I urval från Stockholms universitets publikationsdatabas

• Organic matter degradation causes enrichment of organic pollutants in hadal sediments

  2023. Anna Sobek (et al.). Nature Communications 14 (1)

  Artikel

  Burial of persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) in deep-sea sediments contributes to 60% of their historical emissions. Yet, empirical data on their occurrence in the deep-ocean is scarce. Estimates of the deep-ocean POP sink are therefore uncertain. Hadal trenches, representing the deepest part of the ocean, are hotspots for organic carbon burial and decomposition. POPs favorably partition to organic carbon, making trenches likely significant sinks for contaminants. Here we show that PCBs occur in both hadal (7720–8085 m) and non-hadal (2560–4050 m) sediment in the Atacama Trench. PCB concentrations normalized to sediment dry weight were similar across sites while those normalized to sediment organic carbon increased exponentially as the inert organic carbon fraction of the sediment increased in degraded hadal sediments. We suggest that the unique deposition dynamics and elevated turnover of organic carbon in hadal trenches increase POP concentrations in the deepest places on Earth.

  Läs mer om Organic matter degradation causes enrichment of organic pollutants in hadal sediments

• Removal of 293 organic compounds in 15 WWTPs studied with non-targeted suspect screening

  2022. Michael S. McLachlan (et al.). Environmental Science: Water Research & Technology 8 (7), 1423-1433

  Artikel

  Understanding how contaminant breakthrough in wastewater treatment plants is influenced by chemical structure and treatment technology is important for protecting the aquatic environment. In order to assess this question, consistent contaminant breakthrough measurements are required for a large number of chemicals. Using direct injection UHPLC-Orbitrap-MS/MS with data-dependent non-target data acquisition followed by suspect screening against a library of >7000 compounds with exact mass and MS2 spectra, we quantified the removal of 293 chemicals in 15 WWTPs with widely varying treatment technology. Principle component analysis showed a clear and consistent influence of treatment technology on contaminant breakthrough. Log breakthrough was significantly correlated with log TSS and log BOD in treated effluent for 71% and 68% of the chemicals, respectively. Chemicals were identified which could be used as indicators of the standard of wastewater treatment. Furthermore, chemicals were identified that could be used to predict the breakthrough of groups of other chemicals. A high degree of correlation was found for the breakthrough of different groups of chemicals, which suggests that the data could be used to develop models describing how chemical structure influences breakthrough or removal efficiency. Non-targeted suspect screening is a useful method for generating consistent WWTP breakthrough data for large numbers of chemicals.

  Läs mer om Removal of 293 organic compounds in 15 WWTPs studied with non-targeted suspect screening

• Socioeconomic status and public health in Australia: A wastewater-based study

  2022. Nikolaos I. Rousis (et al.). Environment International 167

  Artikel

  Analysis of untreated municipal wastewater is recognized as an innovative approach to assess population exposure to or consumption of various substances. Currently, there are no published wastewater-based studies investigating the relationships between catchment social, demographic, and economic characteristics with chemicals using advanced non-targeted techniques. In this study, fifteen wastewater samples covering 27% of the Australian population were collected during a population Census. The samples were analysed with a workflow employing liquid chromatography high-resolution mass spectrometry and chemometric tools for non-target analysis. Socioeconomic characteristics of catchment areas were generated using Geospatial Information Systems software. Potential correlations were explored between pseudo-mass loads of the identified compounds and socioeconomic and demographic descriptors of the wastewater catchments derived from Census data. Markers of public health (e.g., cardiac arrhythmia, cardiovascular disease, anxiety disorder and type 2 diabetes) were identified in the wastewater samples by the proposed workflow. They were positively correlated with descriptors of disadvantage in education, occupation, marital status and income, and negatively correlated with descriptors of advantage in education and occupation. In addition, markers of polypropylene glycol (PPG) and polyethylene glycol (PEG) related compounds were positively correlated with housing and occupation disadvantage. High positive correlations were found between separated and divorced people and specific drugs used to treat cardiac arrhythmia, cardiovascular disease, and depression. Our robust non-targeted methodology in combination with Census data can identify relationships between biomarkers of public health, human behaviour and lifestyle and socio-demographics of whole populations. Furthermore, it can identify specific areas and socioeconomic groups that may need more assistance than others for public health issues. This approach complements important public health information and enables large-scale national coverage with a relatively small number of samples.

  Läs mer om Socioeconomic status and public health in Australia

• Micropollutants in four Brazilian water reservoirs

  2021. Gabrielle Rabelo Quadra (et al.). Limnologica 90

  Artikel

  The concern about emerging contaminants such as pharmaceuticals is growing, mainly due to the increased global consumption of synthetic chemicals and the potential risk to environmental and human health. Although developing countries may be hotspots of pharmaceutical pollution, the knowledge about the occurrence of pharmaceuticals is still limited and patchy. Brazil holds one of the largest freshwater volumes globally, yet, little is known about the occurrence of pharmaceuticals in reservoirs although they make up key water sources. The aim of this study was, therefore, to investigate micropollutant occurrence, mainly pharmaceuticals, in four freshwater reservoirs distributed in Brazil. Water samples were collected in the Curuá-Una (CUN, Amazon region), Chapéu D’Uvas (CDU, Atlantic Forest region), Funil (FUN, Atlantic Forest region), and Simplício (SIM, Atlantic Forest region) reservoirs. The occurrence of 28 different micropollutants, including 26 pharmaceuticals, was investigated with target analysis on a UHPLC-Orbitrap-MS/MS, and a non-target screening approach was performed on all water samples to identify the presence of additional contaminants. The highest micropollutant concentrations were observed in FUN and SIM, which are the reservoirs with the largest population size in the catchment. Only caffeine was detected in CDU and CUN, which are reservoirs less influenced by urbanization. Metformin was the pharmaceutical with the highest concentrations, reaching 2 191 ng L⁻¹ in FUN. The non-target screening identified 125 chemicals, of which most were pharmaceuticals. The numbers of compounds identified and which were above the LOQ were higher in FUN and SIM, in agreement with results from the target analysis. Metformin is the compound with the highest risk to affect FUN reservoir negatively, based on calculated risk quotients. Considering that the reservoirs are used for multiple purposes, including water supply, irrigation, and aquaculture, it is important to continue investigating micropollutant occurrence to guarantee environmental and human health.

  Läs mer om Micropollutants in four Brazilian water reservoirs

• Temporal and Spatial Variability of Micropollutants in a Brazilian Urban River

  2021. Gabrielle Rabelo Quadra (et al.). Archives of Environmental Contamination and Toxicology 81 (1), 142-154

  Artikel

  In Brazil, environmental occurrence of micropollutants, such as pharmaceuticals, is rarely studied, and these compounds are not part of national water quality guidelines. In this study, we evaluated the occurrence of micropollutants in the Paraibuna River, located in the southeast region of Brazil, which is the most populated region of the country. Surface water samples were taken every 3 months for 1.5 years at four different sites downstream the city of Juiz de Fora. A total of 28 compounds were analyzed on an UHPLC-Orbitrap-MS/MS using a direct injection method. Nine substances were found in at least one water sample, with concentrations ranging from 11 to 4471 ng L-1. The micropollutants found in the river were not detected at the reference site upstream of the city, except for caffeine, which was present at low concentrations in the reference site. Additionally, a nontarget screening of the river samples was applied, which resulted in the identification of 116 chemicals, most of which were pharmaceuticals. Concentrations of most of the micropollutants varied with season and correlated significantly with rainfall events, which caused dilution in the river. The highest observed concentrations were for pharmaceuticals used for treating chronic diseases, such as metformin, which is used to treat diabetes, and were among the most consumed in Juiz de Fora during the study period. Moderate ecotoxicological risks were found for metformin, oxazepam, triclosan, and tramadol. Considering the complex mixture of micropollutants in the environment, more knowledge is needed to elucidate their ecological risk in aquatic ecosystems.

  Läs mer om Temporal and Spatial Variability of Micropollutants in a Brazilian Urban River

• What is in Nigerian waters? Target and non-target screening analysis for organic chemicals

  2021. Li-Xin Hu (et al.). Chemosphere 284

  Artikel

  Emerging organic contaminants (e.g., active pharmaceutical ingredients and personal care products ingredients) are ubiquitous in the environment and potentially harmful to ecosystems, have gained increasing public attention worldwide. Nevertheless, there is a scarcity of data on these contaminants in Africa. In this study, various types of water samples (wastewater, surface water and tap water) collected from Lagos, Nigeria were analyzed for these chemicals by both target and non-target analysis on an UHPLC-Orbitrap-MS/MS. In total, 109 compounds were identified by non-target screening using the online database mzCloud. Level 1 identification confidence was achieved for 13 compounds for which reference standards were available and level 2 was achieved for the rest. In the quantitative analysis, 18 of 38 target compounds were detected, including the parent compounds and their metabolites. Acetaminophen, sulfamethoxazole, acesulfame, and caffeine were detected in all samples with their highest concentrations at 8000, 5300, 16, and 7700 μg/L in wastewater, 140000, 3300, 7.7, and 12000 μg/L in surface water, and 66, 62, 0.17 and 1000 μg/L in tap water, respectively. The occurrence of psychoactive substances, anticancer treatments, antiretrovirals, antihypertensives, antidiabetics and their metabolites were reported in Nigeria for the first time. These results indicate poor wastewater treatment and management in Nigeria, and provide a preliminary profile of organic contaminants occurring in Nigerian waters. The findings from this study urge more future research on chemical pollution in the aquatic environments in Nigeria.

  Läs mer om What is in Nigerian waters? Target and non-target screening analysis for organic chemicals

• A simple field-based biodegradation test shows pH to be an inadequately controlled parameter in laboratory biodegradation testing

  2020. Matthew Goss, Zhe Li, Michael S. McLachlan. Environmental Science 22 (4), 1006-1013

  Artikel

  Biodegradation tests are essential for characterizing the behavior of organic micropollutants in the environment, but they are carried out almost exclusively in the laboratory. Test parameters such as temperature and test chemical concentration are often applied in ways that affect observed biodegradation, and laboratory testing requires sophisticated temperature-controlled facilities. We developed a field-based test based on OECD 309 which minimizes the need for laboratory resources such as temperature-controlled facilities by using bottles incubated in the natural water body. The test also utilized contaminant residues present in unspiked natural water to increase the relevance of the results to the local system. A test in a local river and a matching lab-based test were conducted in parallel. We quantified 26 of 40 targeted micropollutants and observed dissipation for 13. Significant differences in half-life (up to a factor of 3.5) between lab and field bottles were observed for 7 compounds, with 6 of 7 degrading more slowly in field bottles. For 4 of these, dissipation was positively correlated to the neutral fraction of the chemical. Differences in the neutral fraction arose due to a higher pH in the lab bottles induced by outgassing of CO₂ from the oversaturated river water. We conclude that pH is an important parameter to control in biodegradation testing and that field-based tests may be more environmentally relevant.

  Läs mer om A simple field-based biodegradation test shows pH to be an inadequately controlled parameter in laboratory biodegradation testing

• Association between Aquatic Micropollutant Dissipation and River Sediment Bacterial Communities

  2020. Claudia Coll (et al.). Environmental Science and Technology 54 (22), 14380-14392

  Artikel

  Assessment of micropollutant biodegradation is essential to determine the persistence of potentially hazardous chemicals in aquatic ecosystems. We studied the dissipation half-lives of 10 micropollutants in sediment–water incubations (based on the OECD 308 standard) with sediment from two European rivers sampled upstream and downstream of wastewater treatment plant (WWTP) discharge. Dissipation half-lives (DT50s) were highly variable between the tested compounds, ranging from 1.5 to 772 days. Sediment from one river sampled downstream from the WWTP showed the fastest dissipation of all micropollutants after sediment RNA normalization. By characterizing sediment bacteria using 16S rRNA sequences, bacterial community composition of a sediment was associated with its capacity for dissipating micropollutants. Bacterial amplicon sequence variants of the genera Ralstonia, Pseudomonas, Hyphomicrobium, and Novosphingobium, which are known degraders of contaminants, were significantly more abundant in the sediment incubations where fast dissipation was observed. Our study illuminates the limitations of the OECD 308 standard to account for variation of dissipation rates of micropollutants due to differences in bacterial community composition. This limitation is problematic particularly for those compounds with DT50s close to regulatory persistence criteria. Thus, it is essential to consider bacterial community composition as a source of variability in regulatory biodegradation and persistence assessments.

  Läs mer om Association between Aquatic Micropollutant Dissipation and River Sediment Bacterial Communities

• Comparing non-targeted chemical persistence assessed using an unspiked OECD 309 test to field measurements

  2020. Zhe Li, Michael S. McLachlan. Environmental Science 22 (5), 1233-1242

  Artikel

  Previous research has shown that unspiked OECD 309 tests can be used to quantify chemical biodegradation in surface waters, relying on chemical residues already present in the water. Here we test the hypothesis that unspiked OECD 309 tests can quantitatively predict chemical persistence in the environment by comparing chemical half-lives assessed in the laboratory against those measured in the field. The study object was a Swedish lake heavily impacted by treated municipal wastewater. Half-lives in the field were measured by mass balance over 12 weeks. In parallel, half-lives in the lab were determined with an unspiked OECD 309 test run for 60 days. Chemical analysis was conducted using a non-target screening approach. The field study yielded a half-life <100 days for 38 chemicals for which the dominant source was wastewater; 32 of these were also detected in the lab test, whereby 18 had half-lives with a well-constrained uncertainty that did not intersect infinity. For 14 of the 18 chemicals, the field and lab half-lives agreed within a factor 3. In summary, the lab test predicted chemical attenuation in the field well. Limitations of the approach include the need for measurable chemical concentrations in the water body and failure to account for some attenuation mechanisms like phototransformation.

  Läs mer om Comparing non-targeted chemical persistence assessed using an unspiked OECD 309 test to field measurements

• Biodegradation of Chemicals in Unspiked Surface Waters Downstream of Wastewater Treatment Plants

  2019. Zhe Li, Michael S. McLachlan. Environmental Science and Technology 53 (4), 1884-1892

  Artikel

  The OECD 309 guideline uses spiked incubation tests to provide data on biodegradation kinetics in surface waters. However, potential limitations of spiking test chemicals into the studied water have not been investigated. We conducted the OECD 309 test with unspiked surface water relying on chemical residues present in the water. Parallel experiments were conducted with the same water spiked with 13 chemicals at higher concentrations (50 mu g L-1). Six chemicals detected in both the spiked and the unspiked systems were biodegraded. For each chemical the concentration change over time differed between the systems. Tramadol and venlafaxine showed constant concentrations in the spiked systems but increasing concentrations in the unspiked systems. Atenolol and metoprolol showed first-order elimination with no lag in the unspiked systems, compared to a lag of 15-28 d followed by zero-order elimination kinetics in the spiked systems. Acesulfame was only slightly degraded (<50%) in the unspiked system, while removal was complete (>99%) in the spiked systems. Gabapentin displayed a complex behavior where the features differed markedly between the spiked and the unspiked systems. We conclude that spiking can strongly influence biodegradation, reducing the environmental relevance of test results. Under some conditions biodegradation can be measured in unspiked natural waters instead.

  Läs mer om Biodegradation of Chemicals in Unspiked Surface Waters Downstream of Wastewater Treatment Plants

• High-throughput evaluation of organic contaminant removal efficiency in a wastewater treatment plant using direct injection UHPLC-Orbitrap-MS/MS

  2018. Zhe Li (et al.). Environmental Science 20 (3), 561-571

  Artikel

  The removal efficiency (RE) of organic contaminants in wastewater treatment plants (WWTPs) is a major determinant of the environmental impact of these contaminants. However, RE data are available for only a few chemicals due to the time and cost required for conventional target analysis. In the present study, we applied non-target screening analysis to evaluate the RE of polar contaminants, by analyzing influent and effluent samples from a Swedish WWTP with direct injection UHPLC-Orbitrap-MS/MS. Matrix effects were evaluated by spiking the samples with isotope-labeled standards of 40 polar contaminants. For 85% of the compounds, the matrix effects in the influent and effluent were not significantly different. Approximately 10000 compounds were detected in the wastewater, of which 319 were identified by using the online database mzCloud. Level 1 identification confidence was achieved for 31 compounds for which we had reference standards, and level 2 was achieved for the remainder. RE was calculated from the ratio of the peak areas in the influent and the effluent from the non-target analysis. Good agreement was found with RE determined from the target analysis of the target compounds. The method generated reliable estimates of RE for large numbers of contaminants with comparatively low effort and is foreseen to be particularly useful in applications where information on a large number of chemicals is needed.

  Läs mer om High-throughput evaluation of organic contaminant removal efficiency in a wastewater treatment plant using direct injection UHPLC-Orbitrap-MS/MS

• A strategic screening approach to identify transformation products of organic micropollutants formed in natural waters

  2017. Zhe Li (et al.). Environmental Science 19 (4), 488-498

  Artikel

  Many transformation products (TPs) from organic micropollutants are not included in routine environmental monitoring programs due to limited knowledge of their occurrence and fate. An efficient method to identify and prioritize critical compounds in terms of environmental relevance is needed. In this study, we applied a strategic screening approach based on a case-control concept to identify TPs formed along wastewater-impacted rivers. Time-integrated samples were collected over one week at both ends of a river stretch downstream of a wastewater treatment plant (WWTP) outfall and were analyzed by ultrahigh performance liquid chromatography interfaced with quadrupole time-of-flight mass spectrometry (UHPLC-QToF-MS/MS). The screening procedure of the high-resolution MS (HRMS) datasets consisted of three major steps: (i) screening for parent compounds (PCs) attenuated along the stretch; (ii) prediction of potential TPs from these PCs; and (iii) screening for TPs from this list with an increasing trend along the stretch. In total, 32 PCs decreased along the investigated river stretches. From these PCs, eight TPs had increasing concentrations along the studied stretches and could be tentatively identified. The identification of one TP (benzamide) was confirmed by its corresponding reference standard, while no standards were available for the remaining TPs.

  Läs mer om A strategic screening approach to identify transformation products of organic micropollutants formed in natural waters

• Exploring Trends of C and N Isotope Fractionation to Trace Transformation Reactions of Diclofenac in Natural and Engineered Systems

  2016. Michael P. Maier (et al.). Environmental Science and Technology 50 (20), 10933-10942

  Artikel

  Although diclofenac ranks among the most frequently detected pharmaceuticals in the urban water cycle, its environmental transformation reactions remain imperfectly understood. Biodegradation-induced changes in N-15/N-14 ratios (epsilon(N) = -7.1 parts per thousand +/- 0.4 parts per thousand) have indicated that compound-specific isotope analysis (CSIA) may detect diclofenac degradation. This singular observation warrants exploration for further transformation reactions. The present study surveys carbon and nitrogen isotope fractionation in other environmental and engineered transformation reactions of diclofenac. While carbon isotope fractionation was generally small, observed nitrogen isotope fractionation in degradation by MnO2 (epsilon(N) = -7.3 parts per thousand +/- 0.3 parts per thousand), photolysis (epsilon(N) = +1.9 parts per thousand +/- 0.1 parts per thousand), and ozonation (epsilon(N) = +1.5 parts per thousand +/- 0.2 parts per thousand) revealed distinct trends for different oxidative transformation reactions. The small, secondary isotope effect associated with ozonation suggests an attack of O-3 in a molecular position distant from the N atom. Model reactants for outer-sphere single electron transfer generated large inverse nitrogen isotope fractionation (epsilon(N) = +5.7 parts per thousand +/- 0.3 parts per thousand), ruling out this mechanism for biodegradation and transformation by MnO2. In a river model, isotope fractionation-derived degradation estimates agreed well with concentration mass balances, providing a proof-of-principle validation for assessing micropollutant degradation in river sediment. Our study highlights the prospect of combining CSIA with transformation product analysis for a better assessment of transformation reactions within the environmental life of diclofenac.

  Läs mer om Exploring Trends of C and N Isotope Fractionation to Trace Transformation Reactions of Diclofenac in Natural and Engineered Systems

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

  2016. Zhe Li, Anna Sobek, Michael Radke. Environmental Science and Technology 50 (11), 5614-5621

  Artikel

  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.

  Läs mer om Fate of Pharmaceuticals and Their Transformation Products in Four Small European Rivers Receiving Treated Wastewater

• Fate of Pharmaceuticals and Their Transformation Products in Rivers: An integration of target analysis and screening methods to study attenuation processes

  2015. Zhe Li.

  Avhandling (Dok)

  Pharmaceuticals are environmental contaminants causing steadily increasing concern due to their high usage, ubiquitous distribution in the aquatic environment, and potential to exert adverse effects on the ecosystems. After being discharged from wastewater treatment plants (WWTPs), pharmaceuticals can undergo transformation processes in surface waters, of which microbial degradation in river sediments is considered highly significant. In spite of a substantial number of studies on the occurrence of pharmaceuticals in aquatic systems, a comprehensive understanding of their environmental fate is still limited. First of all, very few consistent datasets from lab-based experiments to field studies exist to allow for a straightforward comparison of observations. Secondly, data on the identity and occurrence of transformation products (TPs) is insufficient and the relation of the behavior of TPs to that of their parent compounds (PCs) is poorly understood. In this thesis, these knowledge gaps were addressed by integrating the TP identification using suspect/non-target screening approaches and PC/TP fate determination. The overarching objective was to improve the understanding of the fate of pharmaceuticals in rivers, with a specific focus on water-sediment interactions, and formation and behavior of TPs. In paper I, 11 pharmaceutical TPs were identified in water-sediment incubation experiments using non-target screening. Bench-scale flume experiments were conducted in paper II to simultaneously investigate the behavior of PCs and TPs in both water and sediment compartments under more complex and realistic hydraulic conditions. The results illustrate that water-sediment interactions play a significant role for efficient attenuation of PCs, and demonstrate that TPs are formed in sediment and released back to surface water. In paper III the environmental behavior of PCs along stretches of four wastewater-impacted rivers was related to that of their TPs. The attenuation of PCs is highly compound and site specific. The highest attenuation rates of the PCs were observed in the river with the most efficient river water-pore water exchange. This research also indicates that WWTPs can be a major source of TPs to the receiving waters. In paper IV, suspect screening with a case-control concept was applied on water samples collected at both ends of the river stretches, which led to the identification of several key TPs formed along the stretches. The process-oriented strategies applied in this thesis provide a basis for prioritizing and identifying the critical PCs and TPs with respect to environmental relevance in future fate studies.

  Läs mer om Fate of Pharmaceuticals and Their Transformation Products in Rivers

• Flume experiments to investigate the environmental fate of pharmaceuticals and their transformation products in streams

  2015. Zhe Li, Anna Sobek, Michael Radke. Environmental Science and Technology 49 (10), 6009-6017

  Artikel

  The hyporheic zone—the transition region beneath and alongside the stream bed—is a central compartment for attenuation of organic micropollutants in rivers. It provides abundant sorption sites and excellent conditions for biotransformation. We used a bench-scale flume to study the fate of 19 parent pharmaceuticals (PPs) and the formation of 11 characteristic transformation products (TPs) under boundary conditions similar to those in hyporheic zones. The persistence of PPs ranged from readily degradable with a dissipation half-life (DT50) as short as 1.8 days (acetaminophen, ibuprofen) to not degradable (chlorthalidone, fluconazole). The temporal and spatial patterns of PP and TP concentrations in pore water were heterogeneous, reflecting the complex hydraulic and biogeochemical conditions in hyporheic zones. Four TPs (carbamazepine-10,11-epoxide, metoprolol acid, 1-naphthol, and saluamine) were exclusively formed in the sediment compartment and released to surface water, highlighting their potential to be used as indicators for characterizing hyporheic transformation of micropollutants in streams. The accumulation of certain TPs over the experimental period illustrates that we might face a peak of secondary contamination by TPs far from the point of release of the original contaminants into a stream. Such TPs should be considered as priority candidates for a higher-tier environmental risk assessment.

  Läs mer om Flume experiments to investigate the environmental fate of pharmaceuticals and their transformation products in streams

• Screening for pharmaceutical transformation products formed in river sediment by combining ultrahigh performance liquid chromatography/high resolution mass spectrometry with a rapid data-processing method

  2014. Zhe Li, Michael P. Maier, Michael Radke. Analytica Chimica Acta 810, 61-70

  Artikel

  While the occurrence of pharmaceuticals in the aquatic environment has been extensively investigated, their environmental fate is less thoroughly explored. Scarce information on their transformation pathways and transformation products (TPs) limits conventional target analytical approaches. In this study, samples from water/sediment tests were analyzed by ultrahigh performance liquid chromatography interfaced with quadrupole time-of-flight mass spectrometry (UHPLC/QToF-MS). A data processing method based on peak detection, time-trend filtration and structure assignment was established to provide an efficient way for identifying the key TPs in terms of persistence; all software used for the individual steps of this method is freely available. The accurate mass and meaningful time-trends were major contributors in facilitating the isolation of plausible TP peaks. In total, 16 TPs from 9 parent pharmaceuticals were identified. Eleven out of the 16 TPs were confirmed by corresponding reference standards; no standards were available for the remaining TPs. For additional 6 potential TPs, a molecular formula was suggested but no additional structural information could be generated. Among the TPs identified in the water/sediment tests, carbamazepine-10,11-epoxide (parent: carbamazepine), saluamine (parent: furosemide), chlorothiazide and 4-amino-6-chloro-1,3-benzenedisulfonamide (parent of both: hydrochlorothiazide), and 1-naphthol (parent: propranolol) accumulated over the entire incubation period of 35 days.

  Läs mer om Screening for pharmaceutical transformation products formed in river sediment by combining ultrahigh performance liquid chromatography/high resolution mass spectrometry with a rapid data-processing method

• Effects of input uncertainty and variability on the modelled environmental fate of organic pollutants under global climate change scenarios

  2013. Deguo Kong (et al.). Chemosphere 93 (9), 2086-2093

  Artikel

  Global climate change (GCC) is expected to influence the fate, exposure and risks of organic pollutants to wildlife and humans. Multimedia chemical fate models have been previously applied to estimate how GCC affects pollutant concentrations in the environment and biota, but previous studies have not addressed how uncertainty and variability of model inputs affect model predictions. Here, we assess the influence of climate variability and chemical property uncertainty on future projections of environmental fate of six polychlorinated biphenyl congeners under different GCC scenarios using a spreadsheet version of the ChemCAN model and the Crystal Ball® software. Regardless of emission mode, results demonstrate: (i) uncertainty in degradation half-lives dominates the variance of modelled absolute levels of PCB congeners under GCC scenarios; (ii) when the ratios of predictions under GCC to predictions under present day climate are modelled, climate variability dominates the variance of modelled ratios; and (iii) the ratios also indicate a maximum of about a factor of 2 change in the long-term average environmental concentrations due to GCC that is forecasted between present conditions and the period between 2080 and 2099. We conclude that chemical property uncertainty does not preclude assessing relative changes in a GCC scenario compared to a present-day scenario if variance in model outputs due to chemical properties and degradation half-lives can be assumed to cancel out in the two scenarios.

  Läs mer om Effects of input uncertainty and variability on the modelled environmental fate of organic pollutants under global climate change scenarios

Visa alla publikationer av Zhe Li vid Stockholms universitet