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Sökning: WFRF:(Harir Mourad)

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1.
  • Andersson, Anna, et al. (författare)
  • Extending the potential of Fourier transform ion cyclotron resonance massspectrometry for the analysis of disinfection by-products
  • 2023
  • Ingår i: TrAC. Trends in analytical chemistry. - : ELSEVIER SCI LTD. - 0165-9936 .- 1879-3142. ; 167
  • Forskningsöversikt (refereegranskat)abstract
    • Potentially harmful disinfection by-products (DBPs) are formed upon drinking water treatment when disinfectantsreact with organic matter in the water. Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS) provides information on the compositions of individual DBPs in the unknown, toxicologically relevantfraction, comprising non-volatile, high-molecular weight DBPs. This review evaluates current applications of FTICR-MS for DBP analysis to assist improved analysis with this technique. Four methodological aspects are infocus, 1) The use of quenching agents, 2) The choice of extraction method 3) The choice of ionization techniques/modes, and 4) Data processing including DBP formula verification and interpretation. Quenching can lead todecomposition or adduct formation and needs to be further evaluated or avoided. There is a large potential toexpand FT-ICR-MS DBP analysis by applying different SPE sorbents and ionization techniques, and improvedsystematic verification procedures are important to ensure reliable non-target analysis.
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2.
  • Andersson, Anna, et al. (författare)
  • Molecular changes among non-volatile disinfection by-products between drinking water treatment and consumer taps
  • 2021
  • Ingår i: Environmental Science. - : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; 7:12, s. 2335-2345
  • Tidskriftsartikel (refereegranskat)abstract
    • The formation of disinfection by-products (DBPs) during drinking water treatment has been associated with various health concerns but the total DBP exposure is still unknown. In this study, molecular level non-target analysis by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to study non-volatile DBPs, and how their composition changes during water distribution in four drinking water treatment plants (DWTPs) in Sweden using different types of raw water and disinfection processes. The largest portion of tap water DBP compositions were detected also at the DWTPs, highlighting that these DBP formulae were rather stable and contribute to human DBP exposure. Yet the number of detected DBPs decreased 14-48% between drinking water treatment and consumer taps in the three plants in which no mixing of water from other DWTPs in the distribution system occurred showing active DBP processing in the water distribution network. While considerable amounts of bromine-containing DBPs were detected upon chemical disinfection in some DWTPs, few of them were detected in the tap water samples, likely due to debromination by hydrolytic reactions. The overall fewer non-volatile DBPs detected in tap waters, along with changed distribution among chlorine and bromine DBPs, demonstrate that DBP mixtures are highly dynamic and that DBP measurements at DWTPs do not adequately reflect exposure at the point-of-use. Clearly, more knowledge about changes of DBP mixtures through the distribution system is needed to improve DBP exposure assessments.
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3.
  • Andersson, Anna, et al. (författare)
  • Selective removal of natural organic matter during drinking water production changes the composition of disinfection by-products
  • 2020
  • Ingår i: Environmental Science. - : ROYAL SOC CHEMISTRY. - 2053-1400 .- 2053-1419. ; 6:3, s. 779-794
  • Tidskriftsartikel (refereegranskat)abstract
    • Disinfection by-products (DBPs) are potentially toxic compounds formed upon chemical disinfection of drinking water. Controlling the levels and characteristics of dissolved organic matter (DOM) as precursor material for DBPs is a major target to reduce DBP formation. A pilot-scale treatment including suspended ion exchange (SIX (R)), a ceramic microfilter (CeraMac (R)) with in-line coagulation and optional pre-ozonation followed by granular activated carbon (GAC) filtration was compared with a conventional full-scale treatment based on DOM removal and DBP formation using Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), rapid fractionation, liquid chromatography organic carbon detection (LC-OCD), adsorbable organic halogens (AOX) and trihalomethane (THM) analysis. The new treatment combination showed different selectivity for DOM removal, compared to the conventional, leading to changes in composition of the DBPs formed. SIX (R) and GAC had the largest impacts on reducing AOX and THM formation potentials but the high adsorptive capacity of GAC affected the diversity of detected DBPs most. Chlorination and chloramination of pilot treated water with doses normally used in Sweden produced low levels of AOX compared to the full-scale treatment, but FT-ICR MS revealed an abundance of brominated DBP species in contrast with the conventional treatment, which were dominated by chlorinated DBPs. This finding was largely linked to the high DOM removal by the pilot treatment, causing an increased Br-/C ratio and a higher formation of HOBr. Potential increases in Br-DBPs are important to consider in minimizing health risks associated with DBPs, because of the supposed higher toxicity of Br-DBPs compared to Cl-DBPs.
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4.
  • Andersson, Anna, et al. (författare)
  • Waterworks-specific composition of drinking water disinfection by-products
  • 2019
  • Ingår i: Environmental Science. - Cambridge : Royal Society of Chemistry. - 2053-1400 .- 2053-1419. ; :5, s. 861-872
  • Tidskriftsartikel (refereegranskat)abstract
    • Reactions between chemical disinfectants and natural organic matter (NOM) upon drinking water treatment result in formation of potentially harmful disinfection by-products (DBPs). The diversity of DBPs formed is high and a large portion remains unknown. Previous studies have shown that non-volatile DBPs are important, as much of the total toxicity from DBPs has been related to this fraction. To further understand the composition and variation of DBPs associated with this fraction, non-target analysis with ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was employed to detect DBPs at four Swedish waterworks using different types of raw water and treatments. Samples were collected five times covering a full year. A common group of DBPs formed at all four waterworks was detected, suggesting a similar pool of DBP precursors in all raw waters that might be related to phenolic moieties. However, the largest proportion (64–92%) of the assigned chlorinated and brominated molecular formulae were unique, i.e. were solely found in one of the four waterworks. In contrast, the compositional variations of NOM in the raw waters and samples collected prior to chemical disinfection were rather limited.This indicated that waterworks-specific DBPs presumably originated from matrix effects at the point of disinfection, primarily explained by differences in bromide levels, disinfectants (chlorine versus chloramine) and different relative abundances of isomers among the NOM compositions studied. The large variation of observed DBPs in the toxicologically relevant non-volatile fraction indicates that non-targeted monitoring strategies might be valuable to ensure relevant DBP monitoring in the future.
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5.
  • Fernández-Remolar, David C., et al. (författare)
  • Productivity contribution of Paleozoic woodlands to the formation of shale hosted massive sulfide deposits in the Iberian Pyrite Belt (Tharsis, Spain)
  • 2018
  • Ingår i: Journal of Geophysical Research - Biogeosciences. - : John Wiley & Sons. - 2169-8953 .- 2169-8961. ; 123:3, s. 1017-1040
  • Tidskriftsartikel (refereegranskat)abstract
    • The geological materials produced during catastrophic and destructive events are an essential source of paleobiological knowledge. The paleobiological information recorded by such events can be rich in information on the size, diversity, and structure of paleocommunities. In this regard, the geobiological study of late Devonian organic matter sampled in Tharsis (Iberian Pyrite Belt) provided some new insights into a Paleozoic woodland community,which was recorded as massive sulfides and black shale deposits affected by a catastrophic event. Sample analysis using TOF-SIMS (Time of Flight Secondary Ion Mass Spectrometer), and complemented by GC/MS (Gas Chromatrograph/Mass Spectrometer) identified organic compounds showing a very distinct distribution in the rock. While phytochemical compounds occur homogeneously in the sample matrix that is composed of black shale, the microbial-derived organics are more abundant in the sulfide nodules. The co-occurrence of sulfur bacteria compounds and the overwhelming presence of phytochemicals provide support for the hypothesis that the formation of the massive sulfides resulted from a high rate of vegetal debris production and its oxidation through sulfate reduction under suboxic to anoxic conditions. A continuous supply of iron from hydrothermal activity coupled with microbial activity was strictly necessary to produce this massive orebody. A rough estimate of the woodland biomass was made possible by accounting for the microbial sulfur production activity recorded in the metallic sulfide. As a result, the biomass size of the late Devonian woodland community was comparable to modern woodlands like the Amazon or Congo rainforests.
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6.
  • Fernández-Remolar, David C., et al. (författare)
  • Unveiling microbial preservation under hyperacidic and oxidizing conditions in the Oligocene Rio Tinto deposit
  • 2021
  • Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 11:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The preservation of biosignatures on Mars is largely associated with extensive deposits of clays formed under mild early Noachian conditions (> 3.9 Ga). They were followed by widespread precipitation of acidic sulfates considered adverse for biomolecule preservation. In this paper, an exhaustive mass spectrometry investigation of ferric subsurface materials in the Rio Tinto gossan deposit (~ 25 Ma) provides evidence of well-preserved molecular biosignatures under oxidative and acidic conditions. Time of flight secondary ion mass spectrometry (ToF–SIMS) analysis shows a direct association between physical-templating biological structures and molecular biosignatures. This relation implies that the quality of molecular preservation is exceptional and provides information on microbial life formerly operating in the shallow regions of the Rio Tinto subsurface. Consequently, low-pH oxidative environments on Mars could also record molecular information about ancient life in the same way as the Noachian clay-rich deposits.
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7.
  • Gonsior, Michael, et al. (författare)
  • Chemodiversity of dissolved organic matter in the Amazon Basin
  • 2016
  • Ingår i: Biogeosciences. - : COPERNICUS GESELLSCHAFT MBH. - 1726-4170 .- 1726-4189. ; 13:14, s. 4279-4290
  • Tidskriftsartikel (refereegranskat)abstract
    • Regions in the Amazon Basin have been associated with specific biogeochemical processes, but a detailed chemical classification of the abundant and ubiquitous dissolved organic matter (DOM), beyond specific indicator compounds and bulk measurements, has not yet been established. We sampled water from different locations in the Negro, Madeira/Jamari and Tapajos River areas to characterize the molecular DOM composition and distribution. Ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) combined with excitation emission matrix (EEM) fluorescence spectroscopy and parallel factor analysis (PARAFAC) revealed a large proportion of ubiquitous DOM but also unique area-specific molecular signatures. Unique to the DOM of the Rio Negro area was the large abundance of high molecular weight, diverse hydrogen-deficient and highly oxidized molecular ions deviating from known lignin or tannin compositions, indicating substantial oxidative processing of these ultimately plant-derived polyphenols indicative of these black waters. In contrast, unique signatures in the Madeira/Jamari area were defined by presumably labile sulfur-and nitrogen-containing molecules in this white water river system. Waters from the Tapajos main stem did not show any substantial unique molecular signatures relative to those present in the Rio Madeira and Rio Negro, which implied a lower organic molecular complexity in this clear water tributary, even after mixing with the main stem of the Amazon River. Beside ubiquitous DOM at average H / C and O / C elemental ratios, a distinct and significant unique DOM pool prevailed in the black, white and clear water areas that were also highly correlated with EEM-PARAFAC components and define the frameworks for primary production and other aspects of aquatic life.
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8.
  • Li, Siyu, et al. (författare)
  • Comprehensive assessment of dissolved organic matter processing in the Amazon River and its major tributaries revealed by positive and negative electrospray mass spectrometry and NMR spectroscopy
  • 2023
  • Ingår i: Science of the Total Environment. - : ELSEVIER. - 0048-9697 .- 1879-1026. ; 857
  • Tidskriftsartikel (refereegranskat)abstract
    • Rivers are natural biogeochemical systems shaping the fates of dissolved organic matter (DOM) from leaving soils to reaching the oceans. This study focuses on Amazon basin DOM processing employing negative and positive electro-spray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI[+/-] FT-ICR MS) and nuclear mag-netic resonance spectroscopy (NMR) to reveal effects of major processes on the compositional space and structural characteristics of black, white and clear water systems. These include non-conservative mixing at the confluences of (1) Solimoes and the Negro River, (2) the Amazon River and the Madeira River, and (3) in-stream processing of Amazon River DOM between the Madeira River and the Tapajos River. The Negro River (black water) supplies more highly oxygenated and high molecular weight compounds, whereas the Solimoes and Madeira Rivers (white water) contribute more CHNO and CHOS molecules to the Amazon River main stem. Aliphatic CHO and abundant CHNO compounds prevail in Tapajos River DOM (clear water), likely originating from primary production. Sorption onto particles and heterotrophic microbial degradation are probably the principal mechanisms for the observed changes in DOM composition in the Amazon River and its tributaries.
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9.
  • Li, Siyu, et al. (författare)
  • Dearomatization drives complexity generation in freshwater organic matter
  • 2024
  • Ingår i: Nature. - : NATURE PORTFOLIO. - 0028-0836 .- 1476-4687. ; 628:8009
  • Tidskriftsartikel (refereegranskat)abstract
    • Dissolved organic matter (DOM) is one of the most complex, dynamic and abundant sources of organic carbon, but its chemical reactivity remains uncertain 1-3 . Greater insights into DOM structural features could facilitate understanding its synthesis, turnover and processing in the global carbon cycle 4,5 . Here we use complementary multiplicity-edited 13C nuclear magnetic resonance (NMR) spectra to quantify key substructures assembling the carbon skeletons of DOM from four main Amazon rivers and two mid-size Swedish boreal lakes. We find that one type of reaction mechanism, oxidative dearomatization (ODA), widely used in organic synthetic chemistry to create natural product scaffolds 6-10 , is probably a key driver for generating structural diversity during processing of DOM that are rich in suitable polyphenolic precursor molecules. Our data suggest a high abundance of tetrahedral quaternary carbons bound to one oxygen and three carbon atoms (OCqC3 units). These units are rare in common biomolecules but could be readily produced by ODA of lignin-derived and tannin-derived polyphenols. Tautomerization of (poly)phenols by ODA creates non-planar cyclohexadienones, which are subject to immediate and parallel cycloadditions. This combination leads to a proliferation of structural diversity of DOM compounds from early stages of DOM processing, with an increase in oxygenated aliphatic structures. Overall, we propose that ODA is a key reaction mechanism for complexity acceleration in the processing of DOM molecules, creation of new oxygenated aliphatic molecules and that it could be prevalent in nature. Using complementary multiplicity-edited 13C nuclear magnetic resonance spectra, oxidative dearomatization is shown to be a key driver for generating structural diversity during processing of dissolved organic matter and the data also suggest high abundance of OCqC3 units.
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10.
  • Li, Siyu, et al. (författare)
  • Distinct Non-conservative Behavior of Dissolved Organic Matter after Mixing Solimoes/Negro and Amazon/Tapajo s River Waters
  • 2023
  • Ingår i: ACS - ES & T Water. - : AMER CHEMICAL SOC. - 2690-0637. ; 3:8, s. 2083-2095
  • Tidskriftsartikel (refereegranskat)abstract
    • Positive and negative electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry and H-1 NMR revealed major compositional and structural changes of dissolved organic matter (DOM) after mixing two sets of river waters in Amazon confluences: the Solimoes and Negro Rivers (S + N) and the Amazon and Tapajo s Rivers (A + T). We also studied the effects of water mixing ratios and incubation time on the composition and structure of DOM molecules. NMR spectra demonstrated large-scale structural transformations in the case of S + N mixing, with gain of pure and functionalized aliphatic units and loss of all other structures after 1d incubation. A + T mixing resulted in comparatively minor structural alterations, with a major gain of small aliphatic biomolecular binding motifs. Remarkably, structural alterations from mixing to 1d incubation were in essence reversed from 1d to 5d incubation for both S + N and A + T mixing experiments. Heterotrophic bacterial production (HBP) in endmembers S, N, and S + N mixtures remained near 0.03 mu gC L-1 h(-1), whereas HBP in A, T, and A + T were about five times higher. High rates of dark carbon fixation took place at S + N mixing in particular. In-depth biogeochemical characterization revealed major distinctions between DOM biogeochemical changes and temporal evolution at these key confluence sites within the Amazon basin.
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  • Resultat 1-10 av 13

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