Sources and distribution of organic carbon and nitrogen in the Tagliamento River, Italy

Kaiser, Edith; Arscott, David B.; Tockner, Klement; Sulzberger, Barbara

doi:10.1007/s00027-003-0683-4

Cited by 34 publications

(22 citation statements)

References 51 publications

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“…Detailed information on the catchment, main study reach, and water chemistry is provided by Ward et al (1999), Tockner et al (2003), and Kaiser et al (2004). Physical and chemical variables of the different habitats were measured during the experiment and are summarized in Table 1.…”

Section: Site Descriptionmentioning

confidence: 99%

Leaf-decomposition heterogeneity across a riverine floodplain mosaic

et al. 2008

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Abstract. Riverine floodplains are a mosaic of aquatic, semi-aquatic and terrestrial habitats. While spatially distinct, these habitats are well connected by flows of carbon and nutrients, often in the form of leaf litter, and thus the ecological processes occurring in one habitat have ramifications for others. The aim of this study was to compare leaf decomposition, a key process in riverine ecosystems, across diverse floodplain-habitat types and to assess the role of leafshredding detritivores and fungi. Black poplar, Populus nigra L., leaves were exposed in seven contrasting habitat types (total of 28 sites) on the floodplain of the Tagliamento River (NE-Italy). Three distinct classes of decomposition rates emerged, corresponding to sites in the river channel (fast), terrestrial sites (slow), and ponds (intermediate). In the river channel and in ponds, leaf decomposition was driven by both microbial and detritivore activity, as evidenced by differences in coarse-and fine-mesh bags, which respectively allowed and prevented access to the leaves by leaf-consuming detritivores. Additionally, we cannot rule out that decomposition in the channel was also promoted by physical abrasion and/or fragmentation. In terrestrial floodplain habitats, very little plant litter was utilized, and leaching of soluble compounds appeared to be the primary process responsible for leaf-mass loss. Our results demonstrate that the wide range of habitats of braided floodplain rivers can have diverse decomposition potentials, creating spatial variability in both the rates of decomposition and its causes. Alterations to the natural flow regime (e.g., water abstraction, or retention by dams) and morphological changes (e.g., channelization) strongly reduce habitat diversity. These impacts will likely reduce the heterogeneity in decomposition rates across floodplains of braided rivers, with unknown consequences for overall functioning of floodplain ecosystems.

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Section: Site Descriptionmentioning

confidence: 99%

Leaf-decomposition heterogeneity across a riverine floodplain mosaic

et al. 2008

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“…The in situ biological and chemical transformations of OC in aquatic systems are largely dependent on its source, physical packaging (e.g., mineral associations), and prior diagenetic alterations in both the water column and surface sediments (Kaiser et al 2004). However, the sources and processing of OC are poorly constrained in many ocean, river, and lake systems, even though delineating these is critical to understanding their transformation pathways and ultimate fate.…”

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confidence: 99%

“…Natural abundance stable and/or radiocarbon isotopes have been useful for studying OC sources and carbon cycling in the oceans (Druffel et al 1992;Bauer et al 2002), estuaries (Peterson et al 1994), rivers (Raymond and Bauer 2001;Kaiser et al 2004), and lakes (Karlsson et al 2007;McCallister and del Giorgio 2008). The decadal-scale resolution added by the spike in D 14 C resulting from 1950s aboveground nuclear testing has been employed to study C cycling and turnover in both terrestrial and aquatic environments (McCallister et al 2004;Trumbore 2009) and has provided an additional timescale to that offered by radioactive decay methods.…”

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confidence: 99%

Radiocarbon and stable carbon isotopic insights into provenance and cycling of carbon in Lake Superior

Zigah

Minor

Werne

et al. 2011

Limnology & Oceanography

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This study applies radiocarbon and stable carbon isotopic distributions to investigate carbon sources and cycling within Lake Superior. We report the radiocarbon (D 14 C) and stable carbon isotope (d 13 C) values and the carbon concentrations within dissolved organic carbon (DOC), particulate organic carbon (POC), and dissolved inorganic carbon (DIC) in the lake's western basin water column. Samples were taken during spring mixing and late-summer thermal stratification over a 2-yr period (2007)(2008)(2009). Distinct processes operating in the surface (photosynthesis) and deep waters (sediment resuspension and pore-water intrusion) control the relative contribution of modern and ancient DOC and POC in the water column. The terrigenous carbon input to the open lake POC varied from 13% 6 4% during late summer stratification to 9% 6 3% during spring mixing, with most of the terrestrial carbon being 14 C-enriched (modern). The DIC reservoir cycles rapidly, with a bulk D 14 C DIC value that records atmospheric radiocarbon levels from 3 yr prior to sampling. The DOC pool recycles on a longer time scale than does the DIC, with a DOC residence time of # 60 yr. The suspended POC was in most cases older than co-occurring DOC, most likely as a result of resuspension of lake sediments.

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“…69, 2007 Research Article Evaluation of environmental processing and DOM reactivity The results of this study also provide insight into changes occurring in the chemical characteristics of plant-derived fulvic acids due to environmental "humification" processes, such as microbial degradation and photodegradation. Transformations of DOM, originating from diagenetically young FPOM, were shown to be important controls on carbon cycling in the Tagliamento River, Italy (Kaiser et al, 2004). Bulk ( 13 C-NMR spectra) and trace (C and N content) characteristics were evaluated to show that DOM transformations in this setting resulted in the production and export of highly reactive, biologically recalcitrant DOM to the northern Adriatic Sea (Kaiser et al, 2004).…”

Section: Discussionmentioning

confidence: 99%

“…Because C3 and C4 plants have distinctive carbon isotopic signatures, with a mean d 13 C for C3 plants of -13% and a mean d 13 C for C4 plants of -27%, d 13 C has been successfully used to resolve plant sources of DOM in large wetlands, such as the northern Florida Everglades (Wang et al, 2002) and in the Pantanal of Brazil (Fellerhoff et al, 2003). In addition to using carbon and nitrogen isotopic signatures, Kaiser et al (2004) have further examined elemental composition and 13 C-NMR spectra of bulk DOM and hydrophobic DOM isolates from the Tagliamento River, Italy to show multiple sources of DOM, transformation of bioreactive DOM, and export of highly degraded DOM to the northern Adriatic Sea.…”

Section: Introductionmentioning

confidence: 99%

Chemical characterization of DOM in channels of a seasonal wetland

et al. 2007

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Although wetlands are known to be important sources of dissolved organic matter (DOM) within watersheds, production of DOM within wetlands is not well understood. In the Okavango Delta, a large wetland located in Botswana, large amounts of DOM produced in the wetland are transported in the river network and to the subsurface. The purpose of this study was to gain insight into environmental processing of DOM in wetland surface waters by examining chemical characteristics of plant litter leachates and fulvic acids isolated from two surface water sites in the Panhandle (PHFA) and Seasonal Swamp (SSFA) of the Okavango Delta. Spectroscopic properties measured over the course of leaching experiments indicated a greater abundance of plantderived DOM over time. Results of elemental and 13 C-NMR analyses showed that aromaticities and C:N ratios of PHFA and SSFA and a Cyperus papyrus leachate fulvic acid (CPLFA) were in the range typical for fulvic acids derived from vascular plants. Fluorescence analyses of fulvic acids using parallel factor analysis (PARAFAC) further indicated the importance of plant litter sources in surface water DOM. Environmental processing of DOM in downstream surface waters by bacterial and photodegradation was suggested by higher N and S content for SSFA compared to CPLFA and by differences in d 15 N, d 34 S, d 13 C and fluorescence signatures among the 3 fulvic acid samples. These chemical characterization results suggest that a progressive enrichment of DOM by plant-derived material occurs with distance downstream and that this DOM undergoes some environmental processing within the surface water system.

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Sources and distribution of organic carbon and nitrogen in the Tagliamento River, Italy

Cited by 34 publications

References 51 publications

Leaf-decomposition heterogeneity across a riverine floodplain mosaic

Leaf-decomposition heterogeneity across a riverine floodplain mosaic

Radiocarbon and stable carbon isotopic insights into provenance and cycling of carbon in Lake Superior

Chemical characterization of DOM in channels of a seasonal wetland

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