• Journal of Soil and Groundwater Environment
• /
• v.22 no.5
• /
• pp.89-97
• /
• 2017

In this study, we evaluated effect of particle size on arsenic solid-state speciation and bioaccessibility in soils highly contaminated with arsenic from smelting and mining. Soils were partitioned into six particle size fractions ($2000-500{\mu}m$, $500-250{\mu}m$, $250-150{\mu}m$, $150-75{\mu}m$, $75-38{\mu}m$, <$38{\mu}m$), and arsenic solid-state speciation and bioaccessibility were characterized in each particle size fraction. Arsenic solid-state speciation was characterized via sequential extraction and XRD analysis, and arsenic bioaccessibility was evaluated by SBRC (Solubility Bioaccessibility Research Consortium) method. In smelter site soil, arsenic was mainly present as arsenic bound to amorphous iron oxides. Fine particle size fractions showed higher arsenic concentration, but lower arsenic bioaccessibility. On the other hand, arsenic in mine site soil showed highest concentration in largest particle size fraction ($2000-500{\mu}m$), while higher bioaccessibility was observed in smaller particle size fractions. Arsenic in mine site soil was mainly present as arsenolite ($As_2O_3$) phase, which seemed to affect the distribution of arsenic and arsenic bioaccessibility in different particle size fractions of the mine soil.

• Korean Journal of Soil Science and Fertilizer
• /
• v.40 no.4
• /
• pp.326-329
• /
• 2007

Quantifying soil organic carbon (SOC) has long been considered to improve our understanding of soil productivity, soil carbon dynamics, and soil quality. And also SOC could contribute as a major soil management factor for prescribing fertilizers and controlling of soil erosion and runoff. Reducing tillage intensity has been recommended to sequester SOC into soil. On the other hand, determination of traditional SOC could barely identify the tillage practices effect. Physical soil fractionation has been reported to improve interpretation of soil tillage practices impact on SOC dynamics. However, most of these researches were focused onupland soils and few researches were conducted on paddy soils. Therefore, the objective of this research was to evaluate paddy soil tillage impact on SOC by physical soil fractionation. Soils were sampled in conventional-tillage (CT), partial-tillage (PT), no-tillage (NT), and shallow-tillage (ST)plots at the National Institute of Crop Science research farm. Samples were obtained at the three sampling depth with 7.5-cm increment from the surface and were sieved with 0.25- and 0.053-mm screen. Soil organic carbon was determined by wet combustion method. Significant difference of SOC contentwas found among sampling soil depth and soil particle size. SOC content tended to increase at the ST plot with increasing size of soil particle fraction. We conclude that quantifying soil organic carbon by physical soil particle fractionation could improve understanding of SOC dynamics by soil tillage practices.

• Journal of the Korean Geotechnical Society
• /
• v.15 no.5
• /
• pp.193-204
• /
• 1999

Particle crushing is an important and essential factor in interpreting the strength and deformation properties of granular materials in the case of geotechnical problems related to soil crushability. As a recent field problem, the exploitation of offshore oil reserves in tropical and sub-tropical coastal shelf areas has shown that the behaviour of soils containing carbonates is markedly different from predominantly silica sands. In this study, as a first step in making a mechanical framework of granular materials incorporating the soil crushability, single particle fragmentation tests were carried out on four different types of sands in order to clarify the characteristics of the single particle fragmentation strength as related to soil crushability. The single particle strength was considered with the influence of the particle shapes, the amount of mineral components and the particle sizes. The soil particle strength corresponding $D_{50}$ of soil distribution curve has shown the lower value, the more the carbonate component and the more angular the particle shape.

• Progress in Superconductivity and Cryogenics
• /
• v.18 no.1
• /
• pp.10-13
• /
• 2016

In this study, we developed a new volume reduction technique for cesium contaminated soil by magnetic separation. Cs in soil is mainly adsorbed on clay which is the smallest particle constituent in the soil, especially on paramagnetic 2:1 type clay minerals which strongly adsorb and fix Cs. Thus selective separation of 2:1 type clay with a superconducting magnet could enable to reduce the volume of Cs contaminated soil. The 2:1 type clay particles exist in various particle sizes in the soil, which leads that magnetic force and Cs adsorption quantity depend on their particle size. Accordingly, we examined magnetic separation conditions for efficient separation of 2:1 type clay considering their particle size distribution. First, the separation rate of 2:1 type clay for each particle size was calculated by particle trajectory simulation, because magnetic separation rate largely depends on the objective size. According to the calculation, 73 and 89 % of 2:1 type clay could be separated at 2 and 7 T, respectively. Moreover we calculated dose reduction rate on the basis of the result of particle trajectory simulation. It was indicated that 17 and 51 % of dose reduction would be possible at 2 and 7 T, respectively. The difference of dose reduction rate at 2 T and 7 T was found to be separated a fine particle. It was shown that magnetic separation considering particle size distribution would contribute to the volume reduction of contaminated soil.

• Asian Journal of Turfgrass Science
• /
• v.19 no.2
• /
• pp.95-102
• /
• 2005

USGA green specification is currently accepted in construction method of Korea. This study was carried out to find the factors influencing growth of turfgrass associated with soil physical properties of soil root-zone on golf green constructed with USGA method. Three putting greens in poor turfgrass and one in good turfgrass condition were selected for investigation on one golf course site at mid-South Korean peninsula. Soil hardness, moisture content, root length, and turf density were measured on-site greens, and soil physical properties and soil chemical properties also analyzed in laboratory. As a result of on-site surveys and soil physical tests in laboratory, soil physical properties were most important factors which influenced on turfgrass growth at tested greens. The results of soil particle analysis on green No. 2, in good turf condition, matched USGA sand particle recommendations. But those greens such as Nos. 1, 11 and 16, in poor putting greens, showed high soil compaction and improper soil particle distribution. Those factors created low leaf density, poor root depth, and higher moisture content compared with lower part of topsoil. Such phenomena caused inadequate turfgrass growth with soil hardening associated with poor drainage. Therefore, declines of soil physical properties associated with improper particle distribution caused a major factor influencing on turfgrass growth in golf green. Adequate test of soil particle analysis by USGA specification and proper construction method followed by adequate turf maintenance should be performed to obtain optimal turf quality on putting green.

• Korean Journal of Environmental Agriculture
• /
• v.37 no.1
• /
• pp.1-8
• /
• 2018

BACKGROUND: Different physical and chemical properties of biochar, which is made out of a variety of biomass materials, can impact water movement through amended soil. The objective of this research was to develop a decision support tool evaluating the impact of the shape and the size distribution of biochar on soil saturated hydraulic conductivity ($K_{sat}$). METHODS AND RESULTS: Plastic beads of different size and morphology were compared with biochar to assess impacts on soil $K_{sat}$. Bead and biochar were added at the rate of 5% (v/w) to coarse sand. The particle size of bead and biochar had an effect on the $K_{sat}$, with larger and smaller particle sizes than the original sand grain (0.5 mm) decreasing the $K_{sat}$ value. The equivalent size bead or biochar to the sand grains had no impact on $K_{sat}$. The amendment shape also influenced soil hydraulic properties, but only when the particle size was between 3-6 mm. Intra-particle porosity had no significant influence on the $K_{sat}$ due to its small pore size and increased tortuosity compared to the inter-particle spaces (macro-porosity). CONCLUSION: The results supported the conclusion that both particle size and shape of the amended biochar impacted the $K_{sat}$ value.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.6 no.3
• /
• pp.69-78
• /
• 2003

The main purpose of this study was to verify the shore margin protection effect of the root system of Salix gracilistyla Miq. developed from direct sticking cuttings on wetland, focusing on the effect of the root system reducing soil particle dissociation rate in water. The soil dissociation rate was examined through slaking tests with cylindric pure soil column at maximum particle density and the same size column of root reinforced soil. The dry weight of remained soil was measured after 5, 10, 15, 30minutes and 1, 6, 12, 24, 48hours inundation. As results, the soil particles began to dissociate severely at 10 minutes and only 10% of soil particles were left after 25minutes inundation. The stable slope angle of pure soil was $36^{\circ}$after 24 hours. On the other hand, the columns of root reinforced soil were stable even after 24hours, being dissociated only 7.2% of soil particles. So, it was revealed that the root system was very effective materials protecting more than 80% of soil particle from dissociation in inundation.

• Applied Chemistry for Engineering
• /
• v.19 no.1
• /
• pp.98-104
• /
• 2008

This research was performed to evaluate the extraction characteristics of heavy metals for soil washing of mine tailings-contaminated soil according to particle size distribution and the chemical distributional existence of the metals. As the soil particle size was decreased, the extracted concentrations of heavy metals was increased except Fe and Mn. Most of all heavy metals were extracted within 6 h by soil washing with 0.05 M EDTA. Extraction efficiency of metals was decreased for Pb, Cu, and Zn with decreasing of particle size. Significant difference was not observed in extraction efficiency for Cd according to particle size distribution. Extraction efficiency for Cd was the highest as 86~91%, while the lowest as 5~14% for Fe. Most metals of the soil without soil washing was distributed as reducible, oxidizable, and residual fractions. Pb, Zn, and Cd existed as reducible (Fe/Mn oxide) and residual fractions and Cu existed as oxidizable and residual fractions after soil washing treatment with 0.05 M EDTA. As the soil particle size was decreased, residual fraction was increased for Pb and Cu. About 90% of reducible fraction in Pb, Zn, and Cd was removed by soil washing with 0.05 M EDTA. As the results, it was founded that soil particle size was the important parameter to effect on distributional fraction and extraction efficiency of metals in mine tailings-contaminated soil.

• Journal of Biosystems Engineering
• /
• v.26 no.5
• /
• pp.475-480
• /
• 2001

Sensing soil organic matter is crucial for precision farming and environment friendly agriculture. Near infra-red(NIR) was utilized to measure the soil organic matter. Multivariate calibration methods, including stepwise multiple linear regression(MLR), principal components recession(PCR) and partial least squares regression(PLS), were applied to soil spectral reflectance data to predict the organic matter content. The effect of soil particle size and water content was studied. The range of soil organic matter contents was from 0.5 to 11%. Near infrared (NIR) region from 700 to 2,500nm was applied. For uniform soil particle size, result had good correlation (R$\^$2/ = 0.984, standard error of prediction= 0.596). The effect of soil particle size could be eliminated with 1st order derivative of the NIR signal. However. moist soil had a little lower correlation. R$\^$2/ was 0.95 and standard error of prediction was 0.94% using the PLS method. The results showed the possibility of soil organic matter measurement using NIR reflectance on the field.

• The Journal of Engineering Geology
• /
• v.32 no.2
• /
• pp.241-255
• /
• 2022

In this study, sieve analysis testing was performed on weathered granite soil from Yecheon (eastern South Korea) before and after water washing in accordance with the sieve analysis regulations of KS F 2302. The changes in particle separation and particle size distribution after washing with water were analyzed. Image analysis using an optical microscope revealed that soil particles were separated into smaller particles by water washing. The change in the particle size distribution curve was assessed using five index values. The increase in the fine particle fraction (<0.075 mm) was 13.67%, the increase in the 0.075-0.25 mm fraction was 19.44%, and the mean particle diameter (D₅₀) decreased by 0.663 mm. In addition, the maximum passage width (B_M) of the particle size distribution curve increased by 21.08% for the #30 sieve, and the moving area (A) of the particle size distribution curve was 69.28%·mm. These results suggest that washing with water is an effective way to prevent underestimation of the fine particle content in soil.