共查询到20条相似文献,搜索用时 31 毫秒
1.
V. A. Belyaev D. A. Kozlov A. A. Terent’ev A. E. Trenin 《Plasma Physics Reports》2017,43(10):1039-1041
A method for determining the lifetime of unstable ions is described. The method is based on measuring the decrease in the ion beam current onto a fixed detector with increasing path length of the ion beam from the ion source to the detector. The measurements performed for D? 2 and HD? molecular ions have shown that their lifetimes are 3.5 ± 0.1 and 4.4 ± 0.1 μs, respectively. 相似文献
2.
V. A. Belyaev M. M. Dubrovin D. A. Kozlov A. A. Terent’ev A. E. Trenin G. V. Sholin 《Plasma Physics Reports》2010,36(11):964-968
D2− ions produced in collisions of D− ions with relative energies of 2.5–9.2 eV were detected for the first time. It is shown that the effective cross section
for this reaction is no less than 1.5 × 10−14 cm2. Along with the theoretically predicted short-lived state of negative molecular deuterium ions, a state existing for more
than 1 μs was observed. 相似文献
3.
Ab initio (RHF, MP2) and Density Functional Theory (DFT) methods have been used to examine six isomers of the N15m cluster with the 6-31+G* basis set. Different from the known odd-numbered anionic N7m, N9m, and N11m clusters, in which the open-chain structures are the most stable species, the most stable N15m isomer is structure 1 (C1), which may be considered as a complex between the fragments cyclic N5m (D5h) and staggered N10 (D2d). The decomposition pathways of structure 2 (CS), containing two aromatic N5 rings connected by a N5 chain, and the open-chain structure 3 (C2v) were studied at the B3LYP/6-31+G* level of theory. Relative energies were refined at the level of B3LYP/6-311+G(3df,2p)//B3LYP/6-31+G*+ZPE (B3LYP/6-31+G*). The barriers for N2 and N5m (D5h) fission reactions for structure 2 are predicted to be 18.2 and 14.2 kcal x mol(-1), respectively. The corresponding N2+N3m fission barrier for structure 3 is predicted to be 11.2 kcal x mol(-1). Supplementary material is available for this article if you access the article at http://dx.doi.org/10.1007/s00894-003-0118-0. A link in the frame on the left on that page takes you directly to the supplementary material. Figure Structure 1 of the N15m cluster, showing bond distances in A and bond angles in degrees 相似文献
4.
A confined aquifer in the Malm Karst of the Franconian Alb, South Germany was investigated in order to understand the role of the vadose zone in denitrifiaction processes. The concentrations of chemical tracers Sr2+ and Cl– and concentrations of stable isotope 18O were measured in spring water and precipitation during storm events. Based on these measurements a conceptual model for runoff was constructed. The results indicate that pre-event water, already stored in the system at the beginning of the event, flows downslope on vertical and lateral preferential flow paths. Chemical tracers used in a mixing model for hydrograph separation have shown that the pre-event water contribution is up to 30%. Applying this information to a conceptual runoff generation model, the values of 15N and 18O in nitrate could be calculated. Field observations showed the occurence of significant microbial denitrification processes above the soil/bedrock interface before nitrate percolates through to the deeper horizon of the vadose zone. The source of nitrate could be determined and denitrification processes were calculated. Assuming that the nitrate reduction follows a Rayleigh process one could approximate a nitrate input concentration of about 170 mg/l and a residual nitrate concentration of only about 15%. The results of the chemical and isotopic tracers postulate fertilizers as nitrate source with some influence of atmospheric nitrate. The combined application of hydrograph separation and determination of isotope values in 15N and 18O of nitrate lead to an improved understanding of microbial processes (nitrification, denitrification) in dynamic systems. 相似文献
5.
Tessari F Bortolami S Zoccarato F Alexandre A Cavallini L 《Journal of bioenergetics and biomembranes》2011,43(3):267-274
Sodium Nitroprusside (SNP) and S-Nitrosoglutathione (GSNO) differently affect mitochondrial H2O2 release at Complex-I. mM SNP increases while GSNO decreases the release induced by succinate alone or added on top of NAD-linked
substrates. Stimulation likely depends on Nitric Oxide (
.
NO) (released by SNP but not by GSNO) inhibiting cytochrome oxidase and mitochondrial respiration. Preincubations with SNP
or high GSNO (10 mM plus DTE to increases its
.
NO release) induces an inhibition of the succinate dependent H2O2 production consistent with a
.
NO dependent covalent modification. However maximal inhibition of the succinate dependent H2O2 release is obtained in the presence of low GSNO (20–100 μM), but not with SNP. This inhibition appears independent of
.
NO release since μM GSNO does not affect mitochondrial respiration, or the H2O2 detection systems and its effect is very rapid. Inhibition may be partly due to an increased removal of O2.− since GSNO chemically competes with NBT and cytochrome C in O2.− detection. 相似文献
6.
The ability of an ecosystem to retain anthropogenic nitrogen (N) deposition is dependent upon plant and soil sinks for N,
the strengths of which may be altered by chronic atmospheric N deposition. Sugar maple (Acer saccharum Marsh.), the dominant overstory tree in northern hardwood forests of the Lake States region, has a limited capacity to take
up and assimilate NO3−. However, it is uncertain whether long-term exposure to NO3− deposition might induce NO3− uptake by this ecologically important overstory tree. Here, we investigate whether 10 years of experimental NO3− deposition (30 kg N ha−1 y−1) could induce NO3− uptake and assimilation in overstory sugar maple (approximately 90 years old), which would enable this species to function
as a direct sink for atmospheric NO3− deposition. Kinetic parameters for NH4+ and NO3− uptake in fine roots, as well as leaf and root NO3− reductase activity, were measured under conditions of ambient and experimental NO3− deposition in four sugar maple-dominated stands spanning the geographic distribution of northern hardwood forests in the
Upper Lake States. Chronic NO3− deposition did not alter the V
max or K
m for NO3− and NH4+ uptake nor did it influence NO3− reductase activity in leaves and fine roots. Moreover, the mean V
max for NH4+ uptake (5.15 μmol 15N g−1 h−1) was eight times greater than the V
max for NO3− uptake (0.63 μmol 15N g−1 h−1), indicating a much greater physiological capacity for NH4+ uptake in this species. Additionally, NO3− reductase activity was lower than most values for woody plants previously reported in the literature, further indicating
a low physiological potential for NO3− assimilation in sugar maple. Our results demonstrate that chronic NO3− deposition has not induced the physiological capacity for NO3− uptake and assimilation by sugar maple, making this dominant species an unlikely direct sink for anthropogenic NO3− deposition. 相似文献
7.
Abstract
Sugar maple (Acer saccharum Marsh.)-dominated northern hardwood forests of the Great Lakes Region commonly receive elevated levels of atmospheric nitrate
(NO3−) deposition, which can alter belowground carbon (C) cycling. Past research has demonstrated that chronic experimental NO3− deposition (3 g N m−2 y−1 above ambient) elicits a threefold increase in the leaching loss of dissolved organic carbon (DOC). Here, we used DOC collected
from tension-cup lysimeters to test whether increased DOC export under experimental NO3− deposition originated from forest floor or mineral soil organic matter (SOM). We used DOC radiocarbon dating to quantify
C sources and colorimetric assays to measure DOC aromaticity and soluble polyphenolic content. Our results demonstrated that
DOC exports are primarily derived from new C (<50-years-old) in the forest floor under both ambient and experimental NO3− deposition. Experimental NO3− deposition increased soluble polyphenolic content from 25.03 ± 4.26 to 49.19 ± 4.23 μg phenolic C mg DOC−1, and increased total aromatic content as measured by specific UV absorbance. However, increased aromatic compounds represented
a small fraction (<10%) of the total observed increased DOC leaching. In combination, these findings suggest that experimental
NO3− deposition has altered the production or retention as well as phenolic content of DOC formed in forest floor, however exact
mechanisms are uncertain. Further elucidation of the mechanism(s) controlling enhanced DOC leaching is important for understanding
long-term responses of Great Lakes forests to anthropogenic N deposition and the consequences of those responses for aquatic
ecosystems. 相似文献
8.
Franco Zoccarato Lucia Cavallini Adolfo Alexandre 《Journal of bioenergetics and biomembranes》2009,41(4):387-393
Mitochondrial production of H2O2 is low with NAD substrates (glutamate/pyruvate, 3 and 2 mM) (G/P) and increases over ten times upon further addition of succinate,
with the formation of a sigmoidal curve (semimaximal value at 290 μM, maximal H2O2 production at 600 μM succinate). Malate counteracts rapidly the succinate induced increased H2O2 release and moves the succinate dependent H2O2 production curve to the right. Nitric oxide (NO) and carbon monoxide (CO) are cytochrome c oxidase inhibitors which increase
mitochondrial ROS production. Cyanide (CN−) was used to mimic NO and CO. In the presence of G/P and succinate (300 μM), CN− progressively increased the H2O2 release rate, starting at 1.5 μM. The succinate dependent H2O2 production curve was moved to the left by 30 μM CN−. The Vmax was little modified. We conclude that succinate is the controller of mitochondrial H2O2 production, modulated by malate and CN−. We propose that succinate promotes an interaction between Complex II and Complex I, which activates O2− production. 相似文献
9.
The molecular weight and subunit composition of Cl-,HCO3(-)- and picrotoxin-stimulated Mg2+-ATPase from rat brain plasma membrane solubilized in sodium deoxycholate were studied by gel filtration chromatography. The enzyme activity eluted from a Sephacryl S-300 column in a single peak associated with a protein of molecular weight approximately 300 kD and a Stokes radius of 5.4 nm. The enzyme-enriched fraction, concentrated and denatured by SDS, migrated through a Sephacryl S-200 column as three peaks with molecular weights of approximately 57, 53, and 45 kD. SDS-PAGE also showed three major protein bands with molecular weights of about 57, 53, and 48 kD. The molecular weight and subunit composition of the Cl- and HCO3(-)-stimulated Mg2+-ATPase from neuronal membrane of rat brain are similar with the molecular properties of GABA(A)-benzodiazepine receptor complex from mammalian brain but are different from those of P-type transport ATPases. 相似文献
10.
Foliar N application reduces soil NO<Stack><Subscript>3</Subscript><Superscript>−</Superscript></Stack>-N leaching loss in apple orchards 总被引:1,自引:0,他引:1
A comparison of the effects of foliar and soil N application was made in field-grown mature fruiting Gala/M9 apple trees (Malus domestica Borkh) in 2001 and 2002 growing seasons under Pacific Northwest growing conditions in southern British Columbia, Canada. The trees, six years old at the start of the experiment, were treated: (1) with 5 g/l urea sprays supplied every two weeks (7 times) from mid May to mid August (total about 50 g N/tree/year), (2) with the same amount of N applied to the soil with the same timing and quantity as for the foliar treatment, and (3) with no N (control). Leaf color (as SPAD readings) and N concentrations (mg/g), and soil NH4+-N and NO3–-N were measured periodically throughout the two seasons. Leached NO3–-N was monitored monthly via an anion exchange probe from June to October in 2001 and from May to November in 2002. Shoot length was measured in October and N concentration of one-year-old wood and roots was determined in December of each growing s eason. Soil N application significantly increased shoot length relative to control or foliar N application. Leaf color, leaf N, and N concentration of one-year-old wood and roots were similarly increased relative to control by both soil and foliar N application. These treatments also increased fruit yield relative to control. There was no significant difference in yield and fruit quality between soil and foliar N applications. Soil N application increased soil NH4+-N and NO3–-N content in the root zone, and also increased the NO3– leaching loss below the root zone especially late in the growing season. Our results suggested that tree N status and yield and fruit quality could be maintained by multiple urea sprays during the growing season in apple orchards, and foliar N application will reduce the risk of soil NO3–-N leaching. 相似文献
11.
The structures and stabilities of eleven N13
+ and N13
– isomers have been investigated with second-order Møller–Plesset (MP2) and density functional theory (DFT) methods. Five N13
+ isomers and six N13
– isomers are all reasonable local minima on their potential energy hypersurfaces. The most stable N13
+ cation is structure C-2 with C2v symmetry, which contains a pentazole ring and two N4 open chains. It is different from those of the N7
+ and N9
+ clusters, but similar to the N11
+ cluster. Meanwhile, the most stable N13
– structure A-2 is composed of a pentazole ring and a six-membered ring connected by two nitrogen atoms. It is not only different from those of the N7
– and N9
– clusters, but also from the N11
– cluster. The decomposition pathways of structures C-2 and A-2 were investigated at the B3LYP/(aug)-cc-pVDZ level. From the barrier heights of the structures C-2 and A-2 decomposition processes, it is suggested that C-2 is difficult to observe experimentally and A-2 may be observed as a short-lived species.
Figure Optimized geometrical parameters of N13
+ isomer C-2
相似文献
12.
The cystine/glutamate exchanger (antiporter xc−) is a membrane transporter involved in the uptake of cystine, the rate-limiting amino acid in the synthesis of glutathione.
Recent studies suggest that the antiporter plays a role in the slow oxidative excitotoxity and in the pathological effects
of β-N-oxalylamino-l-alanine, the molecule responsible for neurolathyrism, a neurotoxic upper motor neuron disease. The mouse cystine/glutamate
exchanger has been cloned and showed to be composed of two distinct proteins, one of which being a novel protein, named xCT,
of 502 amino acids and 12 putative trans-membrane domains. We have generated and purified a polyclonal antibody to mouse xCT
and studied its expression in rat brain and in different cultured cells (astrocytes, fibroblasts and neurons) using Western
blot and immunocytochemical techniques. Expression of xCT was also studied in rat brain and muscle at different developmental
stages. Parallel experiments were carried out with antibodies to the heavy chain of 4F2 surface antigen, the non-specific
subunit of the antiporter xc−. xCT antibody detected in all cell and tissue extracts a specific band of about 40 kDa. Subcellular fractionation demonstrated
that xCT is concentrated mainly in the microsomal-mitochondrial fraction, in accord with its structure as transmembrane protein.
Immunocytochemical analysis showed a strong staining in all cells examined, included neurons. Furthermore, both xCT and the
heavy chain of 4F2 surface antigen increased in the brain during development, reaching the highest expression in adulthood.
The study of the expression and developmental profile of xCT represents a first step towards a better characterization of
its biochemical properties and function, which in turn may help to understand the relative contribution of the xc− antiporter in the pathogenesis of certain neurodegenerative diseases. 相似文献
13.
Although field studies have demonstrated an ecosystem-specific effect of experimental atmospheric nitrogen (N) deposition
on litter decomposition, a mechanistic understanding of how ligninolytic microbial communities respond to atmospheric deposition
is lacking. Because high levels of inorganic N suppress lignin decomposition by some basidiomycetes, it is plausible that
the abundance and activity of these key microorganisms underlies differential ecosystem responses of decomposition to atmospheric
N deposition. We hypothesize that: (a) atmospheric N deposition will cause an ecosystem-specific reduction in basidiomycete
activity and abundance with greatest decreases in ecosystems with lignin-rich forest litter and (b) the abundance of lignin
degrading basidiomycetes will be positively correlated with ligninolytic enzyme activity. To test these hypotheses, we measured
the effects of experimental N deposition on the potential activity of phenol oxidase enzymes, and the abundance of basidiomycete
genes encoding laccase, a primary phenol oxidase enzyme, in three hardwood forests spanning a range of leaf litter lignin
content. The black oak-white oak (BOWO) contains high lignin litter, the sugar maple-basswood (SMBW) has low lignin litter,
and the sugar maple-red oak (SMRO) is intermediate. An ecosystem by N deposition interaction significantly influenced phenol
oxidase activity in the surface soil (P = 0.05), where phenol oxidase activity decreased with increasing experimental N deposition in the BOWO ecosystem. No consistent
response to N deposition was evident for surface soil phenol oxidase activity within either the SMRO or SMBW ecosystem. This
interaction did not influence laccase gene abundance. Instead, basidiomycete laccase gene abundance was reduced by experimental
N deposition (main effect) in surface soil. There was only a weak correlation between basidiomycete laccase gene abundance
and potential phenol oxidase enzyme activity, suggesting that the abundance of organisms possessing laccase genes may not
control phenol oxidase activity in soil. Our results suggest that the regulation of laccase gene expression may mediate the
decomposition response to atmospheric N deposition. 相似文献
14.
In two mountain ecosystems at the Alptal research site in central Switzerland, pulses of 15NO3 and 15NH4 were separately applied to trace deposited inorganic N. One forested and one litter meadow catchment, each approximately
1600 m2, were delimited by trenches in the Gleysols. K15NO3 was applied weekly or fortnightly over one year with a backpack sprayer, thus labelling the atmospheric nitrate deposition.
After the sampling and a one-year break, 15NH4Cl was applied as a second one-year pulse, followed by a second sampling campaign. Trees (needles, branches and bole wood),
ground vegetation, litter layer and soil (LF, A and B horizon) were sampled at the end of each labelling period. Extractable
inorganic N, microbial N, and immobilised soil N were analysed in the LF and A horizons. During the whole labelling period,
the runoff water was sampled as well. Most of the added tracer remained in both ecosystems. More NO3− than NH4+ tracer was retained, especially in the forest. The highest recovery was in the soil, mainly in the organic horizon, and in
the ground vegetation, especially in the mosses. Event-based runoff analyses showed an immediate response of 15NO3− in runoff, with sharp 15N peaks corresponding to discharge peaks. NO3− leaching showed a clear seasonal pattern, being highest in spring during snowmelt. The high capacity of N retention in these
ecosystems leads to the assumption that deposited N accumulates in the soil organic matter, causing a progressive decline
of its C:N ratio. 相似文献
15.
Christian Herbst Jirada Herbst Jörg Leppert Oliver Ohlenschläger Matthias Görlach Ramadurai Ramachandran 《Journal of biomolecular NMR》2009,44(4):235-244
An approach for the efficient implementation of RN
n
ν symmetry-based pulse schemes that are often employed for recoupling and decoupling of nuclear spin interactions in biological
solid state NMR investigations is demonstrated at high magic-angle spinning frequencies. RF pulse sequences belonging to the
RN
n
ν symmetry involve the repeated application of the pulse sandwich {R
ϕ
R
−ϕ}, corresponding to a propagator U
RF = exp(−i4ϕI
z), where ϕ = πν/N and R is typically a pulse that rotates the nuclear spins through 180° about the x-axis. In this study, broadband, phase-modulated 180° pulses of constant amplitude were employed as the initial ‘R’ element and the phase-modulation profile of this ‘R’ element was numerically optimised for generating RN
n
ν symmetry-based pulse schemes with satisfactory magnetisation transfer characteristics. At representative MAS frequencies,
RF pulse sequences were implemented for achieving 13C–13C double-quantum dipolar recoupling and through bond scalar coupling mediated chemical shift correlation and evaluated via
numerical simulations and experimental measurements. The results from these investigations are presented here.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
16.
Christian Herbst Jirada Herbst Anika Kirschstein Jörg Leppert Oliver Ohlenschläger Matthias Görlach Ramadurai Ramachandran 《Journal of biomolecular NMR》2009,44(4):175-184
The CN
n
ν class of RF pulse schemes, commonly employed for recoupling and decoupling of nuclear spin interactions in magic angle spinning
solid state NMR studies of biological systems, involves the application of a basic “C” element corresponding to an RF cycle with unity propagator. In this study, the design of CN
n
ν symmetry-based RF pulse sequences for achieving 13C–13C double-quantum dipolar recoupling and through bond scalar coupling mediated 13C–13C chemical shift correlation has been examined at high MAS frequencies employing broadband, constant-amplitude, phase-modulated
basic “C” elements. The basic elements were implemented as a sandwich of a small number of short pulses of equal duration with each
pulse characterised by an RF phase value. The phase-modulation profile of the “C” element was optimised numerically so as to generate efficient RF pulse sequences. The performances of the sequences were
evaluated via numerical simulations and experimental measurements and are presented here.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
17.
S. A. Menzikov O. V. Menzikova 《Journal of Evolutionary Biochemistry and Physiology》2007,43(3):295-304
Action of Cl? + HCO3 ?1 ions on Mg2+-ATPase from brain plasma membranes of fish and rats has been studied. Maximal effect of the anions on the “basal” Mg2+-ATPase activity is revealed in the presence of 10 mM Cl? and 3 mM HCO3 ?1 at physiological values of pH of incubation medium. The studied Cl?, HCO3 ?-activated Mg2+-ATPases of both animal species, by their sensitivity to SH-reagents (5,5-dithio-bis-nitrobenzoic acid, N-ethylmaleimide), oligomycin, and orthovanadate, are similar to transport ATPase of the P-type, but differ from them by molecular properties and by sensitivity to ligands of GABAA-receptors. It has been established that the sensitive to GABAA-ergic ligands, Cl?, HCO3 ?-activated Mg2+-ATPase from brain of the both animal species is protein of molecular mass around 300 kDa and of Stock’s radius 5.4 nm. In fish the enzyme is composed of one major unit of molecular mass approximately 56 kDa, while in rats-of three subunits of molecular masses about 57, 53, and 45 kDa. A functional and structural coupling of the ATP-hydrolyzing areas of the studied enzyme to sites of binding of GABAA-receptor ligands is suggested. 相似文献
18.
MHC class I molecules are heterotrimeric complexes composed of heavy chain, 2-microglobulin (2m) and short peptide. This trimeric complex is generated in the endoplasmic reticulum (ER), where a peptide loading complex (PLC) facilitates transport from the cytosol and binding of the peptide to the preassembled ER resident heavy chain/2m dimers. Association of mouse MHC class I heavy chain with 2m is characterized by allelic differences in the number and/or positions of amino acid interactions. It is unclear, however, whether all alleles follow common binding patterns with minimal contributions by allele-specific contacts, or whether essential contacts with 2m are different for each allele. While searching for the PLC binding site in the 3 domain of the mouse MHC class I molecule H-2Db, we unexpectedly discovered a site critical for binding mouse, but not human, 2m. Interestingly, amino acids in the corresponding region of another MHC class I heavy chain allele do not make contacts with the mouse 2m. Thus, there are allelic differences in the modes of binding of 2m to the heavy chain of MHC class I. 相似文献
19.
Sandoval A Arikkath J Monjaraz E Campbell KP Felix R 《Cellular and molecular neurobiology》2007,27(7):901-908
(1) Voltage-gated Ca2+ (CaV) channels are multi-subunit membrane complexes that allow depolarization-induced Ca2+ influx into cells. The skeletal muscle L-type CaV channels consist of an ion-conducting CaV1.1 subunit and auxiliary α2δ−1, β1 and γ1 subunits. This complex serves both as a CaV channel and as a voltage sensor for excitation–contraction coupling. (2) Though much is known about the mechanisms by which
the α2δ−1 and β1 subunits regulate CaV channel function, there is far less information on the γ1 subunit. Previously, we characterized the interaction of γ1 with the other components of the skeletal CaV channel complex, and showed that heterologous expression of this auxiliary subunit decreases Ca2+ current density in myotubes from γ1 null mice. (3) In the current report, using Western blotting we show that the expression of the CaV1.1 protein is significantly lower when it is heterologously co-expressed with γ1. Consistent with this, patch-clamp recordings showed that transient transfection of γ1 drastically inhibited macroscopic currents through recombinant N-type (CaV2.2/α2δ−1/β3) channels expressed in HEK-293 cells. (4) These findings provide evidence that co-expression of the auxiliary γ1 subunit results in a decreased expression of the ion-conducting subunit, which may help to explain the reduction in Ca2+ current density following γ1 transfection. 相似文献
20.
Massive anthropogenic acceleration of the global nitrogen (N) cycle has stimulated interest in understanding the fate of excess
N loading to aquatic ecosystems. Nitrate (NO3
−) is traditionally thought to be removed mainly by microbial respiratory denitrification coupled to carbon (C) oxidation,
or through biomass assimilation. Alternatively, chemolithoautotrophic bacterial metabolism may remove NO3
− by coupling its reduction with the oxidation of sulfide to sulfate (SO4
2−). The NO3
− may be reduced to N2 or to NH4
+, a form of dissimilatory nitrate reduction to ammonium (DNRA). The objectives of this study were to investigate the importance
of S oxidation as a NO3
− removal process across diverse freshwater streams, lakes, and wetlands in southwestern Michigan (USA). Simultaneous NO3
− removal and SO4
2− production were observed in situ using modified “push-pull” methods in nine streams, nine wetlands, and three lakes. The
measured SO4
2− production can account for a significant fraction (25–40%) of the overall NO3
− removal. Addition of 15NO3
− and measurement of 15NH4
+ production using the push–pull method revealed that DNRA was a potentially important process of NO3
− removal, particularly in wetland sediments. Enrichment cultures suggest that Thiomicrospira denitrificans may be one of the organisms responsible for this metabolism. These results indicate that NO3
−-driven SO4
2− production could be widespread and biogeochemically important in freshwater sediments. Removal of NO3
− by DNRA may not ameliorate problems such as eutrophication because the N remains bio-available. Additionally, if sulfur (S)
pollution enhances NO3
− removal in freshwaters, then controls on N processing in landscapes subject to S and N pollution are more complex than previously
appreciated.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献