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Strength and compressibility behaviors of expansive soil treated with coffee husk ash

Journal of Rock Mechanics and Geotechnical Engineering 2019年第2期11卷 337-348页

作者： M.K.Atahu F.Saathoff A.Gebissa Geotechnical Engineering and Coastal Engineering Faculty of Agriculture and Environmental SciencesUniversity of Rostock，Germany

Various factors can affect the durability of roads, such as the strength of sub-grade, the quality of the subbase and base course, the environments and properties of the soil used. Particularly, roads built on expansive soil are susceptible to early damage due to the swelling and shrinkage characteristics of this kind of soil under changing moisture conditions. The most common technique used to improve the properties of problematic soil is stabilization with additives. Using waste materials to improve the properties of expansive soil is a recent trend in soil stabilization. This study deals with the treatment of expansive soil with coffee husk ash(CHA). Coffee husk is a by-product of coffee production, and CHA is the resulting ash after burning it. In this study, the bearing capacity and compressibility characteristics of expansive soil(specifically black cotton(BC) soil) stabilized with varying percentages of CHA(5%, 10%,15%, and 20%) are investigated. Then, scanning electron microscopy(SEM) and energy dispersive X-ray(EDX) were used to analyze the influence of CHA on surface morphology and chemical composition of the studied soil. The results showed that the soil treated with CHA is generally improved in terms of *** of 20% CHA increases the bearing capacity of the soil by three-fold. In addition, the morphological studies of the soil samples treated with 10% and 15% CHA indicated the formation of hydrated particles and cementitious compounds as a result of the reaction between the soil and CHA. This indicates the potential usage of CHA as a stabilization agent and subsequently, it can address the disposal and environmental concerns related to coffee husk.

关键词： Black cotton (BC) soil Coffee husk Stabilization California bearing ratio (CBR) Consolidation Scanning electron microscopy (SEM)

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Greenhouse gases fluxes and soil thermal properties in a pasture in central Missouri

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Journal of environmental sciences 2010年第7期22卷 1029-1039页

作者： Nsalambi Vakanda Nkongolo Shane Johnson Kent Schmidt Frieda Eivazi Department of Agriculture and environmental sciences College of Agriculture and Natural Science Lincoln University Harvard Forest Faculty of Arts and Sciences Harvard University

Fluctuations of greenhouse gases emissions and soil properties occur at short spatial and temporal scales, however, results are often reported for larger scales studies. We monitored CO2, CH4, and N2O fluxes and soil temperature （T）, thermal conductivity （K）, resistivity （R） and thermal diffusivity （D） from 2004 to 2006 in a pasture. Soil air samples for determination of CO2, CH4 and N2O concentrations were collected from static and vented chambers and analyzed within two hours of collection with a gas chromatograph. T, K, R and D were measured in-situ using a KD2 probe. Soil samples were also taken for measurements of soil chemical and physical properties. The pasture acted as a sink in 2004, a source in 2005 and again a sink of CH4 in 2006. CO2 and CH4 were highest, but N2O as well as T, K and D were lowest in 2004. Only K was correlated with C02 in 2004 while T correlated with both N2O （r = 0.76, p = 0.0001） and CO2 （r = 0.88, p = 0.0001） in 2005. In 2006, all gases fluxes were significantly correlated with T, K and R when the data for the entire year were considered. However, an in-depth examination of the data revealed the existence of month-to-month shifts, lack of correlation and differing spatial structures. These results stress the need for further studies on the relationship between soil properties and gases fluxes. K and R offer a promise as potential controlling factors for greenhouse gases fluxes in this pasture.

关键词： greenhouse gases soil thermal properties fluxes

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Toxicity studies of elemental sulfur in marine sediments

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International Journal of Sediment Research 2018年第2期33卷 191-197页

作者： Monika Cieszynska-Semenowicz Justyna Rogowska Wojciech Ratajczyk Joanna Ratajczyk Lidia Wolska Department of environmental Toxicology Faculty of Health Sciences Medical University of Gdansk

Elemental sulfur(ES) is a component essential for proper development of animals, but it can be toxic for aquatic organisms. The objectives of the study reported here included determination of ES concentrations in sediment collected in the area of the Gulf of Gdansk(Baltic Sea) and search for the possible correlations with the ecotoxicity results. Sediment samples were collected from four locations: the Vistula River mouth, in the Port Basin, in the area of discharge of the treated wastewater from the Wastewater Treatment Plant(WWTP) and in the area of the sunken World War Ⅱ s/s 'Stuttgart' shipwreck. The levels of elemental sulfur were determined using a gas chromatograph coupled with a mass spectrometer(GC-MS). Toxicity of marine sediment samples was estimated for three biotest organisms-bioluminescent bacteria Vibrio fischeri, crustacean Heterocypris incongruens, and Synapis alba plant. The highest toxicity of sediments for all indicator organisms was observed in samples taken at the place of the shipwreck(2-100%). The same samples had a high sulfur content(16.7-143.2 μg/g dry weight(d.w.))therefore, it was decided to investigate whether the presence of ES in the sediment in the studied area can have an impact on the results of the ecotoxicity determination in real samples. However, the removal of sulfur from the samples resulted in no significant changes in the level of toxicity of the samples. In this research it could not be confirmed that the presence of elemental sulfur is the only factor responsible for the observed sediment toxicity. It seems that other compounds or their mixtures present in the sediment may have a significant influence on the results obtained.

关键词： Elemental sulfur(ES) Ecotoxicity Sediment Aquatic environment

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Image texture indices and trend analysis for forest disturbance assessment under wood harvest regimes

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Journal of Forestry Research 2021年第2期32卷 579-587页

作者： Abdolrassoul Salmanmahiny Malihe Erfani Afshin Danehkar Vahid Etemad Department of environmental Science Gorgan University of Agricultural Sciences and Natural ResourcesGorgānIran Department of environmental sciences Faculty of Natural ResourcesUniversity of ZabolZabolIran Department of environmental sciences Faculty of Natural ResourcesUniversity of TehranTehranIran Department of Forestry and Forest Economics Faculty of Natural ResourcesUniversity of TehranTehranIran

Effective disturbance indices for Hyrcanian forests in Kheyroud,Nowshahr,Iran were *** study area was divided into landscape mosaics based on ecosystem parameters including profile type,slope and ***-occurrence texture indices were derived as forest disturbance factors on the first five bands of Landsat TM,ETM+and OLI images for the prevailing wood harvest disturbance *** indices were screened using ten types of trend analyses and used for modeling disturbance of the harvesting regime through artificial neural *** results show that the selected indices can be useful in distinguishing areas with different disturbance intensities and as such,used in the context of health assessment through the health distance *** accuracy of the health maps derived from the indices[increasing disturbance]led to give rise higher disturbance classification accuracy.

关键词： Ecosystem health Disturbance Trend analysis Co-occurrence texture indices Landscape mosaics

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Forest structure and carbon dynamics of an intact lowland mixed dipterocarp forest in Brunei Darussalam

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Journal of Forestry Research 2018年第1期29卷 199-203页

作者： Sohye Lee Jongyeol Lee Seongjun Kim Yujin Roh Kamariah Abu Salim Woo-Kyun Lee Yowhan Son Department of environmental Science and Ecological Engineering Graduate School Korea University environmental and Life sciences Faculty of ScienceUniversiti Brunei Darussalam Department of Biological of environmental sciences Qatar University

Tropical forests play a critical role in mitigating climate change because they account for large amount o terrestrial carbon storage and ***,there are many uncertainties associated with the estimation o carbon *** estimated forest structure and carbon dynamics along a slope（17.3°–42.8°）and to assess the relations between forest structures,carbon dynamics,and slopes in an intact lowland mixed dipterocarp forest,in Kuala Belalong,Brunei *** biomass,basa area,stand density,crown properties,and tree family composition were measured for forest *** rate,litter production,and litter decomposition rates were also measured for carbon *** crown form index and the crown position index were used to assess crown properties,which we categorized into five stages,from very poor to *** living biomass,basal area and stand density were 261.5–940.7 Mg ha-1,43.6–63.6 m2ha-1and 6,675–8400 tree ha-1,*** average crown form and position index were 4,which means that the crown are mostly symmetrical and sufficiently exposed for *** mean biomass growth rate,litter production,litter decomposition rate were estimated as11.9,11.6 Mg ha-1a-1,and 7.2 g a-1,*** growth rate was significantly correlated with living biomass,basal area,and crown *** form appeared to strongly influence living biomass,basal area and biomass growth rate in terms of light ***,basal area,stand density,crown properties,and biomass growth rate did not vary by slope or tree family *** results indicate that carbon accumulation by tree growth in an intact lowland mixed dipterocarp forest depends on crown *** of any effect of tree family composition on carbon accumulation suggests that the main driver of biomass accumulation in old-growth forests of Borneo is not species-specific characteristics of tree species.

关键词： Carbon dynamics Growth rate Litter flux Lowland mixed dipterocarp forest Slope

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Evolution of seasonal land surface temperature trend in pond-breeding newt(Neurergus derjugini)in western Iran and eastern Iraq

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Ecological Processes 2023年第1期12卷 217-231页

作者： Peyman Karami Sajad Tavakoli Mina Esmaeili Department of environmental sciences Faculty of Natural Resources and Environment SciencesMalayer UniversityMalayerIran Department of environmental and Forest Science Faculty of Natural Resources and EnvironmentScience and Research BranchIslamic Azad UniversityTehranIran Department of Biology Faculty of ScienceRazi UniversityKermanshahIran

Background Temperature,as one of the effective environmental stimuli in many aspects of species life and ecosystems,can affect amphibians in many *** and predicting temperature change and its possible effects on the habitat suitability and movements of amphibians have led many researchers to use climate change scenarios and species distribution models(SDMs).One of the important remote-sensing products that received less attention of conservation biologists is the land surface temperature(LST).Due to the small difference between LST and air temperature,this component can be used to investigate and monitor the daily and seasonal changes of *** study aims to investigate the seasonal trend of LST in the habitat suitability and connectivity of the critically endangered newt(Neurergus derjugini)in its small distribution range,using the MODIS LST time series(2003 to 2021)and with the help of SDMs,Mann–Kendall(MK)and Pettitt non-parametric *** In the last decade,the increasing trend of LST versus its decreasing trends is *** on MK and Pettitt tests,in the winter and spring,with the decrease in latitude of 35.45°and increase in longitude of 46.14°,the core populations which are located in the southeast have experienced an increase in *** the period time of breeding and overwintering,the continuity of winter and spring can be effective on the survival of adult newts as well as larvae in the *** with the highest current flow between core populations in the winter and summer are the most likely to be *** the level of habitat,the increase in LST is proportional to the trend of thermal landscape changes,and all seasons have had an increase in LST,but in winter and summer,the largest area of the habitat has been *** continuing the current trend,many high-altitude southern habitats in Iran will be endangered,and the species will be at risk of local *** The increasing tre

关键词： Seasonal change Local extinction Climate refuge Amphibian

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Tree growth decline to warm-wet conditions in boreal forests is linked to stand density

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Forest Ecosystems 2025年第1期 74-82页

作者： Bingqian Zhao Yihong Zhu Lushuang Gao Qibing Zhang Mingqian Liu Klaus von Gadow Research Center of Forest Management Engineering of State Forestry and Grassland Administration Beijing Forestry University State Forestry and Grassland Administration Key Laboratory of Forest Resources&environmental Management Beijing Forestry University Department of environmental Science Policy and ManagementUniversity of California State Key Laboratory of Vegetation and environmental Change Institute of BotanyChinese Academy of Sciences Laboratory of Wood Technology Ghent University faculty of Forestry and Forest Ecology Georg-August-University G?ttingen Department of Forestry and Wood Science Faculty of AgriSciencesStellenbosch University

Warm-wet climatic conditions are widely regarded as conducive to remarkable tree growth, alleviating climatic pressures. However, the notable decline in tree growth observed in the southern edge of boreal forests has heightened concerns over the spatial-temporal dynamics of forest decline. Currently, attaining a comprehensive grasp of the underlying patterns and their propelling factors remains a formidable challenge. We collected tree ring samples from a network of 50 sites across the Greater Xing'an Mountains. These samples were subsequently grouped into two distinct clusters, designated as Groups A and B. The percentage change of growth(GC, %) and the proportion of declining sites were utilized to assess forest decline. The decline in tree growth within Larix gmelinii forests exhibits significant regional variation, accompanied by temporal fluctuations even within a given region. Group A exhibited a pronounced increase in frequency(59.26%) of occurrences and encountered more severe declines(21.65%) in tree growth subsequent to the 1990s, contrasting sharply with Group B, which observed lower frequencies(20.00%) and relatively less severe declines(21.02%) prior to the 1980s. The primary impetus underlying the opposite radial growth increments observed in Larix gmelinii trees from the interplay between their differential response to temperatures and wetter climatic conditions, which is significantly influenced by varying stand densities. In cold-dry conditions, low-density forests may experience soil water freezing,exacerbating drought conditions and thereby inhibiting tree growth, in Group B. Trees growth in high-density stands is restrained by warm-wet conditions, in Group A. These results provide new insights into the variability at the southern edge of the boreal forest biome with different responses to density and climate.

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Intraspecific Variations of Phosphorus Absorption and Remobilization, P Forms, and Their Internal Buffering in Brassica Cultivars Exposed to a P-Stressed Environment

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Journal of Integrative Plant Biology 2008年第6期50卷 703-716页

作者： M. Shahbaz Akhtar Yoko Oki Tadashi Adachi Department of environmental Management Engineering Faculty of Environmental Science and Technology Graduate School of Environmental Science Okayama University CADGK and Institute of Soil and environmental sciences University of Agriculture Faisalabad Pakistan

Translocation of absorbed phosphorus （P） from metabolically inactive sites to active sites in plants growing under P deprivation may increase its P utilization efficiency （PUE）. Acclimation to phosphate （Pi） starvation may be caused by a differential storage pool of vacuolar P, its release, and the intensity of re-translocation of absorbed P as P starvation inducible environmental cues （PSlEC） from ambient environment. Biomass assay and three P forms, namely inorganic （Pi）, organic （Po）, and acid-soluble total （Ptas） were estimated in Brassica cultivars exposed to 10 d P deprivation in the culture media. Considering that -aPi/at denotes the rate of Pi release, Pi release velocity （RSPi） was determined as the tangent to the equations obtained for Pi f（t） at the mean point in the period of greatest Pi decrease, whereas the inverse of the RSPi was an estimate of the internal Pi buffering capacity （IBCPi）. Inter cultivar variations in size of the non-metabolic Pi pool, RSPi, re-translocation of Pi from less to more active metabolic sites, and preferential Pi source and sink compartments were evaluated under P starvation. The cultivar ＇Brown Raya＇ showed the highest Pi storage ability under adequate external P supply, and a more intensive release than ＇Rain Bow＇ and ＇Dunkled＇ under P stress. Cultivar ＇B.S.A＇ was inferior to ＇Con-l＇ in its ability to store and use Pi. Roots and upper leaves were the main sink of Pi stored in the lower and middle leaves of all cultivars and showed lower IBCPi and larger RSPi values than lower and middle leaves. In another trial, six cultivars were exposed to P-free nutrition for 29 d after initial feeding on optimum nutrition for 15 d. With variable magnitude, all of the cultivars re-translocatad P from the above ground parts to their roots under P starvation, and [P] at 44 d after transplanting was higher in developing leaves compared with developed leaves. Under P deprivation, translocation of absorbed P from metabolically inactive to ac

关键词： Brassica internal Pi buffering capacity P absorption and remobilization Pi homeostasis Pi release velocity vacuolar P

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Numerical study on tidal currents and seawater exchange in the Benoa Bay, Bali, Indonesia

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Acta Oceanologica Sinica 2014年第3期33卷 90-100页

作者： HENDRAWAN I Gede ASAI Koji Department of Marine sciences Faculty of Marine Sciences and Fisheries Udayana University Department of Civil and environmental Engineering Yamaguchi University

A three-dimensional （3-D） finite volume coastal ocean model （FVCOM） was used for the study of water cir culation and seawater exchange in the Benoa Bay, Bali Island. The M2 tidal component was forced in open boundary and discharge from six rivers was included in the numerical calculation. The M2 tidal elevation produced by the FVCOM has a good agreement with the observation data. The M2 tidal current is also suc cessfully calculated under the ebb tide and flood tide conditions. The non-linear M2 tidal residual current was produced by the coastline geometry, especially surrounding the narrow strait between the Serangan Is- land and the Benoa Peninsula. The tidal residual current also generated two small eddies within the bay and one small eddy in the bay mouth. The salinity distribution influenced by river discharge could be success- fully calculated, where the numerical calculation and the observation results have a good correlation （r2） of 0.75. Finally in order to examine the seawater exchange in the Benoa Bay, the Lagrangian particle tracking method and calculation of residence time are applied. The mechanism of particle transport to the flushing of seawater is depicted clearly by both methods.

关键词： FVCOM M2 tidal current M2 residual current salinity seawater exchange

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Effects of temperature and water limitation on the germination of Stipagrostis ciliata seeds collected from Sidi Bouzid Governorate in Central Tunisia

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Journal of Arid Land 2018年第2期10卷 304-315页

作者： Lobna M FAKHFAKH Naser A ANJUM Mohamed CHAIEB Department of Life sciences Faculty of Sciences University of Sfax Centre for environmental and Marine Studies and Department of Chemistry University of Aveiro

Most ecological studies in North Africa reveal a process of continuous degradation of rangeland ecosystems as a result of overgrazing. This degradation appears across the decreasing of perennial grass diversity. Indeed, the majority of steppe ecosystems are characterized by a low density of perennial grass species at present. This study evaluated the effects of temperature and water limitation on the seed germination of Stipagrostis ciliata（Desf.） de Winter, a perennial grass species. The seeds were collected from the Bou Hedma Park, Sidi Bouzid Governorate, Central Tunisia. The thermal time and hydrothermal time models were used to describe the seed germination of S. ciliata under different water potentials and temperatures. The germination response of S. ciliata seeds in darkness was evaluated over a range of temperatures（15°C, 20°C, 25°C, 30°C and 35°C） and across a wide range of osmotic potentials（0.0, –0.2, –0.6, –1.2, –1.6 and –2.0 MPa） of the polyethylene glycol（PEG6000） solutions at each temperature level. Among the tested temperatures, 25°C was found to be the optimal temperature to the germination of S. ciliata seeds. The final germination percentage（75.2%） was obtained with distilled water. The progressive decrease of osmotic potential of the PEG6000 solutions inhibited the seed germination. However, the number of days to first germination was increased with a reduction of osmotic potential. A significant positive relationship was identified between final germination percentage of S. ciliata seeds and osmotic potential of the PEG6000 solutions, with R^2 ranging from 0.5678 to 0.8761. Furthermore, a high degree of congruency between predicted and observed germination time course curves was observed. In general, S. ciliata exhibits a significant adaptation capacity for water limitation and high temperature in arid ecosystems.

关键词： Stipagrostis ciliata germination temperature water potential hydrothermal model arid zone Bou Hedma Park

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