scholarly journals Marine biogenic source of atmospheric organic nitrogen in the subtropical North Atlantic

2016 ◽  
Vol 113 (4) ◽  
pp. 925-930 ◽  
Author(s):  
Katye E. Altieri ◽  
Sarah E. Fawcett ◽  
Andrew J. Peters ◽  
Daniel M. Sigman ◽  
Meredith G. Hastings
Keyword(s):  
Chemical Composition ◽  
North Atlantic ◽  
N Deposition ◽  
Water Soluble ◽  
Atmospheric Environment ◽  
Global Ocean ◽  
Organic N ◽  
Anthropogenic Activity ◽  
Total N ◽  
Biogenic Source

Global models estimate that the anthropogenic component of atmospheric nitrogen (N) deposition to the ocean accounts for up to a third of the ocean’s external N supply and 10% of anthropogenic CO2 uptake. However, there are few observational constraints from the marine atmospheric environment to validate these findings. Due to the paucity of atmospheric organic N data, the largest uncertainties related to atmospheric N deposition are the sources and cycling of organic N, which is 20–80% of total N deposition. We studied the concentration and chemical composition of rainwater and aerosol organic N collected on the island of Bermuda in the western North Atlantic Ocean over 18 mo. Here, we show that the water-soluble organic N concentration ([WSON]) in marine aerosol is strongly correlated with surface ocean primary productivity and wind speed, suggesting a marine biogenic source for aerosol WSON. The chemical composition of high-[WSON] aerosols also indicates a primary marine source. We find that the WSON in marine rain is compositionally different from that in concurrently collected aerosols, suggesting that in-cloud scavenging (as opposed to below-cloud “washout”) is the main contributor to rain WSON. We conclude that anthropogenic activity is not a significant source of organic N to the marine atmosphere over the North Atlantic, despite downwind transport from large pollution sources in North America. This, in conjunction with previous work on ammonium and nitrate, leads to the conclusion that only 27% of total N deposition to the global ocean is anthropogenic, in contrast to the 80% estimated previously.

Characterization of several on-farm and industrial composted materials

1999 ◽  
Vol 79 (1) ◽  
pp. 201-210 ◽  
Author(s):  
Bernard Gagnon ◽  
Robert Robitaille ◽  
Régis R. Simard
Keyword(s):  
Electrical Conductivity ◽  
Cluster Analysis ◽  
Chemical Composition ◽  
Dairy Manure ◽  
Farm Management ◽  
Water Soluble ◽  
Manure Management ◽  
Total N ◽  
Organic C ◽  
On Farm

Manure management and composting methods may greatly affect compost characteristics. An experiment was conducted to characterize 23 on-farm and 6 industrial composts in Québec (Canada). Cluster analysis identified two major groups characterized by their chemical composition, source materials, management intensity and degree of decomposition. Electrical conductivity, total N and K, water-soluble NH4+, PO4, K, Al and organic C, and a cress test were the best chemical and biological parameters for grouping composts. These groups were strongly associated with bedding rate, turning frequency, composting duration, profile windrow appearance, material aggregation and odor. When restricted to dairy manure composts, no clear relationship could be established by cluster analysis between material grouping and their farm management. Statistical analysis on single chemical parameters of dairy manure composts, however, identified five farm management factors: type and amount of bedding, system of manure handling and storage, compost windrow turning, composting length and milk production intensity. These factors affected one or several major parameters: pH, dry matter, electrical conductivity, total and water-soluble C, N, P and K, and humic components characteristics. This study demonstrated the importance of leaching losses in the on-farm composting operations in humid cold regions and the need for more environmentally sustainable composting methods. Key words: Farm manure management, composting, chemical composition

scholarly journals Nitrogen cycling in the deep sedimentary biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

2015 ◽  
Vol 12 (24) ◽  
pp. 7483-7502 ◽  
Author(s):  
S. D. Wankel ◽  
C. Buchwald ◽  
W. Ziebis ◽  
C. B. Wenk ◽  
M. F. Lehmann
Keyword(s):  
Organic Matter ◽  
Dissolved Oxygen ◽  
Isotopic Composition ◽  
North Atlantic ◽  
Diffusion Reaction ◽  
Global Ocean ◽  
Nitrifying Bacteria ◽  
Organic N ◽  
Sediment Column ◽  
Nitrification And Denitrification

Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, its cycling and availability are central factors governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3−) from a site in the oligotrophic North Atlantic (Integrated Ocean Drilling Program – IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3- accumulates far above bottom seawater concentrations (~ 21 μM) throughout the sediment column (up to ~ 50 μM) down to the oceanic basement as deep as 90 m b.s.f. (below sea floor), reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3- isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide stable isotopic evidence for expanded zones of co-occurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR (NTR, referring to nitrification) and δ18ONTR), as well as the isotope effect for denitrification (15ϵDNF) (DNF, referring to denitrification), parameters with high relevance to global ocean models of N cycling. Estimated values of δ15NNTR were generally lower than previously reported δ15N values for sinking particulate organic nitrogen in this region. We suggest that these values may be, in part, related to sedimentary N2 fixation and remineralization of the newly fixed organic N. Values of δ18ONTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ18ONTR values were elevated, suggesting incorporation of 18O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH4+ and NO2− oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supplies a large fraction of the biomass and organic substrate for heterotrophy in these sediments, supplementing the small organic-matter pool derived from the overlying euphotic zone. This work sheds new light on an active nitrogen cycle operating, despite exceedingly low carbon inputs, in the deep sedimentary biosphere.

scholarly journals Nitrogen cycling in the subsurface biosphere: nitrate isotopes in porewaters underlying the oligotrophic North Atlantic

2015 ◽  
Vol 12 (16) ◽  
pp. 13545-13591 ◽  
Author(s):  
S. D. Wankel ◽  
C. Buchwald ◽  
W. Ziebis ◽  
C. B. Wenk ◽  
M. F. Lehmann
Keyword(s):  
Organic Matter ◽  
Dissolved Oxygen ◽  
Isotopic Composition ◽  
North Atlantic ◽  
Diffusion Reaction ◽  
Global Ocean ◽  
Nitrifying Bacteria ◽  
Organic N ◽  
Sediment Column ◽  
Nitrification And Denitrification

Abstract. Nitrogen (N) is a key component of fundamental biomolecules. Hence, the cycling and availability of N is a central factor governing the extent of ecosystems across the Earth. In the organic-lean sediment porewaters underlying the oligotrophic ocean, where low levels of microbial activity persist despite limited organic matter delivery from overlying water, the extent and modes of nitrogen transformations have not been widely investigated. Here we use the N and oxygen (O) isotopic composition of porewater nitrate (NO3−) from a site in the oligotrophic North Atlantic (IODP) to determine the extent and magnitude of microbial nitrate production (via nitrification) and consumption (via denitrification). We find that NO3− accumulates far above bottom seawater concentrations (∼ 21 μM) throughout the sediment column (up to ∼ 50 μM) down to the oceanic basement as deep as 90 mbsf, reflecting the predominance of aerobic nitrification/remineralization within the deep marine sediments. Large changes in the δ15N and δ18O of nitrate, however, reveal variable influence of nitrate respiration across the three sites. We use an inverse porewater diffusion–reaction model, constrained by the N and O isotope systematics of nitrification and denitrification and the porewater NO3− isotopic composition, to estimate rates of nitrification and denitrification throughout the sediment column. Results indicate variability of reaction rates across and within the three boreholes that are generally consistent with the differential distribution of dissolved oxygen at this site, though not necessarily with the canonical view of how redox thresholds separate nitrate regeneration from dissimilative consumption spatially. That is, we provide isotope evidence for expanded zones of co-ocurring nitrification and denitrification. The isotope biogeochemical modeling also yielded estimates for the δ15N and δ18O of newly produced nitrate (δ15NNTR and δ18ONTR), as well as the isotope effect for denitrification (15ϵDNF), parameters with high relevance to global ocean models of N cycling. Estimated values of δ15NNTR were generally lower than previously reported δ15N values for sinking PON in this region. We suggest that these values can be related to sedimentary N-fixation and remineralization of the newly fixed organic N. Values of δ18ONTR generally ranged between −2.8 and 0.0 ‰, consistent with recent estimates based on lab cultures of nitrifying bacteria. Notably, some δ18ONTR values were elevated, suggesting incorporation of 18O-enriched dissolved oxygen during nitrification, and possibly indicating a tight coupling of NH4+ and NO2− oxidation in this metabolically sluggish environment. Our findings indicate that the production of organic matter by in situ autotrophy (e.g., nitrification, nitrogen fixation) supply a large fraction of the biomass and organic substrate for heterotrophy in these sediments, supplementing the small organic matter pool derived from the overlying euphotic zone. This work sheds new light on an active nitrogen cycle operating, despite exceedingly low carbon inputs, in the deep sedimentary biosphere.

scholarly journals Organic and inorganic nitrogen leaching from incubated soils subjected to freeze-thaw and flooding conditions

1994 ◽  
Vol 74 (2) ◽  
pp. 201-206 ◽  
Author(s):  
F. L. Wang ◽  
J. R. Bettany
Keyword(s):  
Inorganic Nitrogen ◽  
Sharp Decrease ◽  
Nitrogen Leaching ◽  
Water Soluble ◽  
Organic N ◽  
Total N ◽  
Freeze Thaw ◽  
Ammonium N ◽  
Nitrate And Nitrite ◽  
The Impact

Freeze-thaw and flooding of usually well-drained soils occur in the spring in the prairie and boreal regions of Canada. We studied the impact of these conditions on nitrogen leaching in a Black Chernozemic soil (Udic Boroll). Soil samples, subjected to different treatments, were incubated for 12 wk in the laboratory and leached every 2 wk with 0.001 M CaCl2 solution. The cumulative leaching loss of total N (mg kg−1 soil) was reduced by freeze-thaw (76.0), flooding (41.4) and a superimposition of the two treatments (28.8) compared to the control (109). All treatments affected the distribution of the forms of N leached. The total loss of water soluble organic N (SON) and ammonium-N was in the order of flooded > flooded-freeze-thaw > freeze-thaw = control. In the leachates from the flooded treatments, SON accounted for 71.5–77.4% of the total N leached. Nitrate- and nitrite-N dominated the total leachable N in the unflooded treatments following an order of control > freeze-thaw > flooded = flooded-freeze-thaw. During the incubation, the Eh of the flooded soils decreased from 344 to −46 mV, compared to a variation in Eh from 355 to 301 mV for the unflooded soils. The maximum rate of leaching of organic nitrogen from the flooded treatment (0.53 mg N kg−1 d−1) coincided with a sharp decrease in Eh, from 131 to 42 mV. It is concluded that climatic events will have a significant impact on the dynamics of soil nitrogen. Flooding, in particular, may promote the loss of N in water soluble organic matter. Key words: Flooding, freeze-thaw, organic and inorganic nitrogen leaching, redox potential

scholarly journals Characterization of organic nitrogen in aerosols at a forest site in the southern Appalachian Mountains

2018 ◽  
Author(s):  
Xi Chen ◽  
Mingjie Xie ◽  
Michael D. Hays ◽  
Eric Edgerton ◽  
Donna Schwede ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Organic Nitrogen ◽  
Bulk Water ◽  
Water Soluble ◽  
Organic N ◽  
Forest Site ◽  
Total N ◽  
Formation Pathway ◽  
Nitro Aromatics

Abstract. This study investigates the composition of organic particulate matter in a remote montane forest in the southeastern U.S., focusing on the role of organic nitrogen (N) in sulfur-containing secondary organic aerosol (nitrooxy-organosulfates) and aerosols associated with biomass burning (nitro-aromatics). Bulk water soluble organic N (WSON) represented ~ 14 % w/w of water soluble total N (WSTN) in PM2.5, on average, across seasonal measurement campaigns conducted in the spring, summer, and fall of 2015. Largest contributions of WSON to WSTN were observed in spring (~ 18 % w/w) and lowest in the fall (~ 10 % w/w). On average, identified nitro-aromatic and nitrooxy-organosulfate compounds accounted for a small fraction of WSON, ranging from ~ 1 % in spring to ~ 4 % in fall, though were observed to contribute as much as 28 % w/w of WSON in individual samples. Highest concentrations of oxidized organic N species occurred during summer (average of 0.65 ngN/m3) along with a greater relative abundance of higher generation oxygenated terpenoic acids, indicating an association with more aged aerosol. Highest concentrations of nitro-aromatics (e.g. nitrocatechol and methyl-nitrocatechol), levoglucosan, and aged SOA tracers were observed during fall, associated with aged biomass burning plumes. Nighttime nitrate radical chemistry is the most likely formation pathway for nitrooxy-organosulfates observed at this low NOx site (generally

scholarly journals Organic nitrogen in precipitation across Europe

2012 ◽  
Vol 9 (7) ◽  
pp. 8093-8109 ◽  
Author(s):  
J. N. Cape ◽  
Y. S. Tang ◽  
J. González-Benítez ◽  
M. Mitošinková ◽  
U. Makkonen ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Wet Deposition ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
N Deposition ◽  
Organic N ◽  
Single Source ◽  
Total N ◽  
Nitrogen Budgets ◽  
Nitrogen Concentrations

Abstract. Measurements of total nitrogen and inorganic nitrogen in precipitation samples from NitroEurope sites across Europe permit the calculation of organic nitrogen concentrations and wet deposition, by difference. The contribution of organic N to total N in precipitation ranged from only a few % to around 40% across sites from Northern Finland to Italy, similar to results from previous individual studies. This paper presents the absolute and relative contributions of organic N to wet N deposition across Europe, and examines seasonal trends. There were only weak correlations with other solutes in precipitation. These simple statistics indicate that sources of organic N in precipitation vary across Europe, and that no single source is responsible. The organic N contributes to total N deposition, yet this input is rarely quantified in nitrogen budgets.

scholarly journals Soil and Thatch Microbial Populations in an 80% Sand : 20% Peat Creeping Bentgrass Putting Green

HortScience ◽  
1993 ◽  
Vol 28 (3) ◽  
pp. 189-191 ◽  
Author(s):  
Charles F. Mancino ◽  
Mohammad Barakat ◽  
Alison Maricic
Keyword(s):  
Creeping Bentgrass ◽  
Water Soluble ◽  
Microbial Populations ◽  
Organic N ◽  
Agrostis Palustris ◽  
Total N ◽  
N Source ◽  
Putting Green ◽  
Dry Soil ◽  
Nitrate And Nitrite

This study examined the numbers of specific soil and thatch microbial populations in a U.S. Golf Association (USGA) specification sand-peat putting green of creeping bentgrass (Agrostis palustris Huds.) over 17 months. Changes caused by adding a water-soluble or bio-organic (water-insoluble, contains microbial inoculum) N source were examined. Thatch was found to contain 40 to 1600 times as many bacteria as the soil, 500 to 600 times as many fungi, and up to 100 times as many actinomycetes. Soil populations of nitrate- and nitrite-reducing anaerobes were similar and ranged from 103 to 105 per gram of dry soil. Adding the bio-organic N source increased soil fungal counts and thatch thickness when compared with the control (no N applied), but not as much as the water-soluble N source. The amendments had no effect on soil respiration, total organic carbon. or total N content.

scholarly journals Characterization of organic nitrogen in aerosols at a forest site in the southern Appalachian Mountains

2018 ◽  
Vol 18 (9) ◽  
pp. 6829-6846 ◽  
Author(s):  
Xi Chen ◽  
Mingjie Xie ◽  
Michael D. Hays ◽  
Eric Edgerton ◽  
Donna Schwede ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Organic Nitrogen ◽  
Weighted Average ◽  
Bulk Water ◽  
Water Soluble ◽  
Organic N ◽  
Forest Site ◽  
Total N ◽  
Southeastern Us ◽  
Nitro Aromatics

Abstract. This study investigates the composition of organic particulate matter in PM2.5 in a remote montane forest in the southeastern US, focusing on the role of organic nitrogen (N) in sulfur-containing secondary organic aerosol (nitrooxy-organosulfates) and aerosols associated with biomass burning (nitro-aromatics). Bulk water-soluble organic N (WSON) represented  ∼  14 % w∕w of water-soluble total N (WSTN) in PM2.5 on average across seasonal measurement campaigns conducted in the spring, summer, and fall of 2015. The largest contributions of WSON to WSTN were observed in spring ( ∼  18 % w∕w) and the lowest in the fall ( ∼  10 % w∕w). On average, identified nitro-aromatic and nitrooxy-organosulfate compounds accounted for a small fraction of WSON, ranging from  ∼  1 % in spring to  ∼  4 % in fall, though were observed to contribute as much as 28 % w∕w of WSON in individual samples that were impacted by local biomass burning. The highest concentrations of oxidized organic N species occurred during summer (average of 0.65 ng N m−3) along with a greater relative abundance of higher-generation oxygenated terpenoic acids, indicating an association with more aged aerosol. The highest concentrations of nitro-aromatics (e.g., nitrocatechol and methyl-nitrocatechol), levoglucosan, and aged SOA tracers were observed during fall, associated with aged biomass burning plumes. Nighttime nitrate radical chemistry is the most likely formation pathway for nitrooxy-organosulfates observed at this low NOx site (generally < 1 ppb). Isoprene-derived organosulfate (MW216, 2-methyltetrol derived), which is formed from isoprene epoxydiols (IEPOX) under low NOx conditions, was the most abundant individual organosulfate. Concentration-weighted average WSON ∕ WSOC ratios for nitro-aromatics + organosulfates + terpenoic acids were 1 order of magnitude lower than the overall aerosol WSON ∕ WSOC ratio, indicating the presence of other uncharacterized higher-N-content species. Although nitrooxy-organosulfates and nitro-aromatics contributed a small fraction of WSON, our results provide new insight into the atmospheric formation processes and sources of these largely uncharacterized components of atmospheric organic N, which also helps to advance the atmospheric models to better understand the chemistry and deposition of reactive N.

scholarly journals Organic nitrogen in precipitation across Europe

2012 ◽  
Vol 9 (11) ◽  
pp. 4401-4409 ◽  
Author(s):  
J. N. Cape ◽  
Y. S. Tang ◽  
J. M. González-Ben&amp;iacute;ez ◽  
M. Mitošinková ◽  
U. Makkonen ◽  
...  
Keyword(s):  
Total Nitrogen ◽  
Wet Deposition ◽  
Organic Nitrogen ◽  
Inorganic Nitrogen ◽  
N Deposition ◽  
Organic N ◽  
Single Source ◽  
Total N ◽  
Nitrogen Budgets ◽  
Nitrogen Concentrations

Abstract. Measurements of total nitrogen and inorganic nitrogen in precipitation samples from NitroEurope sites across Europe permit the calculation of organic nitrogen concentrations and wet deposition, by difference. The contribution of organic N to total N in precipitation ranged from only a few % to around 40% across 18 sites from northern Finland to Italy, similar to results from previous individual studies. This paper presents the absolute and relative contributions of organic N to wet N deposition across Europe, and examines seasonal trends. There were only weak correlations with other solutes in precipitation. These simple statistics indicate that sources of organic N in precipitation vary across Europe, and that no single source is responsible. The organic N contributes to total N deposition, yet this input is rarely quantified in nitrogen budgets.

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