• Structural Engineering and Mechanics
• /
• v.40 no.6
• /
• pp.829-845
• /
• 2011

This paper evaluates the effects of topographical and geotechnical irregularities on the dynamic response of the 2-D soil-structure systems under ground motion by coupling finite and infinite elements. A numerical procedure is employed, and a parametric study is carried out for single-faced slope topographies. It is concluded that topographic conditions may have important effects on the ground motion along the slope. The geotechnical properties of the soil will also have significantly amplified effects on the whole system motion, which cannot be neglected for design purposes. So, dynamic response of a soil-structure systems are primarily affected by surface shapes and geotechnical properties of the soil. Location of the structure is another parameter affecting the whole system response.

• Journal of Microbiology and Biotechnology
• /
• v.22 no.9
• /
• pp.1264-1270
• /
• 2012

The ecotoxicological effects of nanomaterials on animal, plant, and soil microorganisms have been widely investigated; however, the nanotoxic effects of plant-soil interactive systems are still largely unknown. In the present study, the effects of ZnO nanoparticles (NPs) on the soil-plant interactive system were estimated. The growth of plant seedlings in the presence of different concentrations of ZnO NPs within microcosm soil (M) and natural soil (NS) was compared. Changes in dehydrogenase activity (DHA) and soil bacterial community diversity were estimated based on the microcosm with plants (M+P) and microcosm without plants (M-P) in different concentrations of ZnO NPs treatment. The shoot growth of M+P and NS+P was significantly inhibited by 24% and 31.5% relative to the control at a ZnO NPs concentration of 1,000 mg/kg. The DHA levels decreased following increased ZnO NPs concentration. Specifically, these levels were significantly reduced from 100 mg/kg in M-P and only 1,000 mg/kg in M+P. Different clustering groups of M+P and M-P were observed in the principal component analysis (PCA). Therefore, the M-P's soil bacterial population may have more toxic effects at a high dose of ZnO NPs than M+P's. The plant and activation of soil bacteria in the M+P may have a less toxic interactive effect on each of the soil bacterial populations and plant growth by the ZnO NPs attachment or absorption of plant roots surface. The soil-plant interactive system might help decrease the toxic effects of ZnO NPs on the rhizobacteria population.

• Journal of Environmental Science International
• /
• v.30 no.2
• /
• pp.145-152
• /
• 2021

Soil conservation management is necessary for sustainable agriculture, in highland areas, and cover crops are one of the best soil conservation methods for slopes. In this study, we evaluated the effects of alfalfa cultivation on maize production, as well as soil conservation and quality. There was an outstanding soil conservation effect with alfalfa cultivation in the fallow and maize growing seasons. In particular, alfalfa cultivation reduced soil loss by up to 98% compared with bare field. It also increased the activities of soil microorganisms and the supply of organic matter. Maize production with alfalfa cultivation showed no significant differences in yield. In conclusion, alfalfa is an advantageous perennial cover crop in highland agricultural slope areas, which can have positive effects on soil quality and conservation, as well as maize production.

• Applied Biological Chemistry
• /
• v.41 no.8
• /
• pp.587-594
• /
• 1998

The objective of this research was to characterize effects of Cu or Cd additions on chemistry of soil quality indices, such as pH, EC, cation distribution and buffering capacity. Metals were added at rates ranging from 0 to 400 mg $kg^{-1}$ of soil. Soil solution was sequentially extracted from saturated pastes using vacuum. Concentrations of Cu or Cd remaining in soil solutions were very low as compared to those added to the soils, warranting that most of the added metals were recovered as nonavailable fractions. Adsorption of the added metals released cations into soil solution causing increases of ionic strength of soil solution. At metal additions of $200{\sim}400\;mg\;kg^{-1}$, EC of soil solution increased to as much as $2{\sim}4\;m^{-1}$; salinity levels considered high enough to cause detrimental effects on plant production. More divalent cations than monovalent cations were exchanged by Cu or Cd adsorption. The nutrient buffering capacity of soils was decreased due to the metal adsorption and release of cations. pH of soil solution decreased linearly with increasing metal loading rates, with a decrement of up to 1.3 units at 400 mg Cu $kg^{-1}$ addition. Influences of Cu on each of these soil quality parameters were consistently greater than those of Cd. These effects were of a detrimental nature and large enough in most cases to significantly impact soil productivity. It is clear that new protocols are needed for evaluating potential effects of heavy metal loading of soils.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.1
• /
• pp.104-114
• /
• 2021

Petroleum-contaminated soil is considered among the most important potential anthropogenic atmospheric methane sources. Additionally, various rhizoremediation factors can affect methane emissions by altering soil ecosystem carbon cycles. Nonetheless, greenhouse gas emissions from soil have not been given due importance as a potentially relevant parameter in rhizoremediation techniques. Therefore, in this study we sought to investigate the effects of different plant and soil amendments on both remediation efficiencies and methane emission characteristics in diesel-contaminated soil. An indoor pot experiment consisting of three plant treatments (control, maize, tall fescue) and two soil amendments (chemical nutrient, compost) was performed for 95 days. Total petroleum hydrocarbon (TPH) removal efficiency, dehydrogenase activity, and alkB (i.e., an alkane compound-degrading enzyme) gene abundance were the highest in the tall fescue and maize soil system amended with compost. Compost addition enhanced both the overall remediation efficiencies, as well as pmoA (i.e., a methane-oxidizing enzyme) gene abundance in soils. Moreover, the potential methane emission of diesel-contaminated soil was relatively low when maize was introduced to the soil system. After microbial community analysis, various TPH-degrading microorganisms (Nocardioides, Marinobacter, Immitisolibacter, Acinetobacter, Kocuria, Mycobacterium, Pseudomonas, Alcanivorax) and methane-oxidizing microorganisms (Methylocapsa, Methylosarcina) were observed in the rhizosphere soil. The effects of major rhizoremediation factors on soil remediation efficiency and greenhouse gas emissions discussed herein are expected to contribute to the development of sustainable biological remediation technologies in response to global climate change.

• Proceedings of the Earthquake Engineering Society of Korea Conference
• /
• 2006.03a
• /
• pp.327-336
• /
• 2006

Site coefficients in IBC and KBC codes have some limits to predict the rational seismic responses of a structure, because they consider only the effect of the soil amplification without the effects of the structure-soil interaction. In this study, upper and lower limits of site coefficients are estimated through the pseudo 3-D elastic seismic response analyses of structures built on linear or nonlinear soil layers considering the structure-soil interaction effects. Soil characteristics of site classes of A, B, and C were assumed to be linear, and those of site classes of D and E were done to be nonlinear and the Ramberg-Osgood model was used to evaluate shear modulus and damping ratio of a soil layer depending on the shear wave velocity of a soil layer. Seismic analyses were performed with 12 weak or moderate earthquake records, scaled the peak acceleration to 0.1g or 0.2g and deconvoluted as earthquake records at the bedrock 30m beneath the outcrop. With the study results of the elastic seismic response analyses of structures, new standard response spectrum and upper and lower limits of the site coefficients of Fa and Fv at the short period range and the period of 1 second are suggested Including the structure-soil interaction effects.

• Journal of Microbiology and Biotechnology
• /
• v.26 no.7
• /
• pp.1303-1310
• /
• 2016

Although many studies on the effects of genetically modified (GM) crops on soil microorganisms have been carried out over the past decades, they have provided contradictory information, even for the same GM crop, owing to the diversity of the soil environments in which they were conducted. This inconsistency in results suggests that the effects of GM crops on soil microorganisms should be considered from many aspects. In this study, we investigated the effects of the GM drought-tolerant rice MSRB2-Bar-8, which expresses the CaMSRB2 gene, on soil microorganisms based on the culture-dependent and culture-independent methods. To this end, rhizosphere soils of GM and non-GM (IM) rice were analyzed for soil chemistry, population densities of soil microorganisms, and microbial community structure (using pyrosequencing technology) at three growth stages (seedling, tillering, and maturity). There was no significant difference in the soil chemistry between GM and non-GM rice. The microbial densities of the GM soils were found to be within the range of those of the non-GM rice. In the pyrosequencing analyses, Proteobacteria and Chloroflexi were dominant at the seedling stage, while Chloroflexi showed dominance over Proteobacteria at the maturity stage in both the GM and non-GM soils. An UPGMA dendrogram showed that the soil microbial communities were clustered by growth stage. Taken together, the results from this study suggest that the effects of MSRB2-Bar-8 cultivation on soil microorganisms are not significant.

• Korean Journal of Soil Science and Fertilizer
• /
• v.47 no.5
• /
• pp.340-344
• /
• 2014

Compost and gypsum can be used to ameliorate soil physicochemical properties in reclaimed tidal lands as an organic and inorganic amendment, respectively. To evaluate effects of compost and gypsum on soil water movement and retention as a soil physical property, we measured the soil's saturated hydraulic conductivity and field capacity after treating the soil collected in a reclaimed tidal land with compost and gypsum. Saturated hydraulic conductivity of soil increased when compost was applied at the conventional application rate of $30Mg\;ha^{-1}$. However, the further application of compost insignificantly (P > 0.05) increased saturated hydraulic conductivity. On the other hand, additional gypsum application significantly increased soil saturated hydraulic conductivity while it decreased soil field capacity, implying the possible effect of gypsum on flocculating soil colloidal particles. The results in this study suggested that compost and gypsum can be used to improve hydrological properties of reclaimed tidal lands through increasing soil water retention and movement, respectively.

• Ecology and Resilient Infrastructure
• /
• v.7 no.2
• /
• pp.134-144
• /
• 2020

In-situ stabilization is a remediation method using amendments to reduce contaminant availability in contaminated soil. We tested the effects of two amendments (furnace slag and red mud) on the availability of toxic trace elements (TTEs) and soil enzyme activities (dehydrogenase, phosphatase, and urease). The application of amendments significantly decreased the availability of TTEs in soil (p < 0.05). The decreased availability of TTE content in soils was accompanied by increased soil enzyme activities. We found significant negative relationships between the TTE content assessed using Ca(NO₃)_2^-, TCLP, and PBET extraction methods and soil enzyme activities (p < 0.01). Soil enzyme activities responded sensitively to changes in the soil environment (pH, EC, and availability of TTEs). It could be concluded that soil enzyme activities could be used as bioindicators or ecological indicators for soil quality and health in environmental soil monitoring owing to their high sensitivity to changes in soil.

• Journal of the Korean Society of Safety
• /
• v.26 no.1
• /
• pp.36-42
• /
• 2011

This paper presents a nonlinear soil-structure interaction analysis approach, which can consider precisely characteristics of structures, complicated soil profiles and nonlinear characteristics of soil. Although many methods have been developed to deal with the soil-structure interaction effects in past years, most of them are nearly unpractical since it is difficult to model complicated characteristics of structure and soil precisely. The presented approach overcomes the difficulties by adopting an maligned mesh generation approach and multi-linear model. The applicability of the proposed approach is validated and the effects of complicated characteristics of structure and soil on soil-structure interaction are investigated through the numerical example by the proposed nonlinear soil-structure interaction analysis approach.