Micropollutants In Surface Waters Research Articles

Photosensitizing and antioxidant activities of humic substances: A case study of β2-adrenoceptor agonist terbutaline

Humic substances (HS) play an important role in the phototransformation of micro-pollutants in surface waters and a significant part of this reactivity is often attributed to oxidant triplet excited states (3HS*). The present study aims to understand why 3HS* were found to be negligibly involved in the HS-mediated phototransformation of β2-adrenoceptor agonist terbutaline (TBL) while this chemical shows a high reactivity towards triplet 3-carboxybenzophenone (3CBP*), a typical HS model sensitizer. To clarify this apparent discrepancy, several experiments were conducted. We first confirmed that TBL can be easily oxidized by triplet riboflavin (3RF*), another sensitizer (k = (1.7 ± 0.4) × 109 M−1 s−1). Afterwards, we studied the effect of TBL on the HS-mediated phototransformation of 2,4,6-trimethylphenol (TMP), chosen for its high reactivity with 3HS*. TBL was found to enhance the rate of TMP loss. This result is rationalized by postulating that (i) TMP and TBL are both oxidized by 3HS* to yield the phenoxyl radicals TMP-H• and TBL-H•, respectively, and (ii) TBL-H• is further reduced by TMP which generates additional TMP-H•. Fitting the experimental data gives k = (1.8 ± 0.5) × 109 M−1 s-1 for the reaction between 3HS* and TBL and DFT calculations further support the conclusion that TBL-H• can be reduced by a lot of phenols. Hence, in the case of TBL, the oxidant effect of 3HS* is counterbalanced by the antioxidant properties of HS.

Biodegradation and adsorption of micropollutants by biological activated carbon from a drinking water production plant

The presence of micropollutants in surface water is a potential threat for the production of high quality and safe drinking water. Adsorption of micropollutants onto granular activated carbon (GAC) in fixed-bed filters is often applied as a polishing step in the production of drinking water. Activated carbon can act as a carrier material for biofilm, hence biodegradation can be an additional removal mechanism for micropollutants in GAC filters. To assess the potential of biofilm to biodegrade micropollutants, it is necessary to distinguish adsorption from biodegradation as a removal mechanism. We performed experiments at 5 °C and 20 °C with biologically active and autoclaved GAC to assess the biodegradation of micropollutants by the biofilm grown on the GAC surface. Ten micropollutants were selected as model compounds. Three of them, iopromide, iopamidol and metformin, were biodegraded by the GAC biofilm. Additionally, we observed that temperature can increase or decrease adsorption, depending on the micropollutant studied. Finally, we compared the adsorption capacity of GAC used for more than 100,000 bed volumes and fresh GAC. We demonstrated that used GAC shows a higher adsorption capacity for guanylurea, metformin and hexamethylenetetramine and only a limited reduction in adsorption capacity for diclofenac and benzotriazole compared to fresh GAC.

Concentration of chosen organic micropollutants in surface water

Concentration of chosen organic micropollutants in surface water

CH3NCl2 Formation from Chlorination of Carbamate Insecticides.

Carbamate insecticides, which are common micropollutants in surface waters, were found to generate dichloromethlyamine (DCMA) during chlorination. DCMA formation from other precursors has been reported previously; it is part of the emerging class of nitrogen-based disinfection byproducts (N-DBPs) of health concern in chlorinated water. However, there is a limited understanding about its formation, stability, and toxicity. Four carbamate insecticides (methomyl, carbofuran, carbaryl, and thiodicarb) were examined as DCMA precursors over a range of reaction conditions, based on variables of chlorine/precursor (Cl/P) molar ratio, pH, time, and temperature. DCMA was found to be the dominant volatile DBP to result from chlorination of all four carbamate insecticides, with molar yields ranging from 12% to 150% at a Cl/P molar ratio of 20. Further experiments indicated CH3NCl2 to be relatively stable, with a half-life of up to 35 h in water. The toxicity of CH3NCl2 was investigated using a bacterial bioluminescence inhibition test and survival of human lung tumor cells. The results of these toxicity assays indicated that CH3NCl2 is about 3 orders of magnitude more toxic than CHCl3. CH3NCl2 concentrations in the ppb range were observed to result from chlorination of surface water or tap water samples collected from several different locations in China. The results suggest that precursors to CH3NCl2 formation are ubiquitous and that CH3NCl2 poses a hazard to public health and the environment and should be considered in disinfection chemistry and water treatment.

Prioritising site-specific micropollutants in surface water from LC-HRMS non-target screening data using a rarity score

BackgroundCurrent compound prioritisation and monitoring approaches within Europe focus mainly on widely occurring priority and river basin specific pollutants but may overlook site-specific contamination from local emission sources. Thus, we propose a robust and semiautomated approach for the identification of site-specific chemicals and a prioritisation of water bodies with specific contamination based on non-target screening data from liquid chromatography coupled to high-resolution mass spectrometry.ResultsFor prioritisation of site-specific contaminants, we calculated rarity scores for all peaks occurring in a set of 31 surface water samples, which combine the maximum signal intensity of a peak in a dataset with its frequency of occurrence in that dataset in one single number. These were a robust measure without the need to address the problems of missing data in more sophisticated multivariate statistical methods. For our dataset, site-specific compounds were defined for rarity scores > 1000, and the studied 31 sites showed a huge difference in the number of such peaks (0–91 in positive and 0–48 in negative ion mode). Together with isotopologue detection, the evaluation of mass defects and the occurrence of homologue series, which all could be obtained from automated data processing, a more detailed characterisation of these site-specific contaminations was possible. For three selected sites with a high number of site-specific peaks, novel or unexpected compounds could be identified, which stem from specific usage or (former) industrial production upstream of these sites.Conclusions and outlookThe proposed approach allows for a rapid screening of large non-target screening datasets for site-specific contaminants, the prioritisation of sites with such a specific contamination and the subsequent identification of these compounds. Thus, the risk of overlooking possibly hazardous chemicals (including unknowns) which are not covered in conventional monitoring and prioritisation schemes is reduced.

An immission perspective of emerging micropollutant pressure in Luxembourgish surface waters: A simple evaluation scheme for wastewater impact assessment

While wastewater treatment plants have been identified as the most prominent source of emerging micropollutants in surface waters, prediction of their ambient concentrations remains a challenge. This is due to the variability of loads entering individual treatment plants and of the elimination capacity by the latter as well as potential attenuation in the river network. Although geospatially detailed models exist, they suffer from the same data input uncertainties. Here, we investigated the concentration profiles of 20 emerging pollutants in different river stretches in Luxembourg with variable sanitary pressures. Using carbamazepine as a recalcitrant wastewater indicator, the correlation of the compounds to the latter revealed source and fate variability as well as specific emitters. Relating carbamazepine to sanitary pressure, expressed as the sum of population equivalents in a catchment divided by its surface [PE ha−1] allowed predicting the impact of emerging pollutants on the entire river network. The limited variability of the pollutant profiles allowed for prioritization of impacted stretches depending on the different sanitary pressures at risk quotient exceedance. The main drivers of impact were triclosan, diclofenac, clarithromycine and diuron.

Effects of Ozone on the Photochemical and Photophysical Properties of Dissolved Organic Matter.

This study focused on the effects of ozonation on the photochemical and photophysical properties of dissolved organic matter (DOM). Upon ozonation, a decrease in DOM absorbance was observed in parallel with an increase in singlet oxygen (1O2) and fluorescence quantum yields (Φ1O2 and ΦF). The increase in Φ1O2 was attributed to the formation of quinone-like moieties during ozonation of the phenolic moieties of DOM, while the increase in ΦF can be explained by a significant decrease in the internal conversion rate of the first excited singlet state of the DOM (1DOM*). It is a consequence of an increase in the average energy of the first electronic transition (S1 → S0) that was assessed using the wavelength of maximum fluorescence emission (λF,max). Furthermore, ozonation did not affect the ratio of the apparent steady-state concentrations of excited triplet DOM (3DOM*) and 1O2, indicating that ozonation does not affect the efficiency of 1O2 production from 3DOM*. The consequences of these changes for the phototransformation rates of micropollutants in surface waters were examined using photochemical model calculations. The decrease in DOM absorbance caused by ozonation leads to an enhancement of direct photolysis rates due to the increased transparency of the water. Rates of indirect photooxidation induced by 1O2 and 3DOM* slightly decrease after ozonation.

Photophysical and photochemical insights of the photodegradation of norfloxacin: The rate-limiting step and the influence of Ca2+ ion

Photodegradation is one of the major degradation paths for antibiotics as aquatic micropollutants in surface water. The photodegradation involves a number of complicated photophysical and photochemical processes. Exploration for the rate-limiting step among these processes can be essential for the elimination of antibiotics. In this work norfloxacin was selected as a target compound. The rate constants of photophysical transitions and their competitions were discussed under the framework of Fermi Golden rule and time-depended perturbation theory. Using density functional theory, the reaction paths in triplet state were searched. The competitions among the photophysical transitions and photochemical reaction paths indicate the intersystem crossing (ISC) from the S1 state to T1 state is the rate-limiting step in the aquatic photodegradation of norfloxacin. Ca2+ ion significantly accelerates this bottleneck by coordinating with the carbonyl and carboxyl groups of norfloxacin. The coordination creates more ISC paths to triplet states and increases the spin-orbit coupling, Huang-Rhys factors, and the vibrational coupling of the ISCs.

Highly Effective Removal of Nonsteroidal Anti-inflammatory Pharmaceuticals from Water by Zr(IV)-Based Metal–Organic Framework: Adsorption Performance and Mechanisms

Nonsteroidal anti-inflammatory pharmaceuticals are emerging organic micropollutants in surface water, groundwater, and wastewater, whose removal is very important yet challenging. As a new class of porous functional materials, metal-organic frameworks (MOFs) have attracted extensive attention for their adsorption applications. Here, we report that Zr(IV)-based MOFs (defective UiO-66, and MOF-808) have extraordinary adsorption ability to remove nonsteroidal anti-inflammatory pharmaceuticals from water. Excellent adsorption performances are obtained for UiO-66 and MOF-808, particularly for UiO-66, of which the adsorption capacities are the highest in a wide series of adsorptive materials previously reported. It is elucidated that the incomplete-coordinated cationic Zr in the cluster has high affinity for the anionic pharmaceutical (chemical adsorption) and that the adsorption interaction between the benzene ring of the pharmaceutical and MOF's ligand is involved to enhance or as an alternative to the adsorption interactions (π-π interaction). In particular, adsorption of ibuprofen, ketoprofen, naproxen, indomethacin, and furosemide by UiO-66 and MOF-808 and the synergetic effect of chemical adsorption and π-π interaction are outstanding, leading to extremely higher binding energies ( Ebind) and sorption abilities.

Survey on the micro-pollutants presence in surface water system of northern Serbia and environmental and health risk assessment

This study demonstrates the occurrence of 940 organic micro-pollutants in surface water of four rivers, one irrigation canal system, and two lakes in Vojvodina Province, the northern part of Serbia, summing in total eighteen samples. The number of detected chemicals ranged from 22 to 84, with 127 micro-pollutants detected at least once, representing 13% of the studied substances. The targeted compounds include n-alkanes, sterols, polycyclic aromatic hydrocarbons (PAHs), organochlorine pesticides polychlorinated biphenyls, pesticides, pharmaceutical active compounds, industrial chemicals, plasticizers, etc. Among the analysed compounds, sterols were the most dominant with maximum quantified concentrations. The substances which were quantified with frequency over 50% were two PAHs (2-methylnaphthalene, benzo(ghi)perylene), five sterols (cholesterol, cholestanol, stigmasterol, fucosterol, beta-sitosterol), three pharmaceuticals and personal care products (L-menthol, diethyltoluamide, caffeine), and ten household chemicals (4-tert-octylphenol, dimethyl phthalate, methyl palmitate, phenylethyl alcohol, 1-nonanol, alpha-terpineol, 2-phenoxy-ethanol, methyl myristate, acetophenone, and 2-ethyl-1-hexanol). The list of priority substances under the European Union Directive 2013/39/EU includes 49 priority substances (PSs) out of which 34 were analysed. Among these, eleven PSs were quantified, and only two compounds (fluoranthene and benzo (a) pyrene) exceeded EU Environmental Quality Standards targeted values. The obtained results were compared with the previously published data that dealt with the same targeted number of micro-pollutants in sediment samples. This revealed connections between the same sampling locations. Environmental risk assessment showed the existence of potential ecological risk as 72% of the obtained values for the ecological hazard index (HI) at investigated locations were higher that the targeted value (HI > 1). Estimated values for hazard quotient (HQ) and hazard index (HI) for non-carcinogenic risk were lower than the targeted value, indicating no non-carcinogenic risk through dermal contact and non-intentional ingestion of water. Estimated values for cancer risk were all below 1 × 10−6, which is not considered to pose significant human health risk.

Removal of pharmaceuticals from water by clay-cationic starch sorbents

Abstract Significant concerns have been raised up due to the presence of organic micropollutants in surface waters. The ability of two polymer-clay sorbents based on a functionalized cationic starch was examined for the removal of three pharmaceuticals: atenolol, sulfamethoxazole and diclofenac sodium. In batch experiments, the complex which exhibited a planar conformation of the polymer on the clay surface and higher cationic charge density showed higher sorption of diclofenac and sulfamethoxazole over those of the composite with a loops and tails configuration, but similar with atenolol. The introduction of functional moieties on the polymers that are capable to create a network of hydrogen-bonds with the pollutants promoted their removal as revealed by thermal and infrared techniques: diclofenac molecules formed an ion pair including hydrogen bonds through their secondary amine groups; sulfamethoxazole sorbed by strong electrostatic interactions followed by proton transfer involving its sulphon-nitrogen group and the hydroxyl moieties of the composite. Filtration experiments showed a better performance of the columns made of the composite with higher cationic charge density on the removal of diclofenac and sulfamethoxazole over that of granular activated carbon. The filtration processes were successfully modeled by using an adsorption-convection model which enabled predictions under different operational conditions used in drinking water plants. Experimental removal of diclofenac by filtration within the range found in environmental concentrations was in good agreement with the predicted amounts.

European demonstration program on the effect-based and chemical identification and monitoring of organic pollutants in European surface waters

Growing concern about the adverse environmental and human health effects of a wide range of micropollutants requires the development of novel tools and approaches to enable holistic monitoring of their occurrence, fate and effects in the aquatic environment. A European-wide demonstration program (EDP) for effect-based monitoring of micropollutants in surface waters was carried out within the Marie Curie Initial Training Network EDA-EMERGE. The main objectives of the EDP were to apply a simplified protocol for effect-directed analysis, to link biological effects to target compounds and to estimate their risk to aquatic biota. Onsite large volume solid phase extraction of 50 L of surface water was performed at 18 sampling sites in four European river basins. Extracts were subjected to effect-based analysis (toxicity to algae, fish embryo toxicity, neurotoxicity, (anti-)estrogenicity, (anti-)androgenicity, glucocorticoid activity and thyroid activity), to target analysis (151 organic micropollutants) and to nontarget screening. The most pronounced effects were estrogenicity, toxicity to algae and fish embryo toxicity. In most bioassays, major portions of the observed effects could not be explained by target compounds, especially in case of androgenicity, glucocorticoid activity and fish embryo toxicity. Estrone and nonylphenoxyacetic acid were identified as the strongest contributors to estrogenicity, while herbicides, with a minor contribution from other micropollutants, were linked to the observed toxicity to algae. Fipronil and nonylphenol were partially responsible for the fish embryo toxicity. Within the EDP, 21 target compounds were prioritized on the basis of their frequency and extent of exceedance of predicted no effect concentrations. The EDP priority list included 6 compounds, which are already addressed by European legislation, and 15 micropollutants that may be important for future monitoring of surface waters. The study presents a novel simplified protocol for effect-based monitoring and draws a comprehensive picture of the surface water status across Europe.

Significant changes in the photo-reactivity of TiO2 in the presence of a capped natural dissolved organic matter layer

Natural dissolved organic matter (NDOM) in surface waters has a high sorption affinity for TiO2 during long contact. An attached NDOM layer can act as a conduction band electron and/or valance band hole acceptor, and NDOM can also decrease the concentration of hydroxyl radicals (OH) in the bulk phase. Therefore, the degradation kinetics and mechanism for degradation of acetaminophen on NDOM capped TiO2 (NDOM-TiO2) are significantly different from those on raw TiO2. Quantum calculation results suggest that hydroxylation to the ortho position in relation to the acetamide group is more favorable. Although OH induced hydroxylation is the predominant pathway for degradation of acetaminophen on TiO2, one-electron oxidation of acetaminophen by a valance band hole, excited triplet NDOM or NDOM radical cation is the major degradation pathway on NDOM-TiO2. This study is the first to detect and confirm APAP oligomers as intermediates during the degradation of acetaminophen by TiO2 photocatalysis, especially when using NDOM-TiO2 as a catalyst. The results suggest the reactivity of TiO2 could change significantly after long exposure to natural water, which need to be concerned about for removal of micropollutants in surface water by TiO2 photocatalysis.

Occurrence and removals of micropollutants in water environment

Micropollutants are often discharged to surface waters through untreated wastewater from sewage treatment plants and wastewater treatment plants. The presence of micropollutants in surface waters is a serious concern because surface water is usually provided to water treatment plants (WTP) to produce drinking water. Many micropollutants can withstand conventional WTP systems and stay in tap water. In particular, pharmaceuticals and endocrine disruptors are examples of micropollutants that are detected at the drinking water, ppb, or even ppb level. A variety of techniques and processes, especially advanced oxidation processes, have been applied to remove micropollutants from water to control drinking water contamination. This paper reviews recent researches on the occurrence and removal of micropollutants in the aquatic environments and during water treatment processes.

Policy Diffusion in the Context of International River Basin Management

AbstractThis paper deals with policy diffusion across countries in the context of collaborative river basin management. Borrowing from the literature on policy diffusion and ‘smart strategies’ of small European Union member states, we argue that policy diffusion is fostered by structural and agency‐related factors. We illustrate our theoretical ideas with a case study on the new Swiss policy on micropollutants in surface waters. Based on a rich set of documents and interviews with key actors, we show that the integration of Switzerland into formal and informal transnational networks fosters the diffusion of its micropollutants policy to other Rhine riparian countries. In addition, we analyse agency‐related factors favouring policy diffusion in river basins, such as a country's pioneer role, its expertise, the fact that its policy is in line with general policy goals in other countries and the political acceptance of the policy at home. Our analysis suggests that policy diffusion can be an important phenomenon in integrated water resources management. Copyright © 2016 John Wiley & Sons, Ltd and ERP Environment.

Fate of Pharmaceuticals and Their Transformation Products in Four Small European Rivers Receiving Treated Wastewater.

A considerable knowledge gap exists with respect to the fate and environmental relevance of transformation products (TPs) of polar organic micropollutants in surface water. To narrow this gap we investigated the fate of 20 parent compounds (PCs) and 11 characteristic TPs in four wastewater-impacted rivers. Samples were obtained from time-integrated active sampling as well as passive sampling using polar organic chemical integrative samplers (POCIS). Seventeen out of the 20 PCs were detected in at least one of the rivers. All the PCs except acesulfame, carbamazepine, and fluconazole were attenuated along the studied river stretches, with the largest decrease found in the smallest river which had an intense surface water-pore water exchange. Seven TPs were detected, all of which were already present directly downstream of the WWTP outfall, suggesting that the WWTPs were a major source of TPs to the recipients. For anionic compounds, attenuation was the highest in the two rivers with the lowest discharge, while the pattern was not as clear for neutral or cationic compounds. For most compounds the results obtained from active sampling were not significantly different from those using POCIS, demonstrating that the cost and labor efficient POCIS is suitable to determine the attenuation of organic micropollutants in rivers.

Linking in Vitro Effects and Detected Organic Micropollutants in Surface Water Using Mixture-Toxicity Modeling.

Surface water can contain countless organic micropollutants, and targeted chemical analysis alone may only detect a small fraction of the chemicals present. Consequently, bioanalytical tools can be applied complementary to chemical analysis to detect the effects of complex chemical mixtures. In this study, bioassays indicative of activation of the aryl hydrocarbon receptor (AhR), activation of the pregnane X receptor (PXR), activation of the estrogen receptor (ER), adaptive stress responses to oxidative stress (Nrf2), genotoxicity (p53) and inflammation (NF-κB) and the fish embryo toxicity test were applied along with chemical analysis to water extracts from the Danube River. Mixture-toxicity modeling was applied to determine the contribution of detected chemicals to the biological effect. Effect concentrations for between 0 to 13 detected chemicals could be found in the literature for the different bioassays. Detected chemicals explained less than 0.2% of the biological effect in the PXR activation, adaptive stress response, and fish embryo toxicity assays, while five chemicals explained up to 80% of ER activation, and three chemicals explained up to 71% of AhR activation. This study highlights the importance of fingerprinting the effects of detected chemicals.

Laboratory calibration of twelve pesticides using polar organic chemical integrative samplers

Passive sampling is an emerging tool for monitoring micropollutants in surface waters and enables the determination of time-weighted average (TWA) concentration over extended sampling periods. For the determination of TWA concentration, the sampling rates (Rs) for the compounds of interest are required. Laboratory calibration experiments were conducted in order to determine the sampling rates of 12 selected pesticides using Polar Organic Chemical Integrative Samplers (pest-POCIS). The experiments were performed on the basis of static renewal exposure of pest-POCIS under stirred conditions for different time intervals up to 28 days. The recoveries of target pesticides ranged between 71 % and 120 % with relative standard deviation (RSD) <18%. Detection limits (LODs) and quantification limits (LOQs) ranged between 0.5 and 6 ng L−1 and 1.6 and 19.7 ng L−1, respectively. The uptake in POCIS for the studied pesticides followed a linear pattern throughout the 28 days of exposure, except for fipronil. The calculated sampling rates ranged from 0.030 L day−1 to 0.223 L day−1. The pesticides pirimiphos methyl, clofentezine, cyprodinil, fipronil and kresoxim methyl have never been studied before in calibration experiments using pest-POCIS passive samplers. Using the described analytical procedure, trace levels (ng L−1) of the target pesticides could be determined in surface waters.

Screening for over 1000 organic micropollutants in surface water and sediments in the Liaohe River watershed

High throughout screening method has gained attractive prospects because it offers a fast and effective approach to obtain a holistic picture of organic micropollutant (OM) pollution in a site specific environment. However, reliability and usefulness of the generated data sets for OM pollution profiles and occurrence levels have not been fully evaluated. In this paper, we screened 1030 OMs in surface water and sediments from the selected rivers of the Liaohe River watershed to (1) examine the usefulness of using qualitative data to gain insights into source identification and (2) further evaluate the reliability of the semi-quantification results in a filed study. The results showed that 81 and 89 OMs at concentrations up to 5670ng/L and 6714ng/g were identified in surface water and sediments, respectively. Qualitative data could be used to identify the similarity (or dissimilarity) of pollution sources at different locations for surface water, which could provide insights for source back tracking of water contamination. Accuracy tests showed that our semi-quantification results agree well with those from previously reported values and our target analysis. Though our results for the majority of newly quantified OMs need to be further confirmed, we have demonstrated that this method is suitable for understanding the pollution characteristics and occurrence levels of OMs in the environment for environmental scientists and managers.

Monitoring of 1300 organic micro-pollutants in surface waters from Tianjin, North China

In spite of the quantities and species of chemicals dramatically increased with rapid economic growth in China in the last decade, the focus of environmental research was mainly on limited number of priority pollutants. Therefore, to elucidate environmental pollution by organic micro-pollutants, this work was conducted as the first systematic survey on the occurrence of 1300 substances in 20 surface water samples of Tianjin, North China, selected as a representative area of China. The results showed the presence of 227 chemicals. The most relevant compounds in terms of frequency of detection and median concentration were bis(2-ethylhexyl) phthalate (100%; 0.26μgL−1), siduron (100%; 0.20μgL−1), lidocaine (100%; 96ngL−1), antipyrine (100%; 76ngL−1), caffeine (95%; 0.28μgL−1), cotinine (95%; 0.20μgL−1), phenanthrene (95%; 0.17μgL−1), metformin (90%; 0.61μgL−1), diethyl phthalate (90%; 0.19μgL−1), quinoxaline-2-carboxylic acid (90%; 0.14μgL−1), 2-(methylthio)-benzothiazole (85%; 0.11μgL−1) and anthraquinone (85%; 54ngL−1). Cluster analysis discriminated three highly polluted sites from others based on data similarity. Principle component analysis identified four factors, corresponding to industrial wastewater, domestic discharge, tire production and atmospheric deposition, accounting for 78% of the total variance in the water monitoring data set. This work provides a wide reconnaissance on broad spectrum of organic micro-contaminants in surface waters in China, which indicates that the aquatic environment in China has been polluted by a large number of chemicals.