Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

Abstract. The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, Northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. We found tremendously high denitrification rates, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope vales at the sediment-water interface.

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Nitrogen isotope dynamics and fractionation during sedimentary denitrification in Boknis Eck, Baltic Sea

Biogeosciences ◽

10.5194/bg-10-3079-2013 ◽

2013 ◽

Vol 10 (5) ◽

pp. 3079-3088 ◽

Cited By ~ 27

Author(s):

K. Dähnke ◽

B. Thamdrup

Keyword(s):

Baltic Sea ◽

Water Column ◽

Isotope Fractionation ◽

Isotope Effects ◽

Nitrogen Isotope ◽

Current View ◽

Underlying Assumption ◽

Stable Isotope Fractionation ◽

Seasonal Hypoxia ◽

Sediment Denitrification

Abstract. The global marine nitrogen cycle is constrained by nitrogen fixation as a source of reactive nitrogen, and denitrification or anammox on the sink side. These processes with their respective isotope effects set the marine nitrate 15N-isotope value (δ15N) to a relatively constant average of 5‰. This value can be used to better assess the magnitude of these sources and sink terms, but the underlying assumption is that sedimentary denitrification and anammox, processes responsible for approximately one-third of global nitrogen removal, have little to no isotope effect on nitrate in the water column. We investigated the isotope fractionation in sediment incubations, measuring net denitrification and nitrogen and oxygen stable isotope fractionation in surface sediments from the coastal Baltic Sea (Boknis Eck, northern Germany), a site with seasonal hypoxia and dynamic nitrogen turnover. Sediment denitrification was fast, and regardless of current paradigms assuming little fractionation during sediment denitrification, we measured fractionation factors of 18.9‰ for nitrogen and 15.8‰ for oxygen in nitrate. While the input of nitrate to the water column remains speculative, these results challenge the current view of fractionation during sedimentary denitrification and imply that nitrogen budget calculations may need to consider this variability, as both preferential uptake of light nitrate and release of the remaining heavy fraction can significantly alter water column nitrate isotope values at the sediment–water interface.

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Isotope fractionation (δ 13C, δ15N) and microbial community response in degradation of petroleum hydrocarbons by biostimulation in contaminated soil

10.21203/rs.3.rs-183754/v1 ◽

2021 ◽

Author(s):

Heng Liu ◽

Manli Wu ◽

Xiqian Guo ◽

Huan Gao ◽

Yinrui Xu

Keyword(s):

Isotope Effect ◽

Contaminated Soil ◽

Isotope Fractionation ◽

Isotope Effects ◽

Alpha Diversity ◽

Nitrogen Isotope ◽

Community Response ◽

Carbon And Nitrogen ◽

Stable Isotope Fractionation ◽

Compost Amendment

Abstract This study investigated the isotope effects of δ13C and δ15N and microbial response during biodegradation of hydrocarbons by biostimulation with nitrate or compost in the petroleum-contaminated soil. Compost and KNO3 amendments promoted the total petroleum hydrocarbon (TPH) removal accompanied by a significant increase of Actinobacteria and Firmicutes phyla. Soil alpha diversity decreased after 90 days of biostimulation. An inverse significant carbon isotope effect (εc = 16.6 ± 0.8‰) and strong significant nitrogen isotope effect (εN = -24.20 ± 9.54‰) were shown by the KNO3 supplementation. For compost amendment, significant carbon and nitrogen isotope effect were εc = 38.8 ± 1.1‰ and εN = -79.49 ± 16.41‰, respectively. A clear difference of the carbon and nitrogen stable isotope fractionation was evident by KNO3 or compost amendment, which indicated the mechanisms of petroleum degradation by adding compost or KNO3 are different.

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Unravelling the process of petroleum hydrocarbon biodegradation in different filter materials of constructed wetlands by stable isotope fractionation and labelling studies

Biodegradation ◽

10.1007/s10532-021-09942-1 ◽

2021 ◽

Author(s):

Andrea Watzinger ◽

Melanie Hager ◽

Thomas Reichenauer ◽

Gerhard Soja ◽

Paul Kinner

Keyword(s):

Stable Isotope ◽

Constructed Wetlands ◽

Hydrogen Isotope ◽

Petroleum Hydrocarbon ◽

Isotope Fractionation ◽

Isotope Effects ◽

Filter Material ◽

Hydrocarbon Biodegradation ◽

Stable Isotope Fractionation ◽

Filter Materials

AbstractMaintaining and supporting complete biodegradation during remediation of petroleum hydrocarbon contaminated groundwater in constructed wetlands is vital for the final destruction and removal of contaminants. We aimed to compare and gain insight into biodegradation and explore possible limitations in different filter materials (sand, sand amended with biochar, expanded clay). These filters were collected from constructed wetlands after two years of operation and batch experiments were conducted using two stable isotope techniques; (i) carbon isotope labelling of hexadecane and (ii) hydrogen isotope fractionation of decane. Both hydrocarbon compounds hexadecane and decane were biodegraded. The mineralization rate of hexadecane was higher in the sandy filter material (3.6 µg CO2 g−1 day−1) than in the expanded clay (1.0 µg CO2 g−1 day−1). The microbial community of the constructed wetland microcosms was dominated by Gram negative bacteria and fungi and was specific for the different filter materials while hexadecane was primarily anabolized by bacteria. Adsorption / desorption of petroleum hydrocarbons in expanded clay was observed, which might not hinder but delay biodegradation. Very few cases of hydrogen isotope fractionation were recorded in expanded clay and sand & biochar filters during decane biodegradation. In sand filters, decane was biodegraded more slowly and hydrogen isotope fractionation was visible. Still, the range of observed apparent kinetic hydrogen isotope effects (AKIEH = 1.072–1.500) and apparent decane biodegradation rates (k = − 0.017 to − 0.067 day−1) of the sand filter were low. To conclude, low biodegradation rates, small hydrogen isotope fractionation, zero order mineralization kinetics and lack of microbial biomass growth indicated that mass transfer controlled biodegradation.

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Stable isotope fractionation by Clostridium pasteurianum. 4. Sulfur isotope fractionation during enzymatic S3O62−, S2O32−, and SO32− reductions

Canadian Journal of Microbiology ◽

10.1139/m81-127 ◽

1981 ◽

Vol 27 (8) ◽

pp. 824-834

Author(s):

G. I. Harrison ◽

E. J. Laishley ◽

H. R. Krouse

Keyword(s):

Stable Isotope ◽

Isotope Fractionation ◽

Sulfur Isotope ◽

Isotope Effects ◽

Growth Conditions ◽

Enzyme Concentration ◽

Clostridium Pasteurianum ◽

Relative Reduction ◽

Stable Isotope Fractionation ◽

Sulfur Isotope Fractionation

Cell-free extracts from Clostridium pasteurianum grown on SO32− utilize H2 to reduce S3O62−, S2O32−, and SO32− to H2S at a much faster rate than extracts from SO42−-grown cells. This further supports the concept of an inducible dissimilatory type SO32− reductive pathway in this organism. 35S dilution experiments further support the concept that S3O62− and S2O32− are pathway intermediates. The inducible SO32− reductase is ferredoxin linked and the kinetics of the reduction and the sulfur isotope fractionation of the product can be altered by altering the growth conditions. The attending sulfur isotope fractionations are similar to those observed during the chemical decomposition of these compounds. In the case of S2O32−, 35S labelling experiments verified the conclusions derived from the stable isotope fractionation data concerning the relative reduction rates of the sulfane and sulfonate sulfurs. The reduction rates were also affected by enzyme concentration. The integrity of the whole cell is a necessary requirement for the large inverse isotope effects previously reported.

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Stable isotope fractionation by Clostridium pasteurianum. 1.34S/32S: inverse isotope effects during SO42− and SO32− reduction

Canadian Journal of Microbiology ◽

10.1139/m75-034 ◽

1975 ◽

Vol 21 (3) ◽

pp. 235-244 ◽

Cited By ~ 15

Author(s):

R. G. L. McCready ◽

E. J. Laishley ◽

H. R. Krouse

Keyword(s):

Isotope Fractionation ◽

Isotope Effects ◽

Sulfite Reductase ◽

Clostridium Pasteurianum ◽

Stages Of Growth ◽

Dissimilatory Sulfite Reductase ◽

Stable Isotope Fractionation ◽

High Concentrations ◽

Late Stages ◽

Isotopic Effects

During growth on minimal salts – sucrose media supplemented with various concentrations (10−4–10−2 M) of sodium sulfate, Clostridium pasteurianum grew at a normal rate and only evolved sulfide in late stages of growth on 10−2 M SO42−. The evolved sulfide was slightly enriched in 34S as compared to the medium sulfur. On the other hand, sulfide was evolved during growth on all concentrations of sulfite tested. Large normal and inverse isotopic effects were observed in the evolved sulfide during SO32− reductions. In contrast, the intracellular sulphur showed much smaller fractionations. The complexity of the isotopic patterns suggests that a dissimilatory sulfite reductase system may be induced by high concentrations of sulfite.

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Nitrogen isotope fractionation during the reduction of NO3− to NH4+ by Desulfovibrio sp.

Canadian Journal of Microbiology ◽

10.1139/m83-038 ◽

1983 ◽

Vol 29 (2) ◽

pp. 231-234 ◽

Cited By ~ 24

Author(s):

R. G. L. McCready ◽

W. D. Gould ◽

R. W. Barendregt

Keyword(s):

Isotope Fractionation ◽

Nitrogen Isotope ◽

Initial Sample ◽

Minimum Value ◽

Nitrogen Isotope Fractionation ◽

Reductive Process

Desulfovibrio reduce NO3−to NH4+ via a dissimilatory pathway. In 21 days, four strains of Desulfovibrio reduced 36–48% of the available NO3− to ammonium. During this reductive process extensive nitrogen isotope fractionation occurred: the product NH4+ was enriched in 15N in the initial sample, then became enriched in 14N to a minimum value at approximately 20–25% reaction, and then became isotopically heavier as the reaction proceeded.

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Nitrogen isotope effects can be used to diagnose N transformations in wastewater anammox systems

Scientific Reports ◽

10.1038/s41598-021-87184-0 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Paul M. Magyar ◽

Damian Hausherr ◽

Robert Niederdorfer ◽

Nicolas Stöcklin ◽

Jing Wei ◽

...

Keyword(s):

Isotope Effect ◽

Isotope Composition ◽

Isotope Effects ◽

Nitrogen Isotope ◽

Anammox Bacteria ◽

Ammonium Oxidation ◽

Experimental Conditions ◽

N Transformations ◽

Natural Systems ◽

Inverse Isotope Effect

AbstractAnaerobic ammonium oxidation (anammox) plays an important role in aquatic systems as a sink of bioavailable nitrogen (N), and in engineered processes by removing ammonium from wastewater. The isotope effects anammox imparts in the N isotope signatures (15N/14N) of ammonium, nitrite, and nitrate can be used to estimate its role in environmental settings, to describe physiological and ecological variations in the anammox process, and possibly to optimize anammox-based wastewater treatment. We measured the stable N-isotope composition of ammonium, nitrite, and nitrate in wastewater cultivations of anammox bacteria. We find that the N isotope enrichment factor 15ε for the reduction of nitrite to N2 is consistent across all experimental conditions (13.5‰ ± 3.7‰), suggesting it reflects the composition of the anammox bacteria community. Values of 15ε for the oxidation of nitrite to nitrate (inverse isotope effect, − 16 to − 43‰) and for the reduction of ammonium to N2 (normal isotope effect, 19–32‰) are more variable, and likely controlled by experimental conditions. We argue that the variations in the isotope effects can be tied to the metabolism and physiology of anammox bacteria, and that the broad range of isotope effects observed for anammox introduces complications for analyzing N-isotope mass balances in natural systems.

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