Fluorescence as a possible tool for studying the nature and water column distribution of DOC components

Mopper, Kenneth; Schultz, Christopher A.

doi:10.1016/0304-4203(93)90124-7

Cited by 277 publications

(164 citation statements)

References 35 publications

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“…However, some studies adopted methods comparable with our study, including wavelengths and standardization [Mopper and Schultz, 1993;Yamashita et al, 2007;Yamashita and Tanoue, 2008]. Mopper and Schultz [1993] determined a vertical profile of the fluorescence intensity at a midlatitudinal station in the Sargasso Sea (26°N, 76°W), reporting 0.8 and 1.1 QSU at 500 and 1000 m depths, respectively. These values are well within the ranges determined in the present study in the subtropical western Pacific Ocean (0.6-1.0 QSU at 500 m and 0.9-1.1 QSU at 1000 m).…”

Section: Fluorescence Intensity Of Fdom M In Pelagic Areamentioning

confidence: 84%

“…In particular, the development of the technique of excitation-emission matrices spectroscopy (EEMs) has accelerated the study of fluorescent DOM (FDOM) in oceanic environments [e.g., Coble et al, 1990Coble et al, , 1998Mopper and Schultz, 1993]. EEMs make it practicable to estimate the composition of FDOM by comparing the fluorescence intensities in the different wavelengths of excitation and emission.…”

Section: Introductionmentioning

confidence: 99%

“…In the open ocean, meanwhile, relatively limited measurements of the fluorescence intensity of humic substances have been carried out so far. Although vertical profiles [Chen and Bada, 1992;Mopper and Schultz, 1993;Hayase and Shinozuka, 1995;Yamashita et al, 2007] and spatial variation [Chen and Bada, 1992;Determann et al, 1996;Yamashita and Tanoue, 2008] have been determined, the observations are rather fragmentary and little systematic study has been conducted to date covering spatial and temporal changes in the fluorescence intensity.…”

Section: Introductionmentioning

confidence: 99%

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Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific

Omori

Hama

Ishii³

et al. 2010

J. Geophys. Res.

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[1] Spatial and temporal distributions of marine humic-like fluorescent dissolved organic matter (FDOM M ) were determined in the subtropical western North Pacific to evaluate the controlling factors of FDOM M behaviors. The observations were conducted at 4 stations (15-30°N) along 137°E in a subtropical area between January 2006 and April 2007. The florescence intensity of FDOM M was low (0.14-0.25 quinine sulfate units (QSU)) in the surface layer probably due to photodegradation, and increased with depth (0.90-1.10 QSU at 1000 m), irrespective of season and station. In the surface layer, the thickness of the water mass with low fluorescence intensity (<0.3 QSU) showed the seasonal change by being deeper in winter and shallower in summer, depending on the mixed layer depth (MLD). The average fluorescence intensity within the mixed layer also varied seasonally at midlatitudes; the intensity in summer was 40.8-53.8% of that in winter. Since the MLD was very much shallower in summer than in winter, FDOM M in the mixed layer would be kept within a shallow depth during the summer where intensive photodegradation could occur. The concentration of total organic carbon (TOC) was at its maximum at the water surface and decreased with depth, being adverse to FDOM M . Thus, the ratio of fluorescence intensity to TOC concentration was lowest (0.002-0.003) in surface water, which implies that FDOM M is not quantitatively important to the dissolved organic carbon pool. However, considering the possible difference in the stabilities of FDOM M against photochemical and microbial degradation, it is conceivable that photobleached FDOM M is one of the important organic groups constituting marine dissolved organic matter.Citation: Omori, Y., T. Hama, M. Ishii, and S. Saito (2010), Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific,

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Section: Fluorescence Intensity Of Fdom M In Pelagic Areamentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific

Omori

Hama

Ishii³

et al. 2010

J. Geophys. Res.

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“…In a shallow WAIS (West Antarctica) ice core, John Priscu (private communication) measured organic matter at 12 depths from 71 to 128 m and found values from 24 to 295 M of non-acid-purgeable organic carbon, consistent with the above values for marine aerosols. Using fluorescence excitationemission matrices, Mopper and Schultz (38) found that the major component of DOM in the top Ϸ200 m of ocean water has an intensity maximum at exc Ϸ 225 nm, with em decreasing monotonically out to Ϸ380 nm. We find that the most intense non-Trp fluorescence in single particles often shows a monotonic emission spectrum like that found by Mopper and Schultz.…”

Section: Narrow Spikes Of High-microbial Concentration Correspond To mentioning

confidence: 99%

In situ microbial metabolism as a cause of gas anomalies in ice

Rohde

Price

Bay

et al. 2008

Proc. Natl. Acad. Sci. U.S.A.

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Isolated spikes of anomalously high concentrations of N2O have been reported at depths in Greenland and Antarctic ice cores corresponding to narrow time intervals over the past Ϸ10 5 years. Now, using a calibrated spectrofluorimeter to map protein-bound Trp, a proxy for microbes, versus depth in the 3,053-m GISP2 ice core, we find six depths at which localized spikes of high cell concentrations coincide with N2O spikes. We show that the excess gases are consistent with accumulation of in situ metabolic wastes during residence times of the excess microbes in the ice. Because of sparseness of N2O measurements and our spectrofluorimetry versus depth, the total number of microbially produced N2O spikes in GISP2 is probably much larger than six. Spikes of excess methanogens coincident with CH4 spikes are found at three depths in the bottom 3% of GISP2, most likely because of methanogenic metabolism in the underlying silty ice, followed by turbulent flow of the lowest Ϸ90 m of ice. The apparent rates of in situ production of N2O and CH4 spikes by metabolism are observed to be consistent with a single activation energy, U, and maintain proportionality to exp(؊U/RT) over the entire temperature range down to ؊40°C. Fluorescence of nonmicrobial aerosols in GISP2 ice is distinguishable from microbial fluorescence by its different emission spectra. Our spectrofluorimetric scans throughout the GISP2 ice core lead us to conclude that both microbes and nonmicrobial aerosols are deposited in discontinuous bursts, which may provide a tool for studying wind storms in the distant past.climate ͉ ice cores ͉ proxy for dust storms ͉ scanning fluorimetry ͉ N2O

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“…Fluorescence characterization has proven to be a useful means of characterizing oceanic water masses (e.g., Hayase et al 1988;Coble et al 1990;Mopper and Schultz 1993;Coble 1996). In a study of a freshwater lake, Stewart and Wetzel (1980) showed that larger molecular weight aquatic humic fractions had a greater absorbance but lower fluorescence than smaller molecular weight fractions.…”

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confidence: 99%

Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity

McKnight

Boyer

Westerhoff

et al. 2001

Limnology & Oceanography

2,442

1,810

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We studied the fluorescence properties of fulvic acids isolated from streams and rivers receiving predominantly terrestrial sources of organic material and from lakes with microbial sources of organic material. Microbially derived fulvic acids have fluorophores with a more sharply defined emission peak occurring at lower wavelengths than fluorophores in terrestrially derived fulvic acids. We show that the ratio of the emission intensity at a wavelength of 450 nm to that at 500 nm, obtained with an excitation of 370 nm, can serve as a simple index to distinguish sources of isolated aquatic fulvic acids. In our study, this index has a value of ϳ1.9 for microbially derived fulvic acids and a value of ϳ1.4 for terrestrially derived fulvic acids. Fulvic acids isolated from four large rivers in the United States have fluorescence index values of 1.4-1.5, consistent with predominantly terrestrial sources. For fulvic acid samples isolated from a river, lakes, and groundwaters in a forested watershed, the fluorescence index varied in a manner suggesting different sources for the seepage and streamfed lakes. Furthermore, we identified these distinctive fluorophores in filtered whole water samples from lakes in a desert oasis in Antarctica and in filtered whole water samples collected during snowmelt from a Rocky Mountain stream. The fluorescence index measurement in filtered whole water samples in field studies may augment the interpretation of dissolved organic carbon sources for understanding carbon cycling in aquatic ecosystems.Aquatic fulvic acid is a major fraction of dissolved organic matter (DOM) in natural waters. Aquatic fulvic acids are heterogeneous, moderate molecular weight, yellow-colored organic acids. Examples of processes controlled by fulvic acid are (1) chemical speciation and transport of trace metals through complexation reactions (e.g., Breault et al. 1996); (2) formation of trihalomethanes in drinking water by interactions between chlorine and fulvic acid during water AcknowledgmentsWe thank K. Cunningham for help with spectroscopic methods and G. Aiken, J. Debroux, P. Coble, and four anonymous reviewers for valuable comments on the manuscript.

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Fluorescence as a possible tool for studying the nature and water column distribution of DOC components

Cited by 277 publications

References 35 publications

Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific

Relationship between the seasonal change in fluorescent dissolved organic matter and mixed layer depth in the subtropical western North Pacific

In situ microbial metabolism as a cause of gas anomalies in ice

Spectrofluorometric characterization of dissolved organic matter for indication of precursor organic material and aromaticity

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