“…Disturbed samples were used to determine the particle size distribution, separating between cobbles and coarse gravel (CCG, 250 -20 mm), medium and fine gravel (MFG, 20 -2 mm), coarse sand (CS, 2 -0.25 mm), fine sand (FS, 0.25 -0.05 mm), silt (0.05 -0.002 mm) and clay (< 0.002 mm) (Schoeneberger et al, 2012). Sand, silt, and clay were determined by shaking 20 g of the soil fraction passed in a 2 mm mesh sieve in a solution of 1 mol L -1 NaOH with a horizontal reciprocating shaking during (i) 4 h and with nylon spheres for soils of site B and C (not containing fragile sand particles) (Suzuki et al, 2015) and (ii) 2 h and without nylon spheres for soil A, due to the presence of fragile sand particles (Gubiani et al, 2021a). The sand fraction was separated by washing the dispersed sample on a 0.053 mm mesh sieve and the clay fraction was determined with the pipette method (Gee and Or, 2002), while silt was calculated as the remaining part after subtracting sand and clay from the whole sample mass.…”
Stony soils have been increasingly used for agriculture production; however, little is known about their hydraulic properties due to problems, such as sample deformation and hydraulic continuity between samples and suction devices when the sampling and measurements are accomplished with traditional techniques. In this study, the traditional ring sampling technique was replaced by the sampling of undisturbed soil blocks coated with paraffin wax to preserve their structure. A saturated paste of fine-grained mineral particles was used to ensure contact and hydraulic continuity between samples and suction devices (sand table and ceramic plates). This allowed us to determine 30 water retention curves for three stony soils with coarse particle contents (> 2 mm) ranging from zero to 69 %. The van Genuchten model was fitted to the measured retention data and the root mean square errors were between 0.0034 and 0.0331 m 3 m -3 , with no outliers or odd behavior in the retention curves. These results showed that consistent water retention curves for stony soils can be determined with the technique proposed.Fine-grained minerals sandwiched between the surface of suctions sources and sampled blocks improve hydraulic continuity between them. These techniques can be applied to determine water retention properties in structured soil samples with coarse particles where it is unfeasible to collect structured soil samples with metal sampling rings.
“…Disturbed samples were used to determine the particle size distribution, separating between cobbles and coarse gravel (CCG, 250 -20 mm), medium and fine gravel (MFG, 20 -2 mm), coarse sand (CS, 2 -0.25 mm), fine sand (FS, 0.25 -0.05 mm), silt (0.05 -0.002 mm) and clay (< 0.002 mm) (Schoeneberger et al, 2012). Sand, silt, and clay were determined by shaking 20 g of the soil fraction passed in a 2 mm mesh sieve in a solution of 1 mol L -1 NaOH with a horizontal reciprocating shaking during (i) 4 h and with nylon spheres for soils of site B and C (not containing fragile sand particles) (Suzuki et al, 2015) and (ii) 2 h and without nylon spheres for soil A, due to the presence of fragile sand particles (Gubiani et al, 2021a). The sand fraction was separated by washing the dispersed sample on a 0.053 mm mesh sieve and the clay fraction was determined with the pipette method (Gee and Or, 2002), while silt was calculated as the remaining part after subtracting sand and clay from the whole sample mass.…”
Stony soils have been increasingly used for agriculture production; however, little is known about their hydraulic properties due to problems, such as sample deformation and hydraulic continuity between samples and suction devices when the sampling and measurements are accomplished with traditional techniques. In this study, the traditional ring sampling technique was replaced by the sampling of undisturbed soil blocks coated with paraffin wax to preserve their structure. A saturated paste of fine-grained mineral particles was used to ensure contact and hydraulic continuity between samples and suction devices (sand table and ceramic plates). This allowed us to determine 30 water retention curves for three stony soils with coarse particle contents (> 2 mm) ranging from zero to 69 %. The van Genuchten model was fitted to the measured retention data and the root mean square errors were between 0.0034 and 0.0331 m 3 m -3 , with no outliers or odd behavior in the retention curves. These results showed that consistent water retention curves for stony soils can be determined with the technique proposed.Fine-grained minerals sandwiched between the surface of suctions sources and sampled blocks improve hydraulic continuity between them. These techniques can be applied to determine water retention properties in structured soil samples with coarse particles where it is unfeasible to collect structured soil samples with metal sampling rings.
“…Significant negative correlations between fine and coarse fractions were not found. That indicated that the increase of fine particles from destroyed large particles during shaking was not a substantial factor in PSD determination (Gurbani et al., 2021; Suzuki et al., 2015).…”
Concentrations of the fecal indicator bacteria (FIB) Escherichia coli and enterococci are used to assess microbial impairment in irrigation and recreation water sources. Whereas the FIB concentrations’ variability at large temporal scales such as seasons, and large spatial scales encompassing different land use has been studied, the knowledge about smaller‐scale variability remains sparse. This work aimed to research the small‐scale variability of E. coli and enterococci in a montane creek with sandy bottom sediments. Sediment samples were collected weekly for a year in triplicate at sampling sites in a forested headwater, an agricultural area, and a mixed urban‐agricultural area. The average weekly change in concentrations was from two times at the forested site to five times at the urban‐agricultural site. Mean relative deviations from averages across sampling locations increased from ‐25% at the forested site to 45% at the urban‐agricultural site. This trend was also observed separately over cold and warm seasons. Over a week without precipitation, E. coli concentrations decreased on average by 20% in warm period and by45% in cold period; the enterococci concentration declined by 12% in both cold and warm periods. The sediment particle size distributions were significantly different among the three sites and between cold and warm seasons. Rankings of sediment fine mass fractions and FIB concentrations were positively correlated at two of three sampling sites in more than 70% of observation dates. The results of this work indicate the need to evaluate the uncertainty of sediment FIB concentrations before designing sediment FIB monitoring quality.This article is protected by copyright. All rights reserved
“…The disturbed samples were used to determine the particle size distribution, separating between cobbles and coarse gravel (CCG, 250–20 mm), medium and fine gravel (MFG, 20–2 mm), coarse sand (CS, 2–0.25 mm), fine sand (FS, 0.25–0.05 mm), silt (0.05–0.002 mm) and clay (˂0.002 mm) (Schoeneberger et al, 2012). Sand, silt, and clay were determined by shaking 20 g of the soil fraction passed through a sieve of 2 mm mesh in a solution of 1 mol L −1 NaOH with a horizontal reciprocating shaking during (i) 4 h with nylon spheres for soils of site B and C (not containing fragile sand particles) (Suzuki et al, 2015) and (ii) 2 h without nylon spheres for soil A, due to the presence of fragile sand particles (Gubiani et al, 2021a). The sand fraction was separated by washing the dispersed sample on a sieve with a 0.053 mm mesh and the clay fraction was determined with the pipette method (Gee & Or, 2002), while silt was calculated as the remaining part after subtracting sand and clay from the whole sample mass.…”
Information about water retention in stony soils lags behind due to methodological difficulties. We applied a new strategy to measure the water retention in soils with coarse fragments (CFs) and to get insights into the effect of CFs porosity on water retention. Water retention at zero, 10, and 150 m suction, bulk density, and the mass fraction of six particle size classes were measured in undisturbed blocks from soils with variable CFs contents, originating from three parent materials. The results showed that some soils contain porous CFs (2-250 mm) with a water holding capacity as high as the fine fraction (<2 mm). The water held in the suction range of 1-150 m in a soil with porous CFs was twice as high as in soils with non-porous CFs. Multilinear regressions revealed that both the water retention capacity at 1 m suction and in the range 1-150 m were more dependent on bulk density than on the fraction of CFs and fine particles. In the soil with porous CFs, there was no correlation between their fraction and soil water retention. These results show that the bulk water retention capacity of soils with CFs is underestimated when not considering the internal porosity of the CFs. A better understanding of the effect of the porosity of CFs on bulk soil porosity and water retention is important to propose suitable pedotransfer functions and refine physically-based hydraulic functions for stony soils.
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