Nitrogen and carbon isotopic composition of high-molecular-weight dissolved organic matter in marine environments

dc.acquisition-srcDownloaded from-Web of Scienceen_US
dc.call-noen_US
dc.contract-noen_US
dc.contributor.authorGuo LDen_US
dc.contributor.authorTanaka Nen_US
dc.contributor.authorSchell DMen_US
dc.contributor.authorSantschi PHen_US
dc.contributor.otherMarine Ecology-Progress Seriesen_US
dc.date.accessioned2010-02-15T17:16:57Z
dc.date.available2010-02-15T17:16:57Z
dc.date.issued2003en_US
dc.degreeen_US
dc.description51-60en_US
dc.description-otheren_US
dc.description.abstractHigh-molecular-weight (HMW) dissolved organic matter (DOM) was isolated using cross-flow ultrafiltration from seawater across a salinity gradient in 2 estuarine/coastal marine environments-Chesapeake Bay/Middle Atlantic Bight (MAB) and Galveston Bay/Gulf of Mexico. Nitrogen and carbon isotope ratios (delta(15)N and delta(13)C) were measured on the isolated HMW DOM samples (defined here as the size fraction between 1 and 200 nm), which made up similar to50 to 60 % of the total DOM in the estuarine regions and decreased to similar to35 % of the DOM at the MAB and Gulf of Mexico stations. delta(15)N values varied from 4.8 to 8.1 parts per thousand in the Chesapeake Bay/MAB area. In the Galveston Bay/Gulf of Mexico region, delta(15)N and delta(13)C values varied from 3.2 to 9.5 parts per thousand. and -26.1 to -20.9 parts per thousand, respectively. Similar distribution patterns of delta(13)C and delta(15)N were observed in both study areas, with values of delta(15)N showing a mid-salinity maximum of about 8 to 10parts per thousand, whereas delta(13)C continually increased with increasing salinity. The delta(13)C Values clearly demonstrated a shift of HMW organic carbon sources from largely terrestrial inputs in the upper-estuarine areas to marine-dominated organic carbon sources in lower-estuarine and coastal regions. The more complicated distribution patterns of delta(15)N, with delta(15)N values first increasing with salinity in estuarine regions then decreasing towards the seawater endmember, suggest more dynamic N cycling. Thus, in addition to organic matter sources, biogeochemical and isotopic fractionation processes are important factors governing marine HMW DOM delta(15)N values. Vertical profiles of HMW DOM delta(13)C in open-ocean stations generally decrease from surface water to deep waters, whereas the opposite was found for delta(15)N. HMW DOM components with heavier delta(13)C and lighter delta(15)N values seem to be preferentially degraded during their transport from surface to deep waters. However, other processes could also have contributed to this distribution trend. While the carbon isotopic signature can be used as an indicator of DOM sources, nitrogen isotopic composition, on the other hand, appears to be related to both source functions and subsequent recycling in marine environments. Comparisons of delta(15)N with previously published Delta(14)C values for the same samples support these conclusions about possible N-15 degradation pathwaysen_US
dc.description.urihttp://gbic.tamug.edu/request.htmen_US
dc.historyen_US
dc.identifier.urihttp://hdl.handle.net/1969.3/23424
dc.latitudeen_US
dc.locationen_US
dc.longitudeen_US
dc.notesTimes Cited: 3ArticleEnglishGuo, L. DUniv Alaska Fairbanks, Int Arctic Res Ctr, Fairbanks, AK 99775 USACited References Count: 49686MPNORDBUNTE 23, D-21385 OLDENDORF LUHE, GERMANYOLDENDORF LUHEen_US
dc.placeen_US
dc.publisheren_US
dc.relation.ispartofseries51071.00en_US
dc.relation.urien_US
dc.scaleen_US
dc.seriesen_US
dc.subjectdissolved organic matteren_US
dc.subjectstable isotopesen_US
dc.subjectcolloidsen_US
dc.subjectESTUARYen_US
dc.subjectultrafiltrationen_US
dc.subjectSEAWATERen_US
dc.subjectCROSS-FLOW ULTRAFILTRATIONen_US
dc.subjectSTABLE CARBONen_US
dc.subjectNATURAL ABUNDANCEen_US
dc.subjectCHESAPEAKE BAYen_US
dc.subjectwater columnen_US
dc.subjectOCEANen_US
dc.subjectPARTICULATEen_US
dc.subjectPARTICLESen_US
dc.subjectRELEASEen_US
dc.subjectPACIFICen_US
dc.titleNitrogen and carbon isotopic composition of high-molecular-weight dissolved organic matter in marine environmentsen_US
dc.typeJournalen_US
dc.universityen_US
dc.vol-issue252()en_US

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