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  • 15N-tracer; 15N tracer incubations (Bourbonnais et al. 2021); Ammonium; Ammonium, labelled, fraction; Ammonium, oxidation rate; Ammonium, oxidation rate, standard error; ammonium oxidation; amoA gene, copy number; amoA gene, copy number, standard deviation; Bottle number; Calculated; Cast number; Chemiluminescence detection (Braman and Hendrix 1989); Comment; CTD, Sea-Bird; CTD/Rosette; CTD-RO; DATE/TIME; Density, sigma-theta (0); Depth, bottom/max; DEPTH, water; eastern tropical north pacific; Event label; Fluorometry (Holmes et al. 1999); greenhouse gas; Identification; LATITUDE; LONGITUDE; Mass spectrometry (McIlvin and Casciotti 2010); N2O production rates; Nitrate; Nitrite; nitrogen cycle; Nitrous oxide, dissolved; Nitrous oxide, hybrid; Nitrous oxide, hybrid, standard error; Nitrous oxide, standard deviation; Nitrous oxide, yield; Nitrous oxide, yield, standard error; Nitrous oxide production; Nitrous oxide production, standard error; North Pacific Ocean; ocean; Oxygen; Photometry (Strickland & Parsons, 1972); Radiation, photosynthetically active; Real-time quantitative polymerase chain reaction (qPCR); Salinity; Sally Ride; SR1805; SR1805_PS1_CTD16; SR1805_PS1_CTD5; SR1805_PS2_CTD32; SR1805_PS2_CTD45; SR1805_PS3_CTD71; SR1805_PS3_CTD84; Station label; STOX; Switchable trace oxygen sensor; Temperature, water; Treatment  (1)
  • 3H-CH4 incubation; Campaign of event; CTD/Rosette; CTD-RO; Date/Time of event; Depth, bottom/max; DEPTH, water; Event label; Latitude of event; Longitude of event; Methane; Methane oxidation rate; Methane oxidation rate, standard deviation; Norway, Norwegian Basin; POS419; POS419_599-2; POS419_615-9; POS419_654-33; POS419_671-36; Poseidon; Sample code/label; Turnover rate, methane oxidation; Turnover rate, standard deviation; Type  (1)
  • Bering Sea  (1)
  • Germany  (1)
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  • 1
    Publication Date: 2023-08-08
    Description: Over the past decades, fractured and karst groundwater systems have been studied intensively due to their high vulnerability to nitrate (NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉) contamination, yet nitrogen (N) turnover processes within the recharge area are still poorly understood. This study investigated the role of the karstified recharge area in NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 transfer and turnover by combining isotopic analysis of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 and nitrite (NO〈sub〉2〈/sub〉〈sup〉−〈/sup〉) with time series data of hydraulic heads and specific electrical conductivity from groundwater monitoring wells and a karstic spring in Germany. A large spatial variability of groundwater NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 concentrations (0.1–0.8 mM) was observed, which cannot be explained solely by agricultural land use. Natural-abundance N and O isotope measurements of NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 (δ〈sup〉15〈/sup〉N and δ〈sup〉18〈/sup〉O) confirm that NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 derives mainly from manure or fertilizer applications. Fractional N elimination by denitrification is indicated by relatively high δ〈sup〉15〈/sup〉N- and δ〈sup〉18〈/sup〉O-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉 values, elevated NO〈sub〉2〈/sub〉〈sup〉−〈/sup〉 concentrations (0.05–0.14 mM), and δ〈sup〉15〈/sup〉N-NO〈sub〉2〈/sub〉〈sup〉−〈/sup〉 values that were systematically lower than the corresponding values of δ〈sup〉15〈/sup〉N-NO〈sub〉3〈/sub〉〈sup〉−〈/sup〉. Hydraulic and chemical response patterns of groundwater wells suggest that rain events result in the displacement of water from transient storage compartments such as the epikarst or the fissure network of the phreatic zone. Although O〈sub〉2〈/sub〉 levels of the investigated groundwaters were close to saturation, local denitrification might be promoted in microoxic or anoxic niches formed in the ferrous iron-bearing carbonate rock formations. The results revealed that (temporarily) saturated fissure networks in the phreatic zone and the epikarst may play an important role in N turnover during the recharge of fractured aquifers.
    Description: Projekt DEAL
    Keywords: ddc:551.49 ; Nitrate ; Karst ; Groundwater recharge ; Stable isotopes ; Germany
    Language: English
    Type: doc-type:article
    Location Call Number Limitation Availability
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  • 2
    Publication Date: 2024-06-12
    Description: In March/April 2018 during a cruise on R/V Sally Ride, SR1805, 15N-NH4+ incubations in 60mL glass serum bottles were performed to measure ammonium oxidation rates to nitrite and nitrous oxide in different depth at 3 different stations in the oxygen deficient zone (ODZ) of the Eastern Tropical North Pacific off the coast of Mexico. Water samples were collected from 30L Niskin bottles deployed with a conductivity-temperature-depth profiler (CTD, Seabird Electronics). The goal was to get a better understanding on the controls of nitrous oxide (N2O) production. The N2O production rate experiments were performed according to Bourbonnais et al. 2021 (https://doi.org/10.3389/fmars.2021.611937). Furthermore, ammonium (NH4+), nitrite (NO2-) and nitrate (NO3-) as well as N2O concentrations were determined using standard fluorometric (Holmes et al. 1999, https://doi.org/10.1139/f99-128), photometric (Strickland and Parsons 1972, hdl:10013/epic.46454.d001), chemiluminescent (Braman and Hendrix 1989, doi:10.1021/ac00199a007) and mass spectrometric techniques (McIlvin and Casciotti 2010, https://doi.org/10.4319/lom.2010.8.54), respectively. The N2O yield per nitrite produced was calculated. The archaeal ammonia monooxygenase gene subunit A (amoA) copy numbers/mL were determined using qPCR as described previously (Peng et al. 2015, https://doi.org/10.1002/2015GB005278).
    Keywords: 15N-tracer; 15N tracer incubations (Bourbonnais et al. 2021); Ammonium; Ammonium, labelled, fraction; Ammonium, oxidation rate; Ammonium, oxidation rate, standard error; ammonium oxidation; amoA gene, copy number; amoA gene, copy number, standard deviation; Bottle number; Calculated; Cast number; Chemiluminescence detection (Braman and Hendrix 1989); Comment; CTD, Sea-Bird; CTD/Rosette; CTD-RO; DATE/TIME; Density, sigma-theta (0); Depth, bottom/max; DEPTH, water; eastern tropical north pacific; Event label; Fluorometry (Holmes et al. 1999); greenhouse gas; Identification; LATITUDE; LONGITUDE; Mass spectrometry (McIlvin and Casciotti 2010); N2O production rates; Nitrate; Nitrite; nitrogen cycle; Nitrous oxide, dissolved; Nitrous oxide, hybrid; Nitrous oxide, hybrid, standard error; Nitrous oxide, standard deviation; Nitrous oxide, yield; Nitrous oxide, yield, standard error; Nitrous oxide production; Nitrous oxide production, standard error; North Pacific Ocean; ocean; Oxygen; Photometry (Strickland & Parsons, 1972); Radiation, photosynthetically active; Real-time quantitative polymerase chain reaction (qPCR); Salinity; Sally Ride; SR1805; SR1805_PS1_CTD16; SR1805_PS1_CTD5; SR1805_PS2_CTD32; SR1805_PS2_CTD45; SR1805_PS3_CTD71; SR1805_PS3_CTD84; Station label; STOX; Switchable trace oxygen sensor; Temperature, water; Treatment
    Type: Dataset
    Format: text/tab-separated-values, 796 data points
    Location Call Number Limitation Availability
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  • 3
    Publication Date: 2024-07-01
    Keywords: 3H-CH4 incubation; Campaign of event; CTD/Rosette; CTD-RO; Date/Time of event; Depth, bottom/max; DEPTH, water; Event label; Latitude of event; Longitude of event; Methane; Methane oxidation rate; Methane oxidation rate, standard deviation; Norway, Norwegian Basin; POS419; POS419_599-2; POS419_615-9; POS419_654-33; POS419_671-36; Poseidon; Sample code/label; Turnover rate, methane oxidation; Turnover rate, standard deviation; Type
    Type: Dataset
    Format: text/tab-separated-values, 229 data points
    Location Call Number Limitation Availability
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2005. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Global Biogeochemical Cycles 19 (2005): GB4005, doi:10.1029/2005GB002508.
    Description: On the basis of the normalization to phosphate, a significant amount of nitrate is missing from the deep Bering Sea (BS). Benthic denitrification has been suggested previously to be the dominant cause for the BS nitrate deficit. We measured water column nitrate 15N/14N and 18O/16O as integrative tracers of microbial denitrification, together with pore water-derived benthic nitrate fluxes in the deep BS basin, in order to gain new constraints on the mechanism of fixed nitrogen loss in the BS. The lack of any nitrate isotope enrichment into the deep part of the BS supports the benthic denitrification hypothesis. On the basis of the nitrate deficit in the water column with respect to the adjacent North Pacific and a radiocarbon-derived ventilation age of ∼50 years, we calculate an average deep BS (〉2000 m water depth) sedimentary denitrification rate of ∼230 μmol N m−2 d−1 (or 1.27 Tg N yr−1), more than 3 times higher than high-end estimates of the average global sedimentary denitrification rate for the same depth interval. Pore water-derived estimates of benthic denitrification were variable, and uncertainties in estimates were large. A very high denitrification rate measured from the base of the steep northern slope of the basin suggests that the elevated average sedimentary denitrification rate of the deep Bering calculated from the nitrate deficit is driven by organic matter supply to the base of the continental slope, owing to a combination of high primary productivity in the surface waters along the shelf break and efficient down-slope sediment focusing along the steep continental slopes that characterize the BS.
    Description: This study was supported by NSF grants OCE-0136449 and OCE-9981479 to D. M. S., OCE-0118126 and OCE-0324987 to D. C. M., and DFG grant LE 1326/1-1 to M. F. L. The BS cruise was funded by grant OPP-9912122.
    Keywords: Bering Sea ; Denitrification ; Nitrate isotopes
    Repository Name: Woods Hole Open Access Server
    Type: Article
    Format: application/pdf
    Format: text/plain
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