Top PDF N<sub>2</sub> fixation in eddies of the eastern tropical South Pacific Ocean

N<sub>2</sub> fixation in eddies of the eastern tropical South Pacific Ocean

N<sub>2</sub> fixation in eddies of the eastern tropical South Pacific Ocean

For cDNA library construction, residual DNA was re- moved from the purified RNA by a DNase I treatment (Life Technologies, Carlsbad, CA, USA). The extracted RNA was gene-specifically reverse-transcribed to cDNA using the Su- perscript III First Strand synthesis Kit (Life Technologies, Carlsbad, CA, USA) following the manufacturers’ proto- col, and nifH cluster-specific no-template quantitative poly- merase chain reactions (qPCRs) were performed to assure the purity of RNA. Quantitative PCRs were performed with cDNA as described before (Löscher et al., 2014); however, a ViiA7 qPCR system (Life Technologies, Carlsbad, CA, USA) was used and the reaction volume was reduced to 12.5 µL. The detection limit of the qPCRs was deducted from non-template controls. No amplification was detected after 45 cycles, setting the theoretical detection limit to one copy per liter. As the detection limit depends on the sam- ple and elution volumes, we calculated a detection limit of 40 copies L −1 . For nifH transcript diversity analysis, a poly- merase chain reaction (PCR) based amplification of the nifH gene was performed followed by Topo TA cloning and se-
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Water column biogeochemistry of oxygen minimum zones in the eastern tropical  North Atlantic and eastern tropical South Pacific oceans

Water column biogeochemistry of oxygen minimum zones in the eastern tropical North Atlantic and eastern tropical South Pacific oceans

2.1 The impact of changing N : P ratios as a result of ocean deoxygenation: a mesocosm approach A series of on-board mesocosm experiments and bioassay incubations were performed in order to identify nutrient lim- itations in both areas and to specifically address the impact of stoichiometry on primary production. Despite the funda- mental differences between the ETNA and ETSP with regard to the N deficit, the results of short-term mesocosm experi- ments implied N limitation of surface plankton communities in both areas (Franz et al., 2012a, b). Further, the partitioning and elemental composition of dissolved and particulate or- ganic matter were investigated. Maximum accumulation of particulate organic carbon (POC) and particulate organic ni- trogen (PON) was observed under high N supply, indicat- ing that primary production was controlled by N availability. Part of the excess P was consumed by non-Redfield produc- tion, predominantly by diatoms, as also observed from di- rect monitoring as described above. While particulate N : P of the accumulated biomass generally exceeded the supply ratio (Franz et al., 2012b), excess P of the dissolved nutrient pool was channeled into release of dissolved organic phos- phorus (DOP) by phytoplankton. These results demonstrated that excess P upwelled into the surface ocean overlying O 2 -
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On the role of mesoscale eddies for the biological productivity and biogeochemistry in the eastern tropical Pacific Ocean off Peru

On the role of mesoscale eddies for the biological productivity and biogeochemistry in the eastern tropical Pacific Ocean off Peru

of the nitrogen loss processes during aging of mode water eddies on their way from the coast to the open ocean. In sharp contrast to eddies A and B, the vertical distribution ofN* (Fig. 3) shows positive values in the OMZ (150–450 m). However, these data cannot be interpreted as being caused by enhanced nitrogen sources but resulted from the fact that N* at the fringes of the cyclonic eddy C (see e.g. NO −

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A dissolved cobalt plume in the oxygen minimum zone of the eastern tropical South Pacific

A dissolved cobalt plume in the oxygen minimum zone of the eastern tropical South Pacific

Because acidified community reference materials such as the SAFe standards require a delicate neutralization to pH 7.5–8 prior to analysis, a large batch of UV oligotrophic seawater was generated prior to the cruise and used to assess instrument performance during at-sea analysis. This consis- tency seawater standard was run roughly three times per week, as were blanks, and values were stable over several reagent batches for the duration of the cruise (4.5 ± 2.1 pM, n = 28) (Table 1). SAFe standard D1 was measured at sea (48.5 ± 2.4 pM, n = 3) and fell within 1 SD of the consensus value (46.6 ± 4.8 pM). SAFe standard D2 and GEOTRACES standard GSP were run at higher frequency for analyses at Woods Hole. Our measurements of D2 (46.9 ± 3.0 pM, n = 7) agreed with consensus values (45.7 ± 2.9 pM) and concentrations from our lab published previously (Noble et al., 2012). While the GSP standard does not have a consensus value, our determinations (2.5 ± 2.0 pM, n = 10) are within the range for SAFe S (4.9 ± 1.2 pM), which was collected at the same offshore location as GSP. Acidified SAFe and GEOTRACES standards were neutralized with concentrated ammonium hydroxide (Seastar), mixing the entire sample be- tween drops, prior to UV digestion. When base was added more quickly, measured dCo was halved, presumably due to adsorption or coprecipitation onto magnesium hydroxides formed during base addition. For analysis of neutralized stan- dards, we found that a ∼ 6 : 1 EPPS : NH 4 OH (M : M) buffer
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TransCom N<sub>2</sub>O model inter-comparison – Part 2:  Atmospheric inversion estimates of N<sub>2</sub>O emissions

TransCom N<sub>2</sub>O model inter-comparison – Part 2: Atmospheric inversion estimates of N<sub>2</sub>O emissions

There are several reasons why the inversions differ so sub- stantially for South Asia. First, this region is not well covered by the observation network. Emissions from this region are only constrained by the two in situ sites, HAT and COI, and by the discrete sampling sites, BKT, GMI, LLN, and TAP. Second, since the prior flux uncertainties are calculated pro- portionally to the prior flux, the prior uncertainty for this re- gion is large allowing the inversions considerable freedom to adjust the fluxes here. Lastly, differences in the modelled transport, such as the tropical convection, monsoon flow, and shifts in the North Pacific storm track, which are important in determining outflow from the Asian continent (Stohl et al., 2002), may also contribute to the disparity among emis- sion estimates for South Asia. Stohl et al. (2002) showed that tracers emitted in Asia south of 30 ◦ N, particularly in India,
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Influence of mesoscale eddies on the distribution of nitrous oxide in the  eastern tropical South Pacific

Influence of mesoscale eddies on the distribution of nitrous oxide in the eastern tropical South Pacific

Acknowledgements. This study was funded by the DFG-supported project SFB754 (http://www.sfb754.de), the BMBF joint project SOPRAN II and III (FKZ 03F0611A and FKZ 03F662A), and the EU FP7 project InGOS (grant agreement no. 284274). We thank the Peruvian authorities for authorizing us to conduct the study in their territorial waters. We also would like to thank our Peruvian colleagues from IMARPE (M. Graco, A. Bernal, G. Flores, and V. León) for their logistical support. We thank the captains and crew of the R/V Meteor for their assistance during the cruises M90 and M91. Likewise, we thank T. Baustian, A. Bernal, J. Craig, G. Eirund, G. Flores, V. León, M. Lohmann, N. Martogli, K. Nachtigall, and G. Krahmann for their contributions to the processing of the different data sets. The altimeter data used for Fig. 1 were produced by Ssalto/Duacs and distributed by Aviso with support from CNES.
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Dissolved iron distribution in the tropical and sub tropical South Eastern Pacific

Dissolved iron distribution in the tropical and sub tropical South Eastern Pacific

Abstract. Dissolved iron (DFe) distributions (<0.2 µm) were determined in the upper water column (0–400 m) of the south eastern tropical and subtropical Pacific, in October– November 2004. Data were collected along a transect ex- tending from the Marquesas Islands to the Chilean coast with most of the stations located in the south Pacific gyre. The concentrations of DFe presented large variability with highest values observed at both extremities of the transect. In the Chilean upwelling, DFe concentrations ranged be- tween 1.2–3.9 nM. These high values result from inputs from the continental margin and are likely maintained by anoxic conditions in the water corresponding to the Oxygen Min- imum Zone (OMZ). In subsurface waters near the Marque- sas, that were also associated with the extension of the OMZ, DFe concentrations varied between 0.15–0.41 nM. Vertical transport of this water by mesoscale activity eastward of the archipelago may explain the dissymmetric east-west distri- bution of chlorophyll-a evidenced by satellite images. Us- ing the new tracer Fe*=DFe−r Fe:P (PO 3− 4 ) we show that DFe
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Changing nutrient stoichiometry affects phytoplankton production, DOP build up and dinitrogen fixation – a mesocosm experiment in the eastern tropical North Atlantic

Changing nutrient stoichiometry affects phytoplankton production, DOP build up and dinitrogen fixation – a mesocosm experiment in the eastern tropical North Atlantic

Moreover, recent field surveys demonstrated the occurrence of N 2 fixation in nutrient rich water masses of the eastern tropical South Pacific (ETSP) and equatorial Atlantic upwelling re[r]

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Assessment of the interannual variability and impact of the QBO and upwelling on tracer-tracer distributions of N<sub>2</sub>O and O<sub>3</sub> in the tropical lower stratosphere

Assessment of the interannual variability and impact of the QBO and upwelling on tracer-tracer distributions of N<sub>2</sub>O and O<sub>3</sub> in the tropical lower stratosphere

Perun, V. S., Schwartz, M. J., Stek, P. C., Thurstans, R. P., Boyles, M. A., Chandra, K. M., Chavez, M. C., Chen, G. S., Chudasama, B. V., Dodge, R., Fuller, R. A., Girard, M. A., Jiang, J. H., Jiang, Y. B., Knosp, B. W., LaBelle, R. C., Lam, J. C., Lee, K. A., Miller, D., Oswald, J. E., Patel, N. C., Pukala, D. M., Quintero, O., Scaff, D. M., Van Snyder, W., Tope, M. C., Wagner, P. A., and Walch, M. J., The Earth Observing System Microwave Limb Sounder (EOS MLS)

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Deposition of dinitrogen pentoxide, N<sub>2</sub>O<sub>5</sub>, to the snowpack at high latitudes

Deposition of dinitrogen pentoxide, N<sub>2</sub>O<sub>5</sub>, to the snowpack at high latitudes

Acknowledgements. The authors would like to thank the following people for their assistance: Javier Fochesatto and John Mayfield, Jr. for the set up and use of the sonic anemometers. Thomas Douglas, Matthew Sturm, and Art Galvin for access to the meteorological tower and portable field hut; Eric Dick for access to the NO x instrument; and Paul Quist for use of his farm as a field site. Without the generosity of these people, this study would not have been possible.

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On the ability of chemical transport models to simulate the vertical structure of the N<sub>2</sub>O, NO<sub>2</sub> and HNO<sub>3</sub> species in the mid-latitude stratosphere

On the ability of chemical transport models to simulate the vertical structure of the N<sub>2</sub>O, NO<sub>2</sub> and HNO<sub>3</sub> species in the mid-latitude stratosphere

Fig. 1. In situ volume mixing ratios (VMRs) of N 2 O measured by the SPIRALE instrument on 2 October 2002 at mid-latitudes (black line) and compared to the VMRs simulated by the Reprobus 3-D CTM at the time of SPIRALE observations (between 07:30 UT and 08:30 UT). The profiles simulated at the two model grid points closest to the measurement positions have been averaged (red line). The model is computed using ECMWF operational analysis data. For more clarity the measurement error bars are represented every 100 m.
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Fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O from soil of burned grassland savannah of central Africa

Fluxes of CO<sub>2</sub>, CH<sub>4</sub> and N<sub>2</sub>O from soil of burned grassland savannah of central Africa

CO 2 than unburned plots during the 1st campaign (one month after burning, dry sea- son) but this difference was not detectable any longer in the 2nd campaign (growing season). The clearest effect of fire was the immediate disappearance of the above- ground vegetation, which despite being partially dry due to the strong water limitation, had still about 20% of green biomass. This was most probably supporting the main-

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On the ability of chemical transport models to simulate the vertical structure of the N<sub>2</sub>O, NO<sub>2</sub> and HNO<sub>3</sub> species in the mid-latitude stratosphere

On the ability of chemical transport models to simulate the vertical structure of the N<sub>2</sub>O, NO<sub>2</sub> and HNO<sub>3</sub> species in the mid-latitude stratosphere

et al., 1998; Hoppel et al., 2002). The model is designed to perform annual simulations as well as detailed process studies. It computes the evolution of 55 species by means of about 160 photolytic gas-phase and heterogeneous reactions, with a time step of 15 minutes in this study. A semi-lagrangian code transports 40 species or chemical fami- lies, typically long-lived tracers but also more unstable compounds which may have a

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The European CO<sub>2</sub>, CO, CH<sub>4</sub> and N<sub>2</sub>O balance between 2001 and 2005

The European CO<sub>2</sub>, CO, CH<sub>4</sub> and N<sub>2</sub>O balance between 2001 and 2005

Table 1. Spatial and temporal extent of the component fluxes and stock changes of the European C and GHG balance. For the spatial extent the ISO3166 country is used. Component fluxes are expressed in Tg C y −1 for CO 2 , CO and CH 4 , Tg CO 2 -eq C y −1 for CH 4 (global warming potential of 23 over 100 yr; shown between brackets) and Tg CO 2 - eq C y −1 for N 2 O (global warming potential of 298 over 100 yr; shown between brackets) for the periods 1996–2000 and 2001–2005. Estimates of the different sources of uncertainty and heterogeneity for the fluxes are expressed in Tg C y −1 for CO 2 , CO and CH 4 and Tg CO 2 -eq C y −1 N 2 O. The uncertainty and heterogeneity for the fluxes and stock changes are expressed in Tg C. The following uncertainties and heterogeneities (defined in Sect. 2.5) are reported: (a) Quasi uniform range of likely model outputs derived from sensitivity analyses (standard deviation of a uniform distribution), (b) Normally distributed uncertainty due to the set-up of the inversion model and is typically obtained through the Bayesian approach (standard deviation of a normal distribution), (c) Expert estimate of the total uncertainty (%), (d) Spatial heterogeneity (standard deviation of a normal distribution), (e) Temporal heterogeneity (standard deviation of a normal distribution).
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Differences between coastal and open ocean distributions of   N<sub>2</sub>O in the oxygen minimum zone off Peru

Differences between coastal and open ocean distributions of N<sub>2</sub>O in the oxygen minimum zone off Peru

ment campaigns during the upwelling in the ETSP. This region is characterized by one of the largest and most intense OMZs in the oceans, extending from the Peruvian shelf about 1000 km offshore with a maximum thickness of more than 600 m (Fuenzalida et al., 2009). It is located in the shadow zone of large ocean current systems which leads to a sluggish ventilation and long residence times of waters within the OMZ.

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Decadal variability of soil CO<sub>2</sub> NO, N<sub>2</sub>O, and CH<sub>4</sub> fluxes at the Höglwald Forest, Germany

Decadal variability of soil CO<sub>2</sub> NO, N<sub>2</sub>O, and CH<sub>4</sub> fluxes at the Höglwald Forest, Germany

Bernhofer, C., Carrara, A., Chevallier, F., De Noblet, N., Friend, A. D., Friedlingstein, P., Grunwald, T., Heinesch, B., Keronen, P., Knohl, A., Krinner, G., Loustau, D., Manca, G., Matteucci, G., Miglietta, F., Ourcival, J. M., Papale, D., Pilegaard, K., Rambal, S., Seufert, G., Soussana, J. F., Sanz, M. J., Schulze, E. D., Vesala, T., and Valentini, R.: Europe-wide reduction in primary productivity caused by the heat and drought in 2003, Nature, 437, 529–

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N<sub>2</sub>O fluxes from the littoral zone of a Chinese reservoir

N<sub>2</sub>O fluxes from the littoral zone of a Chinese reservoir

Soil water content (SWC) was measured every month after all gas sampling with a soil water sensor (UNI1000, Shun- long, China). Soil–sediment samples (0–30 cm) at site DW, SW, SF and NF were collected at each replicate location in November 2011, except site SFC in October 2012. Fresh soil–sediment samples were used for NH + 4 and NO − 3 analy- sis using a discrete analyser (Smartchem 300, AMS, Italy). After air-drying and grinding (passing through a 100 mesh sieve), pH of 1 : 5 soil-water extractions was measured using a pH meter (IQ160, Hach, USA) while soil total carbon (TC) and nitrogen (TN) were analysed using an elemental anal- yser (vario MACRO cube, Elementar, Germany). Soil bulk density was measured following Chinese national standards NY/T 1121.4-2006 (MAPRC, 2007).
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An aircraft based three channel broadband cavity enhanced absorption spectrometer for simultaneous measurements of NO<sub>3</sub>, N<sub>2</sub>O<sub>5</sub> and NO<sub>2</sub>

An aircraft based three channel broadband cavity enhanced absorption spectrometer for simultaneous measurements of NO<sub>3</sub>, N<sub>2</sub>O<sub>5</sub> and NO<sub>2</sub>

The BBCEAS technique and spectral analysis procedure has been widely reported in the literature and is only briefly described here. For further details the reader is directed to recent publications by Ball and Jones (2009) and Langridge et al. (2008). A BBCEAS experiment involves irradiation of a high finesse optical cavity, formed using two highly reflective mirrors, by an incoherent broadband CW light source. Under irradiation,

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A two-channel, Thermal Dissociation Cavity-Ringdown Spectrometer for the detection of ambient NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub> and RONO<sub>2</sub>

A two-channel, Thermal Dissociation Cavity-Ringdown Spectrometer for the detection of ambient NO<sub>2</sub>, RO<sub>2</sub>NO<sub>2</sub> and RONO<sub>2</sub>

regular spaces in the data are zeroing periods as they would have been measured in a normal experiment. The baseline which is plotted for a two hour time interval here shows no long term trend, indicating that the zero measurements every 5–10 min are sufficient to capture drifts in ring-down related to the variability of the cavity perfor- mance. The lower panel is an Allan deviation plot for this cavity (red curve), which

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Ship emitted NO<sub>2</sub> in the Indian Ocean: comparison of model results with satellite data

Ship emitted NO<sub>2</sub> in the Indian Ocean: comparison of model results with satellite data

istry general circulation model ECHAM5/MESSy1 (January 2000 to October 2005). The data set from SCIAMACHY yields the first monthly analysis of ship induced NO 2 enhancements in the Indian Ocean. For both data and model consistently the tropo- spheric excess method was used to obtain mean NO 2 columns over the shipping lane from India to Indonesia, and over two ship free regions, the Bay of Bengal and the cen-

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