Transport of Dissolved Organic Nitrogen in Mississippi River Plume and Texas-Louisiana Continental Shelf Near-Surface Waters

López-Veneroni, Diego; Cifuentes, Luis A.

doi:10.2307/1352748

Cited by 35 publications

(15 citation statements)

References 16 publications

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“…Concentrations of NH,' and nitrite plus nitrate were assayed according to Parsons et al (1985). Total dissolved nitrogen (TDN) was measured by the method of Lopez-Veneroni & Cifuentes (1994). Dissolved free amino acid (DFAA) sample collection and analysis was according to Nagata & Kirchnian (1990) and used a reverse-phase HPLC technique modified from Mopper & Lindroth (1982) Concentrations of unidentified amines were calculated assuming a fluorescence yleld equal to that of glycine.…”

Section: Methodsmentioning

confidence: 99%

Stable isotope dynamics of nitrogen recycled during interactions among marine bacteria and protists

Hoch¹,

Ra²,

La³

et al. 1996

Mar. Ecol. Prog. Ser.

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Variation in the distribution of stable nitrogen isotopes among different size classes of particulate organic nitrogen (PON) in aquatic environments may be partly explained by isotope effects associated with regeneration of NH,* by the microbial food web. Protists fed the marine bacterium Vibno natl-ieg~ns were grown in batch and continuous culture to define the isotope discrimination between NH,', microbial biornass, and dissolved organic nitrogen (DON) for culture systems closed or open to exogenous nutrient inputs. In batch cultures of a flagellate Pseudobodo sp. and a scut~cocil~ate Uronema sp., the nitrogen isotope discriminat~on between b~omass and NII.,' was 3 to 5 "6, during exponential growth of protists corresponding to the highest rates of b~omass-specific NH,' release The 6"N of D O N , calculated by mass balance, was very depleted in 15N relative to NIi,' and biomass dunng exponential and early stationary growth when D O N and dissol\ied free amino acid (DFAA) concentrations increased. In contrast to batch culture results, for continuous culture of the flagellate the Isotope discrimination between biomass and NH,' and the change in the calculated 6I5N of DON were small. 1 to 2 X,. Based on rates of thymidine incorporation and turnover of DFAA, protist excretion and bacterial uptake of DON were less coupled for exponentially growing protists fed starved bacteria in batch cultures than for the flagellate fed active bacteria growing in a 2-stage continuous culture. Coupling between release and utilization of DON, as well as isotope effects associated with protist metabolism, are proposed to constrain the nitrogen isotope dynamics of NH,', suspended PON, and DON within marine ecosystems, especially those environments dominated by regenerated primary production.

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Section: Methodsmentioning

confidence: 99%

Stable isotope dynamics of nitrogen recycled during interactions among marine bacteria and protists

Hoch¹,

Ra²,

La³

et al. 1996

Mar. Ecol. Prog. Ser.

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“…Horrigan et al 1990, Fisher et al 1992. In batch cultures and a number of other aquatic environments, however, DON has been shown to be a dynamic component of the nitrogen cycle (Collos 1992, Bronk et al 1994, Lopez-Veneroni & Cifuentes 1994, Slawyk & Raimbault 1995. Specifically, in Chesapeake Bay we know that during the decline of the spring bloom, rates of DON release from phytoplankton can be quite high, and rates of uptake of recently released DON during these periods can rival rates of uptake of DIN (Bronk & Glibert 1991, 1993a.…”

Section: Introductionmentioning

confidence: 99%

Inorganic and organic nitrogen cycling in Chesapeake Bay: autotrophic versus heterotrophic processes and relationships to carbon flux

Bronk¹,

Glibert²,

Malone³

et al. 1998

Aquat. Microb. Ecol.

131

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To define the role of dissolved organic nitrogen (DON) in Chesapeake Bay (USA) nitrogen cycling, w e performed experiments in the mesohaline Chesapeake Bay d u n n g 3 seasons: May, during the mid to late spring bloom, August, when patchy summer blooms often develop, and October, after the fall overturn. Every 3 h for 30 h we measured ambient nitrogen concentrations and used "N tracers to determine uptake and regeneration rates of NH,' and urea, uptake rates of NO,-(NO; was measured in October only), and rates of DON release due to NH,' uptake. Autotrophic production and dissolved organic carbon (DOC) release were determined sunultaneously using 'v tracer techniques to compare with nitrogen flux rates We found that first, the water column nitrogen demand exceeded nitrogen regeneration in May but n~t r o g e n regeneration was over 3 times greater than the nitrogen demand in October. Second, mean rates of autotrophic DON release were highest in May but heterotrophic release was more important in summer and fall. Third, d u n n g all 3 studies, the C N ratio of DOC to DON release rates was 3.4 to 4.5, indicating release of nitrogen-rich compounds. Release of dissolved organic matter (DOM) \nth a low C:N ratio was corroborated by an observed increase in DON concentrations from 7 to 4 2 pg-at. N I-' from May to August and a concomitant decrease in the C . N ratio of the ambient DOM pool from 36.6 to 8.8. These data suggest that Chesapeake Bay IS primarily autotrophic In the spring, but becomes progressively more heterotrophic later in the year. These data also suggest that DON is an Important intermediate in this transition and serves as a link between the allochthonous nitrogen-based autotrophic production In the spring and the autochthonous nitrogen-based heterotrophic system in the summer and fall.

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“…Microbial respiration of terrestrial particulate and dissolved organic matter (Lopez-Veneroni and Cifuentes, 1994) that is also introduced in high concentrations by the river may be important. There is reason to believe that biogenic terrestrial detritus is substantially more reactive than thought previously (Amon and Benner, 1996;Sun et al, 1997;Mayer et al, 1998).…”

mentioning

confidence: 99%

Continental Shelf Hypoxia: Some Nagging Questions

Rowe

Chapman

2002

goms

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Transport of Dissolved Organic Nitrogen in Mississippi River Plume and Texas-Louisiana Continental Shelf Near-Surface Waters

Cited by 35 publications

References 16 publications

Stable isotope dynamics of nitrogen recycled during interactions among marine bacteria and protists

Stable isotope dynamics of nitrogen recycled during interactions among marine bacteria and protists

Inorganic and organic nitrogen cycling in Chesapeake Bay: autotrophic versus heterotrophic processes and relationships to carbon flux

Continental Shelf Hypoxia: Some Nagging Questions

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