نتایج جستجو برای: neutral soils

تعداد نتایج: 131289  

Journal: :Proceedings of the National Academy of Sciences of the United States of America 2007
Robert John James W Dalling Kyle E Harms Joseph B Yavitt Robert F Stallard Matthew Mirabello Stephen P Hubbell Renato Valencia Hugo Navarrete Martha Vallejo Robin B Foster

The importance of niche vs. neutral assembly mechanisms in structuring tropical tree communities remains an important unsettled question in community ecology [Bell G (2005) Ecology 86:1757-1770]. There is ample evidence that species distributions are determined by soils and habitat factors at landscape (<10(4) km(2)) and regional scales. At local scales (<1 km(2)), however, habitat factors and ...

2015
Adiari I. Vázquez-Rodríguez Colleen M. Hansel Tong Zhang Carl H. Lamborg Cara M. Santelli Samuel M. Webb Scott C. Brooks

Mercury (Hg) is a toxic heavy metal that poses significant environmental and human health risks. Soils and sediments, where Hg can exist as the Hg sulfide mineral metacinnabar (β-HgS), represent major Hg reservoirs in aquatic environments. Metacinnabar has historically been considered a sink for Hg in all but severely acidic environments, and thus disregarded as a potential source of Hg back to...

Journal: :Environmental science & technology 2002
Esmeralda Morillo Celia Maqueda Rocío Reinoso Tomás Undabeytia

The influence of two organic amendments on norflurazon sorption-desorption processes in four soils with very different physicochemical characteristics was studied in laboratory experiments to evaluate the potential leaching of this pesticide through organic fertilized soils. Sorption-desorption experiments were performed on original soils and on a mixture of these soils with urban waste compost...

2003
S. Martyniuk M. Martyniuk

In the year 2000 the occurrence of Azotobacter spp. in 31 Polish soils was examined and results of this study were compared with those published by Ziemięcka for 28 soils analysed in 1917-18. Almost 52% of the soils tested in 2000 were colonised by Azotobacter spp. indicating that intensification of agricultural practices that took place during the past century has not significantly changed (50...

Journal: :Environmental science & technology 2007
Etelvino H Novotny Eduardo R deAzevedo Tito J Bonagamba Tony J F Cunha Beáta E Madari Vinícius de M Benites Michael H B Hayes

The compositions of humic acids (HAs) isolated from cultivated and forested "Terra Preta de Indio" or Amazonian Dark Earth soils (anthropogenic soils) were compared with those from adjacent non-anthropogenic soils (control soils) using elemental and thermogravimetric analyses, and a variety of solid-state nuclear magnetic resonance techniques. The thermogravimetric index, which indicates the mo...

2013
Timothy G. Whitby Michael D. Madritch

Anthropogenic climate change is expected to increase global temperatures and potentially increase soil carbon (C) mineralization, which could lead to a positive feedback between global warming and soil respiration. However the magnitude and spatial variability of belowground responses to warming are not yet fully understood. Some of the variability may depend on the native temperature regimes o...

2012
Mahmoud Abd-Elgawad Asmaa M. Ahmed

S.A. Shahid et al. (eds.), Developments in Soil Salinity Assessment and Reclamation: Innovative Thinking and Use of Marginal Soil and Water Resources in Irrigated Agriculture, DOI 10.1007/978-94-007-5684-7_14, © Springer Science+Business Media Dordrecht 2013 Abstract Geographical distribution of soil salinity, alkalinity, calcicity, soil texture, and organic matter (grid system-log distance of ...

Mohsen Emdadifard Seyed,Majdedin Mir Mohammad Hosseini

In the present paper, discrete element method (DEM) is used to study wave propagation phenomenon in granular soils. The effect of factors such as coefficient of friction, frequency, normal stiffness and soil gradation on the wave velocity is studied. Using the wall motion based on the sinusoidal function is the method of loading used in this simulation, through which the pressure wave is transf...

Journal: :Pest management science 2008
L Jason Krutz Ian C Burke Krishna N Reddy Robert M Zablotowicz

BACKGROUND Enhanced atrazine degradation has been observed in agricultural soils from around the globe. Soils exhibiting enhanced atrazine degradation may be cross-adapted with other s-triazine herbicides, thereby reducing their control of sensitive weed species. The aims of this study were (1) to determine the field persistence of simazine in atrazine-adapted and non-adapted soils, (2) to comp...

2003
Elisa D’Angelo

ant between the solid phase and dissolved phase (sorption), which is governed by the physical and chemical Sorption of four chlorophenols (CPs) was studied in ten wetland properties of the solute, the sorbent, and the solvent. soils with organic C contents between 1 and 44%, which were incuMuch research on organic pollutant sorption has dembated under aerobic or anaerobic conditions to simulate...

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