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Soil physics

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https://www.readbyqxmd.com/read/28651354/cambial-response-of-norway-spruce-to-modified-carbon-availability-by-phloem-girdling
#1
Andrea Winkler, Walter Oberhuber
We tested the hypothesis that increase in carbon (C) availability in Norway spruce saplings (Picea abies (L.) Karst.) intensifies cambial cell division and increases cell lumen diameter (CLD) and cell wall thickness (CWT) when water availability is adequate. To accomplish this, we experimentally subjected 6-year-old P. abies saplings (n = 80 trees) to two levels of soil humidity (watered versus drought conditions) and manipulated tree C status by physically blocking phloem transport at three girdling dates (GDs)...
June 23, 2017: Tree Physiology
https://www.readbyqxmd.com/read/28651314/stabilization-of-heavy-metals-in-soil-using-two-organo-bentonites
#2
Kai Yu, Jian Xu, Xiaohong Jiang, Cun Liu, Wesley McCall, Jinlong Lu
Stabilization of Cu, Zn, Cd, Hg, Cr and As in soil using tetramethylammonium (TMA) and dodecyltrimethylammonium (DTMA) modified bentonites (T-Bents and D-Bents) as amendments was investigated. Toxicity characteristic leaching procedure (TCLP) was used to quantify the metal mobility after soil treatment. The structural parameters of modified bentonites, including the BET surface area, basal spacing and zeta potential were obtained as a function of the TMA and DTMA loading at 40, 80, 120, 160 and 200% of the bentonite's cation exchange capacity, respectively...
June 20, 2017: Chemosphere
https://www.readbyqxmd.com/read/28649411/the-microbiome-of-glaciers-and-ice-sheets
#3
Alexandre M Anesio, Stefanie Lutz, Nathan A M Chrismas, Liane G Benning
Glaciers and ice sheets, like other biomes, occupy a significant area of the planet and harbour biological communities with distinct interactions and feedbacks with their physical and chemical environment. In the case of the glacial biome, the biological processes are dominated almost exclusively by microbial communities. Habitats on glaciers and ice sheets with enough liquid water to sustain microbial activity include snow, surface ice, cryoconite holes, englacial systems and the interface between ice and overridden rock/soil...
2017: NPJ Biofilms and Microbiomes
https://www.readbyqxmd.com/read/28647238/adsorption-desorption-behavior-of-atrazine-on-agricultural-soils-in-china
#4
Lin Yue, ChengJun Ge, Dan Feng, Huamei Yu, Hui Deng, Bomin Fu
Adsorption and desorption are important processes that affect atrazine transport, transformation, and bioavailability in soils. In this study, the adsorption-desorption characteristics of atrazine in three soils (laterite, paddy soil and alluvial soil) were evaluated using the batch equilibrium method. The results showed that the kinetics of atrazine in soils was completed in two steps: a "fast" adsorption and a "slow" adsorption and could be well described by pseudo-second-order model. In addition, the adsorption equilibrium isotherms were nonlinear and were well fitted by Freundlich and Langmuir models...
July 2017: Journal of Environmental Sciences (China)
https://www.readbyqxmd.com/read/28644849/rapid-development-of-cyanobacterial-crust-in-the-field-for-combating-desertification
#5
Chan-Ho Park, Xin Rong Li, Yang Zhao, Rong Liang Jia, Jae-Seoun Hur
Desertification is currently a major concern, and vast regions have already been devastated in the arid zones of many countries. Combined application of cyanobacteria with soil fixing chemicals is a novel method of restoring desertified areas. Three cyanobacteria, Nostoc sp. Vaucher ex Bornet & Flahault, Phormidium sp. Kützing ex Gomont and Scytonema arcangeli Bornet ex Flahault were isolated and tested in this study. Tacki-SprayTM (TKS7), which consists of bio-polysaccharides and tackifiers, was used as a soil fixing agent...
2017: PloS One
https://www.readbyqxmd.com/read/28639022/citrus-stand-ages-regulate-the-fraction-alteration-of-soil-organic-carbon-under-a-citrus-stropharua-rugodo-annulata-intercropping-system-in-the-three-gorges-reservoir-area-china
#6
Yang Zhang, Jiupai Ni, John Yang, Tong Zhang, Deti Xie
Soil carbon fractionation is a valuable indicator in assessing stabilization of soil organic matter and soil quality. However, limited studies have addressed how different vegetation stand ages under intercropping agroforestry systems, could affect organic carbon (OC) accumulation in bulk soil and its physical fractions. A field study thus investigated the impact of citrus plantation age (15-, 25-, and 45-year citrus) on the bulk soil organic carbon (SOC) and SOC fractions and yields of Stropharia rugoso-annulata (SRA) in the Three Gorges Reservoir area, Chongqing, China...
June 22, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28638622/the-synergistic-use-of-plant-and-isolated-bacteria-to-clean-up-polycyclic-aromatic-hydrocarbons-from-contaminated-soil
#7
S Eskandary, A Tahmourespour, M Hoodaji, A Abdollahi
BACKGROUND: Biological methods of polycyclic aromatic hydrocarbons (PAH) contamination elimination typically involve the transformation of contaminants to non-toxic materials by microorganisms and plants and appear to be the most effective methods available. METHODS: In this study, Bacillus licheniformis and Bacillus mojavensis isolated from oil-contaminated soils were inoculated onto Festuca arundinacea seeds before planting in the pot and 3 weeks after planting by syringe injection into the rhizospheric zone in order to study the elimination of PAHs from Festuca's rhizosphere in the greenhouse...
2017: Journal of Environmental Health Science & Engineering
https://www.readbyqxmd.com/read/28638393/non-chemical-control-of-root-parasitic-weeds-with-biochar
#8
Hanan Eizenberg, Dina Plakhine, Hammam Ziadne, Ludmila Tsechansky, Ellen R Graber
This study tested whether soil-applied biochar can impact the seed germination and attachment of root parasitic weeds. Three hypotheses were evaluated: (i) biochar adsorbs host-exuded signaling molecules; (ii) biochar activates plants' innate system-wide defenses against invasion by the parasite; and (iii) biochar has a systemic influence on the amount of seed germination stimulant produced or released by the host plant. Three types of experiments were performed: (I) pot trials with tomato (Solanum lycopersicum) infested with Phelipanche aegyptiaca PERS...
2017: Frontiers in Plant Science
https://www.readbyqxmd.com/read/28634801/ameliorating-soil-acidity-and-physical-properties-of-two-contrasting-texture-ultisols-with-wastewater-sludge-biochar
#9
Yutong Zong, Yefeng Wang, Ye Sheng, Chengfeng Wu, Shenggao Lu
The production of biochar is a safe and beneficial disposal way for wastewater sludge. The biochar produced from wastewater sludge can be used as soil amendments for improving soil properties and for increasing crop yield. This work investigated the influences of wastewater sludge biochar (WSB) on the pH, exchangeable acidity, and physical properties of strongly acidic Ultisols with contrasting texture (clayey soil and sandy loam). Two soils were mixed with WSB at the rate of 0, 10, 20, and 40 g biochar kg(-1) soil and incubated for 240 days at 75% field water capacity...
June 21, 2017: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/28623832/a-review-on-in-situ-phytoremediation-of-mine-tailings
#10
REVIEW
Li Wang, Bin Ji, Yuehua Hu, Runqing Liu, Wei Sun
Mine tailings are detrimental to natural plant growth due to their physicochemical characteristics, such as high pH, high salinity, low water retention capacity, high heavy metal concentrations, and deficiencies in soil organic matter and fertility. Thus, the remediation of mine tailings has become a key issue in environmental science and engineering. Phytoremediation, an in situ cost-effective technology, is emerging as the most promising remediation method for mine tailings by introducing tolerant plant species...
June 7, 2017: Chemosphere
https://www.readbyqxmd.com/read/28618279/analyzing-the-impacts-of-three-types-of-biochar-on-soil-carbon-fractions-and-physiochemical-properties-in-a-corn-soybean-rotation
#11
Saroop S Sandhu, David A N Ussiri, Sandeep Kumar, Rajesh Chintala, Sharon K Papiernik, Douglas D Malo, Thomas E Schumacher
Biochar is a solid material obtained when biomass is thermochemically converted in an oxygen-limited environment. In most previous studies, the impacts of biochar on soil properties and organic carbon (C) were investigated under controlled conditions, mainly laboratory incubation or greenhouse studies. This 2-year field study was conducted to evaluate the influence of biochar on selected soil physical and chemical properties and carbon and nitrogen fractions for two selected soil types (clay loam and a sandy loam soil) under a corn (Zea mays L...
May 30, 2017: Chemosphere
https://www.readbyqxmd.com/read/28618203/modelling-the-dynamic-physical-protection-of-soil-organic-carbon-insights-into-carbon-predictions-and-explanation-of-the-priming-effect
#12
Zhongkui Luo, Jeff Baldock, Enli Wang
The role and significance of physically protected soil organic carbon (SOC) in regulating SOC dynamics is unclear. Here we developed a simple theoretical model (DP model) considering dynamic physical protection to simulate the dynamics of protected (Cp ) and unprotected SOC (Cu ), and compared the modelling results with a conventional two-pool (fast vs slow) model considering chemical recalcitrance. The two models were first constrained using extensive SOC data collected from soils with and without fresh carbon (C) inputs under incubation conditions, and then applied to project SOC dynamics and explore mechanisms underpinning the priming effect (PE)...
June 15, 2017: Global Change Biology
https://www.readbyqxmd.com/read/28609847/soil-contamination-with-cadmium-consequences-and-remediation-using-organic-amendments
#13
REVIEW
Muhammad Amjad Khan, Sardar Khan, Anwarzeb Khan, Mehboob Alam
Cadmium (Cd) contamination of soil and food crops is a ubiquitous environmental problem that has resulted from uncontrolled industrialization, unsustainable urbanization and intensive agricultural practices. Being a toxic element, Cd poses high threats to soil quality, food safety, and human health. Land is the ultimate source of waste disposal and utilization therefore, Cd released from different sources (natural and anthropogenic), eventually reaches soil, and then subsequently bio-accumulates in food crops...
June 9, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28609462/effects-of-conversion-of-native-cerrado-vegetation-to-pasture-on-soil-hydro-physical-properties-evapotranspiration-and-streamflow-on-the-amazonian-agricultural-frontier
#14
Rodolfo L B Nóbrega, Alphonce C Guzha, Gilmar N Torres, Kristof Kovacs, Gabriele Lamparter, Ricardo S S Amorim, Eduardo Couto, Gerhard Gerold
Understanding the impacts of land-use change on landscape-hydrological dynamics is one of the main challenges in the Northern Brazilian Cerrado biome, where the Amazon agricultural frontier is located. Motivated by the gap in literature assessing these impacts, we characterized the soil hydro-physical properties and quantified surface water fluxes from catchments under contrasting land-use in this region. We used data from field measurements in two headwater micro-catchments with similar physical characteristics and different land use, i...
2017: PloS One
https://www.readbyqxmd.com/read/28606424/influence-of-composition-and-degradation-on-the-shear-strength-of-municipal-solid-waste
#15
A E S Abreu, O M Vilar
This study aimed to evaluate the shear strength of municipal solid waste (MSW) of different landfilling ages exhumed from disposal sites in a subtropical humid environment. Wastes which had been landfilled from ages of 2 up to 25years were characterized using physical, chemical and biochemical tests and were tested in a large scale direct shear device. The results indicate that the tested wastes older than five years had reached similar decomposition stages, but showed different compositions in terms of soft plastics, incompressible material and reinforcing elements...
June 9, 2017: Waste Management
https://www.readbyqxmd.com/read/28602427/mechanical-characterization-of-municipal-solid-waste-from-two-waste-dumps-at-delhi-india
#16
B J Ramaiah, G V Ramana, Manoj Datta
The article presents the physical and mechanical properties of the emplaced municipal solid waste (MSW) recovered from different locations of the Ghazipur and Okhla dumps both located at Delhi, India. Mechanical compressibility and shear strength of the collected MSW were evaluated using a 300×300mm direct shear (DS) shear box. Compression ratio (Cc') of MSW at these two dumps varied between 0.11 and 0.17 and is falling on the lower bound of the range (0.1-0.5) of the data reported in the literature for MSW...
June 8, 2017: Waste Management
https://www.readbyqxmd.com/read/28599372/a-hybrid-machine-learning-model-to-predict-and-visualize-nitrate-concentration-throughout-the-central-valley-aquifer-california-usa
#17
Katherine M Ransom, Bernard T Nolan, Jonathan A Traum, Claudia C Faunt, Andrew M Bell, Jo Ann M Gronberg, David C Wheeler, Celia Z Rosecrans, Bryant Jurgens, Gregory E Schwarz, Kenneth Belitz, Sandra M Eberts, George Kourakos, Thomas Harter
Intense demand for water in the Central Valley of California and related increases in groundwater nitrate concentration threaten the sustainability of the groundwater resource. To assess contamination risk in the region, we developed a hybrid, non-linear, machine learning model within a statistical learning framework to predict nitrate contamination of groundwater to depths of approximately 500m below ground surface. A database of 145 predictor variables representing well characteristics, historical and current field and landscape-scale nitrogen mass balances, historical and current land use, oxidation/reduction conditions, groundwater flow, climate, soil characteristics, depth to groundwater, and groundwater age were assigned to over 6000 private supply and public supply wells measured previously for nitrate and located throughout the study area...
June 5, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28596609/land-use-alters-arbuscular-mycorrhizal-fungal-communities-and-their-potential-role-in-carbon-sequestration-on-the-tibetan-plateau
#18
Meng Xu, Xiaoliang Li, Xiaobu Cai, Xiaolin Li, Peter Christie, Junling Zhang
Loss of belowground biodiversity by land-use change can have a great impact on ecosystem functions, yet appropriate investigations remain rare in high-elevation Tibetan ecosystems. We compared arbuscular mycorrhizal (AM) fungal communities in arable soils with those in native forest and grassland in southeast Tibet and investigated their potential contribution to carbon sequestration. The AM fungi were abundant and diverse. AM fungal diversity was significantly higher in grassland than in forest or arable land...
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28596557/burkholderia-pseudomallei-in-a-lowland-rice-paddy-seasonal-changes-and-influence-of-soil-depth-and-physico-chemical-properties
#19
L Manivanh, A Pierret, S Rattanavong, O Kounnavongsa, Y Buisson, I Elliott, J -L Maeght, K Xayyathip, J Silisouk, M Vongsouvath, R Phetsouvanh, P N Newton, G Lacombe, O Ribolzi, E Rochelle-Newall, D A B Dance
Melioidosis, a severe infection with the environmental bacterium Burkholderia pseudomallei, is being recognised increasingly frequently. What determines its uneven distribution within endemic areas is poorly understood. We cultured soil from a rice field in Laos for B. pseudomallei at different depths on 4 occasions over a 13-month period. We also measured physical and chemical parameters in order to identify associated characteristics. Overall, 195 of 653 samples (29.7%) yielded B. pseudomallei. A higher prevalence of B...
June 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28588402/well-posed-continuum-equations-for-granular-flow-with-compressibility-and-%C3%AE-i-rheology
#20
T Barker, D G Schaeffer, M Shearer, J M N T Gray
Continuum modelling of granular flow has been plagued with the issue of ill-posed dynamic equations for a long time. Equations for incompressible, two-dimensional flow based on the Coulomb friction law are ill-posed regardless of the deformation, whereas the rate-dependent μ(I)-rheology is ill-posed when the non-dimensional inertial number I is too high or too low. Here, incorporating ideas from critical-state soil mechanics, we derive conditions for well-posedness of partial differential equations that combine compressibility with I-dependent rheology...
May 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
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