Seasonal variation in molecular mass and optical properties of chromophoric dissolved organic material in coastal waters of southwest Florida

Zanardi-Lamardo, Eliete; Moore, Cynthia A.; Zika, Rod G.

doi:10.1016/j.marchem.2004.02.018

Cited by 49 publications

(29 citation statements)

References 32 publications

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“…DOC/TN ratios of soil in watershed could be used as a tracer to estimate DOC flux from land to ocean [Aitkenhead and McDowell, 2000]. And CDOM v had a relatively low quantum yield (Figure 3), which is consistent with the results of Findlay et al [2001] and is one characteristics of terrestrial humic substances [McKnight et al, 2001;Zanardi-Lamardo et al, 2004]. Quantum yields of CDOM V were lower than them in river plume, estuarine and coastal CDOM [Green and Blough, 1994;Chen and Gardner, 2004].…”

Section: Cdom From Naturally Vegetated Areassupporting

confidence: 78%

Sources and transformations of chromophoric dissolved organic matter in the Neponset River Watershed

Huang

Chen

2009

J. Geophys. Res.

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[1] The major source of chromophoric dissolved organic matter (CDOM) in coastal waters is often terrestrial dissolved organic matter originating in coastal watersheds and delivered to the ocean by rivers or streams. While studies of carbon cycling in large rivers dominate the literature, small rivers deliver the bulk of the freshwater to coastal waters ($60%). However, the variability of organic matter fluxes in small rivers requires high spatial and temporal resolution measurements to adequately represent the processes controlling distributions and fluxes. In this study, CDOM was measured monthly for 2 years at 15 sampling sites throughout a small, coastal, urban watershed ($300 km 2 ), the Neponset River Watershed, and CDOM variability was found to depend on land use type, discharge/precipitation, and growing degree days (temperature). Forest, wetland, residential, industrial, and golf course CDOM end-members were measured and differentiated using CDOM fluorescence, CDOM absorbance, absorbance slopes, total organic carbon and total nitrogen, and photo-and biological lability. Simple statistical models of CDOM end-member behavior could explain 40-70% of the observed seasonal variability. Using these simple relationships, trends in total CDOM loading behavior can be predicted under various scenarios of land use change and global warming. Overall, detailed measurements of CDOM throughout the Neponset River Watershed yield new insights into the watershed processes that affect terrestrial CDOM delivery to coastal oceans.

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Section: Cdom From Naturally Vegetated Areassupporting

confidence: 78%

Sources and transformations of chromophoric dissolved organic matter in the Neponset River Watershed

Huang

Chen

2009

J. Geophys. Res.

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“…Terrestrial ecosystems are significant sources of CDOM (Bracchini et al, 2006;Duan et al, 2007a;Duan et al, 2007b;Sobek et al, 2007), and rivers serve as important reactors as well as transporters of terrigenous CDOM to lakes, reservoirs, and oceans (Algesten et al, 2004;Blough et al, 1993;Cauwet, 2002;Chen et al, 2004;Conmy et al, 2004;Dittmar et al, 2006;Hansell et al, 2004;Hedges et al, 1997;Hopkinson et al, 1998;Kowalczuk et al, 2003;Kowalczuk et al, 2005;Kowalczuk et al, 2006;Opsahl and Benner, 1997;Opsahl et al, 1999;Waiser and Robarts, 2000;Zanardi-Lamardo et al, 2004). Terrigenous CDOM originates from the decomposition of nonliving plant material, and is introduced into aquatic systems via leaching and runoff from land.…”

Section: Introductionmentioning

confidence: 99%

Chemical characterization of dissolved organic matter (DOM): A prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability

2009

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Abstract. UV-induced transformations of colored dissolved organic matter (CDOM, which is part of dissolved organic matter, DOM) affect CDOM absorption properties resulting in the loss of color (referred to as photobleaching). CDOM photobleaching increases the penetration depths of the damaging UV-B radiation into water bodies and strongly depends on the wavelength of solar radiation and on the pH of aquatic systems. UV-induced transformations also affect DOM availability to bacterioplankton, often enhancing the bioavailability of terrigenous DOM and in turn microbial respiration. The combination of UV-induced enhancement of DOM bioavailability and increased export of terrigeneous DOM into estuaries and coastal waters due to climaterelated changes in continental hydrology could result in a UV-mediated positive feedback of CO 2 accumulation in the atmosphere.The extent and type of CDOM photobleaching and of UV-induced changes in DOM bioavailability depend on (C)DOM chemical composition, which in turn undergoes drastic changes upon UV-induced transformations. Therefore, the chemical characterization of (C)DOM is key for rationalizing UV-induced transformations. In the second section (after the "Introduction"), we review important methods for the elucidation of the chemical composition of (C)DOM. However, this article is not intended to be comprehensive regarding (C)DOM chemical characterization. An important purpose is to provide photochemical bases for the understanding of UV-induced changes of (C)DOM absorption properties and bioavailability (mainly discussed in the sections "Pathways of DOM phototransformations" and "UV-induced changes of the absorption properties of CDOM").

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“…Actually, the decrease of absorbance has already been observed in different fractionation processes (Burba et al, 1995;Aster et al, 1996;Schimpf and Petteys, 1997;Lin et al, 1999Lin et al, , 2000Kitis et al, 2002;Hoque et al, 2003;Hur and Schlautman, 2003;Alberts and Takács, 2004;Zanardi-Lamardo et al, 2004;Richard et al, 2004) or changed in their aggregation through acidic treatment (Piccolo et al, 1999;Cozzolino et al, 2001;Baigorri et al, 2007) but mostly left without explanation. Piccolo explained that absorbance decrease is a consequence of the disruption of weak intermolecular bonds; holding aggregates together (Piccolo et al, 1996b).…”

Section: Resultsmentioning

confidence: 99%

Fluorescence quenching as an indicator of the conformational change of humic<br>acids

Franko

2013

Emir. J. Food Agric

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Humic acids as a water soluble fraction of humus play important role in the plant growth. Even though structure of humic acids is not clear, their spectroscopic properties can reveal us useful information. To investigate influence of humic acids reorganization, HPSEC fractionation at mild fractionation conditions has been carried out. Reconstruction of secondary chromatograms of separated fractions showed molecular size increase and increased response on fluorescence detector, although neither molecular size change nor significant absorbance increase was observed on UV-VIS detector. However, bigger aggregates, that didn't fluoresce in the unfractionated sample started to fluoresce. The reason for this behavior is not some change of spectral properties of a specific fraction, but a general fluorescence increase indicating humic acid reorganization. Therefore spectroscopic changes can be used as a tool for monitoring their reorganization, which might play an important role in nutrients soil plant mobility and should be studied in more details from that perspective.

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Seasonal variation in molecular mass and optical properties of chromophoric dissolved organic material in coastal waters of southwest Florida

Cited by 49 publications

References 32 publications

Sources and transformations of chromophoric dissolved organic matter in the Neponset River Watershed

Sources and transformations of chromophoric dissolved organic matter in the Neponset River Watershed

Chemical characterization of dissolved organic matter (DOM): A prerequisite for understanding UV-induced changes of DOM absorption properties and bioavailability

Fluorescence quenching as an indicator of the conformational change of humic<br>acids

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