Nitrification in a Vertisol subsoil and its relationship to the accumulation of ammonium-nitrogen at depth

Soil Research ◽  
2002 ◽  
Vol 40 (5) ◽  
pp. 727 ◽  
Author(s):  
K. L. Page ◽  
W. M. Strong ◽  
R. C. Dalal ◽  
N. W. Menzies
Keyword(s):  
Organic Carbon ◽  
Environmental Conditions ◽  
Soil Analysis ◽  
Field Studies ◽  
Ammonium Nitrogen ◽  
Carbon Substrate ◽  
Anaerobic Conditions ◽  
Incubation Study ◽  
High Concentrations ◽  
Low Rate

Unusually high concentrations of ammonium have been observed in a Vertisol below 1 m depth in south-east Queensland. This study investigated the possibility that an absence of nitrification is allowing this ammonium to accumulate and persist over time, and examined the soil environmental characteristics that may be responsible for limiting nitrifying organisms. The possibility that anaerobiosis, soil acidity, soil salinity, low organic carbon concentrations, and/or an absence of active nitrifying microorganisms were responsible for limiting nitrification was examined in laboratory and field studies. The presence/absence of anaerobic conditions was determined qualitatively using a field test to give an indication of electron lability. In addition, an incubation study was conducted and soil environmental conditions were improved for nitrifying organisms by adjusting the pH from 4.4 to 7, adjusting the electrical conductivity from 1.6 to 0.5 dS/m, amending with a soluble carbon substrate at a rate of 500 mg/kg, and using microorganisms from the surface horizon to inoculate to the subsoil. Over a 180-day period no nitrification was detected in the control samples from the incubation study, indicating that an extremely low rate of nitrification is likely to be responsible for allowing ammonium to accumulate in this soil. Analysis of the effect of soil environmental conditions on nitrification revealed that anaerobic conditions did not exist at depth and that pH, EC, organic carbon, and inoculation treatments added in isolation had no effect on nitrification. However, when inoculum was added to the soil in combination with pH, a significant increase in nitrification was observed, and the greatest amount of nitrification was observed when inoculum, pH, and EC treatments were added in combination. It was concluded that the reason for the low rate of nitrification in this soil is primarily the absence of a significant population of active nitrifying microorganisms, which may have been unable to colonise the subsoil environment due to its acidic, and to a lesser extent, its saline environment.

Quackgrass (Agropyron Repens) Control with SC-0224 and Glyphosate

1988 ◽  
Vol 2 (2) ◽  
pp. 147-152 ◽  
Author(s):  
Paul T. Kivlin ◽  
Jerry D. Doll
Keyword(s):  
Nonionic Surfactant ◽  
Environmental Conditions ◽  
Field Studies ◽  
Time Intervals ◽  
Fall Application ◽  
Low Rate ◽  
Agropyron Repens

Field studies were conducted from 1982 to 1984 to evaluate the effectiveness of SC-0224 (trimethylsulfonium carboxymethylaminomethylphosphonate) and glyphosate [N-(phosphonomethyl)glycine] for quackgrass [Agropyron repens(L.) Beauv. # AGRRE] control. The herbicides were compared 1) in different rates and carrier volumes, 2) on several spring and fall application dates, and 3) with varying time intervals between application and moldboard plowing. Glyphosate and SC-0224 controlled quackgrass equally well at carrier volumes of 25 to 400 L/ha. Both herbicides generally provided similar control as fall and spring applications and with time intervals of 12 to 96 h between application and plowing. Occasionally the low rate of SC-0024 gave less quackgrass control the next season than the same rate of glyphosate. Adding nonionic surfactant at 0.5% (v/v) did not influence the phytotoxicity of these herbicides at the rates and carrier volumes tested. These herbicides controlled quackgrass comparably and greater than 85% when applied under appropriate environmental conditions.

Total organic carbon and the preservation of organic-walled microfossils in Precambrian shale

Geology ◽  
2020 ◽  
Author(s):  
C.R. Woltz ◽  
S.M. Porter ◽  
H. Agić ◽  
C.M. Dehler ◽  
C.K. Junium ◽  
...  
Keyword(s):  
Species Richness ◽  
Organic Carbon ◽  
Total Organic Carbon ◽  
Microbial Degradation ◽  
Sedimentation Rate ◽  
Surface Pattern ◽  
Causal Factors ◽  
Eukaryotic Diversity ◽  
High Concentrations ◽  
Fossil Preservation

Much of our understanding of early eukaryote diversity and paleoecology comes from the record of organic-walled microfossils in shale, yet the conditions controlling their preservation are not well understood. It has been suggested that high concentrations of total organic carbon (TOC) inhibit the preservation of organic fossils in shale, and although this idea is supported anecdotally, it has never been tested. Here we compared the presence, preservational quality, and assemblage diversity of organic-walled microfossils to TOC concentrations of 346 shale samples that span the late Paleoproterozoic to middle Neoproterozoic in age. We found that fossil-bearing samples have significantly lower median TOC values (0.32 wt%, n = 189) than those containing no fossils (0.72 wt%, n = 157). Preservational quality, measured by the loss of surface pattern, density of pitting, and deterioration of wall margin, decreases as TOC increases. Species richness negatively correlates with TOC within the ca. 750 Ma Chuar Group (Arizona, USA), but no relationship is observed in other units. These results support the hypothesis that high TOC content either decreases the preservational quality or inhibits the preservation of organic-walled microfossils altogether. However, it is also possible that other causal factors, including sedimentation rate and microbial degradation, account for the correlation between fossil preservation and TOC. We expect that as TOC varies in space and time, so too does the probability of finding well-preserved fossils. A compilation of 13,940 TOC values spanning Earth history suggests significantly higher median TOC levels in Mesoproterozoic versus Neoproterozoic shale, potentially biasing the interpreted pattern of increased eukaryotic diversity in the Tonian.

On human blood, rock art and calcium oxalate: further studies on organic carbon content and radiocarbon age of materials relating to Australian rock art

Antiquity ◽  
1997 ◽  
Vol 71 (272) ◽  
pp. 430-437 ◽  
Author(s):  
Richard Gillespie
Keyword(s):  
Organic Carbon ◽  
Calcium Oxalate ◽  
Human Blood ◽  
Ancient Dna ◽  
Rock Art ◽  
Field Studies ◽  
Organic Carbon Content ◽  
Radiocarbon Age ◽  
Archaeological Materials ◽  
Supplementary Report

Minute biological traces, with their prospect of recovering even ancient DNA, are the most attractive of archaeological materials to work with. This supplementary report on field studies of rock-art first published in ANTIQUITY further explores how these studies may in truth be carried out.

scholarly journals Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

2016 ◽  
Vol 43 (4) ◽  
pp. 324 ◽  
Author(s):  
Supriya Tiwari ◽  
Rüdiger Grote ◽  
Galina Churkina ◽  
Tim Butler
Keyword(s):  
Stomatal Conductance ◽  
Environmental Conditions ◽  
Economic Losses ◽  
Plant Responses ◽  
Damage Scenarios ◽  
Biochemical Processes ◽  
Wide Range ◽  
Defence Responses ◽  
High Concentrations ◽  
The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

scholarly journals The effect of dissolved organic carbon on pelagial and near-sediment water traits in lakes

2011 ◽  
Vol 74 (2) ◽  
pp. 133-139 ◽  
Author(s):  
Krzysztof Banaś
Keyword(s):  
Organic Carbon ◽  
Dissolved Organic Carbon ◽  
Redox Potential ◽  
Environmental Conditions ◽  
Calcium Concentration ◽  
Total Hardness ◽  
Sediment Layer ◽  
Ph Values ◽  
Doc Concentration ◽  
Good Transparency

The effect of dissolved organic carbon (DOC) on the environmental conditions of macrophytes has been studied in 35 lakes divided into soft- and hardwater: oligohumic (&lt;4.0 mg C dm<sup>-3</sup>), α-mesohumic (4.0-8.0 mg C dm<sup>-3</sup>), β-mesohumic (8.1-16.0 mg C dm<sup>-3</sup>) and polihumic (&gt;16.0 mg C dm<sup>-3</sup>). The optimum environmental conditions for macrophytes have been found in oligohumic lakes, characterised by low water colour and its good transparency. In soft- and hardwater lakes increasing concentration of DOC is accompanied with an increase in the colour (r=0.95), while the visibility decreases. With increasing DOC in the near-sediment layer the pH values decrease while the concentration of nitrogen increases and the concentration of phosphorus slightly increases. In hardwater lakes with increasing DOC concentration, the redox potential, conductivity, total hardness and calcium concentration in the near-sediment water decrease, whereas the content of CO<sup>2</sup> remains at a very low level.

scholarly journals Characteristics, seasonality and sources of carbonaceous and ionic components in the tropical Indian aerosols

2011 ◽  
Vol 11 (2) ◽  
pp. 3937-3976 ◽  
Author(s):  
C. M. Pavuluri ◽  
K. Kawamura ◽  
S. G. Aggarwal ◽  
T. Swaminathan
Keyword(s):  
Organic Carbon ◽  
Atmospheric Aerosols ◽  
Atmospheric Transport ◽  
Indian Subcontinent ◽  
Ionic Species ◽  
Water Soluble ◽  
Carbonaceous Aerosols ◽  
Mass Fractions ◽  
High Concentrations ◽  
Ionic Components

Abstract. To better characterize South and Southeast Asian aerosols, PM10 samples collected from tropical Chennai, India (13.04° N; 80.17° E) were analyzed for carbonaceous and water-soluble ionic components. Concentration ranges of elemental carbon (EC) and organic carbon (OC) were 2.4–14 μg m−3 and 3.2–15.6 μg m−3 in winter samples whereas they were 1.1–2.5 μg m−3 and 4.1–17.6 μg m−3 in summer samples, respectively. Concentration of secondary organic carbon (SOC) retrieved from EC-tracer method was 4.6 ± 2.8 μg m−3 in winter and 4.3 ± 2.8 μg m−3 in summer. SO42- (8.8 ± 2.5 μg m−3 and 4.1 ± 2.7 μg m−3 in winter and summer, respectively) was found as the most abundant ionic species (57% on average, n = 49), followed by NH4+ (15%) > NO3− > Cl− > K+> Na+ > Ca2+ > MSA− > Mg2+. The mass fractions of EC, organic matter (OM) and ionic species varied seasonally, following the air mass trajectories and corresponding source strength. Based on mass concentration ratios of selected components and relations of EC and OC to marker species, we found that biofuel/biomass burning is the major source of atmospheric aerosols in South and Southeast Asia. The high concentrations of SOC and WSOC/OC ratios (ave. 0.45; n = 49) as well as good correlations between SOC and WSOC suggest that the secondary production of organic aerosols during long-range atmospheric transport is also significant in this region. This study provides the baseline data of carbonaceous aerosols for southern part of the Indian subcontinent.

A new water-soluble bacterial NADH: fumarate oxidoreductase

2020 ◽  
Vol 367 (20) ◽  
Author(s):  
Yulia V Bertsova ◽  
Ilya P Oleynikov ◽  
Alexander V Bogachev
Keyword(s):  
Nadh Dehydrogenase ◽  
Reductase Activity ◽  
Domain Architecture ◽  
Water Soluble ◽  
Fumarate Reductase ◽  
Anaerobic Conditions ◽  
New Type ◽  
Prosthetic Groups ◽  
Low Rate ◽  
Covalently Bound

ABSTRACT The cytoplasmic fumarate reductase of Klebsiella pneumoniae (FRD) is a monomeric protein which contains three prosthetic groups: noncovalently bound FMN and FAD plus a covalently bound FMN. In the present work, NADH is revealed to be an inherent electron donor for this enzyme. We found that the fumarate reductase activity of FRD significantly exceeds its NADH dehydrogenase activity. During the catalysis of NADH:fumarate oxidoreductase reaction, FRD turnover is limited by a very low rate (∼10/s) of electron transfer between the noncovalently and covalently bound FMN moieties. Induction of FRD synthesis in K. pneumoniae cells was observed only under anaerobic conditions in the presence of fumarate or malate. Enzymes with the FRD-like domain architecture are widely distributed among various bacteria and apparently comprise a new type of water-soluble NADH:fumarate oxidoreductases.

Effects of lactate and glutamine on palmitate metabolism in rat kindey cortex

1976 ◽  
Vol 231 (1) ◽  
pp. 14-19 ◽  
Author(s):  
M Barac-Nieto
Keyword(s):  
Renal Cortex ◽  
Palmitate Oxidation ◽  
The Media ◽  
High Concentrations ◽  
Rat Renal Cortical Slices ◽  
Very High ◽  
Cortical Slices ◽  
Palmitate Metabolism ◽  
Low Rate

Rat renal cortical slices were incubated with [1-(14)C]palmitate bound to 2.5% albumin. The following effects were found: a)1 mM palmitate utilization or oxidation to CO(2) varied according to the concentration of lactate in the media, it increased at 0.8 and 3.2 mM, was unchanged at 8 mM, and decreased at 16 mM. Esterification was stimulated at 3.2 mM lactate. b) Addition of glutamine (0.1 mM) instead of lactate stimulated incomplete and complete oxidation of palmitate (1 mM), whereas high medium glutamine (10 mM) inhibited palmitate (1 mM) utilization, esterification, and oxidation to CO(2) but increased its incomplete oxidation. The low rate of exogenous palmitate oxidation observed in this study and the finding that exogenous palmitate oxidation is only partially inhibited at very high concentrations of exogenous lactate or glutamine are consistent with the view that these exogenous substrates contribute little to the oxidative metabolism of rat renal cortex in vitro, which probably depends on the supply of substrates endogenous to the tissue.

The Influence of Nitrogen on Phosphorus Removal in Activated Sludge Plants

1982 ◽  
Vol 14 (1-2) ◽  
pp. 31-45 ◽  
Author(s):  
J L Barnard
Keyword(s):  
Organic Carbon ◽  
Activated Sludge ◽  
Phosphorus Removal ◽  
Complete Removal ◽  
Phosphate Removal ◽  
Electron Donors ◽  
Biological Phosphorus Removal ◽  
Anaerobic Conditions ◽  
Low Level ◽  
Biological Phosphorus

This paper discusses the need for anaerobiases as a pre-requisite for phosphorus removal in activated sludge plants and the effect of nitrates on the anaerobic conditions. If the plant could be operated to avoid nitrification, biological phosphorus removal presents no problems. When nitrification is required, the nitrates must be reduced to a low level through internal denitrification. If sufficient carbon is available to ensure complete removal of the nitrates and anaerobic conditions in a specific zone in the plant, good phosphate removal can be ensured. Below COD : TKN ratios of 10 : 1 it is becoming more difficult to control the plant and special care should be taken to determine not only the quantity of organic carbon available as electron donors for removal of the nitrates but also the form in which it arrives at the plant.

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