Photochemical release of biologically available nitrogen from aquatic dissolved organic matter

Bushaw, Karen L.; Zepp, Richard G.; Tarr, Matthew A.; Schulz-Jander, Daniel; Bourbonniere, Richard A.; Hodson, Robert E.; Miller, William L.; Bronk, Deborah A.; Moran, Mary Ann

doi:10.1038/381404a0

Cited by 398 publications

(321 citation statements)

References 26 publications

Supporting

Mentioning

290

Contrasting

Unclassified

Order By: Relevance

“…The effective light penetration depth for production of these compounds in the open ocean was estimated to be ϳ5 m (Mopper et al 1991), close to our sampling depth of 4 m at Sta. M. Bacterial uptake of fatty acid and nitrogen-rich compounds produced from photooxidation of humic material has been observed in both freshwater and marine systems (Kieber et al 1989;Lindell et al 1995;Wetzel et al 1995;Bushaw et al 1996). Thus, given the energy constraints of the bacterial populations in the eastern North Pacific, we speculate that older, more refractory DOC may be made available for bacterial utilization and assimilation via cometabolism and/or photooxidative processes.…”

Section: Utilization Of Older Bulkmentioning

confidence: 99%

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Cherrier

Bauer

Druffel

et al. 1999

Limnology & Oceanography

107

View full text Add to dashboard Cite

It is generally accepted that marine bacteria utilize labile, recently produced components of bulk dissolved organic matter. This interpretation is based largely on indirect measurements using model compounds and plankton‐derived organic matter. Here, we present an assessment of the relative proportions of modern and older dissolved organic carbon (DOC) utilized by marine bacteria. Bacterial nucleic acids were collected from both estuarine (Santa Rosa Sound, FL) and open‐ocean (eastern North Pacific) sites, and the natural radiocarbon signatures of the nucleic acid carbon in both systems were determined. Bacterial nucleic acids from Santa Rosa Sound were significantly enriched in radiocarbon with respect to the bulk DOC and were similar to the radiocarbon signature of atmospheric CO2 at the time of sampling, indicating that these bacteria exclusively assimilate a modern component of the estuarine bulk DOC. In contrast, bacterial nucleic acids from the oceanic site were enriched in 14C relative to the bulk DOC but depleted in 14C with respect to modern surface dissolved inorganic carbon (DIC) and suspended particulate organic carbon (POCsusp). This suggests that open‐ocean bacteria assimilate both modern and older components of DOC. The distinct radiocarbon signatures of the nucleic acids at these two sites (i.e., +120 ± 17‰ estuarine vs. −34 ± 24‰ oceanic) demonstrate that natural 14C abundance measurements of bacterial biomarkers are a powerful tool for investigations of carbon cycling through microbial communities in different aquatic systems.

show abstract

Section: Utilization Of Older Bulkmentioning

confidence: 99%

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Cherrier

Bauer

Druffel

et al. 1999

Limnology & Oceanography

107

View full text Add to dashboard Cite

show abstract

“…In addition to microbial processes, photochemical processes can alter DON, and in some cases release DIN (e.g., Bushaw et al 1996). UV wavelengths are generally considered to be most important in that regard but do not penetrate deeply into the water column of a turbid estuary.…”

Section: Bioavailability Of Don By Source and Season-mentioning

confidence: 99%

Bioavailability of DON from natural and anthropogenic sources to estuarine plankton

Seitzinger

Sanders

Styles

2002

Limnology & Oceanography

304

188

View full text Add to dashboard Cite

Utilization of dissolved organic nitrogen (DON) from natural (forests) and anthropogenic (animal pastures, urban/ suburban storm water runoff) sources (three sites per source) by estuarine plankton communities was examined in spring, summer, and fall. The proportion of DON utilized ranged from 0 to 73%. Overall, urban/suburban storm water runoff had a higher proportion of bioavailable DON (59% Ϯ 11) compared to agricultural pastures (30% Ϯ 14) and forests (23% Ϯ 19). DON bioavailability varied seasonally; however, the seasonal pattern differed for the three sources. Bacterial production increased linearly with the amount of DON utilized across all sources and seasons; the rate of increase was approximately five times greater per micromole of N as DON used relative to dissolved inorganic N (DIN) used. Although phytoplankton production generally increased with DON addition, the increased production was not correlated with the amount of DON utilized, suggesting that a variable portion of dissolved organic matter (DOM)-N was directly or indirectly available to the phytoplankton. This indicates that phytoplankton production is not a good measure of the amount of bioavailable DON, and measurements of the amount of bioavailable DON based on bacterial responses alone might not reflect N available to phytoplankton. Preliminary seasonal budgets of bioavailable N (DIN plus bioavailable DON) as a function of land use suggest that ϳ80% of the total dissolved N (TDN) from urban/suburban runoff is bioavailable, whereas a lower proportion (20-60%) of TDN is bioavailable from forests and pastures. N budgets for aquatic ecosystems based on only DIN loading underestimate bioavailable N loading, whereas total N or TDN budgets overestimate bioavailable N inputs.

show abstract

“…al., 1995 . Other investigations, however, focus on photochemical and microbial transformations of terrigenous DOM, which may contribute to the produc-Ž tivity in these nearshore systems Moran et al, 1991;Chin-Leo and Benner, 1992;Bushaw et al, 1996; . Opsahl and Benner, 1997 .…”

Section: Introductionmentioning

confidence: 99%

Photogeneration of singlet oxygen and free radicals in dissolved organic matter isolated from the Mississippi and Atchafalaya River plumes

et al. 2000

View full text Add to dashboard Cite

Ž. The photoreactivity to UV light of ultrafiltered dissolved organic matter DOM collected during cruises along salinity transects in the Mississippi and Atchafalaya River plumes was examined by measuring photogenerated free radicals and Ž 1 . singlet molecular oxygen O photosensitization. Singlet oxygen was detected by its infrared phosphorescence at 1270 nm 2 using both steady-state and time-resolved techniques. The 1 O quantum yields were corrected for self-quenching of 1 O by 2 2 Ž . the DOM substrates. Photogenerated free radicals were monitored by electron paramagnetic resonance EPR . Two size fractions of the dissolved organic matter were examined: material retained with a 3 kDa cut-off filter and material retained with a 1 kDa cut-off filter. The highest 1 O quantum yields were found in the lower molecular mass material. There was 2 little change in the 1 O quantum yields with increasing salinity, indicating that the photosensitizing ability of the estuarine 2 DOM does not decrease as terrestrial DOM is transported to sea and mixes with marine DOM. In contrast to 1 O formation, 2 the steady-state levels of photoproduced free radicals did not significantly differ between high and low molecular mass DOM, and the levels were substantially higher in riverine DOM than along plume salinity transects. This rapid transition in free radical level suggests that terrestrially-derived DOM experiences significant changes in this aspect of its photoreactivity Ž . in low -10 ppt salinity waters. Published by Elsevier Science B.V.

show abstract

Photochemical release of biologically available nitrogen from aquatic dissolved organic matter

Cited by 398 publications

References 26 publications

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Radiocarbon in marine bacteria: Evidence for the ages of assimilated carbon

Bioavailability of DON from natural and anthropogenic sources to estuarine plankton

Photogeneration of singlet oxygen and free radicals in dissolved organic matter isolated from the Mississippi and Atchafalaya River plumes

Contact Info

Product

Resources

About