Determination of apparent quantum yield spectra for the formation of biologically labile photoproducts

Miller, William L.; Moran, Mary Ann; Sheldon, Wade M.; Zepp, Richard G.; Opsahl, Stephen P.

doi:10.4319/lo.2002.47.2.0343

Cited by 142 publications

(131 citation statements)

References 54 publications

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“…Ziegler et al (2000) used the microbial uptake of tritiated leucine as their technique for measuring bioavailable photoproducts. In contrast, another recent study using a more sensitive technique involving microbial CO 2 production (Moran et al 2000, Miller et al 2002 indicated that the photodecomposition of CDOM produced by T. testudinum does produce bioavailable photoproducts . The difference in these results may reflect differences in the sensitivity of these 2 methods.…”

Section: Photobleaching Of Seagrass-derived Cdommentioning

confidence: 90%

“…Past studies have indicated that the polymeric substances that make up CDOM are not readily decomposed by microorganisms, but CDOM bioavailability changes on exposure to solar radiation (Mopper & Kieber 2000, Moran et al 2000, Ziegler & Benner 2000, Miller et al 2002). It has been known for years that absorption of solar UV radiation by terrestrially derived humic substances and CDOM results in a reduction in its light absorption and fluorescence (i.e.…”

Section: Photobleaching Of Seagrass-derived Cdommentioning

confidence: 99%

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Role of the seagrass Thalassia testudinum as a source of chromophoric dissolved organic matter in coastal south Florida

Stabenau¹,

Zepp²,

Bartels

et al. 2004

Mar. Ecol. Prog. Ser.

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Seagrasses play a variety of important ecological roles in coastal ecosystems. Here we present evidence that seagrass detritus from the widespread species Thalassia testudinum is an important source of ocean color and a UV-protective substance in a low latitude coastal shelf region of the United States. The production and light-induced degradation of chromophoric (sunlightabsorbing) dissolved organic matter (CDOM) from T. testudinum was examined under field and controlled laboratory conditions to obtain data that could be used to estimate the contribution of seagrass-derived CDOM to the coastal pool. The laboratory studies measured the temperature dependence and photodegradation of the spectral (UV-visible, fluorescence) and molecular mass properties of CDOM produced during the degradation of T. testudinum detritus. The rate of CDOM production is temperature-dependent with rates doubling when temperature increases from 21.4 to 32.6°C. The magnitude of this increase is close to the widely observed Q 10 factor for microbial decomposition, indicating that the CDOM production was likely microbially mediated. The absorption coefficients and fluorescence of CDOM from T. testudinum decreased on exposure to solar UV radiation (UVR) and the wavelength dependence was determined for this photobleaching process.KEY WORDS: Thalassia testudinum · Seagrass · CDOM production · Coastal ocean color · South Florida · UVR · Photobleaching · Mass spectra Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 282: [59][60][61][62][63][64][65][66][67][68][69][70][71][72] 2004 Green & , Hoge et al. 1995, Coble 1996, Vodacek et al. 1997, Del Castillo et al. 2000, Markager & Vincent 2000, Moran et al. 2000, Stedmon & Markager 2001, Twardowski & Donaghay 2001, Hu et al. 2002. CDOM is also an important photochemical source of reactive oxygen species in the sea (Kieber et al. 2003) and it is primarily responsible for the attenuation of solar UV radiation (UVR) in coastal environments (Vodacek et al. 1997. UV exposure has a wide range of potential impacts on coastal ecosystems (Haeder et al. 2003, including inhibition of the photosynthetic activity of corals (Lesser 2000) and of seagrasses (Larkum & Wood 1993, Detres et al. 2001, Figueroa et al. 2002, Durako et al. 2003.A few field studies have suggested that seagrasses may be an important source of CDOM in subtropical and tropical coastal ecosystems (Burdige et al. 2002. UV protective substances in seagrasses (Detres et al. 2001, Brandt & Koch 2003, Durako et al. 2003 could provide one source of CDOM to the overlying ocean water. One class of UV-absorbing compounds, the alkanones, is a component of the water-soluble substances released by decomposing seagrass detritus (Hernandez et al. 2001). In this paper, we use the term 'detritus' to refer to senescent blades of seagrass that are frequently found on the ocean bottom and intertidal zones in coastal regions. CDOM is often susceptible to light-induced loss of its UV and visible absorptio...

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Section: Photobleaching Of Seagrass-derived Cdommentioning

confidence: 90%

Section: Photobleaching Of Seagrass-derived Cdommentioning

confidence: 99%

Role of the seagrass Thalassia testudinum as a source of chromophoric dissolved organic matter in coastal south Florida

Stabenau¹,

Zepp²,

Bartels

et al. 2004

Mar. Ecol. Prog. Ser.

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“…While there is a range of efficiencies with which the microbial community can access DOM (i.e. respiratory quotient RQ; Berggren et al, 2012), for the most part these boreal freshwater RQs fall within a relatively small range (0.5-2) and as such BOD can be used as an effective proxy for the biological reactivity or lability of the DOM (Miller et al, 2002;Asmala et al, 2013). …”

Section: Introductionmentioning

confidence: 99%

Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments

2014

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Abstract. To examine the potential influence of terrestrially derived DOM on the Baltic Sea, a year-long study of dissolved organic matter (DOM) was performed in three river catchments in Sweden. One catchment drains into the Bothnian Sea, while two southern catchments drain into the Baltic proper. Dissolved organic carbon (DOC) concentrations were positively correlated with discharge from forested catchments over the year. While the overall concentrations of DOC were several times higher in the southern two catchments, higher discharge in the northern catchment resulted in the annual loadings of DOC being on the same order of magnitude for all three catchments. Biological oxygen demand (BOD) was used as a proxy for the lability of carbon in the system. The range of BOD values was similar for all three catchments, however, the ratio of BOD to DOC (an indication of the labile fraction) in Ume river was four times higher than in the southern two catchments. Total annual BOD loading to the Baltic Sea was twice as high in the northern catchment than in the two southern catchments. Lower winter temperatures and preservation of organic matter in the northern catchment combined with an intense spring flood help to explain the higher concentrations of labile carbon in the northern catchment. Lower lability of DOM as well as higher colour in the southern catchments suggest that wetlands (i.e. peat bogs) may be the dominant source of DOM in these catchments, particularly in periods of low flow. With climate change expected to increase precipitation events and temperatures across the region, the supply and quality of DOM delivered to the Baltic Sea can also be expected to change. Our results indicate that DOM supply to the Baltic Sea from boreal rivers will be more stable throughout the year, and potentially have a lower bioavailability.

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“…The net effects of dissolved organic matter (DOM) photodegradation include: the alteration of DOM bioavailability (Moran and Zepp, 1997;Mopper and Kieber, 2000;Miller et al, 2002); the bleaching of CDOM colour (Del Vecchio and Blough, 2002;Helms et al, 2008); and the production of a suite of photoproducts, including CO 2 and CO (Valentine and Zepp, 1993;Miller and Zepp, 1995;Stubbins et al, 2006b). Photoproduction is the dominant source of CO in natural waters and results in the supersaturation of surface waters with CO and CO emission to the atmosphere (Conrad et al, 1982;Bates et al, 1995;Stubbins et al, 2006a).…”

Section: Introductionmentioning

confidence: 99%

Carbon monoxide apparent quantum yields and photoproduction in the Tyne estuary

et al. 2011

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Abstract. Carbon monoxide (CO) apparent quantum yields (AQYs) are reported for a suite of riverine, estuarine and sea water samples, spanning a range of coloured dissolved organic matter (CDOM) sources, diagenetic histories, and concentrations (absorption coefficients). CO AQYs were highest for high CDOM riverine samples and almost an order of magnitude lower for low CDOM coastal seawater samples. CO AQYs were between 47 and 80% lower at the mouth of the estuary than at its head. Whereas, a conservative mixing model predicted only 8 to 14% decreases in CO AQYs between the head and mouth of the estuary, indicating that a highly photoreactive pool of terrestrial CDOM is lost during estuarine transit. The CDOM absorption coefficient (a) at 412 nm was identified as a good proxy for CO AQYs (linear regression r 2 > 0.8; n = 12) at all CO AQY wavelengths studied (285, 295, 305, 325, 345, 365, and 423 nm) and across environments (high CDOM river, low CDOM river, estuary and coastal sea). These regressions are presented as empirical proxies suitable for the remote sensing of CO AQYs in natural waters, including open ocean water, and were used to estimate CO AQY spectra and CO photoproduction in the Tyne estuary based upon annually averaged estuarine CDOM absorption data. A minimum estimate of annual CO production was determined assuming that only light absorbed by CDOM leads to the formation of CO and a maximum limit was estimated assuming that all light entering the water column is absorbed by CO producing photoreactants (i.e. that particles are also photoreactive). In this way, annual CO photoproduction in the Tyne was estimated to be between 0.99 and 3.57 metric tons of carbon per year, orCorrespondence to: A. Stubbins (aron.stubbins@skio.usg.edu) 0.004 to 0.014% of riverine dissolved organic carbon (DOC) inputs to the estuary. Extrapolation of CO photoproduction rates to estimate total DOC photomineralisation indicate that less than 1% of DOC inputs are removed via photochemical processes during transit through the Tyne estuary.

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Determination of apparent quantum yield spectra for the formation of biologically labile photoproducts

Cited by 142 publications

References 54 publications

Role of the seagrass Thalassia testudinum as a source of chromophoric dissolved organic matter in coastal south Florida

Role of the seagrass Thalassia testudinum as a source of chromophoric dissolved organic matter in coastal south Florida

Seasonal contribution of terrestrial organic matter and biological oxygen demand to the Baltic Sea from three contrasting river catchments

Carbon monoxide apparent quantum yields and photoproduction in the Tyne estuary

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