography high-resolution tandem mass spectrometry (LC-HRMS/MS). First, samples from 60 sites were classified as having high or low urban or agricultural influence based on 498 target compounds associated with either urban or agricultural sources. Second, all LC-HRMS signals were related to their potential origin (urban, urban and agricultural, agricultural, or not classifiable) based on their occurrence and intensity in the classified samples. A considerable fraction of estimated concentrations associated with urban and/or agricultural sources could not be explained by the 139 detected targets. The most intense nontarget signals were automatically annotated with structure proposals using MetFrag and SIRIUS4/CSI:FingerID with a list of >988,000 compounds. Additionally, suspect screening was performed for 1162 compounds with predicted high groundwater mobility from primarily urban sources. Finally, 12 nontargets and 11 suspects were identified unequivocally (Level 1), while 17 further compounds were tentatively identified (Level 2a/3). amongst these were 13 pollutants thus far not reported in groundwater, such as: the industrial chemicals 2,5-dichlorobenzenesulfonic acid (19 detections, up to 100 ng L^-1), phenylphosponic acid (10 detections, up to 50 ng L^-1), triisopropanolamine borate (2 detections, up to 40 ng L^-1), O-des[2-aminoethyl]-O-carboxymethyl dehydroamlodipine, a transformation product (TP) of the blood pressure regulator amlodipine (17 detections), and the TP SYN542490 of the herbicide metolachlor (Level 3, 33 detections, estimated concentrations up to 100-500 ng L^-1). One monitoring site was far more contaminated than other sites based on estimated total concentrations of potential MPs, which was supported by the elucidation of site-specific nontarget signals such as the carcinogen chlorendic acid, and various naphthalenedisulfonic acids. Many compounds remained unknown, but overall, source related prioritisation proved an effective approach to support identification of compounds in groundwater.

Side Effects of Pesticides and Metabolites in Groundwater: Impact on Denitrification

The impact of two pesticides (S-metolachlor and propiconazole) and their respective main metabolites (ESA-metolachlor and 1,2,4-triazole) on bacterial denitrification in groundwater was studied. For this, the denitrification activity and the bacterial diversity of a microbial community sampled from a nitrate-contaminated groundwater were monitored during 20 days in lab experiments in the presence or absence of pesticides or metabolites at 2 or 10 μg/L. The kinetics of nitrate reduction along with nitrite and N₂O production all suggested that S-metolachlor had no or only little impact, whereas its metabolite ESA-metolachlor inhibited denitrification by 65% at 10 μg/L. Propiconazole and 1,2,4-triazole also inhibited denitrification at both concentrations, but to a lesser extent (29–38%) than ESA-metolachlor. When inhibition occurred, pesticides affected the reduction of nitrate into nitrite step. However, no significant differences were detected on the abundance of nitrate reductase narG and napA genes, suggesting an impact of pesticides/metabolites at the protein level rather than on denitrifying bacteria abundance. 16S rRNA gene Illumina sequencing indicated no major modification of bacterial diversity in the presence or absence of pesticides/metabolites, except for ESA-metolachlor and propiconazole at 10 μg/L that tended to increase or decrease Shannon and InvSimpson indices, respectively. General growth parameters suggested no impact of pesticides, except for propiconazole at 10 μg/L that partially inhibited acetate uptake and induced a decrease in microbial biomass. In conclusion, pesticides and metabolites can have side effects at environmental concentrations on microbial denitrification in groundwater and may thus affect ecosystem services based on microbial activities.