نتایج جستجو برای: natural organic matter

تعداد نتایج: 851631  

ژورنال: علوم آب و خاک 2004
عزت‌اله فرشادفر, , محسن فرشادفر, ,

Agropyron is one of the most resistant plants to biotic and abiotic stresses. It plays an important role in forage yield in rangelands. Genetic variability based on different markers is the important step in crop improvement. In order to evaluate the genetic variation of different Agropyron species based on morphological and chemical traits, this experiment was carried out in the Agriculture an...

2003
Wei-Lung Wang Hsueh-Wen Yeh

The natural abundance of stable carbon isotope values (δ13C) of organic matter of marine macroalgae collected from Taiwan and its offshore islands (Penghu Islands) were analyzed in this study. These values ranged from -10.5 to -29.5‰. The highest δ13C value came from green algae (-10.5‰), Ulva pertusa while most algae exhibited values in the -14 to -19‰ range. On average, the δ13C values of red...

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This study investigated the effect of rate and type of organic matter, and consecutive application of sodium on secondary particle size distribution. At first, a cropland soil was treated with two organic matter (manure and straw stubble) at different rates of 0%, 1% and 5%, with three types replicates during 4 months. Subsequently, four levels of SAR (0, 1, 10 and 30) were added to the pretrea...

Journal: :Applied spectroscopy 2006
Andrew D Czaja Anatoliy B Kudryavtsev J William Schopf

Raman spectroscopy has long been used for the chemical analysis of organic matter, including natural products, using excitation wavelengths in the visible, infrared, or ultraviolet portions of the spectrum. The use of ultraviolet resonance Raman spectroscopy (UVRR) to study bulk samples of plant tissue has typically been carried out by rotating homogeneous macro-samples beneath the laser beam i...

2000
G. Eglinton D. L. Kirchman C. Arnosti S. Derenne J. W. de Leeuw

Molecularly-uncharacterized organic matter comprises most reduced carbon in soils, sediments and natural waters. The origins, reactions and fates of these ubiquitous materials are relatively obscure, in large part because the rich vein of geochemical information that typically derives from detailed structural and stereochemical analysis is yet to be tapped. This discussion highlights current kn...

2003

Very strong organic acids (acid groups ionized at pH 3.0) represent a significant portion of the total acidity (4--25%) in samples of organic matter isolated from two lakes, a landfill leachate, and a Krafft mill effluent. On the basis of model compound behavior and established complexation constants, these very strongly acidic groups are predicted to be the key to the formation of strong surfa...

Journal: :Chemical reviews 2009
Robert S Blake Paul S Monks Andrew M Ellis

Proton-transfer reaction mass spectrometry (PTR-MS) is a technique developed almost exclusively for the detection of gaseous organic compounds in air. Volatile organic compounds (VOCs) in air have both natural and anthropogenic sources. Natural sources include the emission of organic gases by living objects, both plants and animals. A well-known example, which is discussed later in this review,...

2015
Zhongsheng He Jinfu Liu Songjin Su Shiqun Zheng Daowei Xu Zeyan Wu Wei Hong James Li-Ming Wang Raffaella Balestrini

The aim of this study is to analyze the effects of forest gaps on the variations of soil properties in Castanopsis kawakamii natural forest. Soil physical and chemical properties in various sizes and development stages were studied in C. kawakamii natural forest gaps. The results showed that forest gaps in various sizes and development stages could improve soil pore space structure and water ch...

2017
Anika M. Pohlabeln Gonzalo V. Gomez-Saez Beatriz E. Noriega-Ortega Thorsten Dittmar

Dissolved organic sulfur (DOS) is the largest pool of organic sulfur in the oceans, and as such it is an important component of the global sulfur cycle. DOS in the ocean is resistant against microbial degradation and turns over on a millennium time scale. However, sources and mechanisms behind its stability are largely unknown. Here, we hypothesize that in sulfate-reducing sediments sulfur is a...

Journal: :Environmental science & technology 2008
Fernando Galvez Andrew Donini Richard C Playle D Scott Smith Michael J O'Donnell Chris M Wood

Natural organic matter (NOM) is an important constituent of aquatic environments; however, its influence on aquatic biota remains poorly studied. In the current study, NOM was isolated from nine different sites in southern Ontario, Canada, by the on-site treatment of water by reverse osmosis, followed by cation exchange. NOM from each site was reconstituted to 10 mg of C/L and pH 7.0 and expose...

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