Water repellency and distribution of hydrophilic and hydrophobic compounds in soil aggregates from different tillage systems

Geoderma ◽  
2007 ◽  
Vol 140 (1-2) ◽  
pp. 147-155 ◽  
Author(s):  
E. Urbanek ◽  
P. Hallett ◽  
D. Feeney ◽  
R. Horn
Keyword(s):  
Soil Aggregates ◽  
Water Repellency ◽  
Tillage Systems ◽  
Hydrophobic Compounds ◽  
Hydrophilic And Hydrophobic Compounds

The role of tree stem proximity in the spatial variability of soil water repellency in a eucalypt plantation in coastal Portugal

Soil Research ◽  
2005 ◽  
Vol 43 (3) ◽  
pp. 251 ◽  
Author(s):  
J. J. Keizer ◽  
A. J. D. Ferreira ◽  
C. O. A. Coelho ◽  
S. H. Doerr ◽  
M. C. Malvar ◽  
...  
Keyword(s):  
Soil Water ◽  
Water Repellency ◽  
Soil Water Repellency ◽  
Individual Measurement ◽  
Hydrophobic Compounds ◽  
Ethanol Droplet ◽  
Central Portugal ◽  
Living Organisms ◽  
Tree Stem

Certain organic compounds derived from living organisms or their decaying parts are generally accepted to induce soil water repellency. Water repellency may therefore be expected to increase with proximity to organisms releasing hydrophobic compounds. This hypothesis is tested here for Eucalyptus globulus trees, since eucalypt species are frequently associated with elevated repellency levels. In a young, first-rotation plantation on coastal dune sands in central Portugal, repeat measurements of water repellency using the ‘Molarity of an Ethanol Droplet’ (MED) test were carried out in situ between April 2001 and May 2002. On 25 dates, repellency was measured at initially 2 and later 3 distances on 2 sides of 8–11 randomly selected trees. On 15 occasions, additional repellency measurements were performed within small grids aside 3 of the selected trees. The postulated decrease in topsoil water repellency with increased distance from eucalypt tree stems was found to apply on several individual measurement dates, as well as, more unexpectedly since repellency usually is a transient phenomenon, for the study period as a whole. The results confirm the general association of eucalypt trees with water repellency, and indicate that tree stem proximity is an important but not sufficient factor to explain repellency distribution in topsoil.

Bacterial cleanup: lateral diffusion of hydrophobic molecules through protein channel walls

2010 ◽  
Vol 1 (3-4) ◽  
pp. 263-270 ◽  
Author(s):  
Bert van den Berg
Keyword(s):  
Diffusion Mechanism ◽  
Lateral Diffusion ◽  
Biofuel Production ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Hydrophobic Compounds ◽  
Protein Channel ◽  
Biochemical Research ◽  
Established Role ◽  
Hydrophilic And Hydrophobic Compounds

AbstractThe outer membrane (OM) of Gram-negative bacteria forms a very efficient barrier against the permeation of both hydrophilic and hydrophobic compounds, owing to the presence of lipopolysaccharides on the outside of the cell. Although much is known about the OM passage of hydrophilic molecules, it is much less clear how hydrophobic molecules cross this barrier. Members of the FadL channel family, which are widespread in Gram-negative bacteria, are so far the only proteins with an established role in the uptake of hydrophobic molecules across the OM. Recent structural and biochemical research has shown that these channels operate according to a unique lateral diffusion mechanism, in which the substrate moves from the lumen of the barrel into the OM via an unusual opening in the wall of the barrel. Understanding how hydrophobic molecules cross the OM is not only of fundamental importance but could also have applications in the design of novel, hydrophobic drugs, biofuel production and the generation of more efficient bacterial biodegrader strains.

scholarly journals Factors Determining Soil Water Repellency in Two Coniferous Plantations on a Hillslope

Forests ◽  
2019 ◽  
Vol 10 (9) ◽  
pp. 730 ◽  
Author(s):  
Moein Farahnak ◽  
Keiji Mitsuyasu ◽  
Kyoichi Otsuki ◽  
Kuniyoshi Shimizu ◽  
Atsushi Kume
Keyword(s):  
Soil Water ◽  
Overland Flow ◽  
Soil Aggregates ◽  
Aggregate Size ◽  
Water Repellency ◽  
Soil Aggregate ◽  
Water Infiltration ◽  
Soil Water Repellency ◽  
Tree Cutting ◽  
Coniferous Plantations

Soil water repellency (SWR) is a cause of low water infiltration, overland flow and soil erosion in mountainous coniferous plantations in Japan. The factors determining SWR intensity were investigated in two coniferous plantations of Chamaecyparis obtusa (Siebold et Zucc.) Endl. and Cryptomeria japonica (L.f.) D. Don, using intact tree plots and cut tree plots on the same hillslope. The SWR of Ch. obtusa plots was stronger than that of Cr. japonica plots. SWR intensity decreased after tree cutting. There were no significant differences in SWR upslope and downslope of individual trees/stumps for both tree species, though areas downslope of individual Ch. obtusa trees had higher SWR intensity than those upslope. SWR intensity and soil aggregate stability were positively correlated in the Ch. obtusa intact tree plot (r = 0.88, p < 0.01), whereas in the cut tree plot, this correlation was weak with no significance (r = 0.29, p = 0.41). Soil aggregate size had a non-significant influence on SWR intensity. These findings suggest that SWR intensity was not related to the soil aggregate size, but SWR intensity seemed have a role in soil aggregation in the Ch. obtusa intact tree plot. Destruction of soil aggregates could occur after tree cutting because of physical disturbances or increased input of different types of organic matter from other vegetation into soil. The presence of Ch. obtusa introduces a source of SWR, although uncertainty remains about how water repellency is distributed around soil aggregates. The distribution pattern of soil water content and soil hydraulic conductivity around Cr. japonica was related to other factors such as the litter layer and non-water-repellant soil.

Preferential uptake of hydrophilic and hydrophobic compounds by bacteria and fungi in upland and paddy soils

2020 ◽  
Vol 148 ◽  
pp. 107879
Author(s):  
Yinhang Xia ◽  
Xiangbi Chen ◽  
Xiaodong Zheng ◽  
Shaohong Deng ◽  
Yajun Hu ◽  
...  
Keyword(s):  
Paddy Soils ◽  
Hydrophobic Compounds ◽  
Preferential Uptake ◽  
Bacteria And Fungi ◽  
Hydrophilic And Hydrophobic Compounds

scholarly journals Eucalyptus reforestation induces soil water repellency

Soil Research ◽  
2015 ◽  
Vol 53 (2) ◽  
pp. 168 ◽  
Author(s):  
L. L. Walden ◽  
R. J. Harper ◽  
D. S. Mendham ◽  
D. J. Henry ◽  
J. B. Fontaine
Keyword(s):  
Soil Properties ◽  
Soil Water ◽  
Water Movement ◽  
Computer Modelling ◽  
Clay Content ◽  
Water Repellency ◽  
Water Repellent ◽  
Organic Carbon Content ◽  
Soil Water Repellency ◽  
Hydrophobic Compounds

There is an increasing interest in eucalypt reforestation for a range of purposes in Australia, including pulp-wood production, carbon mitigation and catchment water management. The impacts of this reforestation on soil water repellency have not been examined despite eucalypts often being associated with water repellency and water repellency having impacts on water movement across and within soils. To investigate the role of eucalypt reforestation on water repellency, and interactions with soil properties, we examined 31 sites across the south-west of Western Australia with paired plots differing only in present land use (pasture v. plantation). The incidence and severity of water repellency increased in the 5–8 years following reforestation with Eucalyptus globulus. Despite this difference in water repellency, there were no differences in soil characteristics, including soil organic carbon content or composition, between pasture and plantation soils, suggesting induction by small amounts of hydrophobic compounds from the trees. The incidence of soil water repellency was generally greater on sandy-surfaced (<10% clay content) soils; however, for these soils 72% of the pasture sites and 31% of the plantation were not water repellent, and this was independent of measured soil properties. Computer modelling revealed marked differences in the layering and packing of waxes on kaolinite and quartz surfaces, indicating the importance of interfacial interactions in the development of soil water repellency. The implications of increased water repellency for the management of eucalyptus plantations are considered.

scholarly journals Evaluation of Immobilization of Selected Peat-Isolated Yeast Strains of the Species Candida albicans and Candida subhashii on the Surface of Artificial Support Materials Used for Biotrickling Filtration

Processes ◽  
2020 ◽  
Vol 8 (7) ◽  
pp. 801
Author(s):  
Milena Marycz ◽  
Anna Brillowska-Dąbrowska ◽  
Jacek Gębicki
Keyword(s):  
Flow Cytometry ◽  
Candida Albicans ◽  
Propidium Iodide ◽  
Annexin V ◽  
Support Materials ◽  
Hydrophobic Compounds ◽  
Yeast Strains ◽  
Different Types ◽  
Materials Used ◽  
Hydrophilic And Hydrophobic Compounds

The paper describes the process of n-butanol abatement by unicellular fungi, able to deplete n-butanol content in gas, by using n-butanol as source of carbon. Isolated and identified fungi species Candida albicans and Candida subhashii were subjected to a viability process via assimilation of carbon from hydrophilic and hydrophobic compounds. The isolates, which exhibited the ability to assimilate carbon, were immobilized on four different types of artificial support materials used for biotrickling filtration. Application of optical microscopy, flow cytometry and the tests employing propidium iodide and annexin V revealed viability of the fungi isolated on support materials’ surfaces at the average level of 95%. The proposed method of immobilization and its evaluation appeared to be effective, cheap and fast. Based on performed comparative analyses, it was shown that polyurethane foam and Bialecki rings (25 × 25) could be attractive support materials in biotrickling filtration.

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