| 1. |
- Berggren, Martin, et al.
(författare)
-
Unified understanding of intrinsic and extrinsic controls of dissolved organic carbon reactivity in aquatic ecosystems
- 2022
-
Ingår i: Ecology. - : Wiley. - 0012-9658 .- 1939-9170. ; 103:9
-
Tidskriftsartikel (refereegranskat)abstract
- Despite our growing understanding of the global carbon cycle, scientific consensus on the drivers and mechanisms that control dissolved organic carbon (DOC) turnover in aquatic systems is lacking, hampered by the mismatch between research that approaches DOC reactivity from either intrinsic (inherent chemical properties) or extrinsic (environmental context) perspectives. Here we propose a conceptual view of DOC reactivity in which the combination of intrinsic and extrinsic factors controls turnover rates and determines which reactions will occur. We review three major types of reactions (biological, photochemical, and flocculation) from an intrinsic chemical perspective and further define the environmental features that modulate the expression of chemically inherent reactivity potential. Finally, we propose hypotheses of how extrinsic and intrinsic factors together shape patterns in DOC turnover across the land-to-ocean continuum, underscoring that there is no intrinsic DOC reactivity without environmental context. By acknowledging the intrinsic–extrinsic control duality, our framework intends to foster improved modeling of DOC reactivity and its impact on ecosystem services.
|
|
| 2. |
- Cascone, C., et al.
(författare)
-
AbspectroscoPY, a Python toolbox for absorbance-based sensor data in water quality monitoring
- 2022
-
Ingår i: Environmental Science. - : Royal Society of Chemistry (RSC). - 2053-1400 .- 2053-1419. ; 8:4, s. 836-848
-
Tidskriftsartikel (refereegranskat)abstract
- The long-term trend of increasing natural organic matter (NOM) in boreal and north European surface waters represents an economic and environmental challenge for drinking water treatment plants (DWTPs). High-frequency measurements from absorbance-based online spectrophotometers are often used in modern DWTPs to measure the chromophoric fraction of dissolved organic matter (CDOM) over time. These data contain valuable information that can be used to optimise NOM removal at various stages of treatment and/or diagnose the causes of underperformance at the DWTP. However, automated monitoring systems generate large datasets that need careful preprocessing, followed by variable selection and signal processing before interpretation. In this work we introduce AbspectroscoPY (“Absorbance spectroscopic analysis in Python”), a Python toolbox for processing time-series datasets collected by in situ spectrophotometers. The toolbox addresses some of the main challenges in data preprocessing by handling duplicates, systematic time shifts, baseline corrections and outliers. It contains automated functions to compute a range of spectral metrics for the time-series data, including absorbance ratios, exponential fits, slope ratios and spectral slope curves. To demonstrate its utility, AbspectroscoPY was applied to 15-month datasets from three online spectrophotometers in a drinking water treatment plant. Despite only small variations in surface water quality over the time period, variability in the spectrophotometric profiles of treated water could be identified, quantified and related to lake turnover or operational changes in the DWTP. This toolbox represents a step toward automated early warning systems for detecting and responding to potential threats to treatment performance caused by rapid changes in incoming water quality.
|
|
| 3. |
- Hanson, Blair, et al.
(författare)
-
DOM Molecular Weight Fractionation and Fluorescence Quantum Yield Assessment Using a Coupled In-Line SEC Optical Property System
- 2022
-
Ingår i: ACS ES and T Water. - : American Chemical Society (ACS). - 2690-0637. ; 2:12, s. 2491-2501
-
Tidskriftsartikel (refereegranskat)abstract
- Size exclusion chromatography (SEC) in combination with optical measurements has become a popular form of analysis to characterize dissolved organic matter (DOM) as a function of molecular size. Here, SEC coupled with in-line absorbance scans and fluorescence emission scans was utilized to derive apparent fluorescence quantum yield (φf) as a function of molecular weight (MW) for DOM. Individual instrument-specific SEC-fluorescence detector correction factors were developed by comparison of an SEC-based excitation emission matrix (EEM) to an EEM generated by a calibrated benchtop fluorometer. The method was then applied to several sample sets to demonstrate how to measure the φf of unknown DOM samples and to observe changes to φf following a processing mechanism (ozonation). The φf of riverine water samples and DOM fulvic acid isolates from Suwannee River and Pony Lake increased from < 0.5% to a maximum of 2.5-3% across the medium- to low-MW range. Following ozonation of PLFA, φf increased most notably in the large-MW fractions (elution volumes < 40 mL). Overall, this method provides a means by which highly fluorescent size fractions of DOM can be identified for more detailed analyses of chemical composition and its changes through different processing mechanisms.
|
|
| 4. |
- Heibati, Masoumeh, 1986, et al.
(författare)
-
Assessment of drinking water quality at the tap using fluorescence spectroscopy.
- 2017
-
Ingår i: Water research. - : Elsevier BV. - 1879-2448 .- 0043-1354. ; 125, s. 1-10
-
Tidskriftsartikel (refereegranskat)abstract
- Treated drinking water may become contaminated while travelling in the distribution system on the way to consumers. Elevated dissolved organic matter (DOM) at the tap relative to the water leaving the treatment plant is a potential indicator of contamination, and can be measured sensitively, inexpensively and potentially on-line via fluorescence and absorbance spectroscopy. Detecting elevated DOM requires potential contamination events to be distinguished from natural fluctuations in the system, but how much natural variation to expect in a stable distribution system is unknown. In this study, relationships between DOM optical properties, microbial indicator organisms and trace elements were investigated for households connected to a biologically-stable drinking water distribution system. Across the network, humic-like fluorescence intensities showed limited variation (RSD = 3.5-4.4%), with half of measured variation explained by interactions with copper. After accounting for quenching by copper, fluorescence provided a very stable background signal (RSD
|
|
| 5. |
|
|
| 6. |
- Henderson, R.K., et al.
(författare)
-
Evaluation of effluent organic matter fouling in ultrafiltration treatment using advanced organic characterisation techniques
- 2011
-
Ingår i: Journal of Membrane Science. - : Elsevier BV. - 1873-3123 .- 0376-7388. ; 382:1-2, s. 50-59
-
Tidskriftsartikel (refereegranskat)abstract
- Membrane fouling remains an operational challenge in the ultrafiltration (UF) membrane treatment of wastewater effluent and research is on-going to improve understanding of the organic character of foulants. Two advanced organic characterisation techniques that have potential to lend insight into membrane fouling are size exclusion chromatography with organic carbon, UV254 and nitrogen detection (LC-OCD) and fluorescence excitation-emission matrix (EEM) spectroscopy. In this study, UF treatment was undertaken for five tertiary wastewater effluents. The total hydraulic resistance was determined as well as that contributed by foulant layers fractionated by rinsing, backwashing and chemically desorbing. Organic characterisation for UF feed samples, permeates and each foulant layer was then performed using LC-OCD and FEEM spectroscopy with the aim of improving understanding of the character of foulants present in effluent organic matter (EfOM) and to determine the potential for the use of FEEM spectroscopy as a foulant indicator in such systems. It was determined that the biopolymer fraction was most significantly reduced on UF treatment, as anticipated due to its high molecular size. This was supported by the observation that the majority of the foulant layer comprised predominantly protein-enriched biopolymers (38-60% of total foulant layer DOC) that could be removed by rinsing. The resistance attributed to rinsing was directly related to the combined DOC concentration associated with proteins and low molecular weight neutral compounds as defined by LC-OCD analysis. Furthermore, tyrosine-like fluorescence intensity (λex/em=250/304nm) of both the rinsing solutions and UF feed samples showed good correlation with associated hydraulic resistance for EfOM originating from domestic wastewater, suggesting that fluorescence has potential to be used as a foulant indicator for these systems. © 2011 Elsevier B.V.
|
|
| 7. |
- Hoffmeister, Svenja, et al.
(författare)
-
Evaluating the accuracy of two in-situ optical sensors to estimate DOC concentrations for drinking water production
- 2020
-
Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 6:10, s. 2891-2901
-
Tidskriftsartikel (refereegranskat)abstract
- Two in situ optical sensors, a single-excitation fluorescence-based sensor (fDOM) mounted on a multi-parameter EXO2 sonde (YSI), and a stand-alone, multispectral absorbance-based instrument (spectro::lyser, scan Messtechnik GmbH), were evaluated for their capability to (i) estimate river dissolved organic carbon (DOC) concentrations and (ii) provide oversight of drinking water production. The sensors were deployed between March and November 2017 in the river Fyris, which drains a mixed forested and agricultural 2003 km2 catchment and serves as a drinking water source by managed aquifer recharge. Grab samples were collected every 2 to 3 weeks and compared with logged sensor data collected at 15 minute intervals. The fDOM probe signal was used to estimate DOC concentrations in the range of 10.4 to 24.4 mg L−1 using linear regression (R2 = 0.71, RMSE = 2.5 mg L−1), after correction for temperature, turbidity and inner-filter effects. Temporal changes in DOC character associated with the mixed land use landscape, as indicated by optical indices, reduced this sensor accuracy for estimating DOC concentration. Nevertheless, humic substance concentrations, the fraction of DOC that is preferentially removed during artificial infiltration, were well captured. The spectrolyser signal was used to establish a 2-component partial least square model that captured DOC fluctuations from 10.2 to 29.4 mg L−1 (R2 = 0.92; RMSE = 1.3 mg L−1). This multiple-wavelength model (220 to 720 nm) effectively handled the changes in DOC composition while accurately estimating DOC concentrations. This study explores the advantages and limitations of optical sensors for their use in managed aquifer recharge and drinking water production in relation to DOC levels.
|
|
| 8. |
- Hägg, Kristofer, et al.
(författare)
-
Water quality changes during the first meter of managed aquifer recharge
- 2021
-
Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 7:3, s. 562-572
-
Tidskriftsartikel (refereegranskat)abstract
- The capacity of an artificial recharge field to alter organic matter and the bacterial flora of surface water was assessed by following changes in bacterial communities and composition of natural organic matter (NOM) over the first meter of infiltration depth. The sampling strategy applied in this study ensured that water samples consisted only of infiltrated water, excluding natural groundwater. Water was sampled at 50 and 100 cm below the surface of an infiltration basin divided into two halves; one side was dried and frozen and one was infiltrating water during the winter period prior to the sampling period. Bacterial cell counts, proportions of intact cells and community fingerprints were determined by flow cytometry, and NOM was characterized using total organic carbon (TOC), UV254 nm-absorbance (UVA) and fluorescence spectroscopy. Around 40% of the NOM was removed after only 50 cm. Protein-like components were reduced to a larger extent (45-50%) than the humic-like components (25%), suggesting removal of mostly biodegradable fractions of NOM. After only 50 cm of infiltration, about 99% total cell count (TCC) was removed. The flow cytometric data revealed that the bacterial communities collected after infiltration from the basin area that had been dried and frozen were more similar to those in the raw water. This suggests that drying and freezing the basin negatively impacted its treatment capacity. The results from this study highlight the importance of a well-developed biofilm and unsaturated zone for artificial recharge.
|
|
| 9. |
- Kothawala, Dolly, et al.
(författare)
-
Inner filter correction of dissolved organic matter fluorescence
- 2013
-
Ingår i: Limnology and Oceanography: Methods. - : Wiley. - 1541-5856. ; 11:DEC, s. 616-630
-
Tidskriftsartikel (refereegranskat)abstract
- The fluorescence of dissolved organic matter (DOM) is suppressed by a phenomenon of self-quenching known as the inner filter effect (IFE). Despite widespread use of fluorescence to characterize DOM in surface waters, the advantages and constraints of IFE correction are poorly defined. We assessed the effectiveness of a commonly used absorbance-based approach (ABA), and a recently proposed controlled dilution approach (CDA) to correct for IFE. Linearity between corrected fluorescence and total absorbance (ATotal; the sum of absorbance at excitation and emission wavelengths) across the full excitation-emission matrix (EEM) in dilution series of four samples indicated both ABA and CDA were effective to an absorbance of at least 1.5 in a 1 cm cell, regardless of wavelength positioning. In regions of the EEMs where signal to background noise (S/N) was low, CDA correction resulted in more variability than ABA correction. From the ABA algorithm, the onset of significant IFE (>5%) occurs when absorbance exceeds 0.042. In these cases, IFE correction is required, which was the case for the vast majority (97%) of lakes in a nationwide survey (n= 554). For highly absorbing samples, undesirably large dilution factors would be necessary to reduce absorbance below 0.042. For rare EEMs with ATotal > 1.5 (3.0% of the lakes in the Swedish survey), a 2-fold dilution is recommended followed by ABA or CDA correction. This study shows that for the vast majority of natural DOM samples the most commonly applied ABA algorithm provides adequate correction without prior dilution. © 2013, by the American Society of Limnology and Oceanography, Inc.
|
|
| 10. |
- Lee, Y. K., et al.
(författare)
-
Fluorescence signatures of dissolved organic matter leached from microplastics: Polymers and additives
- 2020
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 54:19, s. 11905-11914
-
Tidskriftsartikel (refereegranskat)abstract
- Despite the numerous studies that have investigated the occurrence and the fate of plastic particles in the environment, only a limited effort has been devoted towards exploring the characteristics of the dissolved organic matter (DOM) leached from microplastics. In this study, using excitation emission matrix-parallel factor analysis (EEM-PARAFAC), we explored the fluorescence signatures of plastic-derived DOM from commonly used plastic materials, which included two polymers (PVC and PS), two additives (DEHP and BPA), and two commercial plastics. The exposure of the selected plastics to UV light facilitated the leaching of DOM measured in terms of dissolved organic carbon and fluorescence intensity. Four fluorescent components were identified, which included three protein/phenol-like components (C1, C3, and C4) and one humic-like component (C2). The C1 and the C4 were highly correlated with the amounts of the DOM leached from DEHP and BPA, respectively, under both leaching conditions, while both the C2 and the C4 presented good correlations with the DOM leached from the polymers under UV light. The C4 may serve as a good fluorescence signature for the DOM leached from BPA or BPA-containing plastics. This study highlights the overlooked issue of plastic-derived DOM leaching into the aquatic environment through optical characterization.
|
|
| 11. |
- Moona, Nashita, 1985, et al.
(författare)
-
Full-Scale Manipulation of the Empty Bed Contact Time to Optimize Dissolved Organic Matter Removal by Drinking Water Biofilters
- 2021
-
Ingår i: ACS ES and T Water. - : American Chemical Society (ACS). - 2690-0637. ; 1:5, s. 1117-1126
-
Tidskriftsartikel (refereegranskat)abstract
- A study was conducted at a water treatment plant to optimize parallel rapid gravity biofilters for dissolved organic matter (DOM) removal. The biofilters treat urban and agriculturally impacted river water using a commercial non-adsorptive, expanded-clay filter medium. The study aimed to locate the optimal operating conditions via experimental manipulation of the biofilter empty bed contact time (EBCT) during full-scale operation at the plant. During a two-month experiment, contact times in four parallel biofilters were switched to and maintained at 15, 30, 50, and 80 min by manipulating the hydraulic loading on each filter. The removal efficiency of organic matter fractions increased with EBCT for dissolved organic carbon (DOC) and microbial humic-like (F290/420) and protein-like (F280/340) fluorescent organic matter. Other DOM fractions were largely unaffected by biofiltration, or at slightly higher concentrations in the effluent. Protein-like fluorescence is associated with labile organic matter fractions, which are known to be removed poorly by drinking water treatment barriers apart from biological filters. The results suggest that long contact times (>30 min) have advantages for the operation of some biological filters, especially if placed ahead of barriers that are sensitive to biofouling, e.g., membranes.
|
|
| 12. |
|
|
| 13. |
- Moona, Nashita, 1985, et al.
(författare)
-
Partial renewal of granular activated carbon filters for improved drinking water treatment
- 2018
-
Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 4:4, s. 529-538
-
Tidskriftsartikel (refereegranskat)abstract
- There is a trend of increasing natural organic matter (NOM) in raw drinking waters of Nordic countries due to climate change. Seasonal deterioration in NOM quality imparts challenges for delivering a consistently high drinking water quality. In this study, a simple and cost-effective operational strategy was investigated that improved short-term NOM removal in a full-scale treatment plant. Three granular activated carbon (GAC) media biofilters were modified by replacing a small fraction of saturated filter media with new media. Relative to replacing the entire biofilter media, this approach required lower capital cost and shorter downtime and maintained conditions for biological filter functioning. NOM removal efficiencies were compared in modified versus unmodified (reference) filters using online UV absorbance, and offline fluorescence and dissolved organic carbon measurements. The modified biofilters showed improved organic matter removal lasting for at least four weeks. Partial replenishment of GAC in full-scale biofilters may be a useful and sustainable operational strategy for coping with temporarily high NOM loads in raw waters that might otherwise cause water quality problems.
|
|
| 14. |
- Moona, Nashita, 1985, et al.
(författare)
-
Partial replenishment of biological activated carbon filters to improve natural organic matter removal
- 2018
-
Ingår i: Proceedings of IWA World Water Congress & Exhibition 2018.
-
Konferensbidrag (refereegranskat)abstract
- Natural organic matter (NOM) in surface waters negatively impacts drinking water treatment and is a precursor of harmful disinfection by-products (DBPs). Granular activate carbon (GAC) filters are integral components of many drinking water treatment plants (WTPs) due to the ability to remove NOM and organic micro pollutants from raw waters. However, GAC filters lose adsorption capacity and convert to biologically activated carbon (BAC) filter relatively quickly. This paper reports on a full-scale BAC filter modification strategy to enhance short-term NOM removal. This is achieved by adding a small amount of fresh GAC to BAC filters which increases adsorption while maintaining biological degradation of organics by the microbes attached to the BAC. This strategy was implemented at two treatment plants in Sweden. Modified filters showed better removal of humic-like and protein-like NOM fractions than reference filters that did not receive fresh GAC, indicating improved functioning of both adsorption and biological treatment. The result shows that both biodegradation and adsorption mechanism improved within the filters.
|
|
| 15. |
- Moona, Nashita, 1985, et al.
(författare)
-
Temperature-dependent mechanisms of DOM removal by biological activated carbon filters
- 2019
-
Ingår i: Environmental Science: Water Research and Technology. - : Royal Society of Chemistry (RSC). - 2053-1419 .- 2053-1400. ; 5:12, s. 2232-2241
-
Tidskriftsartikel (refereegranskat)abstract
- Seasonal variability in the removal of dissolved organic matter (DOM) by drinking water biological activated carbon (BAC) filters is often attributed to temperature changes. However, it can be rather difficult to directly relate temperature to treatment efficiency at full scale due to seasonal variations in other influential parameters like DOM concentration and character, and microbial activity. Furthermore, processes in BAC filters include adsorption, desorption and biodegradation within biofilms while each respond differently to temperature. This study aimed to decouple these processes by studying the removal of various DOM fractions from coagulated and settled drinking water when in contact with aged (>3 years) BAC filter material at different water temperatures. DOM removal was measured as changes in dissolved organic carbon (DOC), ultraviolet absorbance at 254 nm (UV254) and fluorescence. Under the particular experimental conditions there was little evidence of biological removal; instead, removal of DOM fractions emitting at longer wavelengths ("humic-like", >430 nm) was consistent with chemisorption, removal of DOM emitting at intermediate wavelengths ("humic-like", 390-420 nm) was consistent with physisorption, and multiple mechanisms were indicated for "protein-like" (<380 nm) DOM. Non-biological mechanisms of DOM removal by aged BAC filters are often assumed to be unimportant; however, these results suggest they are important for some DOM fractions, especially during periods of reduced microbial activity.
|
|
| 16. |
- Murphy, Kathleen, 1972
(författare)
-
A note on determining the extent of the water Raman peak in fluorescence spectroscopy
- 2011
-
Ingår i: Applied Spectroscopy. - : SAGE Publications. - 1943-3530 .- 0003-7028. ; 65:2, s. 233-236
-
Tidskriftsartikel (refereegranskat)abstract
- A method is proposed for automatically determining the upper and lower boundaries of the Raman scatter peak in fluorescence spectroscopy from empirical data. Accurate peak boundaries are needed to calculate accurate Raman peak areas, used for normalizing fluorescence signals to produce data in units that are comparable between instruments. Comparisons of Raman peak boundaries across nine individual instruments (FluoroMax 3 (FM3) fluorometers from HORIBA Jobin Yvon and Cary Eclipse (CE) fluorometers from Varian Inc.) at the excitation wavelength λex = 350 nm reveal consistent results. At 350 nm excitation, the Raman peak was confined by the emission wavelengths of 382-418 nm, with boundaries determined for the FM3 fluorometers deviating by no more than 0.5 nm and 1.5 nm with respect to the start and end of the peak, and CE fluorometers deviating by up to 1.5 nm and 2 nm, respectively. Peak width was a function of fluorometer type and excitation wavelength. For the FM3 instruments, widths increased from approximately 30 nm at λex = 300 nm to 40 nm at λex = 380 nm, while for the CE instruments, peaks were approximately 5-8 nm narrower. Code for implementing the procedure in MATLAB, which allows for the adjustment of input parameters to compensate for noisy data, is provided in the Supplemental Material (available online). © 2011 Society for Applied Spectroscopy.
|
|
| 17. |
|
|
| 18. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Characterizing odorous emissions using new software for identifying peaks in chemometric models of gas chromatography-mass spectrometry datasets
- 2012
-
Ingår i: Chemometrics and Intelligent Laboratory Systems. - : Elsevier BV. - 0169-7439 .- 1873-3239. ; 118, s. 41-50
-
Tidskriftsartikel (refereegranskat)abstract
- The task of identifying individual compounds within complex gas chromatography - mass spectrometry (GC-MS) chromatograms is made more difficult by interferences between peaks with similar mass spectra eluting at the same time, typically against a background of chemical and electronic noise. Although chemometric techniques like parallel factor analysis and multivariate curve resolution can help to purify spectra and improve correlations with reference compounds, file incompatibilities between GC-MS acquisition software and modeling software prevent the modeled spectra from being easily compared to spectra in reference libraries. In this paper we present an enhancement to OpenChrom, an open-source software for chromatography and mass spectrometry, which implements the automated cross-matching of modeled spectra to NIST08 and NIST11 mass spectral databases. The benefits of this approach are demonstrated using a complex environmental dataset consisting of non-methane volatile organic compound emissions sampled on an Australian poultry farm. © 2012 Elsevier B.V.
|
|
| 19. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Exploring the limits of dissolved organic matter fluorescence for determining seawater sources and ballast water exchange on the US Pacific coast
- 2013
-
Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963. ; 111-112, s. 157-166
-
Tidskriftsartikel (refereegranskat)abstract
- To minimize the risk of biological invasions associated with commercial shipping, vessels are required to conduct ballast water exchange (BWE)≤200 nautical miles offshore when arriving in the US from foreign ports, and some states require coastal BWE≤50 miles offshore along domestic routes. Previous research suggests that the intensity of fluorescent dissolved organic matter (fDOM) can be used to verify whether BWE was implemented. This study examined seasonal and spatial variability of fDOM in Pacific rim ports and the adjacent seas, using the North American coast as a model system to test whether regional fluorescence intensity thresholds consistently distinguish port sites from coastal and oceanic sites at increasing distances from shore. Over 2000 samples from major port systems on the US Pacific coast and along offshore (perpendicular) and alongshore (parallel) transects were analyzed. Overall, humic fDOM fluorescence intensity (C3*=370/494nm) effectively discriminated port versus oceanic sites located further than 100. miles from shore, but discriminated only a subset of coastal versus oceanic sources within the northeastern Pacific. Data from additional global ports are needed to predict the frequency of false positive or false negative ballast source determinations using fDOM for foreign vessel traffic. © 2012 Elsevier B.V.
|
|
| 20. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Fluorescence spectroscopy and multi-way techniques. PARAFAC
- 2013
-
Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 5:23, s. 6557-6566
-
Tidskriftsartikel (refereegranskat)abstract
- PARAllel FACtor analysis (PARAFAC) is increasingly used to decompose fluorescence excitation emission matrices (EEMs) into their underlying chemical components. In the ideal case where fluorescence conforms to Beers Law, this process can lead to the mathematical identification and quantification of independently varying fluorophores. However, many practical and analytical hurdles stand between EEM datasets and their chemical interpretation. This article provides a tutorial in the practical application of PARAFAC to fluorescence datasets, demonstrated using a dissolved organic matter (DOM) fluorescence dataset. A new toolbox for MATLAB is presented to support improved visualisation and sensitivity analyses of PARAFAC models in fluorescence spectroscopy. © 2013 The Royal Society of Chemistry.
|
|
| 21. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Non-methane volatile organic compounds predict odor emitted from five tunnel ventilated broiler sheds
- 2014
-
Ingår i: Chemosphere. - : Elsevier BV. - 0045-6535 .- 1879-1298. ; 95, s. 423-432
-
Tidskriftsartikel (refereegranskat)abstract
- Non-methane volatile organic compounds (NMVOCs) emitted from mechanically ventilated poultry sheds in similar stages (32-36d) of broiler production were measured by thermal desorption-gas chromatography/mass spectrometry (TD-GC/MS), then identified using parallel factor analysis (PARAFAC2) and the NIST11 database. Calibration models predicting odor measured by dilution olfactometry from NMVOC concentrations via orthogonal projection to latent structures (O-PLS) made good predictions (Rp2=0.83-0.87, RMSEp=137-175OU) using one to eight NMVOCs with either one or two latent variables representing odor concentration and character, respectively. Similar changes in odorant composition were observed in each sampling campaign, with samples collected early in the day more odorous and more sulfurous than samples collected later in the day. High litter moisture favored sulfur-containing odorants over alcohols, aldehydes and ketones but had little bearing on perceived odor, whereas high bird density favored alcohols, aldehydes and ketones over sulfur-containing odorants. Eight VOCs that were important predictors of odor across all sheds in order of decreasing importance were dimethyl sulfide (DMS), dimethyl trisulfide (DMTS), 2-3 butanedione, 3-methyl-butanal, 1-butanol, 3-methyl-1-butanol, acetoin, and 2-butanone. Four additional NMVOCs also influenced perceived odor although less predictably; these were n-hexane, 2-butanol, dimethyl disulfide (DMDS), and 1-octen-3-ol. All of the odorants are associated with microbial or fungal activity in the litter and manure, except n-hexane, which may originate from hexane-extracted soybean meal in the chicken feed. The organosulfides measured in this study may have arisen from the field sites as well as from the degradation of thiols captured on sorbent tubes during analysis by TD-GC/MS. © 2013 Elsevier Ltd.
|
|
| 22. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
OpenFluor- an online spectral library of auto-fluorescence by organic compounds in the environment
- 2014
-
Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 6:3, s. 658-661
-
Tidskriftsartikel (refereegranskat)abstract
- An online repository of published organic fluorescence spectra has been developed, which can be searched for quantitative matches with any set of unknown spectra. It fills a critical gap by increasing access to measured and modelled (PARAFAC) spectra, and linking across studies and systems to reveal "global" fluorescence trends.
|
|
| 23. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Organic matter fluorescence in municipal water recycling schemes: Toward a unified PARAFAC model
- 2011
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 45:7, s. 2909-2916
-
Tidskriftsartikel (refereegranskat)abstract
- Organic matter (OM) is a ubiquitous constituent of natural waters quantifiable at very low levels using fluorescence spectroscopy. This technique has recognized potential in a range of applications where the ability to monitor water quality in real time is desirable, such as in water treatment systems. This study used PARAFAC to characterize a large (n = 1479) and diverse excitation emission matrix (EEM) data set from six recycled water treatment plants in Australia, for which sources of variability included geography, season, treatment processes, pH and fluorometer settings. Five components were identified independently in four or more plants, none of which were generated during the treatment process nor were typically entirely removed. PARAFAC scores could be obtained from EEMs by simple regression. The results have important implications for online monitoring of OM fluorescence in treatment plants, affecting choices regarding experimental design, instrumentation and the optimal wavelengths for tracking fluorescent organic matter through the treatment process. While the multimodel comparisons provide a compelling demonstration of PARAFAC's ability to distill chemical information from EEMs, deficiencies identified through this process have broad implications for interpreting and reusing (D)OM-PARAFAC models. © 2011 American Chemical Society.
|
|
| 24. |
- Murphy, Kathleen, 1972, et al.
(författare)
-
Photochemistry Illuminates Ubiquitous Organic Matter Fluorescence Spectra
- 2018
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 52:19, s. 11243-11250
-
Tidskriftsartikel (refereegranskat)abstract
- Dissolved organic matter (DOM) in aquatic environments forms a vast reservoir of carbon present as a complex supermixture of compounds. An efficient approach to tracking the production and removal of specific DOM fractions is needed across disciplines, for purposes that range from improving global carbon budgets to optimizing water treatment in engineered systems. Although widely used to study DOM, fluorescence spectroscopy has yet to deliver specific fractions with known spectral properties and predictable distributions. Here, we mathematically isolate four visible-wavelength fluorescent fractions in samples from contrasting lake, river, and ocean environments. Using parallel factor analysis (PARAFAC), we show that most measured fluorescence in environmental samples can be explained by ubiquitous spectra with nearly stable optical properties and photodegradation behaviors over environmental pH gradients. Sample extraction changed bulk fluorescence spectra but not the number or shape of underlying PARAFAC components, while photobleaching preferentially removed the two longest-wavelength components. New approaches to analyzing fluorescence data sets incorporating these findings should improve the interpretation of DOM fluorescence and increase its utility for tracing organic matter biogeochemistry in aquatic systems.
|
|
| 25. |
- Noble, Monaca, et al.
(författare)
-
Chemical assessment of ballast water exchange compliance: Implementation in North America and New Zealand
- 2016
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 3:MAY
-
Tidskriftsartikel (refereegranskat)abstract
- Fluorescence by naturally occurring dissolved organic matter (FDOM) is a sensitive indicator of ballast water source, with high FDOM in coastal ballast water decreasing typically dramatically when replaced by oceanic seawater during ballast water exchange (BWE). In this study, FDOM was measured in 92 ships arriving at Pacific ports on the US west coast and in New Zealand, and used to assess their compliance with ballast water regulations that required 95% replacement of port water to minimize invasive species risks. Fluorescence in many ships that reported BWE was significantly higher than is usual for oceanic seawater, and in several cases, significantly higher than in other ships with similar provenance and ballast water management. Pre-exchange source port conditions represented the largest source of uncertainty in the analysis, because residual coastal FDOM when highly fluorescent can significantly influence the fluorescence signature of exchanged ballast water. A meta-analysis comparing the intensities of FDOM in un-exchanged ballast tanks with calculated pre-exchange intensities assuming that ships all correctly implemented and reported BWE revealed notable discrepancies. Thus, the incidence of high-FDOM port waters was seven times lower in reality than would be expected on the basis of these calculations. The results suggest that a significant rate of reporting errors occur due to a combination of factors that may include inadequate BWE and unintentional or deliberate misreporting of ballast water management.
|
|
| 26. |
- Paradina-Fernández, Lesly, et al.
(författare)
-
Direct Measurement of Organic Micropollutants in Water and Wastewater Using Fluorescence Spectroscopy
- 2023
-
Ingår i: ACS ES and T Water. - 2690-0637. ; 3:12, s. 3905-3915
-
Tidskriftsartikel (refereegranskat)abstract
- Quantifying organic micropollutants (OMPs) in aquatic environments and assessing their removal by water treatment requires expensive and time-consuming analyses typically using liquid chromatographic separation and tandem mass spectrometry (LC-MS/MS). In this study, we evaluated the potential for detecting fluorescent OMPs via spectroscopy, which is cheap, rapid, and widely accessible. The method involved using a priori PARAFAC models to eliminate interfering background fluorescence emitted by naturally occurring dissolved organic matter. Of 20 screened pharmaceutical OMPs, three (ciprofloxacin, naproxen, and zolpidem) with calculated fluorescence quantum yields 0.14, 0.21, and 0.71, respectively, could be quantified in the low μg L-1 range when added alone or in combination to water samples without any sample pretreatment other than filtration and pH adjustment. Limits of detection for all three OMPs were 1.0-3.3 μg L-1 in surface waters, while in wastewater, they were 0.6-9.0 μg L-1 for ciprofloxacin and naproxen and 1.0-2.6 μg L-1 for zolpidem. Given the high cost of pharmaceutical analyses and widespread availability of fluorometers, the new approach will improve access to rapid and cost-effective results by supporting data-intensive lab-scale studies, wherein the types of OMPs studied and their concentration ranges are under the control of the analyst.
|
|
| 27. |
- Peters, Gregory, 1970, et al.
(författare)
-
Improving odour assessment in LCA - the odour footprint
- 2014
-
Ingår i: International Journal of Life Cycle Assessment. - : Springer Science and Business Media LLC. - 1614-7502 .- 0948-3349. ; 19:11, s. 1891-1900
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose Odour is an important aspect of systems for humanand agricultural waste management and many technologiesare developed with the sole purpose of reducing odour.Compared with greenhouse gas assessment and the assessmentof toxicity, odour assessment has received little attentionin the life cycle assessment (LCA) community. This articleaims to redress this.Methods Firstly, a framework for the assessment of odourimpacts in LCA was developed considering the classicalLCA framework of emissions, midpoint and endpoint indicators.This suggested that an odour footprint midpoint indicatorwas worth striving for. An approach to calculating an arealindicator we call “odour footprint”, which considers the odourdetection threshold, the diffusion rate and the kinetics ofdegradation of odourants, was implemented in MATLAB.We demonstrated the use of the characterisation factors wecalculated in a case study based on odour removal technologyapplied to a pig barn.Results and discussion We produced a list of 33 linear characterisation factors based on hydrogen sulphide equivalents, analogous to the linear carbon dioxide equivalency factors in use in carbon footprinting, or the dichlorobenzene equivalency factors developed for assessment of toxic impacts in LCA. Like the latter, this odour footprint method does not take local populations and exposure pathway analysis into account—its intent is not to assess regulatory compliance or detailed design. The case study showed that despite the need for materials and energy, large factor reductions in odour footprint andeutrophication potential were achieved at the cost of a smaller factor increase in greenhouse emissions.Conclusions The odour footprint method is proposed as animprovement on the established midpoint method for odourassessment in LCA. Unlike it, the method presented hereconsiders the persistence of odourants. Over time, we hopeto increase the number of characterised odourants, enablinganalysts to perform simple site-generic LCA on systems withodourant emissions.
|
|
| 28. |
- Philibert, Marc, et al.
(författare)
-
Drinking water aromaticity and treatability is predicted by dissolved organic matter fluorescence
- 2022
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 220
-
Tidskriftsartikel (refereegranskat)abstract
- Samples from fifty-five surface water resources and twenty-five drinking water treatment plants in Europe, Africa, Asia, and USA were used to analyse the fluorescence composition of global surface waters and predict aromaticity and treatability from fluorescence excitation emission matrices. Nine underlying fluorescence components were identified in the dataset using parallel factor analysis (PARAFAC) and differences in aromaticity and treatability could be predicted from ratios between components Hii (λex/λem= 395/521), Hiii (λex/λem= 330/404), Pi, (λex/λem=290/365) and Pii (λex/λem= 275/302). Component Hii tracked humic acids of primarily plant origin, Hiii tracked weathered/oxidised humics and the “building block” fraction measured by LC-OCD, while Pi and Pii tracked amino acids in the “low molecular weight neutrals” LC-OCD fraction. Ratios between PARAFAC components predicted DOC removal at lab scale for French rivers in standardized tests involving coagulation, powdered activated carbon (PAC), chlorination, ion exchange (IEX), and ozonation, alone and in combination. The ratio Hii/Hiii, for convenience named “PARIX” standing for “PARAFAC index”, predicted SUVA according to a simple relationship: SUVA = 4.0 x PARIX (RMSEp=0.55) Lmg−1m−1. These results expand the utility of fluorescence spectroscopy in water treatment applications, by demonstrating the existence of previously unknown relationships between fluorescence composition, aromaticity and treatability that appear to hold across diverse surface waters at various stages of drinking water treatment.
|
|
| 29. |
- Pucher, Mathias, et al.
(författare)
-
staRdom: Versatile Software for Analyzing Spectroscopic Data of Dissolved Organic Matter in R
- 2019
-
Ingår i: Water. - : MDPI AG. - 2073-4441. ; 11:11, s. 2366-
-
Tidskriftsartikel (refereegranskat)abstract
- The roles of dissolved organic matter (DOM) in microbial processes and nutrient cycles depend on its composition, which requires detailed measurements and analyses. We introduce a package for R, called staRdom (“spectroscopic analysis of DOM in R”), to analyze DOM spectroscopic data (absorbance and fluorescence), which is key to deliver fast insight into DOM composition of many samples. staRdom provides functions that standardize data preparation and analysis of spectroscopic data and are inspired by practical work. The user can perform blank subtraction, dilution correction, Raman normalization, scatter removal and interpolation, and fluorescence normalization. The software performs parallel factor analysis (PARAFAC) of excitation–emission matrices (EEMs), including peak picking of EEMs, and calculates fluorescence indices, absorbance indices, and absorbance slope indices from EEMs and absorbance spectra. A comparison between PARAFAC solutions by staRdom in R compared with drEEM in MATLAB showed nearly identical solutions for most datasets, although different convergence criteria are needed to obtain similar results and interpolation of missing data is important when working with staRdom. In conclusion, staRdom offers the opportunity for standardized multivariate decomposition of spectroscopic data without requiring software licensing fees and presuming only basic R knowledge.
|
|
| 30. |
|
|
| 31. |
- Wuensch, Urban, 1986, et al.
(författare)
-
A simple method to isolate fluorescence spectra from small dissolved organic matter datasets
- 2021
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 190
-
Tidskriftsartikel (refereegranskat)abstract
- Dissolved organic matter (DOM) is a complex pool of compounds with a key role in the global carbon cycle. To understand its role in natural and engineered systems, efficient approaches are necessary for tracking DOM quality and quantity. Fluorescence spectroscopy combined with parallel factor analysis (PARAFAC) is very widely used to identify and quantify different fractions of DOM as proxies of DOM source, concentration and biogeochemical processing. A major limitation of the PARAFAC approach is the requirement for a large data set containing many variable samples in which the fractions vary independently. This severely curtails the possibilities to study fluorescence composition and behavior in small or unique datasets. Herein, we present a simple and inexpensive experimental procedure that makes it possible to mathematically decompose a small dataset containing only highly-correlated fluorescent fractions. The approach, which uses widely-available commercial extraction sorbents and previously established protocols to expand the original dataset and inject the missing chemical variability, can be widely implemented at low cost. A demonstration of the procedure shows how a robust six-component PARAFAC model can be extracted from even a river-water dataset with only five bulk samples. Widespread adoption of the procedure for analyzing small fluorescence datasets is needed to confirm the suspected ubiquity of certain DOM fluorescence fractions and to create a shared inventory of ubiquitous components. Such an inventory could greatly simplify and improve the use of fluorescence as a tool to investigate biogeochemical processing of DOM in diverse water sources.
|
|
| 32. |
- Wuensch, Urban, 1986, et al.
(författare)
-
Emerging patterns in the global distribution of dissolved organic matter fluorescence
- 2019
-
Ingår i: Analytical Methods. - : Royal Society of Chemistry (RSC). - 1759-9679 .- 1759-9660. ; 11:7, s. 888-893
-
Tidskriftsartikel (refereegranskat)abstract
- The spectra responsible for natural dissolved organic matter (DOM) fluorescence in 90 peer-reviewed studies have been compared using new similarity metrics. Numerous spectra cluster in specific wavelength regions. The emerging patterns suggest that most fluorescence spectra are not tied to biogeochemical origin, but exist across a wide range of different environments.
|
|
| 33. |
- Wuensch, Urban, 1986, et al.
(författare)
-
Fluorescence Quantum Yields of Natural Organic Matter and Organic Compounds: Implications for the Fluorescence-based Interpretation of Organic Matter Composition
- 2015
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 2:November, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- Absorbance and fluorescence spectroscopy are economical tools for tracing the supply, turnover and fate of dissolved organic matter (DOM). The colored and fluorescent fractions of DOM (CDOM and FDOM, respectively) are linked by the apparent fluorescence quantum yield (AQY) of DOM, which reflects the likelihood that chromophores emit fluorescence after absorbing light. Compared to the number of studies investigating CDOM and FDOM, few studies have systematically investigated AQY spectra for DOM, and linked them to fluorescence quantum yields (Φ) of organic compounds. To offer a standardized approach, a MATLAB toolbox for the determination of apparent quantum yields of DOM (aquaDOM), featuring two calculation approaches, was developed and used to derive AQYs for samples from the Norwegian Sea. Φ of the organic compounds varied between 0.00079 and 0.35, whereas the average AQY for DOM samples at 350 nm was 0.011 ± 0.003. The AQY at 350 nm increased with depth, while the AQY at 250 nm showed no trend. Laboratory tests indicated that Φ of compound mixtures are additive and represent an intermediate of the constituents. Additionally, the presence of non-fluorescent chromophores greatly suppressed calculated AQYs. Similar trends in the DOM AQY at 350 nm were observed in natural samples. We therefore hypothesize that fluorescence AQYs can indicate changes in the relative abundances of CDOM and FDOM. Additionally, the optical properties of 15 potential DOM constituents were determined and compared to more than 200 modeled spectra (PARAFAC components) in the OpenFluor database. Apparent matches, based on spectral similarity, were subsequently evaluated using molar fluorescence and absorbance. Five organic compounds were potential matches with PARAFAC components from 16 studies; however, the ability to confirm matches was limited due to multiple compounds exhibiting very similar spectra. This reiterates the fact that spectral similarity alone is insufficient evidence of the presence of particular compounds, and additional evidence is required.
|
|
| 34. |
- Wuensch, Urban, 1986, et al.
(författare)
-
Quantifying the impact of solid-phase extraction on chromophoric dissolved organic matter composition
- 2018
-
Ingår i: Marine Chemistry. - : Elsevier BV. - 0304-4203. ; 207, s. 33-41
-
Tidskriftsartikel (refereegranskat)abstract
- Advancing our understanding of the behaviour of dissolved organic matter (DOM) in aquatic environments necessitates efforts to combine complementary analytical data sets. However, some analytical measurements require sample pre-treatment, while others are carried out on bulk water samples, and it remains unclear if the resulting data sets can be compared. Here, we investigated the impact of solid-phase extraction with PPL resins on DOM optical properties. In samples from contrasting Arctic fjords, extraction efficiencies based on optical properties varied spectrally with averages between 31 ± 13% at 411 nm and 40 ± 12% at 363 nm for chromophoric DOM. Similarly, the extraction efficiency for specific fluorescence components varied between 37 ± 16% and 58 ± 18%. Solid-phase extraction also decreased S275–295, fluorescence index, and the freshness index, but increased S350–400, and apparent fluorescence quantum yields, indicating that the extraction process was qualitatively selective. Six fluorescence components identified independently in bulk water samples and extracted DOM using parallel factor analysis exhibited different behaviours. Three had identical spectral properties before and after extraction, although their extraction efficiencies varied with water mass characteristics and DOM composition, whereas three other components appeared to change after extraction. With the exception of one fluorescence component, the dynamics of optical properties in bulk water samples were not accurately reflected by DOM extracts. These results indicate that solid-phase extraction imparts a qualitative selectivity that leads to the homogenization of DOM extracts relative to their original samples. Efforts to integrate chemical information from different analytical methods should prioritize comparisons of measurements obtained on the same samples.
|
|
| 35. |
- Wuensch, Urban, 1986, et al.
(författare)
-
The Molecular Fingerprint of Fluorescent Natural Organic Matter Offers Insight into Biogeochemical Sources and Diagenetic State
- 2018
-
Ingår i: Analytical Chemistry. - : American Chemical Society (ACS). - 0003-2700 .- 1520-6882. ; 90:24, s. 14188-14198
-
Tidskriftsartikel (refereegranskat)abstract
- Investigating the biogeochemistry of dissolved organic matter (DOM) requires the synthesis of data from several complementary analytical techniques. The traditional approach to data synthesis is to search for correlations between measurements made on the same sample using different instruments. In contrast, data fusion simultaneously decomposes data from multiple instruments into the underlying shared and unshared components. Here, Advanced Coupled Matrix and Tensor Factorization (ACMTF) was used to identify the molecular fingerprint of DOM fluorescence fractions in Arctic fjords. ACMTF explained 99.84% of the variability with six fully shared components. Individual molecular formulas were linked to multiple fluorescence components and vice versa. Molecular fingerprints differed in diversity and oceanographic patterns, suggesting a link to the biogeochemical sources and diagenetic state of DOM. The fingerprints obtained through ACMTF were more specific compared to traditional correlation analysis and yielded greater compositional insight. Multivariate data fusion aligns extremely complex, heterogeneous DOM data sets and thus facilitates a more holistic understanding of DOM biogeochemistry.
|
|
| 36. |
- Wuensch, Urban, 1986, et al.
(författare)
-
The One-Sample PARAFAC Approach Reveals Molecular Size Distributions of Fluorescent Components in Dissolved Organic Matter
- 2017
-
Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:20, s. 11900-11908
-
Tidskriftsartikel (refereegranskat)abstract
- Molecular size plays an important role in dissolved organic matter (DOM) biogeochemistry, but its relationship with the fluorescent fraction of DOM (FDOM) remains poorly resolved. Here high-performance size exclusion chromatography (HPSEC) was coupled to fluorescence emission-excitation (EEM) spectroscopy in full spectral (60 emission and 34 excitation wavelengths) and chromatographic resolution (
|
|
| 37. |
- Zhou, Yongqiang, et al.
(författare)
-
Inflow rate-driven changes in the composition and dynamics of chromophoric dissolved organic matter in a large drinking water lake
- 2016
-
Ingår i: Water Research. - : Elsevier BV. - 0043-1354 .- 1879-2448. ; 100, s. 211-221
-
Tidskriftsartikel (refereegranskat)abstract
- Drinking water lakes are threatened globally and therefore in need of protection. To date, few studies have been carried out to investigate how the composition and dynamics of chromophoric dissolved organic matter (CDOM) in drinking water lakes are influenced by inflow rate. Such CDOM can lead to unpleasant taste and odor of the water and produce undesirable disinfection byproducts during drinking water treatment. We studied the drinking water Lake Qiandao, China, and found that the concentrations of suspended particulate matter (SPM) in the lake increased significantly with inflow rate (p
|
|
