Turfy Soil Research Articles

Reply to “Discussion on characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China by He et al. Bulletin of Engineering Geology and the Environment, 81, 481”

Reply to “Discussion on characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China by He et al. Bulletin of Engineering Geology and the Environment, 81, 481”

Discussion on characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China by He et al. Bulletin of Engineering Geology and the Environment, 81, 481

Discussion on characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China by He et al. Bulletin of Engineering Geology and the Environment, 81, 481

Freeze-thaw Evaluation Model of Turfy Soil based on Combination Weighting Method and Extension Theory

Freeze-thaw Evaluation Model of Turfy Soil based on Combination Weighting Method and Extension Theory

Characterization of unfrozen water in highly organic turfy soil during freeze–thaw by nuclear magnetic resonance

The unfrozen water content (ωu) is an important parameter affecting the hydrothermal-mechanical characteristics of soil and is of important significance with regard to engineering construction and environmental effects in cold regions. In this study, a widely-distributed special humus soil called turfy soil, with poor engineering geological properties, from seasonally frozen regions of northeastern China was investigated. Soil fundamental properties were determined, and ωu under various temperatures during a freeze–thaw process was measured by the nuclear magnetic resonance (NMR) method. Based on NMR theory and transverse relaxation time (T2) distribution curves, two thresholds were determined to divide the types of pore water in soil. Soil freezing characteristic curves (SFCC) of the total and pore water were drawn, and changes in the internal microstructure and pore characteristics of the soil during the freeze–thaw process were analyzed. The results showed that a drastic phase change within the soil occurs during −2 °C to −4 °C, and the freezing process can be divided into three stages. The formation of small pores and the connection of large pores make the soil looser after freeze–thaw. The division of pore water and variation in ωu show that freezing starts from large pores, while thawing starts from small pores. The capillary water content significantly decreases after freeze–thaw, and the bulk water content tends to increase. At freezing Stage I, ωu is closely related to the initial properties of the soil, whereas ωu at −3 °C almost determines the value of ωu during subsequent freeze–thaw. Finally, a ωu-power function for turfy soil was proposed, and good fitting results were obtained for both freezing and thawing soil. This work can serve as the basis of studies on soil with high organic matter content as well as soil unfrozen water content during freeze–thaw cycles in cold regions.

Characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China

Characterization of thermal conductivity of seasonally frozen turfy soil from Northeastern China

Macro-mesoscopic Dynamic Responses of Turfy Soil under Multilevel Cyclic Loading with Different Waveforms Based on the Discrete Element Method

Turfy soil is a special soil with numerous undecomposed plant fibers and humus, which can be considered a soil-fiber mixture. In this paper, the macro-mesoscopic dynamic responses of turfy soil subjected to multilevel cyclic loading with different waveforms (triangular, square, sinusoidal) were investigated employing the discrete element method (DEM). The microscopic parameters of the DEM model were confirmed by laboratory tests and calibration procedures. The hysteresis between the applied and measured stress on the loading plates was discussed to determine the appropriate frequency before simulation. Macroscopically, the discrepancies, including the velocity of the loading plates, the deformation of the specimen, and sample size effect were investigated under these three waveform loadings. Microscopically, the differences in energy, coordination number, average normal contact force between pure and turfy soil, internal force alternation and bending degree of fibers in turfy soil were studied to disclose the discrepancies in macroscopic behaviors with different waveforms. Simulation results illustrate that square waveforms can excite the support of the soil matrix by plant fibers in turfy soil to a greater extent. This study is beneficial for further understanding the mechanical behaviors of soil-fiber mixtures under the action of different forms of cyclic loads in safety engineering.

Physical and Mechanical Properties of Turfy Soils under Confining and Axial Pressure Increases Stress Paths in Jilin Province, Northeast China

In recent years, highways have been built rapidly in China’s turfy swamp areas to accommodate economic development. Turfy soil is a type of special soil with high humus and incompletely decomposed plant contents, so its properties are complex and unique. Both the axial and confining pressures of turfy soil increase during embankment filling. Therefore, in this study, three soil tests for analysing the decomposition degree, organic matter content, and triaxial compression under confining and axial pressure increases stress paths were performed to achieve insights into the stress-strain properties of turfy soil. The volumetric and deviatoric strains of turfy soil were summarised to reveal the inner mechanisms of turfy soil, culminating in the establishment of a constitutive model for turfy soil. The results of the constitutive model were compared with the experimental test results to verify the accuracy of the constitutive model. The results showed that the stress-strain and strength of turfy soil are closely related to the organic matter content and decomposition degree. The calculated stress and strain results are also consistent with the experimental results, indicating that this constitutive model can be used to better indicate the original deformation state and strength characteristics of the turfy soil.

Establishment of a Rapid Breeding System for Bletilla striata

Bletilla striata (Thunb. ex A. Murray) Rchb. f., a species of perennial herb of orchidaceae that has remarkable effects and high economic value, has been intensively studied by many scholars. Although this herb has many seeds, the germination rate is exceptionally low, which leads to decreased germplasm resources and increased market demand every year. To solve this problem, this study examined the aseptic germination system and the direct seeding technology system. On Murashige and Skoog (MS) medium, 2.0 mg/L 6-benzylaminopurine (6-BA) and 1.0 mg/L naphthylacetic acid (NAA) were added before seed germination, and 70 g/L banana juice and 0.5 mg/L NAA were added when rooting. Then, the seedlings were transplanted to a mixed substrate of humus, river sand, and bark (volume ratio of 3:1:1). The direct seeding system consists of substrate treatment, sowing, seedling raising, seedling growth, and transplanting. Turfy soil, Huangjiang residue, and river sand were selected as the substrate. The results revealed that the germination rate was increased to 91.8%, whereas the plantlet regeneration was increased to 82.0%. After 180 days of cultivation, the plants could be transplanted as finished seedlings. The establishment of B. striata seedling system provides a safe, rapid, reliable production technology route for industrial development.

Removal performance of high hydraulic loading rate subsurface wastewater infiltration systems with added Si[sbnd]Al porous clay material and scrap iron filings

To enhance pollutant removal performance in the treatment of decentralized domestic sewage, a subsurface wastewater infiltration system (SWIS) with turfy soil was improved by adding SiAl porous clay material W (PCMW) and scrap iron filings. The permeability at different depths of the SWIS was improved. Under the conditions of 186.18 ± 34.82 mg/L COD, 25.84 ± 2.57 mg/L NH4+-N, 3.02 ± 0.91 mg/L NO3−-N, 33.87 ± 3.78 mg/L TN, 6.93 ± 1.21 mg/L TP, a 0.28 m3/m2·d hydraulic loading rate and 716 d operation time, the average effluent concentrations of COD, NH4+-N, NO3−-N, TN and TP were 31.28 ± 5.87 mg/L, 3.39 ± 1.42 mg/L, 3.71 ± 0.87 mg/L, 7.11 ± 0.97 mg/L and 0.24 ± 0.07 mg/L, respectively, and the TN removal efficiency increased by 20.7% compared with that of the control SWIS. According to the pollutant variations with depth, 76.79% COD, 80.96% NH4+-N and 95.35% TP were removed at a depth of 110 cm, after which their concentrations remained stable; the TN concentration decreased with depth and was quite different from that of control SWIS, NH4+-N in TN was removed at a depth of 0–90 cm, and NO3−-N in TN was removed at 90–170 cm depth. Moreover, both the number of nitrifying/denitrifying bacteria and nitrate/nitrite reductase activity reached their maximum at 90 cm depth. Adding PCMW and scrap iron filings to SWISs could be an ideal method to improve the performance and service life of SWISs.

Green waste compost as a substitute for turfy soil in external-soil spray seeding substrate

ABSTRACT The scarcity of turfy soil (TS), which is the most commonly used external-soil spray seeding (ESSS) substrate component, has recently increased. The aim of this study was to introduce a substitute for TS as an organic matter additive in substrate. Green waste compost (GWC) that was combined with sandy loam soil, polyacrylamide (PAM), and super absorbent polymer (SAP) was used for preparing the soil substrate. Further, a modified soil-spraying experiment and artificial rainfall experiments with an orthogonal design (L1643) were conducted. These experiments assessed the feasibility of GWC as a component of ESSS substrate and the optimal formulation. The results indicated that the degree of influence of the three factors controlling the amended substrate is GWC > PAM > SAP. GWC improved the physical and chemical properties of the substrate, as well as the seed germination rate and seedling growth. Significant improvements can be observed with respect to the soil bulk density, soil porosity, steady infiltration rate, and anti-shearing strength (p < .01). Additionally, the runoff and soil loss decreased under heavy rainfall. Except for the soil nutrients and seedling height, all other indicators of the GWC substrates were better than those of the commercially available TS substrates. Principal component analysis and range analysis revealed that the optimum values of various design parameters were 40% for the compost volume content, 200 g m−3 for PAM and 100 g m−3 for SAP. Based on these results, GWC can be considered to be an effective alternative to TS for ESSS.

Reduction and Accumulative Characteristics of Dissolved Heavy Metals in Modified Bioretention Media

Twelve bioretention filter columns with different media were designed to study the effects of media on dissolved heavy metals in bioretention systems by changing three test conditions (inflow concentration, discharge ratio, and recurrence interval). The results showed that the average load reduction efficiency of the bioretention soil media (BSM)+10%water treatment residue, BSM+10%green zeolite, and BSM+10%medicinal stone for Cu and Zn was larger than 80%. The highest volume reduction efficiency is 39.25% by BSM+coconut bran. Among the three factors selected in tests, inflow concentration had the biggest degree of influence, followed by discharge ratio and recurrence interval. The media of the upper, middle, and lower layers of each filter column were detected before and after the treatment to study the accumulative characteristics of heavy metals in the bioretention system. The accumulation of Cu, Zn, and Cd in the media of BSM+medicinal stone, BSM+fly ash, BSM+vermiculite, and BSM+turfy soil was relatively low. The contents of the three metals were positively correlated with urease and negatively correlated with protease in the media, but no obvious rule was showed in the accumulation of dissolved heavy metals with depth.

Effects of Highway-Related Pollutant on the Groundwater Quality of Turfy Swamps in the Changbai Mountain Area.

Transportation activities such as fuel consumption, vehicle wear and road deicing can detrimentally affect the groundwater quality of fragile roadside wetland environments including. Nineteen parameters (Cu, Pb, Zn, Cd, Cr, Ni, Hg, As, pH, TDS, Ca2+, Mg2+, Na+, K+, SO42−, Cl−, HCO3−, NO3− and F−) were determined in groundwater samples from turfy swamps impacted by highway traffic from Jiangyuan (JY), Longquan (LQ), and Huangsongdian (HSD). Our results indicate that the metals Cu, Pb, Zn, Cr, Cd, the ions Na+, K+ and Cl− in groundwater were negatively affected by highway transportation, and the maximum affected distance of these pollutants varied from 15 to 100 m. The content of most of these pollutants in roadside groundwater decreased exponentially with the distance from the highway, as did the heavy metal pollution index HPI and Cd. The values of HPI and Cd in these three sites ranged from 46.8 to 78.4 and −4.9 to −2.9, respectively. The low pollution levels of heavy metals are related to the strong adsorption capacity of turfy soil towards metals. In any case, road transport activities increased the Cu, Pb, Zn, Cr, Cd, Na+, K+ and Cl− content in roadside groundwater in turfy swamp. With the increase of highway operation time, it will inevitably have a great influence on the groundwater quality of these wetlands. Therefore, the long-term monitoring is necessary to protect the sustainable development of turfy swamp.

The Effect of Highway on Heavy Metal Accumulation in Soil in Turfy Swamps, Northeastern China

A detailed investigation was conducted to study the effect of highway on the accumulation of heavy metals in soils of turfy swamps. The concentrations of Cr, Zn, Cu, and Cd showed a decreasing trend with increasing distance from the road, while such trend was not identified in Pb, Ni, Co, and As. The results of factor analysis and cluster analysis indicated that Cr, Zn, Cu, and Cd were in a closer relationship than other metals and might be derived from common sources. The soil samples from JY and LQ sites with the highest traffic volume had the highest heavy metal concentrations of the three highways, while the concentrations of Cr and Cu were significantly positively correlated with traffic volumes (p < 0.05). Contamination levels of traffic-related metals were evaluated using the geo-accumulation index (I geo) and enrichment factor (EF) in turfy soil. The I geo index for Cr, Zn, Cu, and Cd varied from unpolluted to the heavily polluted, and the enrichment factor (EF) ranged from 0.44 (no enrichment) to 8.38 (significant enrichment) at JY and LQ site. For HSD site, the I geo index and EFs of Cr, Zn, and Cd in turfy soils were lower than that in JY and LQ, ranged from uncontaminated to moderate contamination and no enrichment to moderate enrichment, respectively. The I geo index and EFs of Cd were higher than 1 among all three sites. Therefore, Cd should be paid more attention to avoid potential risk to the flora and fauna in turfy swamps. The affected area of traffic-related metals was <30 m from the highway; this may be due to the abundant precipitation and long cold winter in Changbai Mountain area. The heavy metals could move with rainfall runoff and snowmelt in both particulate and dissolved forms.

Optimizing the formulation of external-soil spray seeding with sludge using the orthogonal test method for slope ecological protection

External-soil spray seeding has gradually become a widely used technology for slope ecological rehabilitation in China in the 21st century. Meanwhile, with ever-increasing amounts of municipal sewage sludge being produced, sewage sludge has become a new source of solid waste pollution in the environment. Therefore, the goal of this study was to utilize sludge as a new kind of spray seeding component to replace non-renewable turfy soil. Orthogonal experiments were conducted to optimize the substrate formulation regarding the four factors of soil-to-sludge ratio, fiber content, soil additive concentration, and bioorganic fertilizer concentration. The results showed that sludge improved the physical and chemical properties of the substrate, increased plant growth, and within a certain range of dosage, reduced runoff and soil loss. The improvements of soil bulk density, total porosity and soil nutrients were particularly notable (P<0.01). Plant growth in experimental groups was better than that of control groups (P<0.05), and Festuca arundinace performed best among the three plants (P<0.01). In addition, besides the physical and chemical properties, fiber content mainly affected plant growth, and soil additive reduced runoff and soil loss, whereas bioorganic fertilizer showed no obvious effect. After the experiments, a simple model was used to integrate the effects of the four factors on 28 parameters and thus to get the optimum component proportions, which were a soil-to-sludge ratio of 6:4 (v/v), fiber content of 15% (v/v), and soil additive concentration of 0.6kgm−3.

Distribution and evolutionary of turfy soil identified by remote-sensing images based on fuzzy evaluation

Turfy soil is a kind of special soil accumulated by undecomposed plants which is detrimental to the engineering. In this paper, particular identified patterns for the turfy soil in the northeast of China was raised including the method of extracting threshold value, block analysis and fuzzy evaluation. And field investigations were undertaken to verify the accuracy of identification by remote sensing, and the correlation of field result and remote sensing result was summarized so as to analyze the regularities of distribution and evolutionary mechanism of turfy soil. The result shows that the combination of extracting threshold value, block analysis and fuzzy evaluation are effective methods to predict the distribution of the turfy soil; with the correlation of membership degree and field result, we can analyze the evolutionary mechanism of turfy soil affected by both nature factors and human activities, which is beneficial for the preservation of the turfy soil and also shows significant environmental ecological benefit.

Effects of Decomposition Degree and Organic Matter Content on the Compressibility Index of Agricultural Turfy Soil

Effects of Decomposition Degree and Organic Matter Content on the Compressibility Index of Agricultural Turfy Soil

Analysis on Soil Seed Bank Diversity Characteristics and Its Relation with Soil Physical and Chemical Properties after Substrate Addition.

AimsConsidered as an essential measure in the application of soil seed bank (SSB) projects, the mixing of substrate and surface soil can effectively improve soil condition. This research is aimed at exploring the diversity characteristics of SSBs and the relationships between SSBs and soil properties.MethodsCanonical correspondence analysis (CCA) was adopted to describe the ordination of SSBs on soil properties’ gradients; multiple linear regressions were adopted to analyze the relationship between average growth height and soil properties, density and soil properties.ResultsExperimental groups of mixed substrate (the mixture of organic and inorganic substrates) had high diversity indexes, especially the Shannon-Wiener Index compared with those of single substrate. Meanwhile, a higher number of species and increased density were also noted in those of mixed substrate. The best test group, No.16, had the highest diversity indexes with a Shannon-Wiener of 1.898, Simpson of 0.633 and Pielou of 0.717, and also showed the highest density of 14000 germinants /m2 and 21 species. In addition, an improvement of the soil’s chemical and physical properties was noted when the substrates were mixed. The mixed substrate of turfy soil and perlite could effectively enhance the soil moisture content, whilst a mixed substrate of rice husk carbon and vermiculite could improve the content of available potassium (AK) and phosphorus (AP) and strengthen soil fertility. The germinated plants also reflected obvious regularities of ordination on soil factor gradients. Three distinct cluster groups were presented, of which the first cluster was distributed in an area with a relatively higher content of AK and AP; the second cluster was distributed at places with relatively higher soil moisture content; and the third cluster of plants didn’t show any obvious relationship with soil physical and chemical properties. Through CCA analysis, AK and AP were considered the most important soil factors to influence the SSB, which was illustrated in regression analysis with a high correlation coefficient when dependent values were growth height and density respectively. The linear regression equations with: growth height = 142.728 − 1.514TC + 30.218AP − 5.083TN + 10.839AK + 1.234mc; density = −68.216 − 4.609TC + 9.566AP − 35.492TN + 19.779AK − 1.591mc.were established by multiple linear regression.Conclusions(1) The mixed substrates showed a greater advantage for SSBs than single substrates, both in improving the number of species, density and diversity indexes. (2) The germinated plants reflected an obvious preference to different soil conditions, which different mixed substrates could improve accordingly. (3) AK, AP were important soil factors to influence SSBs, especially in the growth of plants and density.

Complete genome sequence of Bacillus amyloliquefaciens L-S60, a plant growth-promoting and antifungal bacterium

Bacillus amyloliquefaciens L-S60, a gram-positive plant-associated bacterium, which could stimulate plant growth and shows strong antifungal function, was isolated from the turfy soil in Beijing, China. The genome of B. amyloliquefaciens L-S60 comprises a 3903,017bp long circular chromosome that consists of 3909 protein-coding genes and 117 RNA genes. Based on genomic analysis, we identified gene clusters responsible for the biosynthesis of numerous bioactive metabolites with well-established in-vitro activity such as surfactin, iturin and fengycins. Additionally, we also found functionally related genes in the genome of L-S60, which play key roles in the process of plant growth promotion hormone secretion, biofilm formation and volatile compounds production.

Sarcoglottis catharinensis (Orchidaceae): a new species from Brazilian Atlantic Forest

A new species, Sarcoglottis catharinensis Mancinelli & E. C. Smidt, found in the Atlantic Forest of Brazil, is described and illustrated. The species was collected in Serra Quiriri, Garuva municipality, Santa Catarina State and grows in montane forest on turfy soil. It is differentiated from the remaining Sarcoglottis C. Presl species by the truncate and rostrate apex of the lip.

Study on the Difference between Multipotiential Surface Model and Duncan-Chang Model Based on the Triaxial Test of Heda Highway Turfy Soil

Firstly, this paper determined the experiment parameter of Duncan-Chang model, through Heda highway turfy soil ordinary triaxial test. Then get to the elastics strain relationship of the multipotiential surface model according to the data above. And finally get the applicable category of the two model through the contrast of the relationship of body strain and axial strain and the relationship of partial stress and axial strain.