نتایج جستجو برای: gypsum percentage

تعداد نتایج: 137937  

2014
Sara Palacio Matt Aitkenhead Adrián Escudero Gabriel Montserrat-Martí Melchor Maestro A. H. Jean Robertson

Gypsum soils are among the most restrictive and widespread substrates for plant life. Plants living on gypsum are classified as gypsophiles (exclusive to gypsum) and gypsovags (non-exclusive to gypsum). The former have been separated into wide and narrow gypsophiles, each with a putative different ecological strategy. Mechanisms displayed by gypsum plants to compete and survive on gypsum are st...

Journal: :مرتع و آبخیزداری 0
محسن نقیلو کارشناس دانشکده منابع طبیعی، دانشگاه تهران، ایران محمد جعفری استاد دانشکده منابع طبیعی، دانشگاه تهران، ایران محمد طهمورث 3 کارشناس ارشد آبخیزداری، ایران اصغر کهندل استادیار جهاد دانشگاهی واحد تهران، ایران فریناز همدانیان 5 فارغ التحصیل کارشناس ارشد مرتعداری، ایران

the purpose of this research was to investigate the relationship between vegetation cover and soil characteristics in order to determine the most important soil factors which affect on quantitative variations and types of vegetation cover in the study area. the study area is located in west of tehran province and southeast of hashtgerd, next to najm-abad village. after field studies, the index ...

Journal: :مرتع و آبخیزداری 0
محمد جعفری استاد دانشکدة منابع طبیعی دانشگاه تهران محمد طهمورث دانشجوی دکتری تخصصی آبخیزداری دانشکدة منابع طبیعی دانشگاه تهران محسن نقیلو کارشناس ارشد مرکز تحقیقات بین المللی بیابان دانشگاه تهران

the purpose of this research is investigation of relationship between vegetation cover and soil characteristics and determination of the most important soil factor that effects on quantity variations and kinds of vegetation cover in the study area. the study area is located in west of tehran province and south eastern of hashtgerd, next to najm-abad village. after field study, the index vegetat...

Journal: :Annals of botany 2007
Sara Palacio Adrián Escudero Gabriel Montserrat-Martí Melchor Maestro Rubén Milla María J Albert

BACKGROUND AND AIMS Plants from gypsum habitats are classified as gypsophiles and gypsovags. The former include both narrow endemics limited to small gypsum areas and regionally dominant gypsophiles growing in gypsum areas of large regions, whereas gypsovags are plants that can grow both in gypsum and non-gypsum soils. Factors controlling the distribution of gypsum plants are still not fully un...

Journal: :Anais da Academia Brasileira de Ciencias 2006
Jackson D S Paz Dilce F Rossetti

An original and detailed study focusing the petrography of evaporites from the Late Aptian deposits exposed in the eastern and southern São Luís-Grajaú Basin is presented herein, with the attempt of distinguishing between primary and secondary evaporites, and reconstructing their post-depositional evolution. Seven evaporites phases were recognized: 1. chevron gypsum; 2. nodular to lensoidal gyp...

Journal: :pollution 2015
noah abuh akaninyene umoh

agricultural waste fibers have been found to be suitable as reinforcement in cement-based composites, but studies on oil palm fiber as reinforcement in gypsum-cement wall panels are scarce. a mixture of two equal weights of gypsum and cement, with water-binder ratios of 0.45 and 0.55 were prepared. in each mix a varying percentage of fiber contents of 2%, 3% and 4% by weight of the binders were...

Journal: :desert 2011
m.a. zare chahouki a. zare chahouki

the aim of this research was to study the relationships between presence of plant species and environmental factors in garizat rangelands of yazd province and providing their predictive habitat models. after delimitation of the study area, sampling was performed using randomized-systematic method. accordingly, vegetation data including presence and cover percentage were determined in each quadr...

2001

Background Gypsum, or calcium sulfate dihydrate, (CaSO4 l 2H2O) is the major component of drywall, or gypsum board, core. It is a naturally occurring mineral, deposited largely as a result of the evaporation of water in ancient inland seas, which contained large amounts of dissolved gypsum. For example, the evaporation of a typical 20,000 gallon residential swimming pool filled with seawater wi...

2004
C. David Dunbar

The rate of hydration influences many important physical properties of gypsum. Previous research examined the rate of gypsum hydration and related this to compressive strength and microstructure development using BET specific surface area analysis. The analysis of gypsum porosity in combination with BET surface area and rate of hydration remains to be done. In the present study, mesoporosity is...

1998
Jaume Porta

This paper reviews the main methodologies and techniques that have been used to characterize gypsum in soils, especially in gypsiferous soils of semiarid and arid regions and range from the identification of gypsum in soil surveys in the field to the study of gypsum in the laboratory. Many methods of gypsum identification and determination have been developed, each one with its own limitations....

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