Flux and bioavailability of Cape Fear River and rainwater dissolved organic carbon to Long Bay, southeastern United States

Avery, G. Brooks; Willey, Joan D.; Kieber, Robert J.; Shank, Gregory; Whitehead, Robert F.

doi:10.1029/2002gb001964

Cited by 70 publications

(43 citation statements)

References 34 publications

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“…Vol. 65, 2003 Research Article 395 A recent study has also shown that DOC is conservatively mixed in the Cape Fear Estuary (Avery et al, 2003). Because CDOM absorption is negatively correlated with salinity, we expected similar results relating the percent contribution of respective peak intensities to the total EEM intensity and salinity, because fluorescence can be regarded as a proxy for CDOM absorption.…”

supporting

confidence: 70%

Characterization of CDOM in an organic-rich river and surrounding coastal ocean in the South Atlantic Bight

Kowalczuk

Cooper

Whitehead

et al. 2003

Aquatic Sciences - Research Across Boundaries

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191

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Variability in chromophoric dissolved organic carbon (CDOM) was characterized in and around the Cape Fear River and Onslow Bay, North Carolina USA. The river end member of the study is extremely rich in CDOM, thus the Cape Fear River serves as a point source of CDOM-rich water into the southeastern Atlantic bight. The river plume is easily traceable and generally extends in a southwesterly direction along the coastline into Long Bay. Depending on physical processes and river flow, the plume can meander somewhat and may even turn northward for short periods of time. The oceanic end member of this study was the Gulf Stream. Samples from the Gulf Stream were obtained up to 97 km off shore. The experimental approach focused on the qualitative and quantitative description of CDOM from fresh-to-oceanic waters. CDOM was characterized by excitation emission matrix (EEM) fluorescence and UV/VIS spectroscopy. Variability of CDOM absorption in the relatively small area of the Cape Fear River estuary and surrounding coastal ocean was very high. The observed range of variability of CDOM absorption coeffi- Aquat. Sci. 65 (2003) 384-401 cient, a CDOM (350), extended over nearly the entire range of CDOM absorption in the literature: 0.046 = a CDOM (350) = 29.9 m -1 . Changes in CDOM absorption spectrum slope coefficient S, were small in the Cape Fear River plume area, but relatively large in Onslow Bay. CDOM EEM spectra indicated that a radical change in composition of CDOM occurs along the river-to-oceanic salinity gradient. CDOM in the coastal ocean was characterized by strong reduction of the three principal intensity peaks: A, C, and M, and a prominent contribution of the T peak to the fluorescence spectrum. The fluorescence intensity is linearly related with absorption. There is a strong inverse relationship between salinity and CDOM absorption. The distribution of the slope coefficient and the percent contribution of respective peak intensities to the total EEM intensity showed that CDOM undergoes conservative mixing until it approached oceanic salinity. Thus, CDOM is so concentrated in the river that mixing and other physical processes mask photochemical or biological alteration of its composition.

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supporting

confidence: 70%

Characterization of CDOM in an organic-rich river and surrounding coastal ocean in the South Atlantic Bight

Kowalczuk

Cooper

Whitehead

et al. 2003

Aquatic Sciences - Research Across Boundaries

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191

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“…13 Possibility of alterations in the quality and quantity of root exudates has been raised in connection with studies that have reported UV-B-induced changes in soil microbial communities. 10,11,14 However, except rice and mire there are not enough studies on the effects of UV-B radiation on the fate of root exudate profile and associated rhizospheric changes in other plants. 11,15 UV-B radiation induces various adaptive morphological changes in plants such as leaf thickening and shortening, shifts in root: shoot ratio and alterations in reproductive structures.…”

Section: Discussionmentioning

confidence: 99%

“…12 Additionally, upon exposure to UV light, leachates from Phragmites leaves inhibited microbial growth as compared to an untreated control. 13 Although the possibility of alterations in the quality and quantity of root exudates has been raised in connection with studies that reported UV-B-induced changes in soil microbial communities, 10,11,14 we have no knowledge of controlled testing of the effects of increased UV-B radiation on root exudation or rhizospheric processes in any other plant system other than rice. 15 Most of the studies pertaining to the effect of UV light on plant growth ranges from wild plant species are limited to African savanna, 16 arctic ecosystems, 17 salt marshes 18,19 and Mediterranean ecosystems.…”

Section: Introductionmentioning

confidence: 99%

Phragmites australisroot secreted phytotoxin undergoes photo-degradation to execute severe phytotoxicity

Rudrappa

Choi

Levia

et al. 2009

Plant Signaling & Behavior

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Our study organism, Phragmites australis (common reed), is a unique invader in that both native and introduced lineages are found coexisting in North America. This allows one to make direct assessments of physiological differences between these different subspecies and examine how this relates to invasiveness. Recent efforts to understand plant invasive behavior show that some invasive plants secrete a phytotoxin to ward-off encroachment by neighboring plants (allelopathy) and thus provide the invaders with a competitive edge in a given habitat. Here we show that a varying climatic factor like ultraviolet (UV) light leads to photo-degradation of secreted phytotoxin (gallic acid) in P. australis rhizosphere inducing higher mortality of susceptible seedlings. The photo-degraded product of gallic acid (hereafter GA), identified as mesoxalic acid (hereafter MOA), triggered a similar cell death cascade in susceptible seedlings as observed previously with GA. Further, we detected the biological concentrations of MOA in the natural stands of exotic and native P. australis. Our studies also show that the UV degradation of GA is facilitated at an alkaline pH, suggesting that the natural habitat of P. australis may facilitate the photo-degradation of GA. The study highlights the persistence of the photo-degraded phytotoxin in the P. australis's rhizosphere and its inhibitory effects against the native plants.

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“…DOC was determined by high temperature combustion (HTC) using a Shimadzu TOC-5050A total organic carbon analyzer equipped with an ASI 5000 autosampler (Shimadzu, Kyoto, Japan) (Avery et al 2003). Standards were prepared using reagent grade potassium hydrogen phthalate (KHP) in deionized water (DIW).…”

Section: Doc Analysismentioning

confidence: 99%

Nitrogen release from surface sand of a high energy beach along the southeastern coast of North Carolina, USA

2008

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This study examined changes in dissolved organic nitrogen (DON) and dissolved inorganic nitrogen (DIN) in coastal seawater after exposure to sand along a high energy beach face over an annual cycle between April 2004 and July 2005. Dissolved organic nitrogen, NO 3 -, and NH 4 + were released from sand to seawater in laboratory incubation experiments clearly demonstrating that they are a potential source of N to underlying groundwater or coastal seawater. DON increases in seawater, after exposure to surface sands in laboratory experiments, were positively correlated with in situ water column DON concentrations measured at the same time as sand collection. Increase in NO 3 -and NH 4 + were not correlated with their in situ concentrations. This suggests that DON released from beach sands is relatively more recalcitrant while NO 3 -and NH 4 + are utilized rapidly in the coastal ocean. The release of N was seasonal with carbon to nitrogen ratios indicating that recent primary productivity was responsible for the largest fluxes in summer while more degraded humic material contributed to lower fluxes in winter. Fluxes of total dissolved nitrogen (DON and DIN) from surface sand (2.1 9 10 -4 mol m -2 h -1 ) were similar to that of groundwater and more than an order of magnitude larger than rain deposition indicating the potential importance of surface sand derived nitrogen to the coastal zone with a corresponding impact on primary productivity.

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Flux and bioavailability of Cape Fear River and rainwater dissolved organic carbon to Long Bay, southeastern United States

Cited by 70 publications

References 34 publications

Characterization of CDOM in an organic-rich river and surrounding coastal ocean in the South Atlantic Bight

Characterization of CDOM in an organic-rich river and surrounding coastal ocean in the South Atlantic Bight

Phragmites australisroot secreted phytotoxin undergoes photo-degradation to execute severe phytotoxicity

Nitrogen release from surface sand of a high energy beach along the southeastern coast of North Carolina, USA

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