A LABORATORY STUDY OF GLEYING

1965 ◽  
Vol 45 (2) ◽  
pp. 199-206 ◽  
Author(s):  
J. A. McKeague
Keyword(s):  
Organic Matter ◽  
Acetic Acid ◽  
Room Temperature ◽  
Rate Of Change ◽  
Redox Potentials ◽  
Soil Columns ◽  
Flooded Soils ◽  
Soil Material ◽  
Effects Of Temperature ◽  
Extractable Iron

Columns of different soil materials with ground leaves at the surface were maintained for 18 months with the water table continuously above the surface, or fluctuating between the surface and 15 cm. Redox potentials, colors, and extractable iron were determined. The effects of temperature and of organic matter on the rate of change of Eh were studied with flooded soils in test tubes.The rate and degree of development of dull colors and mottling in the soil columns was influenced greatly by the nature of the soil material. Reduction effected marked increases in acetic acid extractable iron from all of the soil materials. Low redox potentials developed rapidly at room temperature in flooded soils containing appreciable amounts of organic matter. Eh values below 0 mv developed slowly in soils at 1 °C and at room temperature in some soils that were almost devoid of organic matter. Release of Fe+2 from ferrous minerals was thought to account for these low Eh values.

Phosphate sorption by reduced and reoxidized rice soils

Soil Research ◽  
1978 ◽  
Vol 16 (3) ◽  
pp. 319 ◽  
Author(s):  
IR Willett ◽  
ML Higgins
Keyword(s):  
Organic Matter ◽  
Clay Content ◽  
Oxide Content ◽  
Phosphorus Sorption ◽  
Flooded Soils ◽  
Rice Soils ◽  
Rice Plants ◽  
Hydrous Oxides ◽  
Eastern Australia ◽  
Extractable Iron

Intact cores of two rice soils of south-eastern Australia were flooded for 146 days to simulate part of a rice-upland crop rotation. The phosphorus sorptivity, and acetate (pH 4.8) and oxalate (pH 3.0) extractable iron levels were monitored for 210 days, before, during and after flooding. The effects of additional organic matter (rice straw) and the growing of rice plants were examined. In non-flooded soils phosphorus sorptivity was mainly influenced by clay content; there were no relationships between extractable iron and phosphorus sorbed. On flooding there were large increases in acetate and oxalate extractable iron and phosphorus sorptivity. Additional organic matter initially increased the rates of formation of extractable iron, and phosphorus sorptivity increased accordingly. However, with prolonged waterlogging, levels of oxalate iron and phosphorus sorptivity reached values dependent on the free iron oxide content of the soils. The growth of rice plants had no significant effects on phosphorus sorptivity or extractable iron at any time of sampling. During oxidation of previously flooded soils, levels of phosphorus sorptivity and oxalate iron decreased rapidly, but did not return to levels occurring before reduction. The results are consistent with domination of phosphorus sorption processes by ferrous hydrous oxides during the flooded (reduced) phase and by poorly crystalline ferric hydrous oxides during the post-flooding reoxidation phase. Agronomic implications of the results are mentioned.

scholarly journals How Small Molecules Affect the Thermo-Oxidative Aging Mechanism of Polypropylene: A Reactive Molecular Dynamics Study

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1243
Author(s):  
Fan Zhang ◽  
Yufei Cao ◽  
Xuan Liu ◽  
Huan Xu ◽  
Diannan Lu ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Acetic Acid ◽  
Small Molecules ◽  
Aging Process ◽  
Experimental Studies ◽  
Hydroxyl Group ◽  
Oxidative Aging ◽  
Reactive Molecular Dynamics ◽  
Aging Mechanism ◽  
Effects Of Temperature

Understanding the aging mechanism of polypropylene (PP) is fundamental for the fabrication and application of PP-based materials. In this paper, we present our study in which we first used reactive molecular dynamics (RMD) simulations to explore the thermo-oxidative aging of PP in the presence of acetic acid or acetone. We studied the effects of temperature and oxygen on the aging process and discussed the formation pathways of typical small molecule products (H2, CO, CO2, CH4, C2H4, and C2H6). The effect of two infection agents, acetic acid and acetone, on the aging reaction was analyzed emphatically. The simulation results showed that acetone has a weak impact on accelerating the aging process, while acetic acid has a significant effect, consistent with previous experimental studies. By tracking the simulation trajectories, both acetic acid and acetone produced small active free radicals to further react with other fragment products, thus accelerating the aging process. The first reaction step of acetic acid is often the shedding of the H atom on the hydroxyl group, while the reaction of acetone is often the shedding of the H atom or the methyl. The latter requires higher energy at lower temperatures. This is why the acceleration effect of acetone for the thermo-oxidative aging of PP was not so significant compared to acetic acid in the experimental temperature (383.15 K).

Color and Antioxidant Changes in Various Natural Rubber Processes

2015 ◽  
Vol 754-755 ◽  
pp. 230-234 ◽  
Author(s):  
Suwimon Siriwong ◽  
Adisai Rungvichaniwat ◽  
Pairote Klinpituksa ◽  
Khalid Hamid Musa ◽  
Aminah Abdullah
Keyword(s):  
Acetic Acid ◽  
Natural Rubber ◽  
Retention Index ◽  
Total Phenolic Content ◽  
Room Temperature ◽  
Phenolic Content ◽  
Total Phenolic ◽  
Lovibond Colorimeter

Fresh field natural rubber was coagulated by acetic acid, soaked in water at room temperature (WRT) or 70°C (W70) for 1 hr, and then dried in an oven at 40°C. Non-soaked natural rubber samples (NoW) served as a control. Two grades of natural rubber, namely air-dry sheet (ADS) and ribbed smoked sheet No.3 (RSS3) derived from the same latex, were also investigated. All dry rubber samples were characterized with Lovibond colorimeter according to ASTM D3157, as well as with a HunterLab spectrophotometer. Furthermore, all the dry rubber samples were dissolved in a chloroform:methanol mixture (4:1 v:v). The rubber was then precipitated out of the solution with methanol, and the remaining solution was quantitatively analyzed for total phenolic content (TPC). The plasticity retention index (PRI) was determined for all the dried rubber samples according to ASTM D3194. It was found that WRT, W70 and ADS were similar in lightness L*, while RSS3 had the lowest L*. W70 had the lowest redness a*, which increased in the order WRT, NoW, RSS3 and ADS. W70 also had the lowest yellowness b*, which increased in the order RSS3, NoW and WRT and ADS. Moreover, TPC was the lowest for the W70 sample, increasing in the order ADS, WRT, NoW and RSS3. The PRI was highest for W70, and decreased in the order WRT, RSS3, NoW and ADS. All of the PRI values observed were comparatively high relative to blocked standard Thai rubber 20 (STR20).

scholarly journals Synthesis of spiro[dihydropyridine-oxindoles] via three-component reaction of arylamine, isatin and cyclopentane-1,3-dione

2013 ◽  
Vol 9 ◽  
pp. 8-14 ◽  
Author(s):  
Yan Sun ◽  
Jing Sun ◽  
Chao-Guo Yan
Keyword(s):  
Acetic Acid ◽  
Reaction Mechanism ◽  
Room Temperature ◽  
The Other ◽  
Other Hand ◽  
Three Component Reaction ◽  
High Yields

A fast and convenient protocol for the synthesis of novel spiro[dihydropyridine-oxindole] derivatives in satisfactory yields was developed by the three-component reactions of arylamine, isatin and cyclopentane-1,3-dione in acetic acid at room temperature. On the other hand the condensation of isatin with two equivalents of cyclopentane-1,3-dione gave 3,3-bis(2-hydroxy-5-oxo-cyclopent-1-enyl)oxindole in high yields. The reaction mechanism and substrate scope of this novel reaction is briefly discussed.

Removal Efficiency of Three Cold-Climate Constructed Wetlands Treating Domestic Wastewater: Effects of Temperature, Seasons, Loading Rates and Input Concentrations

1999 ◽  
Vol 40 (3) ◽  
pp. 273-281 ◽  
Author(s):  
Trond Mæhlum ◽  
Per Stålnacke
Keyword(s):  
Organic Matter ◽  
Constructed Wetlands ◽  
Domestic Wastewater ◽  
Cold Climate ◽  
Treatment Efficiency ◽  
Loading Rates ◽  
P Sorption ◽  
Percentage Points ◽  
Effects Of Temperature ◽  
Pre Treatment

This paper outlines the influence of temperature, flow rate and input concentrations on the treatment efficiency of organic matter and nutrients in constructed wetlands (CWs). Three integrated 10 PE systems with horizontal subsurface flow (HSF) treating domestic wastewater are described. Particular attention is devoted to: (1) aerobic pre-treatment in vertical-flow filters, (2) filter media with high phosphorus (P) sorption capacity, and (3) the treatment efficiency during winters. Aerobic pre-treatment followed by CW units including P sorption media removed most organic matter (BOD> 75%), P (> 90%) and total and ammonia N (40-80%). P retention was relatively stable in wetland filters, both with lightweight aggregates and ferruginous sand during 3-6 years of monitoring. Iron-rich sand from Bsh and Bs horizons of ferro-humic podzols was efficient for P sorption, but removal efficiencies of COD, TOC and SS were negative. The differences in efficiency between cold and warm periods were less than 10 percentage points for all parameters. It is anticipated that temperature effects are partially compensated by the large hydraulic retention time. The findings suggest that HSF systems do not require vegetation.

scholarly journals Chemisorption of acetic acid onSi(100)−2×1at room temperature

2008 ◽  
Vol 77 (11) ◽  
Author(s):  
Han-Koo Lee ◽  
Ki-jeong Kim ◽  
Jin-hee Han ◽  
Tai-Hee Kang ◽  
J. W. Chung ◽  
...  
Keyword(s):  
Acetic Acid ◽  
Room Temperature

Mitigating the Antimicrobial Activities of Selected Organic Acids and Commercial Sanitizers with Various Neutralizing Agents

2011 ◽  
Vol 74 (5) ◽  
pp. 820-825 ◽  
Author(s):  
YOEN JU PARK ◽  
JINRU CHEN
Keyword(s):  
Escherichia Coli ◽  
Acetic Acid ◽  
Lactic Acid ◽  
Organic Acids ◽  
Shiga Toxin ◽  
Room Temperature ◽  
Sodium Thiosulfate ◽  
Antimicrobial Activities ◽  
Phosphate Buffered Saline ◽  
Lactic Acids

This study was conducted to evaluate the abilities of five neutralizing agents, Dey-Engley (DE) neutralizing broth (single or double strength), morpholinepropanesulfonic acid (MOPS) buffer, phosphate-buffered saline (PBS), and sodium thiosulfate buffer, in mitigating the activities of acetic or lactic acid (2%) and an alkaline or acidic sanitizer (a manufacturer-recommended concentration) againt the cells of Shiga toxin–producing Escherichia coli (STEC; n = 9). To evaluate the possible toxicity of the neutralizing agents to the STEC cells, each STEC strain was exposed to each of the neutralizing agents at room temperature for 10 min. Neutralizing efficacy was evaluated by placing each STEC strain in a mixture of sanitizer and neutralizer under the same conditions. The neutralizing agents had no detectable toxic effect on the STEC strains. PBS was least effective for neutralizing the activity of selected organic acids and sanitizers. Single-strength DE and sodium thiosulfate neutralized the activity of both acetic and lactic acids. MOPS buffer neutralized the activity of acetic acid and lactic acid against six and five STEC strains, respectively. All neutralizing agents, except double-strength DE broth, had a limited neutralizing effect on the activity of the commercial sanitizers used in the study. The double-strength DE broth effectively neutralized the activity of the two commercial sanitizers with no detectable toxic effects on STEC cells.

scholarly journals Effects of changing land use in the Netherlands on net carbon fixation.

1991 ◽  
Vol 39 (4) ◽  
pp. 237-246 ◽  
Author(s):  
J. Wolf ◽  
L.H.J.M. Janssen
Keyword(s):  
Land Use ◽  
Organic Matter ◽  
Soil Organic Matter ◽  
The Netherlands ◽  
Input Data ◽  
Carbon Fixation ◽  
Arable Land ◽  
Rate Of Change ◽  
Pool Size ◽  
Average Amount

The changed crop rotation on arable land, the decreasing grassland area and the increase in forest area in the Netherlands resulted in a decrease in C pool size. For the calculation of this C pool a method requiring only three input data (average amount of crop or tree residue rate, soil organic matter decomposition and the humification coefficient) has been applied. However the method can only be applied to situations in equilibrium where all three input data are equal. For a changing land use a new state of equilibrium and rate of change in C pool size can be calculated. (Abstract retrieved from CAB Abstracts by CABI’s permission)

Sign in / Sign up

Export Citation Format

Share Document