DEGRADATION STUDIES WITH 14C-FENOXAPROP IN PRAIRIE SOILS

1990 ◽  
Vol 70 (3) ◽  
pp. 343-350 ◽  
Author(s):  
A. E. SMITH ◽  
A. J. AUBIN
Keyword(s):  
Soil Microbial Biomass ◽  
Field Capacity ◽  
First Order ◽  
Soil Microbial ◽  
Prairie Soils ◽  
First Order Kinetics ◽  
Ring Fission ◽  
Capacity Degradation ◽  
Soil Temperatures ◽  
Moisture Conditions

The persistence of 14C-fenoxaprop acid, the major degradation product of the herbicide 14C-fenoxaprop-ethyl, was studied at different controlled temperature and moisture conditions in three Saskatchewan soils. At 85% of field capacity, degradation approximated to first-order kinetics at soil temperatures of 10, 20, and 30 °C, with half-life values ranging from 42 to 5 d. In a clay at 20 °C, there was no effect of moisture, between 50% and 100% field capacity, on the rate of 14C-fenoxaprop acid breakdown. There was no loss of radioactivity after 65-d in air dry soils. In all soils incubated at 85% field capacity and 20 °C with 14C-fenoxaprop-ethyl, uniformly labeled in the chlorophenyl ring, there was evolution of 14CO2 indicating ring fission. Over a 56-d incubation period, 10–15% of the applied radioactivity was released from the treated soils as 14CO2. Extraction with ammoniated acetonitrile recovered 14–19% of the original radioactivity; between 3 and 5% of the initial 14C was incorporated into soil microbial biomass; and 17–25% into the fulvic acid, 7–12% into the humic acid, and 30–34% into the humin soil fractions. Key words: Herbicide, biomass, fenoxaprop-ethyl, fenoxaprop, persistence

scholarly journals Modelling organic matter dynamics in different soils.

1990 ◽  
Vol 38 (3A) ◽  
pp. 221-238 ◽  
Author(s):  
E.L.J. Verberne ◽  
J. Hassink ◽  
P. de Willigen ◽  
J.J.R. Groot ◽  
J.A. van Veen
Keyword(s):  
Organic Matter ◽  
Soil Organic Matter ◽  
Microbial Biomass ◽  
Soil Microbial Biomass ◽  
State Level ◽  
N Cycling ◽  
First Order ◽  
Soil Microbial ◽  
First Order Kinetics ◽  
Different Soils

A mathematical model was developed to describe carbon (C) and nitrogen (N) cycling in different soil types, e.g. clay and sandy soils. Transformation rates were described by first-order kinetics. Soil organic matter is divided into four fractions (including microbial biomass pool) and three fractions of residues. The fraction of active soil organic matter was assumed to be affected by the extent of physical protection within the soil, as was the soil microbial biomass. The extent of protection influenced the steady state level of the model, and, hence, the mineralization rates. The mineralization rate in fine-textured soils is lower than in coarse-textured soils; in fine-textured soils a larger proportion of the soil organic matter may be physically protected. The availability of organic materials as a substrate for microorganisms is not only determined by their chemical composition, but also by their spatial distribution in the soil. (Abstract retrieved from CAB Abstracts by CABI’s permission)

scholarly journals Composition of Soil Microbial Communities Enriched on a Mixture of Aromatic Hydrocarbons

2000 ◽  
Vol 66 (12) ◽  
pp. 5282-5289 ◽  
Author(s):  
E. Anne Greene ◽  
Jason G. Kay ◽  
Karim Jaber ◽  
Les G. Stehmeier ◽  
Gerrit Voordouw
Keyword(s):  
Aromatic Hydrocarbons ◽  
Contaminated Soils ◽  
Soil Microbial Communities ◽  
Time Dependent ◽  
Community Members ◽  
First Order ◽  
Soil Microbial ◽  
Benzene Degradation ◽  
First Order Kinetics ◽  
Genomic Dnas

ABSTRACT Soil contaminated with C5+, which contained benzene (45%, wt/wt), dicyclopentadiene (DCPD) plus cyclopentadiene (together 20%), toluene (6%), styrene (3%), xylenes (2%), naphthalene (2%), and smaller quantities of other compounds, served as the source for isolation of 55 genomically distinct bacteria (standards). Use of benzene as a substrate by these bacteria was most widespread (31 of 44 standards tested), followed by toluene (23 of 44), xylenes (14 of 44), styrene (10 of 44), and naphthalene (10 of 44). Master filters containing denatured genomic DNAs of all 55 standards were used to analyze the community compositions of C5+ enrichment cultures by reverse sample genome probing (RSGP). The communities enriched from three contaminated soils were similar to those enriched from three uncontaminated soils from the same site. The compositions of these communities were time dependent and showed a succession of Pseudomonas andRhodococcus spp. before convergence on a composition dominated by Alcaligenes spp. The dominant community members detected by RSGP were capable of benzene degradation at all stages of succession. The enrichments effectively degraded all C5+ components except DCPD. Overall, degradation of individual C5+ hydrocarbons followed first-order kinetics, with the highest rates of removal for benzene.

Persistence of Several Dinitroaniline Herbicides as Affected by Soil Moisture

Weed Science ◽  
1978 ◽  
Vol 26 (5) ◽  
pp. 465-471 ◽  
Author(s):  
K. E. Savage
Keyword(s):  
Soil Moisture ◽  
Dissipation Rate ◽  
Sandy Loam ◽  
Field Capacity ◽  
Soil Types ◽  
Moist Soil ◽  
First Order ◽  
First Order Kinetics ◽  
Dissipation Rates ◽  
Dinitroaniline Herbicides

The Persistence of substituted dinitroaniline herbicides in soil varied widely. First-order kinetics were used to describe the dissipation rates. Half-lives of the herbicides in moist soil ranged from 29 to 124 days in two soil types under greenhouse conditions. Flooding the soil significantly increased the dissipation rate of trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine), fluchloralin [N-(2-chloroethyl)-2,6-dinitro-N-propyl-4-(trifluoromethyl)aniline], profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine], and pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine]. Dissipation rates of dinitramine(N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) and butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] were affected to a lesser extent by flooding. Volatilization of trifluralin, fluchloralin, and ethalfluralin [N-ethyl-N-(2-methyl-2-propenyl)-2,6-dinitro-4-(trifluoromethyl)benzenamine] from Bosket sandy loam was reduced by flooding when compared to volatilization from the same soil with a moisture content equivalent to field capacity. Pendimethalin exhibited low volatility. The effect of flooding on dissipation rates is apparently not due to increased volatilization.

scholarly journals Variations in Soil Properties and CO2 Emissions of a Temperate Forest Gully Soil along a Topographical Gradient

Forests ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 226
Author(s):  
Anna Walkiewicz ◽  
Piotr Bulak ◽  
Małgorzata Brzezińska ◽  
Mohammad I. Khalil ◽  
Bruce Osborne
Keyword(s):  
Microbial Biomass ◽  
Soil Respiration ◽  
Co2 Emissions ◽  
Catalase Activity ◽  
Soil Microbial Biomass ◽  
Total N ◽  
Organic C ◽  
Soil Microbial ◽  
N Concentration ◽  
Moisture Conditions

Although forest soils play an important role in the carbon cycle, the influence of topography has received little attention. Since the topographical gradient may affect CO2 emissions and C sequestration, the aims of the study were: (1) to identify the basic physicochemical and microbial parameters of the top, mid-slope, and bottom of a forest gully; (2) to carry out a quantitative assessment of CO2 emission from these soils incubated at different moisture conditions (9% and 12% v/v) and controlled temperature (25 °C); and (3) to evaluate the interdependence between the examined parameters. We analyzed the physicochemical (content of total N, organic C, pH, clay, silt, and sand) and microbial (enzymatic activity, basal respiration, and soil microbial biomass) parameters of the gully upper, mid-slope, and bottom soil. The Fourier Transformed Infrared spectroscopy (FTIR) method was used to measure CO2 emitted from soils. The position in the forest gully had a significant effect on all soil variables with the gully bottom having the highest pH, C, N concentration, microbial biomass, catalase activity, and CO2 emissions. The sand content decreased as follows: top > bottom > mid-slope and the upper area had significantly lower clay content. Dehydrogenase activity was the lowest in the mid-slope, probably due to the lower pH values. All samples showed higher CO2 emissions at higher moisture conditions, and this decreased as follows: bottom > top > mid-slope. There was a positive correlation between soil CO2 emissions and soil microbial biomass, pH, C, and N concentration, and a positive relationship with catalase activity, suggesting that the activity of aerobic microorganisms was the main driver of soil respiration. Whilst the general applicability of these results to other gully systems is uncertain, the identification of the slope-related movement of water and inorganic/organic materials as a significant driver of location-dependent differences in soil respiration, may result in some commonality in the changes observed across different gully systems.

Degradation of Pendimethalin in Soil

Weed Science ◽  
1984 ◽  
Vol 32 (3) ◽  
pp. 408-412 ◽  
Author(s):  
Robert L. Zimdahl ◽  
Pietro Catizone ◽  
Ann C. Butcher
Keyword(s):  
Soil Moisture ◽  
Chemical Analysis ◽  
Soil Temperature ◽  
Soil Type ◽  
Half Life ◽  
Field Capacity ◽  
Quadratic Model ◽  
Laboratory Studies ◽  
First Order ◽  
First Order Kinetics

Pendimethalin [N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine] degradation in three soils did not follow first-order kinetics but could be described by a quadratic model. Degradation increased as soil temperature increased in the order 10, 20, 35, and 30C. The rate was the same as 75 and 100% field capacity but slower at 50%. At the same temperature and soil moisture the influence of soil type was small. Based on chemical analysis of soil from field and laboratory studies, the half-life was approximately 47 days. Based on biological analyses of soil, the half-life was 78 to 111 days.

Photo-catalytic degradation of gaseous pollutants in paper mills of southern China

TAPPI Journal ◽  
2018 ◽  
Vol 17 (03) ◽  
pp. 167-178 ◽  
Author(s):  
Xin Tong ◽  
Jiao Li ◽  
Jun Ma ◽  
Xiaoquan Chen ◽  
Wenhao Shen
Keyword(s):  
Degradation Rate ◽  
Southern China ◽  
Catalytic Degradation ◽  
Pulp And Paper ◽  
Gaseous Pollutants ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Initial Concentration ◽  
First Order ◽  
First Order Kinetics

Studies were undertaken to evaluate gaseous pollutants in workplace air within pulp and paper mills and to consider the effectiveness of photo-catalytic treatment of this air. Ambient air at 30 sampling sites in five pulp and paper mills of southern China were sampled and analyzed. The results revealed that formaldehyde and various benzene-based molecules were the main gaseous pollutants at these five mills. A photo-catalytic reactor system with titanium dioxide (TiO2) was developed and evaluated for degradation of formaldehyde, benzene and their mixtures. The experimental results demonstrated that both formaldehyde and benzene in their pure forms could be completely photo-catalytic degraded, though the degradation of benzene was much more difficult than that for formaldehyde. Study of the photo-catalytic degradation kinetics revealed that the degradation rate of formaldehyde increased with initial concentration fitting a first-order kinetics reaction. In contrast, the degradation rate of benzene had no relationship with initial concentration and degradation did not conform to first-order kinetics. The photo-catalytic degradation of formaldehyde-benzene mixtures indicated that formaldehyde behaved differently than when treated in its pure form. The degradation time was two times longer and the kinetics did not reflect a first-order reaction. The degradation of benzene was similar in both pure form and when mixed with formaldehyde.

Kinetic of oxidation of methyl orange by vanadium(V) under conditions VO2+ and decavanadates coexist: Catalysis by Triton X-100 micellar medium

2019 ◽  
Author(s):  
Chem Int
Keyword(s):  
Methyl Orange ◽  
Solution Ph ◽  
Vanadium Concentration ◽  
Limiting Behavior ◽  
First Order ◽  
First Order Kinetics ◽  
Ph Range ◽  
Kinetic Pattern ◽  
Triton X ◽  
Kinetics Of

The kinetics of oxidation of methyl orange by vanadium(V) {V(V)} has been investigated in the pH range 2.3-3.79. In this pH range V(V) exists both in the form of decavanadates and VO2+. The kinetic results are distinctly different from the results obtained for the same reaction in highly acidic solution (pH < 1) where V(V) exists only in the form of VO2+. The reaction obeys first order kinetics with respect to methyl orange but the rate has very little dependence on total vanadium concentration. The reaction is accelerated by H+ ion but the dependence of rate on [H+] is less than that corresponding to first order dependence. The equilibrium between decavanadates and VO2+ explains the different kinetic pattern observed in this pH range. The reaction is markedly accelerated by Triton X-100 micelles. The rate-[surfactant] profile shows a limiting behavior indicative of a unimolecular pathway in the micellar pseudophase.

Biodegradation rates of aromatic contaminants in biofilm reactors

1995 ◽  
Vol 31 (1) ◽  
pp. 117-128 ◽  
Author(s):  
Jean-Pierre Arcangeli ◽  
Erik Arvin
Keyword(s):  
Aromatic Hydrocarbons ◽  
Competitive Inhibition ◽  
Removal Rate ◽  
First Order ◽  
Biofilm Reactors ◽  
First Order Kinetics ◽  
Reducing Conditions ◽  
Low Concentrations ◽  
Degradation Rates ◽  
Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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