Moving towards a technical specification for fluorescence excitation-emission mapping and absorbance analysis of colored dissolved organic matter

Gilmore, Adam M.; Hurteaux, R.; FitzGerald, Stephen A.; Knowles, A.

doi:10.2495/dn120261

Cited by 8 publications

(8 citation statements)

References 14 publications

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“…Triplet CDOM in temperate wetlands 4 1995 Excitation-emission matrices were collected with a Horiba Aqualog using a 1-cm quartz cell, with a 2 or 3 s integration time with 1, 3, or 5-nm excitation wavelength intervals (Gilmore et al 2012). Spectral corrections were made using the drEEM toolbox in MATLAB (Murphy et al 2013;MathWorks 2014).…”

Section: Mccabe and Arnoldmentioning

confidence: 99%

“…We also observe a moderately strong correlation between AQY c T and SC (0.6248, p value < 0.001). While ionic strength (empirically measured as SC) does influence the photo-physics of 3 CDOM* (Parker et al 2013;Glover and Rosario-Ortiz 2013), our sample set covers a fairly low SC gradient (range 5 3-1133 lS cm 21 ; sea water is 503 higher in SC) and we expect that the trend between SC and AQY c T is also due to other variables that covary with SC.…”

Section: Mccabe and Arnoldmentioning

confidence: 99%

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Multiple linear regression models to predict the formation efficiency of triplet excited states of dissolved organic matter in temperate wetlands

McCabe

Arnold

2018

Limnology & Oceanography

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The source and composition of dissolved organic matter (DOM) dictates light absorption in surface waters. Sunlight absorption by chromophoric dissolved organic matter (CDOM) forms reactive intermediates and drives global organic carbon processing. Triplet excited states of CDOM ( 3 CDOM*) are primary reactive intermediates formed by sunlight absorption by CDOM.3 CDOM* also produce secondary reactive intermediates, including radicals and reactive oxygen species, which are active in biogeochemical pathways. The efficiency of 3 CDOM* formation (apparent quantum yield, AQY T ) depends on DOM composition, especially DOM molecular weight. This dependence may arise from the greater probability of forming intra-molecular chargetransfer (CT) complexes in high-molecular weight DOM that inhibit 3 CDOM* formation. There are few examples that demonstrate this in field samples. In this report, vegetation, general hydrology, and watershed characteristics for 39 temperate wetlands, which are critical sources of high-molecular weight DOM, from the United States were defined and related to DOM composition and AQY T . The DOM bulk composition was assessed using absorbance and fluorescence spectroscopies. AQY T was estimated under simulated sunlight using the probe 2,4,6-trimethylphenol. Relatively high AQY T values (7%) were observed in wetlands with long hydroperiods and > 50% cropland watershed land cover compared to wetlands with >50% forest watershed land cover (< 1-4%). Low molecular weight DOM (E2/E3 > 7 and SUVA 254 < 3 L mg-C 21 m 21) and autochthonous DOM (b/a > 0.7) had relatively high AQY T estimates ($ 10%), indicating that allocthonous, high-molecular weight compounds produce 3 CDOM* less efficiently than autochthonous DOM. The CT theory of DOM light absorption and internal light-screening offer mechanistic explanations for these trends.Naturally occurring dissolved organic matter (DOM) is a complex mixture of components including aromatics from terrestrial plants and biomacromolecules from primary and secondary aquatic producers (Wilson 1987;Stenson et al. 2003;Nebbioso and Piccolo 2013). Wetlands are integral sources of DOM to the hydrosphere and function as natural reactors in DOM transformation (Watanabe et al. 2012;Raymond and Spencer 2015). The relative inputs of terrestrial and aquatic DOM, and thus DOM composition, changes from headwaters and isolated wetlands (terrene wetlands) to wetlands associated with lake basins and rivers (lentic and lotic wetlands, respectively) (M€ unster and Chr ost 1990;Larson et al. 2014;Yu et al. 2015). In headwater systems with surrounding shrubs, trees, or emergent vegetation, inputs of DOM are dominated by terrestrial sources, such as plant matter and soil organic matter (allochthonous DOM). In contrast, the composition of DOM in systems with large open water regions and long water residence times is dominated by exo-metabolites from photoautotrophs and pelagic heterotrophs as well as products of photo-and microbialdegradation (autochthonous DOM) (M€ unster and Chr ost ...

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Section: Mccabe and Arnoldmentioning

confidence: 99%

Section: Mccabe and Arnoldmentioning

confidence: 99%

Multiple linear regression models to predict the formation efficiency of triplet excited states of dissolved organic matter in temperate wetlands

McCabe

Arnold

2018

Limnology & Oceanography

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“…Obviously, errors in absorbance measurements are transferred to the fluorescence spectra during IFE correction and the upper limit of the absorbance spectrophotometer may be a limiting factor. To avoid variability due to differences in band widths and spectral distributions between light sources, it is preferable to use the same light source for measuring fluorescence as for absorbance (Gilmore et al 2012;Miller 1981). New spectrofluorometers have recently entered the market with the capacity to measure fluorescence and absorbance simultaneously, allowing for more direct and accurate IFE corrections.…”

Section: Attributes and Limitations Of Aba And Cdamentioning

confidence: 99%

Inner filter correction of dissolved organic matter fluorescence

Kothawala

Murphy

Stedmon

et al. 2013

Limnology & Ocean Methods

279

167

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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.

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“…15,20,35−37 Excitation−emission matrices (EEMs) were collected with a Horiba Aqualog in a 1 cm quartz cell. Instrument specifications are detailed in Gilmore et al 38 Depending on CDOM content, EEMs were collected with a 2 or 3 s integration time and either 1, 3, or 5 nm excitation wavelength intervals. Samples were diluted with Milli-Q if the absorbance at 254 nm was >0.6.…”

Section: ■ Introductionmentioning

confidence: 99%

Reactivity of Triplet Excited States of Dissolved Natural Organic Matter in Stormflow from Mixed-Use Watersheds

McCabe

Arnold

2017

Environ. Sci. Technol.

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Dissolved organic matter (DOM) quantity and composition control the rate of formation (R) of triplet excited states of dissolved natural organic matter (DOM*) and the efficiency of DOM* formation (the apparent quantum yield, AQY). Here, the reactivity of DOM* in stormflow samples collected from watersheds with variable land covers is examined. Stormflow DOM reflects variability in DOM quantity and composition as a function of land cover and may be important in controlling the fate of cotransported pollutants. R and AQY were measured using 2,4,6-trimethylphenol in stormflow samples under simulated sunlight. The DOM source and composition was characterized using absorbance and fluorescence spectroscopies and high-resolution mass spectrometry. R and the total rate of light absorption by the water samples (R) increased with the dissolved organic carbon (DOC) concentration. AQY was independent of DOC concentration, but varied with DOM source: developed land cover (4-6%) ≈ open water > vegetated land cover (3%). AQY was positively related to an index for microbial/algal DOM content and negatively related to DOM molecular weight, DOM aromaticity, and the content of polyphenols. This work demonstrates that TMP is an effective probe for the determination of R and AQY in whole water samples after accounting for the inhibition of TMP photodegradation by DOM.

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Moving towards a technical specification for fluorescence excitation-emission mapping and absorbance analysis of colored dissolved organic matter

Cited by 8 publications

References 14 publications

Multiple linear regression models to predict the formation efficiency of triplet excited states of dissolved organic matter in temperate wetlands

Multiple linear regression models to predict the formation efficiency of triplet excited states of dissolved organic matter in temperate wetlands

Inner filter correction of dissolved organic matter fluorescence

Reactivity of Triplet Excited States of Dissolved Natural Organic Matter in Stormflow from Mixed-Use Watersheds

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