scholarly journals Improved ultraviolet photo‐oxidation system yields estimates for deep‐sea dissolved organic nitrogen and phosphorus

2019 ◽  
Vol 17 (4) ◽  
pp. 277-291 ◽  
Author(s):  
Rhea K. Foreman ◽  
Karin M. Björkman ◽  
Craig A. Carlson ◽  
Keri Opalk ◽  
David M. Karl
Keyword(s):  
Deep Sea ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Nitrogen And Phosphorus ◽  
Photo Oxidation ◽  
Oxidation System

scholarly journals Flood water quality and marine sediment and nutrient loads from the Tully and Murray catchments in north Queensland, Australia

2009 ◽  
Vol 60 (11) ◽  
pp. 1123 ◽  
Author(s):  
Jim Wallace ◽  
Lachlan Stewart ◽  
Aaron Hawdon ◽  
Rex Keen ◽  
Fazlul Karim ◽  
...  
Keyword(s):  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Nutrient Concentrations ◽  
Large Contribution ◽  
Nutrient Loads ◽  
Nitrogen And Phosphorus ◽  
Annual Average ◽  
Nitrogen Loads ◽  
Flood Flows

Current estimates of sediment and nutrient loads from the Tully–Murray floodplain to the Great Barrier Reef lagoon are updated by taking explicit account of flood events. New estimates of flood discharge that include over-bank flows are combined with direct measurements of sediment and nutrient concentrations in flood waters to calculate the loads of sediment and nutrient delivered to the ocean during 13 floods that occurred between 2006 and 2008. Although absolute concentrations of sediment and nutrient were quite low, the large volume of water discharged during floods means that they make a large contribution (30–50%) to the marine load. By not accounting for flood flows correctly, previous estimates of the annual average discharge are 15% too low and annual loads of nitrogen and phosphorus are 47% and 32% too low respectively. However, because sediments may be source-limited, accounting for flood flows simply dilutes their concentration and the resulting annual average load is similar to that previously estimated. Flood waters also carry more dissolved organic nitrogen than dissolved inorganic nitrogen and this is the opposite of their concentrations in river water. Consequently, dissolved organic nitrogen loads to the ocean may be around twice those previously estimated from riverine data.

scholarly journals Arctic Survey Hunts for Missing Nitrogen and Phosphorus

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
David Shultz
Keyword(s):  
Nutrient Cycling ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
The Arctic ◽  
Nitrogen And Phosphorus ◽  
Shed Light

A new survey of ocean waters flowing in and out of the Arctic may shed light on how dissolved organic nitrogen and phosphorus contribute to nutrient cycling in the Arctic.

Photo-oxidation of proteins facilitates the preservation of high molecular weight dissolved organic nitrogen in the ocean

2021 ◽  
Vol 229 ◽  
pp. 103907
Author(s):  
Luni Sun ◽  
Chen Xu ◽  
Peng Lin ◽  
Antonietta Quigg ◽  
Wei-Chun Chin ◽  
...  
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Photo Oxidation

Seasonal Changes in the Organic Forms of Carbon, Nitrogen and Phosphorus in Sea Water at E1 in the English Channel During 1968

1973 ◽  
Vol 53 (3) ◽  
pp. 695-703 ◽  
Author(s):  
M. W. Banoub ◽  
P. J. leB. Williams
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Particulate Organic Carbon ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Sea Water ◽  
Organic Phosphorus ◽  
English Channel ◽  
Dissolved Organic Phosphorus ◽  
Nitrogen And Phosphorus

A seasonal survey of particulate and dissolved organic material was made at E1 in the English Channel during 1968. The average integral mean values were: dissolved organic carbon 65 μg-at C/l (780 μg C/l); dissolved organic nitrogen 4·6 μg-at N/l (64 μg N/l); dissolved organic phosphorus 0·12 μg-at P/l (3·8 μg P/l); particulate organic carbon 190 μg C/l and particulate organic nitrogen 21 μg N/l. Dissolved organic carbon and the particulate organic carbon and nitrogen showed increases subsequent to the spring bloom; such increases were less evident in the dissolved organic nitrogen results and not apparent in those of dissolved organic phosphorus.Analyses were also made in March and June in 1969 at two other stations in the English Channel, in addition to E1. The results from the three stations were basically similar.

scholarly journals Nitrogen and phosphorus recycling mediated by copepods in Western Tropical South Pacific

2018 ◽  
Author(s):  
Valentina Valdés ◽  
François Carlotti ◽  
Ruben Escribano ◽  
Katty Donoso ◽  
Marc Pagano ◽  
...  
Keyword(s):  
Community Composition ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
South Pacific ◽  
Nutrient Concentrations ◽  
Ammonium Concentration ◽  
Nitrogen And Phosphorus ◽  
In Situ Conditions

Abstract. Zooplankton play a key role in the regeneration of nitrogen and phosphorus in the ocean through grazing and metabolism. This study investigates the role of the organic and inorganic nitrogen and phosphorus compounds released by copepods on biogeochemical processes and on the microbial community composition during the OUTPACE cruise (18 February–3 April 2015) at three long duration stations (LD). Two LD stations were located in the Melanesian Archipelago region (MA; LD A and LD B) and one in the South Pacific Gyre (SG; LD C), which represent oligotrophic and ultraoligotrophic regions respectively. At each station, microcosm onboard experiments were performed with locally sampled organisms, comprising a mix of epipelagic copepods fed with their natural food and then incubated along with wild microbial assemblages. In presence of copepods, ammonium and dissolved organic nitrogen showed a significant increase, compared to a control in two situations: in ammonium concentration (increasing rate: 0.29 μmol L−1 h−1 after 4 h of incubation) in LD C and in dissolved organic nitrogen concentration (rate: 2.13 μmol L−1 h−1 after 0.5 h of incubation) in LD A. In addition, during the three experiments, an enhanced remineralization (ammonification and nitrification) was observed when adding copepods compared to the controls. A shift in the composition of active bacterial community was observed for the experiments in LD A and LD B mainly characterized by an increase in Alteromonadales and SAR11, respectively and linked with changes in nutrient concentrations. In the experiment performed in LD C, both groups increased but at different periods of incubation, Alteromonadales between 1 and 2 h after the beginning of the experiment, and SAR 11 at the end of incubation. Finally, our experimental results in near in situ conditions, show that copepods can be a source of organic and inorganic compounds for bacterial communities, which respond to excretion pulses at different scales, depending on the initial environmental conditions and on their community composition. These processes can contribute significantly to nutrient recycling in the epipelagic ecosystem of ultra and oligotrophic oceanic regions.

scholarly journals Nitrogen and phosphorus recycling mediated by copepods and response of bacterioplankton community from three contrasting areas in the western tropical South Pacific (20° S)

2018 ◽  
Vol 15 (20) ◽  
pp. 6019-6032 ◽  
Author(s):  
Valentina Valdés ◽  
François Carlotti ◽  
Ruben Escribano ◽  
Katty Donoso ◽  
Marc Pagano ◽  
...  
Keyword(s):  
Community Composition ◽  
Dissolved Organic Nitrogen ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
Microbial Community Composition ◽  
South Pacific ◽  
Nutrient Concentrations ◽  
Ammonium Concentration ◽  
Nitrogen And Phosphorus ◽  
In Situ Conditions

Abstract. Zooplankton play a key role in the regeneration of nitrogen and phosphorus in the ocean through grazing and metabolism. This study investigates the role of the organic and inorganic nitrogen and phosphorus compounds released by copepods on biogeochemical processes and on the microbial community composition during the OUTPACE cruise (18 February–3 April 2015) at three long-duration stations (LD). Two LD stations were located in the Melanesian Archipelago region (MA; LD A and LD B) and one in the South Pacific Gyre (SG; LD C), which represent oligotrophic and ultra-oligotrophic regions respectively. At each station, on-board microcosm experiments were performed with locally sampled organisms, comprising a mix of epipelagic copepods fed with their natural food and then incubated along with wild microbial assemblages. In the presence of copepods, ammonium and dissolved organic nitrogen showed a significant increase compared to a control in two situations: in ammonium concentration (rate: 0.29 µmol L−1 h−1 after 4 h of incubation) in LD C and in dissolved organic nitrogen concentration (rate: 2.13 µmol L−1 h−1 after 0.5 h of incubation) in LD A. In addition, during the three experiments, an enhanced remineralization (ammonification and nitrification) was observed when adding copepods compared to the controls. A shift in the composition of the active bacterial community was observed for the experiments in LD A and LD B, which were mainly characterized by an increase in Alteromonadales and SAR11, respectively, and linked with changes in nutrient concentrations. In the experiment performed in LD C, both groups increased but at different periods of incubation. Alteromonadales increased between 1 and 2 h after the beginning of the experiment, and SAR 11 at the end of incubation. Our results in near in situ conditions show that copepods can be a source of organic and inorganic compounds for bacterial communities, which respond to excretion pulses at different timescales, depending on the initial environmental conditions and on their community composition. These processes can significantly contribute to nutrient recycling and regenerated production in the photic zone of ultra-oligotrophic and oligotrophic oceanic regions.

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