Submicroscopic measurements of tracer distribution related to surface features of soil aggregates

Nobles, M. M.; Wilding, L. P.; McInnes, Kevin J.

doi:10.1016/j.geoderma.2004.01.028

Cited by 9 publications

(6 citation statements)

References 22 publications

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“…Unstained aggregate coatings or infilling, which were observed in all horizons, demonstrate the low potential of Brilliant Blue FCF molecules to penetrate into the smaller pores and especially into spatially oriented clay particles (Nobles et al, 2004, 2010). This also indicates, however, that even water flow must be slowed down, as for aggregates with clay coatings documented in the studies of Gerke and Köhne (2002) and Köhne et al (2002).…”

Section: Resultsmentioning

confidence: 92%

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Using Dye Tracer for Visualization of Preferential Flow at Macro‐ and Microscales

Kodešová

Němeček

Kodeš

et al. 2012

Vadose Zone Journal

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The detection of a nonequilibrium water flow and solute transport in structured soil at various scales is essential for better understanding of these phenomena. This study focused on the visualization of preferential flow in a Haplic Luvisol and Haplic Cambisol and their horizons by performing field ponding dye infiltration experiments. In addition, thin soil sections were made and micromorphological images were used to study soil aggregate structure and dye distribution at the microscale. The staining patterns within the vertical and horizontal field‐scale sections documented the different nature of preferential flow in different soil types and also within the soil profiles. While preferential flow in the Haplic Luvisol was caused by soil aggregation and biopores, preferential flow in the Haplic Cambisol was caused only by biopores, large soil fractures, and incorporated straw material. Micromorphological images showed that, in the case of the Haplic Luvisol, the dye was primarily distributed either in the interaggregate pores and then in the pores inside the aggregates or in the isolated large pores connected to the dye source and then into the matrix pores. The dye distribution in the soil matrix was uneven as well. Accumulated organic matter, clay coating, and isolated larger capillary pores, which initially did not contain the dye tracer, behaved as less‐permeable or impermeable barriers. Uneven distribution was caused by hierarchical pore size distribution of the soil matrix. Results indicated a multimodal character of preferential flow in this soil. In the case of the Haplic Cambisol, the dye pattern studied at the microscale was mostly affected by fractures and the size and shape of mineral grains.

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Section: Resultsmentioning

confidence: 92%

“…There has been little attempt to study dye patterns at the microscale, e.g., on images of soil sections at the micromorphological (pore‐scale) level. Nobles et al (2004) measured the Br − and Brilliant Blue FCF distribution in soil at the microscale. They used 30‐cm‐diameter polyvinyl chloride cylinders to infiltrate tracer solutions into the soil.…”

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confidence: 99%

Using Dye Tracer for Visualization of Preferential Flow at Macro‐ and Microscales

Kodešová

Němeček

Kodeš

et al. 2012

Vadose Zone Journal

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“…In addition, smaller sized pores can restrict larger molecules (e.g., Brilliant Blue FCF) from passing through the coatings Nobles et al, 2003Nobles et al, , 2004. Under dry conditions, organo-mineral coatings may decrease the wettability of aggregate surfaces due to an increased hydrophobicity of the soil organic matter Vogelmann et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Fér

Leue

Kodešová

et al. 2016

Journal of Hydrology and Hydromechanics

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Abstract:The organo-mineral coatings of soil aggregates, cracks, and biopores control sorption and macropore-matrix exchange during preferential flow, in particular in the clay-illuvial Bt-horizon of Luvisols. The soil organic matter (SOM) composition has been hypothesized to explain temporal changes in the hydraulic properties of aggregate surfaces. The objective of this research was to find relations between the temporal change in wettability, in terms of droplet infiltration dynamics, and the SOM composition of coated and uncoated aggregate surfaces. We used 20 to 40 mm sized soil aggregates from the Bt2 horizon of a Haplic Luvisol from loess that were (i) coated, (ii) not coated (both intact), and (iii) aggregates from which coatings were removed (cut). The SOM composition of the aggregate surfaces was characterized by infrared spectroscopy in the diffuse reflection mode (DRIFT). A potential wettability index (PWI) was calculated from the ratio of hydrophobic and hydrophilic functional groups in SOM. The water drop penetration times (WDPT) and contact angles (CA) during droplet infiltration experiments were determined on dry and moist aggregate samples of the three types. The decrease in the CA with time was described using the power function (CA(t) = at -b ). For dry aggregates, the WDPT values were larger for coated as compared to uncoated regions on the aggregate surfaces, and increased with increasing PWI value (R 2 = 0.75). The a parameter was significantly related to the WDPT (R 2 = 0.84) and to the PWI (R 2 = 0.64). The relations between the b parameter and the WDPT (R 2 = 0.61) and the PWI (R 2 = 0.53) were also significant. The WDPT values of wet soil aggregates were higher than those of dry aggregates due to high water contents, which limited the droplet infiltration potential. At the wet aggregate surfaces, the WDPT values increased with the PWI of the SOM (R 2 = 0.64). In contrast to dry samples, no significant relationships were found between parameters a or b of CA(t) and WDPT or PWI for wet aggregate surfaces. The results suggest that the effect of the SOM composition of coatings on surface wettability decreases with increasing soil moisture. In addition to the dominant impact of SOM, the wettability of aggregate surfaces could be affected by different mineralogical compositions of clay in coatings and interiors of aggregates. Particularly, wettability of coatings could be decreased by illite which was the dominant clay type in coatings. However, the influence of different clay mineral fractions on surface wettability was not due to small number of measurements (2 and 1 samples from coatings and interiors, respectively) quantified.

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“…For instance Nobles et al (2003Nobles et al ( , 2004 and Kodešová et al (2012) illustrated impact of surface features of soil aggregates on tracers' penetration into the aggregates. Leue et al (2010) documented influence of aggregate coatings on water drop infiltration into the aggregate.…”

Section: Introductionmentioning

confidence: 99%

Estimating hydraulic conductivities of the soil aggregates and their clay-organic coatings using numerical inversion of capillary rise data

Fér¹,

Kodešová²

2012

Journal of Hydrology

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Submicroscopic measurements of tracer distribution related to surface features of soil aggregates

Cited by 9 publications

References 22 publications

Using Dye Tracer for Visualization of Preferential Flow at Macro‐ and Microscales

Using Dye Tracer for Visualization of Preferential Flow at Macro‐ and Microscales

Droplet infiltration dynamics and soil wettability related to soil organic matter of soil aggregate coatings and interiors

Estimating hydraulic conductivities of the soil aggregates and their clay-organic coatings using numerical inversion of capillary rise data

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