scholarly journals The influence of ocean acidification on nitrogen regeneration and nitrous oxide production in the northwest European shelf sea

2014 ◽  
Vol 11 (18) ◽  
pp. 4985-5005 ◽  
Author(s):  
D. R. Clark ◽  
I. J. Brown ◽  
A. P. Rees ◽  
P. J. Somerfield ◽  
P. I. Miller
Keyword(s):  
Multivariate Analysis ◽  
Ocean Acidification ◽  
Water Column ◽  
Data Set ◽  
N2o Production ◽  
Regeneration Rate ◽  
N Assimilation ◽  
European Shelf ◽  
Shelf Sea ◽  
Mechanistic Understanding

Abstract. The assimilation and regeneration of dissolved inorganic nitrogen, and the concentration of N2O, was investigated at stations located in the NW European shelf sea during June/July 2011. These observational measurements within the photic zone demonstrated the simultaneous regeneration and assimilation of NH4+, NO2− and NO3−. NH4+ was assimilated at 1.82–49.12 nmol N L−1 h−1 and regenerated at 3.46–14.60 nmol N L−1 h−1; NO2- was assimilated at 0–2.08 nmol N L−1 h−1 and regenerated at 0.01–1.85 nmol N L−1 h−1; NO3− was assimilated at 0.67–18.75 nmol N L−1 h−1 and regenerated at 0.05–28.97 nmol N L−1 h−1. Observations implied that these processes were closely coupled at the regional scale and that nitrogen recycling played an important role in sustaining phytoplankton growth during the summer. The [N2O], measured in water column profiles, was 10.13 ± 1.11 nmol L−1 and did not strongly diverge from atmospheric equilibrium indicating that sampled marine regions were neither a strong source nor sink of N2O to the atmosphere. Multivariate analysis of data describing water column biogeochemistry and its links to N-cycling activity failed to explain the observed variance in rates of N-regeneration and N-assimilation, possibly due to the limited number of process rate observations. In the surface waters of five further stations, ocean acidification (OA) bioassay experiments were conducted to investigate the response of NH4+ oxidising and regenerating organisms to simulated OA conditions, including the implications for [N2O]. Multivariate analysis was undertaken which considered the complete bioassay data set of measured variables describing changes in N-regeneration rate, [N2O] and the biogeochemical composition of seawater. While anticipating biogeochemical differences between locations, we aimed to test the hypothesis that the underlying mechanism through which pelagic N-regeneration responded to simulated OA conditions was independent of location. Our objective was to develop a mechanistic understanding of how NH4+ regeneration, NH4+ oxidation and N2O production responded to OA. Results indicated that N-regeneration process responses to OA treatments were location specific; no mechanistic understanding of how N-regeneration processes respond to OA in the surface ocean of the NW European shelf sea could be developed.

scholarly journals The influence of ocean acidification on nitrogen regeneration and nitrous oxide production in the North-West European shelf sea

2014 ◽  
Vol 11 (2) ◽  
pp. 3113-3165 ◽  
Author(s):  
D. R. Clark ◽  
I. J. Brown ◽  
A. P. Rees ◽  
P. J. Somerfield ◽  
P. I. Miller
Keyword(s):  
Multivariate Analysis ◽  
Ocean Acidification ◽  
Water Column ◽  
Inorganic Nitrogen ◽  
N2o Production ◽  
Regeneration Rate ◽  
N Assimilation ◽  
European Shelf ◽  
Shelf Sea ◽  
Mechanistic Understanding

Abstract. The assimilation and regeneration of dissolved inorganic nitrogen, and the concentration of N2O, was investigated at stations located in the NW European shelf sea during June/July 2011. These observational measurements within the photic zone demonstrated the simultaneous regeneration and assimilation of NH4+, NO2− and NO3−. NH4+ was assimilated at 1.82–49.12 nmol N L−1 h−1 and regenerated at 3.46–14.60 nmol N L−1 h−1; NO2− was assimilated at 0–2.08 nmol N L−1 h−1 and regenerated at 0.01–1.85 nmol N L−1 h−1; NO3− was assimilated at 0.67–18.75 nmol N L−1 h−1 and regenerated at 0.05–28.97 nmol N L−1 h−1. Observations implied that these processes were closely coupled at the regional scale and nitrogen recycling played an important role in sustaining phytoplankton growth during the summer. The [N2O], measured in water column profiles, was 10.13 ± 1.11 nmol L−1 and did not strongly diverge from atmospheric equilibrium indicating that sampled marine regions where neither a strong source nor sink of N2O to the atmosphere. Multivariate analysis of data describing water column biogeochemistry and its links to N-cycling activity failed to explain the observed variance in rates of N-regeneration and N-assimilation, possibly due to the limited number of process rate observations. In the surface waters of 5 further stations, Ocean Acidification (OA) bioassay experiments were conducted to investigate the response of NH4+ oxidising and regenerating organisms to simulated OA conditions, including the implications for [N2O]. Multivariate analysis was undertaken which considered the complete bioassay dataset of measured variables describing changes in N-regeneration rate, [N2O] and the biogeochemical composition of seawater. While anticipating biogeochemical differences between locations, we aimed to test the hypothesis that the underlying mechanism through which pelagic N-regeneration responded to simulated OA conditions was independent of location and that a mechanistic understanding of how NH4+ oxidation, NH4+ regeneration and N2O production responded to OA could be developed. Results indicated that N-regeneration process responses to OA treatments were location specific; no mechanistic understanding of how N-regeneration processes respond to OA in the surface ocean of the NW European shelf sea could be developed.

scholarly journals The Relationship between Phytoplankton Distribution and Water Column Characteristics in North West European Shelf Sea Waters

PLoS ONE ◽  
2012 ◽  
Vol 7 (3) ◽  
pp. e34098 ◽  
Author(s):  
Johanna Fehling ◽  
Keith Davidson ◽  
Christopher J. S. Bolch ◽  
Tim D. Brand ◽  
Bhavani E. Narayanaswamy
Keyword(s):  
Water Column ◽  
North West ◽  
Phytoplankton Distribution ◽  
European Shelf ◽  
Shelf Sea ◽  
The Relationship ◽  
West European

scholarly journals Nitrogen and oxygen availabilities control water column nitrous oxide production during seasonal anoxia in the Chesapeake Bay

2018 ◽  
Vol 15 (20) ◽  
pp. 6127-6138 ◽  
Author(s):  
Qixing Ji ◽  
Claudia Frey ◽  
Xin Sun ◽  
Melanie Jackson ◽  
Yea-Shine Lee ◽  
...  
Keyword(s):  
Nitrous Oxide ◽  
Chesapeake Bay ◽  
Water Column ◽  
N2o Emissions ◽  
N2o Production ◽  
Isotope Tracer ◽  
Relative Contribution ◽  
Environmental Controls ◽  
Long Run ◽  
Nitrate And Nitrite

Abstract. Nitrous oxide (N2O) is a greenhouse gas and an ozone depletion agent. Estuaries that are subject to seasonal anoxia are generally regarded as N2O sources. However, insufficient understanding of the environmental controls on N2O production results in large uncertainty about the estuarine contribution to the global N2O budget. Incubation experiments with nitrogen stable isotope tracer were used to investigate the geochemical factors controlling N2O production from denitrification in the Chesapeake Bay, the largest estuary in North America. The highest potential rates of water column N2O production via denitrification (7.5±1.2 nmol-N L−1 h−1) were detected during summer anoxia, during which oxidized nitrogen species (nitrate and nitrite) were absent from the water column. At the top of the anoxic layer, N2O production from denitrification was stimulated by addition of nitrate and nitrite. The relative contribution of nitrate and nitrite to N2O production was positively correlated with the ratio of nitrate to nitrite concentrations. Increased oxygen availability, up to 7 µmol L−1 oxygen, inhibited both N2O production and the reduction of nitrate to nitrite. In spring, high oxygen and low abundance of denitrifying microbes resulted in undetectable N2O production from denitrification. Thus, decreasing the nitrogen input into the Chesapeake Bay has two potential impacts on the N2O production: a lower availability of nitrogen substrates may mitigate short-term N2O emissions during summer anoxia; and, in the long-run (timescale of years), eutrophication will be alleviated and subsequent reoxygenation of the bay will further inhibit N2O production.

scholarly journals Biogeochemical processes and buffering capacity concurrently affect acidification in a seasonally hypoxic coastal marine basin

2015 ◽  
Vol 12 (5) ◽  
pp. 1561-1583 ◽  
Author(s):  
M. Hagens ◽  
C. P. Slomp ◽  
F. J. R. Meysman ◽  
D. Seitaj ◽  
J. Harlay ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
Primary Production ◽  
Water Column ◽  
Bottom Water ◽  
Substantial Reduction ◽  
Buffering Capacity ◽  
Total Alkalinity ◽  
Acid Base ◽  
Data Set ◽  
Ph Fluctuations

Abstract. Coastal areas are impacted by multiple natural and anthropogenic processes and experience stronger pH fluctuations than the open ocean. These variations can weaken or intensify the ocean acidification signal induced by increasing atmospheric pCO2. The development of eutrophication-induced hypoxia intensifies coastal acidification, since the CO2 produced during respiration decreases the buffering capacity in any hypoxic bottom water. To assess the combined ecosystem impacts of acidification and hypoxia, we quantified the seasonal variation in pH and oxygen dynamics in the water column of a seasonally stratified coastal basin (Lake Grevelingen, the Netherlands). Monthly water-column chemistry measurements were complemented with estimates of primary production and respiration using O2 light–dark incubations, in addition to sediment–water fluxes of dissolved inorganic carbon (DIC) and total alkalinity (TA). The resulting data set was used to set up a proton budget on a seasonal scale. Temperature-induced seasonal stratification combined with a high community respiration was responsible for the depletion of oxygen in the bottom water in summer. The surface water showed strong seasonal variation in process rates (primary production, CO2 air–sea exchange), but relatively small seasonal pH fluctuations (0.46 units on the total hydrogen ion scale). In contrast, the bottom water showed less seasonality in biogeochemical rates (respiration, sediment–water exchange), but stronger pH fluctuations (0.60 units). This marked difference in pH dynamics could be attributed to a substantial reduction in the acid–base buffering capacity of the hypoxic bottom water in the summer period. Our results highlight the importance of acid–base buffering in the pH dynamics of coastal systems and illustrate the increasing vulnerability of hypoxic, CO2-rich waters to any acidifying process.

scholarly journals Response of N2O production rate to ocean acidification in the western North Pacific

2019 ◽  
Vol 9 (12) ◽  
pp. 954-958 ◽  
Author(s):  
Florian Breider ◽  
Chisato Yoshikawa ◽  
Akiko Makabe ◽  
Sakae Toyoda ◽  
Masahide Wakita ◽  
...  
Keyword(s):  
Ocean Acidification ◽  
Production Rate ◽  
North Pacific ◽  
Western North Pacific ◽  
N2o Production

scholarly journals In situ analysis of LiFePO4 batteries: Signal extraction by multivariate analysis

2010 ◽  
Vol 25 (2) ◽  
pp. 143-148 ◽  
Author(s):  
Mark A. Rodriguez ◽  
Mark H. Van Benthem ◽  
David Ingersoll ◽  
Sven C. Vogel ◽  
Helmut M. Reiche
Keyword(s):  
Multivariate Analysis ◽  
Neutron Diffraction ◽  
Electrochemical Reaction ◽  
Graphite Phase ◽  
Data Set ◽  
Reaction Behavior ◽  
Electrochemical Cycling ◽  
Li Ion

The electrochemical reaction behavior of a commercial Li-ion battery (LiFePO4-based cathode, graphite-based anode) has been measured via in situ neutron diffraction. A multivariate analysis was successfully applied to the neutron diffraction data set facilitating in the determination of Li bearing phases participating in the electrochemical reaction in both the anode and cathode as a function of state-of-charge (SOC). The analysis resulted in quantified phase fraction values for LiFePO4 and FePO4 cathode compounds as well as the identification of staging behavior of Li6, Li12, Li24, and graphite phases in the anode. An additional Li-graphite phase has also been tentatively identified during electrochemical cycling as LiC48 at conditions of ∼5% to 15% SOC.

scholarly journals Phytoplankton Distribution in Relation to Environmental Drivers on the North West European Shelf Sea

PLoS ONE ◽  
2016 ◽  
Vol 11 (10) ◽  
pp. e0164482 ◽  
Author(s):  
Beatrix Siemering ◽  
Eileen Bresnan ◽  
Stuart C. Painter ◽  
Chris J. Daniels ◽  
Mark Inall ◽  
...  
Keyword(s):  
Environmental Drivers ◽  
North West ◽  
The North ◽  
Phytoplankton Distribution ◽  
European Shelf ◽  
Shelf Sea ◽  
West European

scholarly journals Nitrogen leaching from N limited forest ecosystems: the MERLIN model applied to Gårdsjön, Sweden

1998 ◽  
Vol 2 (4) ◽  
pp. 415-429 ◽  
Author(s):  
O. J. Kjønaas ◽  
R. F. Wright
Keyword(s):  
Model Calibration ◽  
Forest Ecosystems ◽  
Inorganic Nitrogen ◽  
Coniferous Forest ◽  
N Deposition ◽  
N Leaching ◽  
Atmospheric N Deposition ◽  
Data Set ◽  
Rooting Zone ◽  
N Assimilation

Abstract. Chronic deposition of inorganic nitrogen (N) compounds from the atmosphere to forested ecosystems can alter the status of a forest ecosystem from N-limited towards N-rich, which may cause, among other things, increased leaching of inorganic N below the rooting zone. To assess the time aspects of excess N leaching, a process-oriented dynamic model, MERLIN (Model of Ecosystem Retention and Loss of Inorganic Nitrogen), was tested on an N-manipulated catchment at Gårdsjön, Sweden (NITREX project). Naturally generated mature Norway spruce dominates the catchment with Scots pine in drier areas. Since 1991, ammonium nitrate (NH4NO3) solution at a rate of about 35 kg N ha-1 yr-1 (250 mmol m-2 yr-1) has been sprinkled weekly, to simulate increased atmospheric N deposition. MERLIN describes C and N cycles, where rates of uptake and cycling between pools are governed by the C/N ratios of plant and soil pools. The model is calibrated through a hindcast period and then used to predict future trends. A major source of uncertainty in model calibration and prediction is the paucity of good historical information on the specific site and stand history over the hindcast period 1930 to 1990. The model is constrained poorly in an N-limited system. The final calibration, therefore, made use of the results from the 6-year N addition experiment. No independent data set was available to provide a test for the model calibration. The model suggests that most N deposition goes to the labile (LOM) and refractory (ROM) organic matter pools. Significant leaching is predicted to start as the C/N ratio in LOM is reduced from the 1990 value of 35 to <28. At ambient deposition levels, the system is capable of retaining virtually all incoming N over the next 50 years. Increased decomposition rates, however, could simulate nitrate leaching losses. The rate and capacity of N assimilation as well as the change in carbon dynamics are keys to ecosystem changes. Because the knowledge of these parameters is currently inadequate, the model has a limited ability to predict N leaching from currently N-limited coniferous forest ecosystems in Scandinavia. The model is a useful tool for bookkeeping of N pools and fluxes, and it is an important contribution to further development of qualitative understanding of forest N cycles.

Use of a proliferation-based mRNA signature to predict outcome in early-stage non-small cell lung adenocarcinoma.

2012 ◽  
Vol 30 (15_suppl) ◽  
pp. 7023-7023
Author(s):  
Carmen Behrens ◽  
Francesca Lombardi ◽  
Susanne Wagner ◽  
Junya Fujimoto ◽  
Maria G Raso ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Multivariate Analysis ◽  
Lung Adenocarcinoma ◽  
Quantitative Pcr ◽  
Prognostic Value ◽  
Early Stage ◽  
Treatment Decisions ◽  
Cancer Center ◽  
Data Set ◽  
Ffpe Samples

7023 Background: Adjuvant treatment of patients with early-stage lung adenocarcinoma is based on post-surgical pathological staging and patient performance status. Disparate outcomes within each staging group suggest that additional prognostic markers could improve our understanding of risk-benefit and potentially lead to better treatment decisions. A proliferation-based, mRNA expression profile was applied to public microarray data of surgically treated lung adenocarcinomas and a cohort of FFPE samples to test its potential prognostic utility. Methods: Public expression data (Director’s Consortium, DC) were derived from Affymetrix HG-U133A arrays. Clinical FFPE samples were assayed by quantitative PCR. A cell cycle progression (CCP) score was calculated from the expression average of 31 cell cycle genes normalized by 15 housekeeper genes. The prognostic value of the CCP score to predict stage I and II patient outcomes was evaluated by Cox proportional hazards analysis with disease-related death as the primary outcome measure. Results: In 256 DC cases, the CCP score was a significant predictor of death in univariate (p=0.0001) and multivariate analysis (p=0.001, HR 1.57, 95%CI 1.20-2.05) using age, stage, gender, smoking status and treatment as covariates. Similarly, in a second data set (GSE31210, n=204) the CCP score was highly associated with death (univariate, p=0.001; multivariate analysis, p=0.003, HR 1.81, 95% CI 1.24-2.66). Using quantitative PCR, the signature was applied to 381 FFPE samples with a median follow-up of 5 years collected at the MD Anderson Cancer Center and the European Institute for Oncology. In the presence of clinical covariates (as above and tumor size and pleural invasion), the CCP score remained the most significant predictor of death in univariate (p=0.0003) and multivariate analysis (p=0.007, HR 1.50, 95% CI 1.11-2.02). Conclusions: A 46 gene mRNA signature is a significant predictor of disease-related death in early-stage lung adenocarcinoma, providing independent prognostic value in the presence of clinical variables. This molecular predictor of cancer survival will be studied in additional cohorts for its ability to impact clinical treatment decisions.

Sign in / Sign up

Export Citation Format

Share Document