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soil compaction

Ronaldo A Medeiros-Junior, Carlos Et Balestra, Maryangela G Lima
The expressive generation of construction and demolition waste is stimulating several studies for reusing this material. The improvement of soft soils by concrete compaction piles has been widely applied for 40 years in some Brazilian cities. This technique is used to improve the bearing capacity of soft soils, allowing executing shallow foundations instead of deep foundations. The compaction piles use a high volume of material. This article explored the possibility of using recycled aggregates from construction waste to replace the natural aggregates in order to improve the bearing capacity of the soft soil, regarding its compressive strength...
November 17, 2016: Waste Management & Research
Ran Holtzman
We present a systematic, quantitative assessment of the impact of pore size disorder and its interplay with flow rates and wettability on immiscible displacement of a viscous fluid. Pore-scale simulations and micromodel experiments show that reducing disorder increases the displacement efficiency and compactness, minimizing the fluid-fluid interfacial area, through (i) trapping at low rates and (ii) viscous fingering at high rates. Increasing the wetting angle suppresses both trapping and fingering, hence reducing the sensitivity of the displacement to the underlying disorder...
October 26, 2016: Scientific Reports
Ariane Isis Barros, Diego Victor de Babos, Edilene Cristina Ferreira, José Anchieta Gomes Neto
Different precursors were evaluated for the generation of reference spectra and correction of the background caused by SiO molecules in the determination of Sb in facial cosmetics by high-resolution continuum source graphite furnace atomic absorption spectrometry employing direct solid sample analysis. Zeolite and mica were the most effective precursors for background correction during Sb determination using the 217.581nm and 231.147nm lines. Full 2(3) factorial design and central composite design were used to optimize the atomizer temperature program...
December 1, 2016: Talanta
Jan Šklíba, Tereza Vlasatá, Matěj Lövy, Ema Hrouzková, Yonas Meheretu, Claudio Sillero-Zubiri, Radim Šumbera
Rodents with prevailing subterranean activity usually play an important role in the ecosystems of which they are a part due to the combined effect of herbivory and soil perturbation. This is also the case of the giant root-rat Tachyoryctes macrocephalus, Rüppell 1842, endemic to the Afroalpine ecosystem of the Bale Mountains, Ethiopia. We studied the impact of root-rats on various ecosystem features within a 3.5ha study locality dominated by Alchemilla pasture, which represents an optimal habitat for this species, in two periods of a year...
October 13, 2016: Integrative Zoology
Tino Colombi, Serge Braun, Thomas Keller, Achim Walter
The structure of compacted soils is characterised by decreased (macro-)porosity, which leads to increased mechanical impedance and decreased fluid transport rates, resulting in reduced root growth and crop productivity. Particularly in soils with high mechanical impedance, macropores can be used by roots as pathways of least resistance. This study investigated how different soil physical states relate to whole plant growth and whether roots grow towards spots with favourable soil physical conditions. Experiments were conducted under controlled and field conditions...
October 3, 2016: Science of the Total Environment
Dimitrios Zekkos, Xunchang Fei
Constant load and constant volume simple shear testing was conducted on relatively fresh municipal solid waste (MSW) from two landfills in the United States, one in Michigan and a second in Texas, at respective natural moisture content below field capacity. The results were assessed in terms of two failure strain criteria, at 10% and 30% shear strain, and two interpretations of effective friction angle. Overall, friction angle obtained assuming that the failure plane is horizontal and at 10% shear strain resulted in a conservative estimation of shear strength of MSW...
September 28, 2016: Waste Management
A S Gregory, K Ritz, S P McGrath, J N Quinton, K W T Goulding, R J A Jones, J A Harris, R Bol, P Wallace, E S Pilgrim, A P Whitmore
National governments are becoming increasingly aware of the importance of their soil resources and are shaping strategies accordingly. Implicit in any such strategy is that degradation threats and their potential effect on important soil properties and functions are defined and understood. In this paper, we aimed to review the principal degradation threats on important soil properties in the UK, seeking quantitative data where possible. Soil erosion results in the removal of important topsoil and, with it, nutrients, C and porosity...
October 2015: Soil Use and Management
Jaesung Park, Younghwan Son, Sookack Noh, Taeho Bong
We assessed the suitability of soil dredged from reservoirs as embankment material and investigated its physical and geochemical properties and strength parameters, as well as its environmental stability. The dredged soil samples were taken from the Ansung, Jechon, and Mulwang Reservoirs in Korea. To evaluate their environmental stability and geochemical properties, we examined their levels of heavy metal contamination, pH, and electrical conductivity. We also conducted X-ray fluorescence and X-ray diffraction analyses...
December 1, 2016: Journal of Environmental Management
Alberto Viglione, Bruno Merz, Nguyen Viet Dung, Juraj Parajka, Thomas Nester, Günter Blöschl
Changes in the river flood regime may be due to atmospheric processes (e.g., increasing precipitation), catchment processes (e.g., soil compaction associated with land use change), and river system processes (e.g., loss of retention volume in the floodplains). This paper proposes a new framework for attributing flood changes to these drivers based on a regional analysis. We exploit the scaling characteristics (i.e., fingerprints) with catchment area of the effects of the drivers on flood changes. The estimation of their relative contributions is framed in Bayesian terms...
July 2016: Water Resources Research
L Lamastra, M Balderacchi, A Di Guardo, M Monchiero, M Trevisan
The wine industry is definitely committed in sustainability: the stakeholders' interest for the topic is constantly growing and a wide number of sustainability programs have been launched in recent years. Most of these programs are focusing on the environmental aspects as environmental sustainability indicators, greenhouse gases emissions and the use of Life Cycle Assessment methodology. Among the environmental indicators the carbon and the water footprint are often used. These indicators, while being useful to assess the sustainability performance of the winegrowing farms, do not take into account important aspects related to the agronomic management of the vineyard...
September 3, 2016: Science of the Total Environment
Louisa Robinson Boyer, Wei Feng, Natallia Gulbis, Klara Hajdu, Richard J Harrison, Peter Jeffries, Xiangming Xu
Strawberry is an important fruit crop within the UK. To reduce the impact of soil-borne diseases and extend the production season, more than half of the UK strawberry production is now in substrate (predominantly coir) under protection. Substrates such as coir are usually depleted of microbes including arbuscular mycorrhizal fungi (AMF) and consequently the introduction of beneficial microbes is likely to benefit commercial cropping systems. Inoculating strawberry plants in substrate other than coir has been shown to increase plants tolerance to soil-borne pathogens and water stress...
2016: Frontiers in Plant Science
M O Caetano, I A H Schneider, L P Gomes, A G Kieling, L A S Miranda
Gas stations constitute important point sources of soil and groundwater pollution. The leaking of hydrocarbons into the soil is a significant environment issue due to the wide-ranging occurrence of leaks and to the high levels and toxicity of pollutants involved in the contamination of groundwater for human use. This study introduces a compact system developed to treat groundwater contaminated with BTEX and TPH leaked from gas station tanks. The system comprises three units: (1) suction and volatilization of volatile organic compounds, (2) aeration tank (to remove volatile organic substances), and (3) an adsorption packed-bed filter (activated carbon and rice husk ash, 50% each, to remove TPH)...
August 31, 2016: Environmental Technology
Marcin Jan Szafran, Martyna Gongerowska, Paweł Gutkowski, Jolanta Zakrzewska-Czerwińska, Dagmara Jakimowicz
: Maintaining an optimal level of chromosomal supercoiling is critical for the progression of DNA replication and transcription. Moreover, changes in global supercoiling affect the expression of a large number of genes and play a fundamental role in adapting to stress. Topoisomerase I (TopA) and gyrase are key players in the regulation of bacterial chromosomal topology through their respective abilities to relax and compact DNA. Soil bacteria such as Streptomyces species, which grow as branched, multigenomic hyphae, are subject to environmental stresses that are associated with changes in chromosomal topology...
November 1, 2016: Journal of Bacteriology
Matthew R Jacobs, Matthew Edwards, Tadeusz Górecki, Pavel N Nesterenko, Robert A Shellie
A novel miniaturised single-stage resistively heated thermal modulator was investigated as an alternative to cryogenic modulation for use in comprehensive two-dimensional gas chromatography (GC×GC). The single-stage thermal modulator described herein yielded average retention time relative standard deviations (RSD) of ≤0.2% RSD (first-dimension) and ≤3.4% RSD (second-dimension). The average peak widths generated by the modulator were 72±3ms, and the peak area precision was better than 5.3% RSD for a range of polar and non-polar test analytes...
September 9, 2016: Journal of Chromatography. A
Alejandro A Royo, Chris J Peterson, John S Stanovick, Walter P Carson
Salvage logging following windthrow is common throughout forests worldwide even though the practice is often considered inimical to forest recovery. Because salvaging removes trees, crushes seedlings, and compacts soils, many warn this practice may delay succession, suppress diversity, and alter composition. Here, over 8 yr following windthrow, we experimentally evaluate how salvaging affects tree succession across 11 gaps in Eastern deciduous forests of Pennsylvania, wherein each gap was divided into salvaged and control (unsalvaged) halves...
June 2016: Ecology
Steffen Schlüter, Hans-Jörg Vogel
Matter turnover in soil is tightly linked to soil structure which governs the heterogeneous distribution of habitats, reaction sites and pathways in soil. Thereby, the temporal dynamics of soil structure alteration is deemed to be important for essential ecosystem functions of soil but very little is known about it. A major reason for this knowledge gap is the lack of methods to study soil structure turnover directly at microscopic scales. Here we devise a conceptual approach and an image processing workflow to study soil structure turnover by labeling some initial state of soil structure with small garnet particles and tracking their fate with X-ray microtomography...
2016: PloS One
Qiu-tong Xu, Zhang-liang Kong, Ming-kui Zhang
There are many problems such as low soil organic matter, available nutrients and microbial activity, compaction, and poor tillage properties for a newly reclaimed cultivated land, and the establishment of a fast, effective measure for improving soil fertility quality is of importance to enhance the quality and production performance of the newly cultivated land. A field experiment was carried out to observe the effect of organic wastes on soil fertility of a newly reclaimed cultivated land, and compared the differences of different types of urban organic wastes...
February 2016: Ying Yong Sheng Tai Xue Bao, the Journal of Applied Ecology
J J Miller, E Bremer, T Curtis
Cattle grazing in wet riparian pastures may influence nutrient dynamics due to nutrient deposition in feces and urine, soil compaction, and vegetation loss. We conducted a lab incubation study with a saline-sodic riparian soil to study nutrient (N, P, S, Fe, Mn, Cu, and Zn) dynamics in soil pore water using Plant Root Simulator (PRS) probes and release of nutrients into the overlying ponded water during flooding. The treatment factors were organic amendment (manure, roots, and unamended control), compaction (compacted, uncompacted), and burial time (3, 7, and 14 d)...
July 2016: Journal of Environmental Quality
Andreas Schaeffer, Wulf Amelung, Henner Hollert, Matthias Kaestner, Ellen Kandeler, Jens Kruse, Anja Miltner, Richard Ottermanns, Holger Pagel, Stephan Peth, Christian Poll, Gerhard Rambold, Michael Schloter, Stefanie Schulz, Thilo Streck, Martina Roß-Nickoll
Soils are faced with man-made chemical stress factors, such as the input of organic or metal-containing pesticides, in combination with non-chemical stressors like soil compaction and natural disturbance like drought. Although multiple stress factors are typically co-occurring in soil ecosystems, research in soil sciences on this aspect is limited and focuses mostly on single structural or functional endpoints. A mechanistic understanding of the reaction of soils to multiple stressors is currently lacking. Based on a review of resilience theory, we introduce a new concept for research on the ability of polluted soil (xenobiotics or other chemical pollutants as one stressor) to resist further natural or anthropogenic stress and to retain its functions and structure...
October 15, 2016: Science of the Total Environment
Haijian Xie, Huaxiang Yan, Shijin Feng, Qiao Wang, Peixiong Chen
One-dimensional mathematical model is developed to investigate the behavior of contaminant transport in landfill composite liner system considering coupled effect of consolidation, diffusion, and degradation. The first- and second-type bottom boundary conditions are used to derive the steady-state and quasi-steady-state analytical solutions. The concentration profiles obtained by the proposed analytical solution are in good agreement with those obtained by the laboratory tests. The bottom concentration and flux of the soil liners can be greatly reduced when the degradation effect and porosity changing are considered...
October 2016: Environmental Science and Pollution Research International
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